AS355N - Training Manual (1998)

INSTRUCTION MANUAL BASIC 1 1

-

OVERVIEW OF THE HELICOPTER

2

-

STRUCTURE

3

-

MAIN ROTOR DRIVE SYSTEM

4

-

MAIN ROTOR

5

-

TAIL ROTOR DRIVE SYSTEM

6

-

TAIL ROTOR

7

-

FLIGHT CONTROLS

8

-

HYDRAULIC SYSTEMS

9

-

SERVO ACTUATORS

10 -

FUEL SYSTEM

11 -

ELECTRIC POWER

12 -

ENGINE INSTALLATION

13 -

FIRE PROTECTION

14 -

HEATING AND VENTILATION

15 -

PITOT STATIC SYSTEM AND INSTRUMENTS

16 -

INTERIOR AND EXTERIOR LIGHTING

17 -

WINDSHIELD WIPERS

18 -

AUTOPILOT

This document is the property of the Eurocopter Training Centre and it must not be reproduced without its permission This manual is intended for instruction purpose and will not be kept up-to-dated It cannot replace manufacturer's documents

Issue 1998

WHAT TO EXPECT FROM THIS INSTRUCTION MANUAL

This helicopter Instruction Manual discusses all of the aircraft systems from a functional standpoint with a pedagogical approach. This is the purpose of the Instruction Manual Purely technological aspects, self-evident descriptions and secondary features are not discussed here, nor are maintenance or servicing considerations, for which the reader is referred to the Maintenance Manual

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1

OVERVIEW OF THE HELICOPTER

1.1 -

DESCRIPTION OF THE HELICOPTER

1.2 -

MAIN DIMENSIONS AND WEIGHTS

1.3 -

AIRFRAME REFERENCE POINTS

1.3.1. 1.3.2. 1.3.3. 1.3.4.

HELICOPTER DATUM REFERENCES C.G. LIMITS LEVELLING STRUCTURAL ALIGNMENT POINTS

1.4 -

SPECIAL HELICOPTER CONFIGURATIONS

1.4.1. 1.4.2. 1.4.3. 1.4.4.

TOWING - GROUND HANDLING PICKETING OPEN-AIR PARKING HOISTING

1.5 -

COCKPIT LAYOUT

1.5.1. 1.5.2. 1.5.3. 1.5.4. 1.5.5.

INSTRUMENT PANEL FAILURE WARNING PANEL GRIP CONTROLS ON CYCLIC PITCH STICK AND COLLECTIVE PITCH LEVER OVERHEAD PANELS CONSOLE

1.6 -

HELICOPTER OPERATING PUBLICATIONS

1.6.1. 1.6.2. 1.6.3.

HELICOPTER PUBLICATIONS ENGINE PUBLICATIONS SPECIFIC EQUIPMENT PUBLICATIONS

Ce document est la propriété d'EUROCOPTER ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'EUROCOPTER et son contenu ne peut être divulgué. This document is the property of EUROCOPTER ; no part of it shall be reproduced or transmitted without the express prior written authorization of EUROCOPTER and its contents shall not be disclosed. © EUROCOPTER 1998.

1.1

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1.1 - DESCRIPTION OF THE HELICOPTER

THE AS 355 N IS A MULTIPURPOSE LIGHT HELICOPTER

With appropriate systems or equipment, this helicopter can fulfil the following missions: - Personnel transport (5 passengers), - VIP transport (4 passengers), - Internal load transport, - External sling load transport, - Search and rescue - Casualty evacuation (2 stretcher cases), - Observation, - Flight training, - Tourism.

Tail rotor drive shaft fairings

MGB cowlings (on LH & RH sides)

Engine cowlings

Air inlet to engine and MGB oil coolers

Canopy

Horizontal stabilizer Vertical fin

Tail boom

Bottom structure and cabin floor

Body structure (with fuel tanks)

Cockpit doors (on LH & RH sides)

Rear structure

Sliding doors (on LH & RH sides)

Skid landing gear mounted on anti-resonance dampers

1.2

Tail guard

Rear baggage compartment doors

LH baggage compartment door (same on RH side)


THM

1.1 - DESCRIPTION OF THE HELICOPTER (Cont.) MAIN ROTOR AND ITS DRIVE SYSTEM

MAIN ROTOR HUB (MRH) Starflex semirigid, bearingless hub (laminated glassresin star) without a drag damper. No grease nipples. Modular, fail-safe design.

MAIN GEARBOX (MGB) Modular design. Attached by flexible bidirectional suspension. Two reduction gear stages (1 bevel gear drive, 1 epicyclic gear train). Pressure lubrication with oil cooling system. Includes the servo actuators, rotor brake and hydraulic pump drive.

MAIN ROTOR BLADES Spar made of fiberglass roving, glass fabric skin and foam core. Fail-safe design.

MAIN ROTOR MAST Removable subassemblies. Mast casing attached by 4 suspension bars which "support" the helicopter.


1.3

THM

1.1 - DESCRIPTION OF THE HELICOPTER (Cont.)

TAIL ROTOR GEARBOX (TGB) Angle reduction gear with splash lubrication. TAIL ROTOR Two-blade, hingeless, greaseless seesaw rotor with glass roving spar. Pitch change by spar twisting. Fail-safe design.

Engine No. 1

Engine No. 2

ENGINES ARRIUS 1A Free-turbine engines installed in 2 separate fireproof bays. Modular design with external oil tank and cooling system. Max. takeoff power (MTOP) .............................. 256 kW Max. continuous power (MCrP) ......................... 239 kW

1.4

MGB


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1.2 - MAIN DIMENSIONS AND WEIGHTS 12.94 m (42.45 ft.) ∅ 10.69 m (35.07 ft.)

0.59 m (1.93 ft.)

3.22 m (10.56 ft.)

3.34 m (10.95 ft.)

∅ 1.86 m (6.10 ft.)

0.73 m (2.39 ft.)

10.93 m (35.86 ft.)

3.05 m (10 ft.)

NOTE: For the low landing gear version, decrease height dimensions by 0.2 m

MAXIMUM PERMISSIBLE WEIGHT ....... 2540 kg - 5600 lb. EMPTY WEIGHT, STANDARD HELICOPTER .................... 1205 kg - 2380 lb.

The maximum permitted takeoff and landing weights (which vary with altitude and temperature) may be less than - but must never exceed - this value.

2.28 m (7.48 ft.)


1.5

THM

1.3 - AIRFRAME REFERENCE POINTS 1.3.1. HELICOPTER DATUM REFERENCES The helicopter datum are specified in the 3 planes X, Y and Z. • X is the datum for the longitudinal dimensions. Its origin is 3.40 m forward of the main rotor centre, perpendicular to the helicopter centerline. • Y is the datum for the lateral dimensions. Its origin is in the helicopter's plane of symmetry. • Z is the reference for the vertical dimensions. Its origin is a horizontal plane located 2.60 m above the cabin floor datum.

Vertical axis

Rotor axis tilted 2° forward

1.3.2. C.G. LIMITS 0.09 m (6.3 in) L

atera l

1.3.3. 0.16 m (3.5 4 in )

LEVELLING

The helicopter is levelled on jacks for weighing.

Clinometer

Blocks (military version only)

5m 3.2 9 in) 7. (12

Aft re/ o F

5m 3.4 8 in) 5. (13

1.3.4. STRUCTURAL ALIGNMENT CHECKS Mainly after hard landings, the alignment of the tail boom with the body structure must be checked. On civil versions, the TGB alignment relative to the tail rotor drive bearings is also checked using a sight installed on the TGB and target bearings. On military versions, holes on the sides and bottom of the structure are used for alignment with a sight and plumb lines after the helicopter is levelled.

1.6

Alignment holes


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1.4 - SPECIAL HELICOPTER CONFIGURATIONS 1.4.1. TOWING - GROUND HANDLING

Two types of twin-wheel systems can be used depending on the type of ground (see Maintenance Manual), as well as a towing fixture (towing bar or cable).

1.4.2. PICKETING

A

Normal picketing: 2 upper points A High wind picketing: tiedown at A and B

1.4.3. OPEN-AIR PARKING B

Exhaust nozzle blanks Air inlet covers

Ventilation air inlet blank Main rotor blade socks (3)

Cabin cover, plus total and static pressure port blanks (not shown)

Tail rotor lock system

1.4.4. HOISTING The helicopter can be hoisted from a ring at the centre of the main rotor hub. It is advisable to reduce the weight: - by defueling the helicopter, - by removing the main rotor blades.


1.7

THM

1.5 - COCKPIT LAYOUT

Overhead panels (fuses + push-button)

Control quadrant

Compass Outside air thermometer

Instrument panel

Console

Demisting control

Heating control

1.5.1. INSTRUMENT PANEL

2 1

18

7 11 17

30

20 26

31

32

1 - Failure warning panel (4α) 2 - Galvanometers (AP) 3 - Fuel contents gauge - Forward tank 4 - Fuel contents gauge - Rear tank 5 - Digital NG, failure annunciator 6 - Δ NG indicator 7 - Gyro servo 8 - Fuel pressure - LH Engine 9 - Fuel pressure - RH engine 10 - Copilot's NR indicator 11 - Engine control unit 12 - Oil pressure - LH engine

1.8

4

5

8

9

5

12 13

10

25 24

3

21 22 23 2 7 28 3 3

35

14

18 6 15

7

16

17 19

29

34

25 24

30

13 -Oil pressure - RH engine 14 -T4 temperature indicator 15 -Dual torquemeter 16 -NR, NF1, NF2 indicator 17 -AP/CPL. monitoring panel 18 -Alarm repeater 19 -TACAN distance indicator (optional) 20 -Radionavigation 21 -Oil temperature - LH engine 22 -Oil temperature - RH engine 23 -Electrical master switch

26

31

32

24 - Airspeed indicator 25 - Gyro horizon 26 - Altimeter 27 - Electric panel 9α 28 - Timer 29 - Stand-bys horizon 30 - Radioaltimeter 31 - HSI 32 - Vertical speed indicator 33 - Radio beacon (Marker) 34 - Fuel flowmeter (option) 35 - RMI


THM

1.5.2. FAILURE WARNING PANEL

Light test push-button

The failure warning panel notifies the crew of a system failure by illuminating the relevant caption light. A push-button on the panel can be used to test the lights and the engine and MGB fire detection lines. The amber lights indicate: - degraded performance of an essential system, - an abnormal functional configuration. The red lights warn of a serious functional hazard. NOTE: An alarm repeater flashes whenever a red light illuminates on the failure warning panel. 67α α

67α α

DIM NORM

ALARM REPEATER

ALARM REPEATER (IFR version)

+28 V POWER PACK

+28 V

Detectors (Circuit surveillance)

ACTIVATION OF AMBER ALARMS

Power pack for failure warning panel

CLEAR

ACTIVATION OF RED ALARMS

FLASHER F/WARNING PANEL

Pressing the pilot's or copilot's alarm repeater cancels the flashing so that the repeater can indicate any other alarm.

1.5.3. GRIP CONTROLS ON CYCLIC PITCH STICK AND COLLECTIVE PITCH LEVER CYCLIC PITCH STICK GRIP

11

1 2

10 9 8 7 6 5

3

4

1 -Open sling hook 2 -AP disengagement 3 -Not used 4 -Radio/ICS PTT switch 5 -Not used 6 -Not used 7 -AP trim load release 8 -AP 4-way switch 9 -AP coupler disengagement 10 -Hoist UP/DOWN control 11 -Flare release or weapon firing

COLLECTIVE PITCH LEVER GRIP 2 3 4 1

5

10

9

8

6

7

1 - Not used 2 - Tail rotor servo actuator hydraulic cutoff 3 - Emergency release (hoist) 4 - Landing light ON/OFF 5 - Light swivel control 6 - Emerg. Float. Gear switch 7 - MCP/ICP control 8 - Not used 9 - Not used 10 - Wiper ON/OFF


1.9

THM

1.5.4. OVERHEAD PANELS ( 1 ) Controls and indicators CONTROL QUADRANT

LH SIDE PANEL 5α1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

- Not used - Pitch trim - Trim loads - Not used - Roll trim - LH engine cranking - F/extinguish 1 (LH eng.) - Not used - Not used - F/extinguish 2 (LH eng.) - Not used - Strobe light - Not used - Elapsed time counter - Copilot's instrument panel lighting 16 - Not used 17 - Copilot w/s wiper 18 - Not used

1 - Engine 1 fuel shutoff cock 2 - Engine 1 fuel flow control lever 3 - Red light indicating failure of engine 1 digital governor 4 - Rotor brake lever 5 - Engine 2 fuel flow control lever 6 - Red light indicating failure of engine 2 digital governor 7 - Engine 2 fuel shutoff cock

1

2

3

1

2

3

4

5

6

4

5

6

7

8

9

7

8

9

10 11 12

10 11 12 13 14 15

AC voltmeter

RH SIDE PANEL 5α2

2

16 17 18

3

5

16 17 18

7

1

3

4

7

8

9

5

6

1

2

3

4

10 11

7

8

9

10 11

LH FRONT PANEL 15α

1 2 3 4 5 6 7 8 9 10 11

- Not used - Acc. (compensator test) - LH alternator - Generator - LH engine pump - LH ext. pwr/battery - Horn - Servo actuators test - Copilot's gyrocompass - Copilot's horizon - Stand-by horizon

AC voltmeter selector

DC voltmeter Ammeter

ENGINE 1 Starting selector Governor selector 2

- Not used - Not used - Fuel crossfeed - Not used - Not used - RH engine cranking - F/extinguish 1 (RH eng.) - Not used - Not used - F/extinguish 2 (RH eng.) - Not used - LH & RH s/lights - Not used - Console lighting - Pilot's instrument panel lighting 16 - Not used 17 - Pilot's w/s wiper 18 - Pitots

13 14 15

6

4

1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

5

6

ENGINE 2 Starting selector Governor selector

RH FRONT PANEL 14α

1 2 3 4 5 6 7 8 9 10 11

Mission selector

LIGHTING

- RH ext. pwr/battery - RH engine pump - RH generator - RH alternator - TAC (Optional) - Not used - Direct battery - Pilot's horizon - Pilot's gyrocompass - Position lights - Collision light

DC ammeter and voltmeter selector

Lighting dimmers

1.10


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1.5.4. OVERHEAD PANELS (Cont.) ( 2 ) Fuse panels CENTRAL PANEL 10α LH PANEL Side 2X1

Vertical 7α1 RH PANEL Side 2X2 Side 7α1

Vertical 7α2 & 8a

Side 7α2

1.5.5. CONSOLE

AUTOPILOT (AP) CONTROL UNIT VHF/VOR RADIOCOMPASS TRANSPONDER VHF I/C SYSTEM

HF SET

"Direct Battery" fuses Direct battery panel Pilot's stand-by static cock


1.11

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1.6 - HELICOPTER OPERATING PUBLICATIONS As pilots and technicians, you will have to service, fly or maintain a new helicopter. To allow you to perform your tasks as safely and as efficiently as possible, you will be given a set of manuals that methodically set down the rules and instructions for maintenance, and the limitations and the procedures specified by the manufacturer - none of which can be ignored without risk. ALWAYS KEEP IN MIND THAT: - a limitation cannot be unaccountably exceeded, - the service life limit of a part is not just a theoretical consideration, - a maintenance instruction often has more effect than meets the eye, - and last of all, never forget that ... IMPROVISATION OF ANY KIND IS BANNED. The set of publications for your helicopter includes the following: HELICOPTER PUBLICATIONS

EQUIPMENT PUBLICATIONS

ENGINE PUBLICATIONS

1.6.1. HELICOPTER PUBLICATIONS 3 families of publications

Operating publications

Maintenance publications

Identification catalogues

• Operating publications - The FLIGHT MANUAL (PMV) is the pilot's basic reference document and describes the limitations, normal and emergency procedures and performance data. The Flight Manual is approved by the Airworthiness Authorities. - The MASTER SERVICING RECOMMENDATIONS (PRE) are specifically for the maintenance manager; they detail the inspection intervals and schedules, oil change and monitoring intervals, and operating time limits.

For the pilot

For the maintenance manager

• Maintenance publications These manuals are for the maintenance technicians. They provide the data necessary for maintaining the helicopter in flightworthy condition. The following manuals are required: - DESCRIPTION AND OPERATION MANUAL (MDF) - WIRING DIAGRAMS AND FAULT ISOLATION MANUALS (MCS/MFI) - STANDARD PRACTICES MANUAL (MTC) - MAINTENANCE (MET), REPAIR (MRR) AND STORAGE (MST) MANUALS - INDEX OF MODIFICATIONS (SIM) For the maintenance technicians

1.12


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1.6.1. HELICOPTER PUBLICATIONS (Cont.) - The Maintenance (MET), Repair (MRR), and Storage (MST) Manuals detail the operations which can be performed at the different maintenance levels. - The Fault Isolation Manual (MFI) gives advice on diagnosing and localizing complex failures.

- The Standard Practices Manual (MTC) specifies the standard application, maintenance, checking and repair procedures applicable to all helicopters.

• Identification Catalogues These manuals provide the procurement specialists with the reference numbers of: - helicopter parts: ILLUSTRATED PARTS CATALOGUE (IPC) - special tools: TOOLS CATALOGUE (ICO) - standard articles: ADDITIONAL SUPPLY CATALOGUE (ICA)

For the procurement specialists

• Services Bulletins (SBT) Service Bulletins allow users to quickly implement all directives issued after a new event (e.g. incidents, modifications, etc.). They supplement the helicopter publications and are incorporated in them by revisions.

• Service Letters (SLT) Service letters keep users informed about current topics of interest; as such, they form temporary supplements to the standard documentation and are integrated when revisions are issued. Service letters with an important technical content have a blue crosshatched border.

1.6.2. ENGINE PUBLICATIONS - MAINTENANCE MANUAL - ILLUSTRATED PARTS AND TOOLS CATALOGUES - SERVICE BULLETINS

1.6.3. SPECIFIC EQUIPMENT PUBLICATIONS - EQUIPMENT DESCRIPTION, MAINTENANCE AND OVERHAUL MANUAL (MCM)

NOTE: All the publications comply with the overall recommendations of the ATA 100 specification. In consequence, all the helicopter maintenance manuals and identification catalogues follow the same ATA breakdown in Chapter/Section/Subject. Ce document est la propriété d'EUROCOPTER ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'EUROCOPTER et son contenu ne peut être divulgué. This document is the property of EUROCOPTER ; no part of it shall be reproduced or transmitted without the express prior written authorization of EUROCOPTER and its contents shall not be disclosed. © EUROCOPTER 1998.

1.13

T HM

2

STRU C TUR E

2.1 -

G ENERAL

2.1.1.

S T R U C T U R AL S U B A S S E MBLIE S

2.1.2.

DIM E N SIO N S O F A C C E S S D O O R S A N D PA N E LS

2.1.3.

U S A BL E A R E A S A N D V O LUM E S - P E RMIS SIBL E F L O O R L O A D S

2.2 -

B O DY STRU C TUR E

2.3 -

B O TT OM STRU C TUR E A ND C A BIN F L O O R

2.4 -

C ANOPY

2.5 -

R E A R STRU C TUR E

2.6 -

TAIL B O O M

2.7 -

TAIL U NIT

2.8 -

D O O RS

2.8.1.

C A BIN D O O R J E T TIS O N S Y S T E M

2.8.2.

L O C KIN G IN DIC AT O R S F O R SID E B A G G A G E C O MPA RTM E N T D O O R S

2.9 -

C O W LIN G S, FAIRIN G S, B U L K H E A D S

2.10 -

S KID T Y P E L A N DIN G G E A R

2.10.1.

G E N E R AL - A S S E MBLY O F LA N DIN G G E A R

2.10.2.

LA N DIN G G E A R FIT TIN G S

2.10.3

G R O U N D R E S O N A N C E A N D F U N C TIO N O F T H E S H O C K A B S O R B E R S

2.10.4.

LA N DIN G G E A R S H O C K A B S O R B E R S

C e document est la propriété d'E UR O C O PT E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'E UR O C O PT E R et son contenu ne peut être divulgué. This document is the property of E UR O C O PT E R ; no part of it shall be reproduced or transmitted without the express prior written authorization of E UR O C O PT E R and its contents shall not be disclosed. © E UR O C O PT E R 1998.

2.1

T HM

2.1 - G E N E R A L 2.1.1.

S T R U C T U R A L S U B A S S E M B LIE S

1 - Canopy 2 - Stabiliz ers 3 - Tail boom 4 - R e ar structure

5 - Body structure 6 - Landing gear 7 - Bottom structure and cabin floor

2

1

3 4

5

MAT E RIALS 7

Altuglass 6

Light alloy Laminates (reinforced plastics) Titanium

The wide use of plastics should be noted. In particular the entire canopy is made of polycarbonate. A F E W W O R D S A B O U T T H E S E N E W MAT E RIALS

They are synthetic resins divided into 2 main classes: - Thermoplastics which soften when he ated and harden when cooled, e.g. polyamides (Nylon, Rilsan), polycarbonates, etc. - Thermosetting resins which, under the combined action of he at and a hardener, hot-cure irreversibly to form a new product, e.g. epoxy resins, silicone, etc. Laminates and laminated honeycomb are reinforced plastics with very good mechanical strength properties. Laminated materials are produced from thermosetting res-

2.2

Thermoplastics (polycarbonate, polyamide) Ste el ins and reinforcing materials (glass, carbon, graphite, boron or other fibers). The reinforcing fibers are formed in lay-ups or woven, then impregnated with the basic resin. S everal lay-ups or fabric layers are stacked up, placed in a mould and cured. The direction of the reinforcing fibers depends on the loads applied. Laminated honeycombs have a honeycomb core (metal, glass fabric, Nomex, etc.), e ach face of which receives one or more preimpregnated layers of fabric. The whole assembly is oven-cured.


T HM 2.1.2. DIM E N SIO N S O F A C C E S S D O O R S A N D PA N E L S

C a bin height 1.35 m

Width H eight

: 0.78 m : 1,10 m

w : 0.94 m h : 1,10 m

w : 1.30 m h : 0,70 m

w : 0.42 m h : 0,60 m

DIM E N SIO N S O F A C C E S S D O O R S A N D PA N E LS

2.1.3. U S A B L E A R E A S A N D V O L UM E S - P E RMIS SIB L E F L O O R L O A D S R H C O MPA RTM E N T

L : W: h : V :

length width height volume

F W D: 0.380 m A F T: 0.160 m - V = 0.200 m3

R E A R C O MPARTM E N T

L = 1.000 m - W

L = 0.800 m - W

h = 0.740 m

h = 0.700 m

P ermiss. distributed load = 100 kg

-

F W D: 1.200 m A F T: 0.700 m V = 0.565 m3

P ermissible distributed load = 80 kg

LH C O MPA RTM E N T C A BIN F L O O R

Usable are a = 2.600 m⇢ F loor structural strength = 600 kg/m⇢

L = 1.300 m - W h = 0.740 m

F W D: 0.380 m A F T: 0.100 m

- V = 0.235 m 3

P ermiss. distributed load = 120 kg 11 tiedown points, e ach with capacity of 1000 daN

T O TAL V O LUM E O F 3 C O MPA RTM E N T S = 1.000 m 3


2.3

T HM

2.2 - B O D Y S T R U C T U R E FN This is the strongest part of the airframe since it directly carries the flight loads (i.e. lift F N and weight P) and the landing loads. T H E B O D Y F O RMS A RIGID B O X S T R U C T U R E

It also supports the main transmission components (M G B and rotor), landing ge ar, cabin floor and re ar structure, and contains the fuel tanks.

1 7

P

2

6

3

5

1 - Transmission deck 2 - R e ar bulkhe ad. Attachment of re ar structure 3 - Longitudinal be ams (1 e ach on LH & R H sides). Attachment of bottom structure be ams 4 - F W D and R E A R structural fuel tanks 5 - Front bulkhe ad inclined 15° re arward 6 - Upper bulkhe ad inclined 7° forward 7 - Longitudinal bulkhe ads. Thick plates.

4

2.3 - B O T T O M S T R U C T U R E A N D C A BIN F L O O R The bottom structure supporting the cabin is cantilevered out from the body structure. Two be ams, laterally stiffened by cross members, are riveted to the body structure side be ams and support the front part of the landing ge ar.

These be ams carry the front jacking pads (balljoints)

2.4


T HM

2.4 - C A N O P Y The following canopy components: - cabin roof (1), - nose (3) - uprights (2) are made of fiberglass-reinforced polycarbonate. They are hot-molded and assembled by welding. The canopy structure bolts onto the cabin floor and onto the body structure bulkhe ad.

4

1

2

5

1 - C abin roof consisting of 2 half-shells inside which the cabin ventilation air is ducted 2 - Windshield uprights 3 - Nose 4 - Roof windows (Makrolon) 5 - Windshield panels 6 - Lower windows on LH & R H sides (transparent polycarbonate)

3

6

2.5 - R E A R S T R U C T U R E The re ar structure consists of 3 frames joined by be ams. The re ar and forward frames support the engine. The tail boom bolts onto the 3rd junction frame and can be e asily removed. The rear structure is arranged as a baggage compartment.

1

2

3

4

13

9 5 12

6

The aft jacking point is on the junction frame

1 - E ngine deck (titanium) 2 - B e am under engine deck 3 - Anchor points of engine access platform (same on R H side) 4 - Tail boom junction frame 5 - S kin 6 - R e ar frame 7 - Access to baggage compartment

11

10

9

8

7

8 - E MI shielding for engine computers 9 - R ecessed footstep for access to transmission deck 10 - B aggage compartment floor (access to electrical master units) 11 - C omputer mounting frames 12 - Forward frame 13 - E ngine mounting be am


2.5

T HM

2.6 - TAIL B O O M The tail boom is constructed of circular frames covered with skin. O verall bending rigidity is provided by plate stiffeners. The tail boom supports: - the tail ge arbox (T G B), secured to 2 frames, - the horizontal stabilizer, mounted between 2 mainframes, - the tail rotor drive shafts, - the fins.

1 - T/R drive shaft be aring mounts 2 - Are a strengthened by stiffeners 3 - T G B forward mount 4 - Horizontal stabiliz er mounting doublers 5 - S kin 6 - H atch to c.g. balance weights 7 - Mainframes 8 - Tail cone 3

2 8

1

4 5 7

B allast plates may be mounted inside the tail cone to correct the c.g. position of the empty helicopter.

6 E F F E C T O F TAIL B O O M S T R A K E

The strake (1) is secured longitudinally from the forward frame to the horizontal stabiliz er. It is designed to generate a pressure equal to the static pressure on the R H side of the tail boom. Main rotor airstre am

1

In sideways flight to the left, the main rotor airstre am is deflected and accelerated over the RH side of the tail boom, which induces a negative pressure of approximately 1 mbar/ cm⇢ along the entire tail boom. This reduces the effect of the tail rotor by roughly 5%. A strake added at 45° causes the main rotor downwash flow to separate and restores the pressure to the static value. The effect of the strake is thus to regain the 5% moment and to improve the tail rotor efficiency (including in hover).

45°

A erodynamic gain

View looking forward

2.6


Tail boom

T HM

2.7 - TAIL U NIT The tail unit consists of: - a horizontal stabiliz er (1), - a dorsal (upper) fin (2), - a ventral (lower) fin (3).

2

In excessively nose-up landings, a tail guard (4) protects the ventral fin. These vertical and horizontal airfoil sections act as stabiliz ers, i.e. when subject to a relative wind, they tend: - to counteract any changes to the helicopter's attitude, - to bring the helicopter back to its original attitude after any deviations.

1

3

4

S P E CIAL F E AT U R E O F H O RIZ O N TAL S TA BILIZ E R

This stabiliz er has an asymmetric N A C A airfoil, set at -1°40' to the horizontal datum; when subject to a relative wind V, the airfoil generates an a erodynamic force F tending to right the helicopter.

S P E CIAL F E AT U R E O F FIN S In cruise flight, the asymmetric N A C A airfoil of the dorsal fin generates an a erodynamic force F 1 that opposes the main rotor's counter torque C R and thus reinforces the tail rotor thrust. This allows the tail rotor pitch to be reduced and power to be saved. The ventral fin has a symmetric N A C A airfoil to stabiliz e the helicopter about its yaw axis.

H oriz ont al

V

1°40'

N os e-up mom e nt

F

CR

D O R S AL FIN

V

F1

CR

V E N T R AL FIN

V


2.7

T HM

2.8 - D O O R S The helicopter has the following doors: - two cabin doors (1), one on either side, accessing the pilot se ats, - two subdoors (2), one on either side, accessing the re ar of the cabin, - a laminated LH baggage compartment door (4) and a symmetric laminated R H baggage compartment door, - a laminated re ar compartment door (5). All the above doors have a key-operated safety lock.

5

4

3

The LH and R H baggage compartment doors are hinged along their top edges and can be held open by a rod (3) which clips on the inside of the door for stowage.

1

2

C ertain missions (hoisting and casualty evacuation) require better access to the rear of the cabin. This is achieved by replacing the LH standard door and LH subdoor by a narrower pilot door and a wider sliding door running on rails. The sliding door may be opened, and locked open, in flight.

C A BIN D O O R S 1

2

1 - " Cle ar vision" window, Altuglass transparency (LH and R H doors) 2 - Door transparency (Altuglass)) 3 - Handle 4 - Spring rod 5 - Hinges

5

3

The compressed air expands to assist the opening of the door (extension force = 15 da N) and to hold it open. The air is compressed when the door is closed.

E xtension 4 Piston C ompre s sion

C ylind er

2.8


T HM

2.8 - D O O R S (C o nt.) 2.8.1. C A BIN D O O R J E T TIS O N S Y S T E M The two front doors are fitted with a jettison system. When operated, a handle (1) on the door jamb pulls out the hinge pins and neutraliz es the door closure lock. The spring rod does not have lock pins at its two ends. In the locked position, the handle is held by a polycarbonate guard (2), which is secured by 3 lugs (3).

2 1

3

2.8.2. L O C KIN G IN DIC AT O R S F O R SID E B A G G A G E C O MPA R TM E N T D O O R S The baggage compartment doors are kept closed by 2 locks, e ach of which controls a microswitch.

When the locks are not engaged, the parallel-connected microswitches illuminate a warning light on the failure warning panel.

Front lock C entral lock

DOORS

C entral lock microswitch Front lock rod Front lock microswitch C e document est la propriété d'E UR O C O PT E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'E UR O C O PT E R et son contenu ne peut être divulgué. This document is the property of E UR O C O PT E R ; no part of it shall be reproduced or transmitted without the express prior written authorization of E UR O C O PT E R and its contents shall not be disclosed. © E UR O C O PT E R 1998.

2.9

T HM

2.9 - C O W LIN G S, F AIRIN G S A N D B U L K H E A D S

1

2

4

3

6

5

H a ndling b ar

7

8

9 11

10

MAT E RIALS Light alloy Laminate (reinforced plastics) G lass fabric

1 - M G B compartment air inlet, secured by bolts 2 - M G B upper cowlings, attached by D Z U S fasteners. 3 - Opening engine cowlings, hinged on firewall. Held open by 1 rod. Locked by Hartwell fasteners and toggle. 4 - Junction fairing, secured by D Z U S fasteners. 5 - Tail rotor drive shaft fairings (3 sections), secured by D Z U S fasteners. 6 - T G B fairing, secured by D Z U S fasteners. 7 - Tail boom end fairing, secured by bolts. 8 - O pening engine cowlings (LH & R H), hinged on engine upper cowlings, held open by rod and locked by H artwell fastener and toggle. 9 - R e ar lower cowling, secured by toggle fasteners. 10 - Two-section intermediate lower fairing, secured by bolts. 11 - Front lower fairing, laminated, secured by toggles. 12 - B aggage compartment firebarrier walls

2.10


12

T HM 2.9 - C O W LIN G S, F AIRIN G S A N D B U L K H E A D S (C o nt.) E N GIN E FIR E B ULK H E A D S 1

2

3

4

1 - Front titanium bulkhe ad, removable in 3 parts 2 - G askets 3 - R e ar titanium bulkhe ad 4 - O pening for engine noz zle 5 - R emovable vertical central bulkhe ad 6 - Protective titanium tunnel for tail rotor drive shaft 7 - Bulkhe ad brace with grip 8 - O pening for flared housings with gasket

5 8

6 7

2.10 - S KID T Y P E L A N DIN G G E A R 2.10.1. G E N E R A L - A S S E M B LY O F L A N DIN G G E A R The landing ge ar supports the helicopter, protects the airframe on landing and damps out vibration when the helicopter is on the ground with the rotor spinning. The landing ge ar assembly comprises: - a front cross tube (2) and a re ar cross tube (4) - two skids (1) - two hydraulic shock absorbers (3)

1 - Skid, light alloy 2 - Front cross tube, ste el 3 - Hydraulic shock absorber 4 - R e ar cross tube, ste el 5 - Attachment point stop 6 - Structure 7 - Upper lining, elastomer 8 - Landing ge ar cross tube 9 - Lower lining, elastomer 10 - H alf-clamp

Clamped to lateral be ams Shock absorbers secured on 15° frame

6 4

3

7 2 5

1 Clamped to lateral be ams


8

9 10

2.11

T HM

2.10.2. L A N DIN G G E A R FIT TIN G S 2

1

3

5

1 - Support bolt for handling whe el fittings 2 - E ngine access re ar footstep. 3 - F lexible ste el strip 4 - Ste el we ar pads 5 - C abin entry footsteps

4

4

Installation holes for handling whe els for different helicopter c.g. positions

2.10.3. G R O U N D R E S O N A N C E A N D F U N C TIO N O F T H E S H O C K A B S O R B E R S When the helicopter is in flight, the rotors, engine and drive shafts generate vibrations that propagate through the airframe, whose components vibrate at their own natural frequency varying mainly with their weight, stiffness or flexibility (i.e. their shape, dimensions and materials). The helicopter is thus subjected to a complex pattern of vibrations, which can sum up (vibration amplitude incre ases) or subtract (vibration amplitude decre ases). The designer obviously attempts to reduce the vibration level by "tuning" the natural frequency of the helicopter components. When the helicopter is in flight, it is isolated and the vibrational level always stabiliz es in given flight conditions neither incre asing nor decre asing. In contrast, when the helicopter is on the ground with its rotor spinning, the vibrations have a support point via the landing ge ar; if the natural frequency of the landing ge ar coincides with the principal vibrational frequencies of the main rotor, the vibrations are augmented every blade revolution as they receive a new "reflected" impulse. The vibration amplitude then incre ases very rapidly, the vibration becomes divergent and the resulting oscillations can destroy and overturn the helicopter. This phenomenon is called G R O U N D R E S O N A N C E . A flexible ste el strip bent downwards behind the skids incre ases the landing ge ar stiffness and changes its natural frequency so that ground resonance can never occur. In addition, the function of the shock absorbers betwe en

2.12

A mplitud e a pproxim ately 1 mm Leg distorts

Ste el strip bent downward

the landing ge ar's "soft" front leg and the structure is to absorb the vibration energy and hence prevent all divergent oscillations. Another point to note is that the flexibility of the cross tubes, skids and ste el strip attenuates the helicopter's vertical deceleration at touchdown where as the impact energy is absorbed by the shock absorbers and by the rubbing action of the skids on the ground.


T HM

2.10.4. L A N DIN G G E A R S H O C K A B S O R B E R S Attachment fitting on 15° frame

The main characteristic of the shock absorber is its damping velocity. When a 500 da N load is applied: - the piston moves through ± 2 mm - at a velocity of 35 mm/s - and a frequency of 3.1 H z

R od-e nd b e aring

S p a c er 1

F WD

Bolt locking clamp on L/G cross tube

2

7

3

4

C hamfered washers 5

1 - F illing plugs 2 - Hydraulic fluid reservoir 3 - Plug 4 - Piston 5 - Cylinder 6 - Shock absorber casing 7 - Filling and ble ed non-return valve 8 - O verpressure spring washer 9 - O verpressure spring washer 10 - Normal throttling orifice

6

O P E RATIO N 1 - Load < 550 da N D amping is produced by throttling fluid through the calibrated orifice (10). 2 - Load > 550 da N O verpressure spring washers (8) and (9) move up to significantly incre ase the fluid flow are a: - upward load: washer (9) moves up - downward load: washer (8) moves up. 3 - Non-return valve (7) automatically ble eds off and fills the working chambers from the fluid reservoir (2). It should be noted that external le akage cannot occur because the fluid recovered betwe en the shock absorber casing and cylinder is fed back into the reservoir (2).

R od-e nd b e aring

8

10

9


2.13

T HM

3

MAIN R O T O R DRIV E SYST EM

3.1 -

M AIN R O T O R D RIV E S Y S T E M F U N C TIO N S

3.2 -

E N GIN E/MG B C O UPLIN G

3.2.1.

C O U P LIN G P RIN C IP L E

3.2.2.

E N GIN E/M G B C O U PLIN G C O MP O N E N T S

3.3 -

MAIN G E A R B O X (MG B)

3.3.1.

M G B D RIV E T R AIN

3.3.2.

M G B C O MP O N E N T S

3.3.3.

M G B E Q UIPM E N T

3.4 -

MAIN G E A R B O X LU B RIC ATIO N SYST EM

3.4.1.

LU B RIC ATIO N S Y S T E M O P E R ATIN G P RIN CIPL E

3.4.2.

LU B RIC ATIO N S Y S T E M C O MP O N E N T S

3.5 -

ROTOR BRAKE

3.5.1

R O T O R B R A K E O P E R ATIN G P RIN CIPL E

3.5.2.

R O T O R B R A K E S P E CIFIC ATIO N S

3.5.3.

R O T O R B R A K E C O MP O N E N T S

3.6 -

MAIN G E A R B O X SUSP E NSIO N

3.6.1.

G E N E RAL

3.6.2.

M G B S U S P E N SIO N C O MP O N E N T S


3.1

T HM

3.1 - M AIN R O T O R D RIV E S Y S T E M F U N C TIO N S MAIN R O T O R F R E E-W H E E L C O U PLIN G S H A F T

LU B RIC ATIO N S Y S T E M

OIL C O O L E R S

E N GIN E 2 FANS

MGB

ROTOR BRAK E

TAIL ROTOR E N GIN E 1

F R E E-W H E E L

The main rotor drive system transmits power from the engines to the main rotor and to the tail rotor drive shaft.

3.2 - E N GIN E/M G B C O U P LIN G

C O U PLIN G S H A F T

It comprises: - the engine/M G B coupling shafts - the main ge arbox (M G B) - the M G B lubrication system, including its oil coolers and fans

3.2.1. C O U P LIN G P RIN CIP L E E ach engine/M G B coupling assembly comprises: - a flared coupling (4) - a gimbal ring (2) connecting the coupling (4) to the M G B.

- a drive shaft (3) which transmits the engine torque to the M G B via the input pinion (1) equipped with a fre ewhe el. THE NE ED F OR THE GIMB AL/F LA R E D C O U PLIN G

MGB displacement

E N GIN E 1

2

3

3.2

The M G B is mounted on a flexible suspension system (§ 3.6) and is therefore subject to low-amplitude oscillations in flight. The gimbal/flared coupling is designed: - to m a int a in th e M G B/e ngin e dist a nc e constant, - to align the drive shaft with the input pinion. - to oppose the engine overturning moment. In these conditions, the drive shaft only transmits the engine torque.

4


T HM

3.2.1. C O U P LIN G P RIN CIP L E (C o nt.) T H E R O L E O F T H E F L E XIBL E C O U PLIN G S B E T W E E N T H E D RIV E S H A F T A N D T H E M G B IN P U T PINIO N

The flexible couplings ("flector" type) deform to absorb the small misalignments betwe en the engine drive shaft and the M G B power takeoff. The flex couplings are subject to high loads as they must not only transmit the engine torque but also deform in case of misalignment. As this deformation is repeated every

shaft revolution, the couplings are subjected to cyclic fatigue stresses and they must therefore be regularly monitored (as per the Master S ervicing R ecommendations). Nonetheless they are designed to be fail-safe and to deteriorate very gradually.

0.2 - 0.3 mm thick

in a stack...

Stainless ste el disks...

The flexible coupling deforms to absorb the small shaft alignment errors

...are mounted betwe en 2 triangular coupling flanges integral with the shafts

3.2.2. E N G IN E /M G B C O U P LIN G C O M P O N E N T S MG B 1

2

1 - G imbal pins 2 - F lex coupling assembly 3 - C oupling flange 4 - E ngine/M G B coupling shaft 5 - G imbal ring 6 - G imbal flange 7 - Splined flange 8 - Flared coupling 9 - Sliding flange 10 - F lex coupling assembly

3

7

4

6

5

8

ENGINE 9 10 C e document est la propriété d'E UR O C O PT E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'E UR O C O PT E R et son contenu ne peut être divulgué. This document is the property of E UR O C O PT E R ; no part of it shall be reproduced or transmitted without the express prior written authorization of E UR O C O PT E R and its contents shall not be disclosed. © E UR O C O PT E R 1998.

3.3

T HM

3.3 - M AIN G E A R B O X (M G B) 3.3.1. M G B D RIV E T R AIN MAIN ROTOR

The M G B transmits power from the engines to the rotors and reduces the rotational speed. The gearbox casing also transmits the main rotor counter torque from the rotor mast to the airframe. The M G B also drives its own lubrication pump and two hydraulic pumps.

394 rpm

1707 rpm E picyclic reduction ge ar module Hydraulic pump drive s B evel reduction ge ar module

E N GIN E 2 6016 rpm

Lubric a tion pump

E N GIN E 1 6016 rpm

TAIL R O T O R D RIV E S H A F T 6125 rpm

3.3.2. M G B C O M P O N E N T S C ombin er g e arbox modul e

( 1 ) Interc h a n g e a ble M G B m o d ule s T h e M G B is a m o d ul a r d e s ig n , i. e . c o n s is tin g o f subassemblies that can be replaced without adjustment or special tooling, and without returning the ge arbox to the factory. This results in lower maintenance costs.

( 2 ) C o m bin er g e arb o x B e v el g e ar

O il pump modul e

Fre ewhe el 2

Input pinion

E N GIN E 2

H ydra ulic pump Tail rotor driv e H ydra ulic pump

E N GIN E 1

Interm e diate pinion Input pinion

3.4

Fre ewhe el 1

The combiner ge arbox couples the power delivered by the 2 engines at the bevel ge ar input pinions, which are equipped with fre ewhe els. The intermediate pinions drive the hydraulic pumps.


T HM

3.3.2. M G B C O MP O N E N T S (C o nt.) ( 2 ) C o m bin er g e arb o x (C o nt.)

2

F R E E W H E E LS IN T H E D RIV E T R AIN

• When both engines are running, fre ewhe els (1) and (2) are engaged: the rotors and accessories are driven. • When one engine is shut down, the corresponding fre ewheel is disengaged: the rotors and accessories are driven by the second engine. • In autorotation, both fre ewhe els are disengaged: the tail rotor and accessories are driven by the main rotor.

Tail rotor

1 F R E E W H E E L O P E R ATIO N

The fre ewhe els only transmit motion from the engine to the rotor. The fre ewhe el shaft (3) rides in two be arings (5-6) in the input pinion (1). Bosses machined on the fre ewhe el shaft form retainers for the fre ewhe el rollers (2) which are pressed against the pinion bore by a spring (4) to ensure smooth engagement. • When the fre ewhe el is engaged, the rollers (2) are held tightly betwe en the tops of the bosses on the fre ewhe el shaft (3) and the input pinion bore (1). The pinion is driven by the shaft. • When the fre ewhe el is disengaged (autorotation or an engine shut down), pinion (1) is driven by the rotor or by the second engine, fre eing the rollers which act like a roller be aring: the engine is isolated from the ge arbox

1

FRE EWHE EL ENGAG ED

2 3

4

F R E E W H E E L DIS E N G A G E D

5 6

VIE W O F C A SIN G F R O M M G B SID E A

C O MBIN E R G E A R B O X F E AT U R E S

When the helicopter is equipped with a freon air conditioning system, a compressor drive pulley is bolted to the R H input pinion only. The standard blanking plate is replaced by a se al retainer and a magnetic se al.

Pulley

B

C

• Pinio n m o nitorin g The combiner ge arbox housing is equipped with inspection plugs (A-B-C) for borescope examination of the power pinion te eth. This type of examination is intended to determine the origin of metal particles in the oil, and to guide maintenance operations.


3.5

T HM

3.3.2. M G B C O MP O N E N T S (C o nt.) ( 3 ) R e d u ctio n g e ar train

Stationary ring ge ar

Rotor shaft 394 rpm

100 te eth

Planet carrier (5 planet ge ars)

30 te eth 394 rpm

E picyclic re duction g e ar Sun ge ar 1707 rpm B e v el p air Ring ge ar 61 te eth

6125 rpm

Pinions 17 te eth

Spe ed ratio: 61 17

The sun ge ar drives the planet ge ars, which rotate in the stationary ring ge ar and drive the planet carrier and hence the rotor shaft at 394 rpm. Spe ed ratio:

= 3.59

30 + 100 30

= 4.33

3.3.3. M G B E Q UIP M E N T 1 5

2

6

3 4

7

3.6

9

8

1 - O il filter 2 - 3-way union (distributes oil to M G B combiner ge arbox) 3 - Low pressure switch 4 - Borescope port plug 5 - O il filler spout and vent 6 - O il level sight 7 - O il pump pressure relief valve 8 - Oil temperature switch 9 - Drain plug and chip detector


T HM

3.4 - M AIN G E A R B O X L U B RIC ATIO N S Y S T E M The M G B ge ars and be arings are cooled and lubricated by a pressuriz ed oil system. At the ge arbox oil outlet, the oil is very hot (about 120°C) and must be cooled in an external he at exchanger, which removes the he at equivalent of 16 kW.

IMP O RTANT N O T E O nly the oils authoriz ed for use by the manufacturer (refer to the F light Manual) ensure satisfactory operation. The oil check procedures are indicated in the Master S ervicing R ecommendations.

3.4.1. L U B RIC ATIO N S Y S T E M O P E R ATIN G P RIN CIP L E P < 1 bar 1

P P11

3

MGB P P P12

6 2

4

18

7

5

8

9

10 14

13

15

16

12

MG B CHIPS

ˇ 

17

P P11

P P12

MGB T

t >115° C

11

3.4.2. L U B RIC ATIO N S Y S T E M C O MP O N E N T S

1 - O il inlet for 2 rotor mast be arings 2 - V ent orifice 3 - "Low oil pressure " warning light 4 - Pressure switch 5 - F low restrictor orifice plate 6 - F ilter bypass valve set at 4.5 bar (opens in case of filter clogging) 7 - O il filter 8 - Two oil coolers connected in parallel 9 - C ooling fans driven by tail rotor drive shaft

10 - O il level sight (system capacity = 7.3 liters) 11 - " Oil overhe ating" warning light 12 - Bimetallic thermal switch 13 - Pressure relief valve set at 8 bar 14 - G e ar pump (flow = 2400 liters/hour) 15 - Strainer 16 - S elf-se aling magnetic chip detector, also used as a drain plug and for spectrometric oil analysis samples 17 - C hip detector warning light 18 - V ented oil filler neck


3.7

T HM

3.4.2. L U B RIC ATIO N S Y S T E M C O MP O N E N T S (C o nt.) ( 1 ) O il filter

F iltered oil

1

Unfiltered oil

2 3

4 5 C L O G G E D FILT E R: BYPASS VALV E O P E N

C L E A N FILT E R

6 7

1 - Bypass valve (set at 4.5 bar) 2 - F ilter mounting bracket 3 - O-ring se al 4 - F ilter element 5 - O-ring se al 6 - O-ring se al (for filter bowl) 7 - Filter bowl grip ring 8 - F ilter bowl

8

( 2 ) O il c o oler s y ste m The fan assembly comprises two fan-stator modules and is driven by the first tail rotor drive shaft element. Air drawn from the M G B compartment and fed via 2 ducts to the engine and M G B oil coolers.

5 4

6

3

2

1

7 8 9

10

3.8

1 - Drive shaft 2 - Two-stage fan assembly 3 - C ooling air ducts 4 - M G B oil return line 5 - M G B oil coolers 6 - Access panel 7 - LH engine oil cooler 8 - O il line from M G B 9 - Scre en protection for 2nd fan impeller 10 - Accelerometer mount


T HM

3.5 - R O T O R B R A K E The rotor brake is designed: - To quickly stopping the rotor spinning after engine shutdown. N.B. Without a brake, the rotor's kinetic energy would keep it spinning. - To prevent wind from turning the rotor in the open air.

B ra kin g prin ciple: The rotor's kinetic energy is absorbed by F errodo friction pads rubbing against a disk driven by the M G B/tail rotor shaft coupling. Since the resulting friction transforms the kinetic energy into he at, there is an rpm limit above which rotor braking is not authoriz ed (too much he at would be dissipated with a risk of damage to the disk and brake).

3.5.1. R O T O R B R A K E O P E R ATIN G P RIN CIP L E A slotted cage (2) secured to the M G B housing (1) supports the rotor brake assembly. A mobile slotted cage (4) carrying the brake pads fits inside the first cage. The mobile cage cannot rotate but can move axially to force the pads against the brake disk. Spring (3) rests on the fixed cage and returns the mobile ring to its "brake off" position when the brake lever is released. C o ntrol a ctio n : Actuated by fork end control (7), ring (8) slides on the fixed cage to push back the mobile cage via diaphragm (5): this forces the brake pads against the disk. 1

6

8

2

7

3

4

O

When the fork is activated in the "braking" direction, roller (6) moves through an arc of a circle with center O and, supported by the fixed cage, pushes back ring (8), which results in B R A KIN G. 6

7

8

5

F unction of diaphragm (5) O nce the required braking force is generated, the diaphragm deforms under constant load and hence: T H E B R A KIN G T O R Q U E IS C O N S TA N T.


3.9

T HM

3.5.2. R O T O R B R A K E S P E CIFIC ATIO N S W eight ............................................................. 2.100 kg Braking torque .............................................. 8.2 m.da N Max. braking spe ed .......................................... 170 rpm

C ompulsory time betwe en 2 brake applications ... 5 min. P ad/disk gap ..................................................... 0.5 mm Brake force on pilot's control ............................ 15 daN

3.5.3. R O T O R B R A K E C O MP O N E N T S F L E XIBL E B ALL T Y P E C O N T R O L Moving part of control.

F lexible stainless ste el strip slides betwe en 2 series of balls.

Rotor brake control

1

2

3

e 4 5

1 - M G B input flange 2 - Diaphragm (spring ste el) 3 - Mobile slotted cage 4 - Brake pad support (F errodo sintered iron brake pads, useful thickness = 2 mm) 5 - Brake disk 6 - C ontrol ring 7 - C ontrol lever (fork end) 8 - Lever swivel pin 9 - C ontrol roller 10 - Stationary slotted cage 11 - Laminated shim for adjusting gap (installation side) e - O peration cle arance

11

3.10

10

9

8

7

6

N O T E - The brake is shown above: - rele ased in the upper half - applied in the lower half


T HM 3.6 - M AIN G E A R B O X S U S P E N SIO N 3.6.1. G E N E R A L The M G B supports the rotor mast casing in which the rotor shaft is mounted. The rotor shaft transmits cyclic periodical vertical and horizontal loads to the M G B (normal rotor vibrations at n where is the rotor angular velocity). If the M G B was rigidly attached to the transmission d e ck, this vibration would b e tra nsmitte d to th e airframe. The solution consists of inserting a flexible suspension betwe en the M G B and airframe to absorb most of the vibrations. Such systems are said to filter out the vibrations. The main rotor/M G B assembly is thus secured to the airframe at 2 points: - at the rotor mast by 4 rigid bars that transmit the lift to the airframe. - on the M G B by a flexible suspension betwe en the ge arbox bottom and the airframe. The suspension absorbs the forces F x, F y, the moments Mx, My and the main rotor counter torque C R .

The M G B is suspended like a pendulum and oscillates about the point O (where the 4 suspension bars intersect).

G e arbox bottom

Y

FX

X

FY

X'

CR

MX

MY

Y'

The basic element of the flexible suspension is a laminated cylindrical pad consisting of a bonded stack of thin rubber and dural disks. D ural

Rubber

O Suspension bar

O ne end of e ach of the 4 laminated pads is fixed to the M G B and the other to the airframe.

MGB F lexible suspension

AIR F RAME

The vibrations are absorbed radially by the pads which deform in she ar.

The main rotor counter-torque (C R ) is transmitted through the pads by compression.

MGB MGB

The laminated pads are flexible in she ar

CR

The laminated pads are stiff in compression


3.11

T HM

3.6.1. G E N E R A L (C o nt.) A R R A N G E M E N T O F LAMIN AT E D PA D S

M G B bottom

T O P VIE W

R I2

I2 Lateral axis

FWD L2 L1

L2 T T

FWD

I1

Longitudinal axis

- Two laminated pads (L1, L2) re act she arwise the loads F x, My along the longitudinal axis. -Two other pads (I1, I2) re act she arwise the loads F y, Mx acting along the lateral axis. The 4 laminated pads re act the main rotor counter torque (C R ) in compression. The 2 pairs of laminated pads are linked by a cross member (T), which closes the load path and is loaded almost entirely in tension. This type of suspension is called "bidirectional" as it acts along the longitudinal and lateral axes.

L1 R esistive torque (tail rotor)

I1

R

CR

3.6.2. M G B S U S P E N SI O N C O M P O N E N T S

2

1

3

4

5

I2 L2

To transmit the autorotation torque which changes direction, e ach laminated pad is paired with a second pad that is only compressed when the torque changes sign. If a laminated pad is destroyed, the assembly is held in position by a block (3) and continues to transmit the rotor torque in compression.

1 - Cross member 2 - Structure fitting 3 - Laminated pad support 4 - Laminated pads 5 - Attachment bolt

AV

L1

I1

N.B. The longitudinal pads (L) and the lateral pads (l) have different thicknesses.

3.12

T O P VIE W


T HM

4

MAIN R O T O R

4.1.

O V E RVIE W

4.2 -

M AIN R O T O R M A S T

4.2.1.

G E N E RAL

4.2.2.

MAIN R O T O R MA S T C O MP O N E N T S

4.2.3.

MAIN R O T O R MA S T A S S E MBLY

4.2.4.

MAIN R O T O R S H A F T/M G B C O U PLIN G

4.2.5.

S W A S H PLAT E A S S E MBLY

4.3 -

M AIN R O T O R H U B (MR H)

4.3.1.

" S TA R F L E X " R O T O R H U B

4.3.2.

R O T O R H U B D Y N AMIC S

4.3.3.

MR H C O MP O N E N T S

4.4 -

MAIN R O T O R B L A D E S

4.5 -

R O T O R SP E E D MO NIT O RIN G

4.5.1.

R O T O R R PM (N R) D E T E C TIO N

4.5.2.

N R MIN/MA X A U R AL ALA RM S Y S T E M

4.5.3.

C O MP O N E N T L O C ATIO N S

4.6 -

VIB R ATIO N A B S O R B E RS

4.6.1

G E N E RAL

4.6.2

C A BIN R E S O N AT O R S

4.6.3

R O T O R H U B S P RIN G T Y P E VIB R ATIO N A B S O R B E R


4.1

T HM

4.1 - O V E R VIE W The main rotor provides the lift of the helicopter and powers its forward flight. The main rotor comprises: - the main rotor mast (3) - the rotor hub (2) - 3 rotor blades (1).

1

2

The main rotor mast is secured to the M G B. It drives the main rotor hub and transmits the rotor lift to the airframe. The hub is attached to the rotor shaft and supports the blades. It is located at the center of the resultant lift of the blades and it absorbs the forces induced by the rotor rotation (centrifugal forces, flapping and drag (le ad/lag) loads). The blades convert the mechanical engine power into aerodynamic forces (lift).

S O M E FIG U R E S N = 390

+4 rpm (spe ed governed in ste ady flight) -5

3

W EIG H T O F R O T O R S U B A S S E MBLIE S - Main rotor mast .............................................. 55.7 kg - Rotor hub ......................................................... 57.5 kg - Blade .............................................................. 33.9 kg - Anti-vibration device ........................................ 28.4 kg

Blade sle eve Bla d e Rotor diameter = 10.69 m

R O T O R ID E N TIFIC ATIO N

The blade sle eves are balanced to compensate for the weight of the rotating scissors. The sle eves and blades are also functionally paired by adjusting their pitch change rod. To prevent the settings being lost on removal/installation of these components: - the rotor hub can only be mounted in one position on the rotor mast (se e 4. 3. 3.). - e ach blade/sle eve/rod forms an assembly that is identified by a different color (in the order: yellow, blue, red). These colors can also be used when tracking the blades, to identify the trace of e ach blade on the tracking flag.

Pitch change rod

" BLA D E/SL E E V E/R O D " A S S E MBLIE S ID E N TIFIE D B Y C O L O R E D A D H E SIV E TA P E

4.2


T HM

4.2 - M AIN R O T O R M A S T 4.2.1. G E N E R A L The main rotor mast consists of: - the rotor shaft (9) driven by the M G B. - the swashplates, i.e. the rotating star (3) and the stationary star (4). The stationary star is actuated at 3 points (indexed at 90°) by the flight controls (5). It is mounted on a balljoint (12) and can: - pivot about the balljoint to vary the cyclic pitch. - move along the shaft to vary the collective pitch; the balljoint then slides up or down on a guide (11). The rotating star rotates on be aring (13) and copies all the movements of the stationary star, transmitting them via 3 pitch change rods (2) to the blade control horns (1) on the blade sle eves. A casing assembly (10) extends beyond the swashplate guide to rigidly connect the mast to the M G B. The main rotor shaft is attached to the housing by a guiding roller be aring (6) and a 4-contact be aring (8) that carries the rotor lift in flight and the rotor weight on the ground. These loads are transmitted by 4 suspension bars (7) secured to the transmission deck.

1 2 3 13

4

12

5

6

11

7 8

10

9

S WA S H PLAT E O P E R ATIN G DIA G R AM F ORWARD

1

2

The upper scissors (1) is attached to the rotor shaft and drives the rotating star. The lower scissors (2) is attached to the casing and stops the stationary star rotating.

Simulta n e ous action on the 3 controls

C O LL E C TIV E PIT C H VA RIATIO N The balljoint slides along the rotor mast. The pitch change is the same on all 3 blades. In the above diagram, the pitch is increasing.

Action on the fore/ aft control

C Y C LIC PIT C H VA RIATIO N The balljoint does not move but the swashplate pivots about it. In the diagram above, the pitch decreases to the front and incre ases to the re ar.


4.3

T HM

4.2.2. M AIN R O T O R M A S T C O MP O N E N T S Although the suspension bars are not part of the rotor mast, they are assumed to be so functionally for explanatory purposes.

Rotor shaft Swashplates

Swashplate guide

C a sing a ss e mbly

Suspension bars (s/ste el)

R e ar attachments

S O M E S P E CIFIC F E AT U R E S O F T H E R O T O R MA S T

O nly one be aring in the control linkage

Swashplate guide covered with Teflon-coated glass fabric: N O LU B RIC ATIO N

The usual hinge be arings (low r e li a b ilit y) a r e r e p l a c e d b y b alljoints a nd s elf-lubric ating be arings. HIG H E R R E LIA BILITY N O LU B RIC ATIO N

N.B. E xcept for the normal visual checks, the rotor mast requires no servicing.

4.4

F urthermore, you can replace all defective parts by your own me ans (no more factory returns).


T HM

4.2.3. M AIN R O T O R M A S T A S S E M B LY 4 P OIN T C O N TA C T B ALL B E A RIN G S 1

2

Periodically lubricated via grease nipple C. D istributing th e lo a ds to 4 points d ecre ases the specific pressures.

3

B E TT E R R E LIA BILITY.

21 20

4 19 C 18

5

17

6

7 16

8

15 9

1 - Scissors drive 2 - Rotor shaft (ste el) 3 - Rotating scissors 4 - B alljoint 5 - Stationary scissors 6 - Spacer 7 - Roller be aring 8 - Slotted (phonic) whe el 9 - O il tube 10 - E lectric chip detector 11 - Thrust be aring 12 - Planet ge ar 13 - V ent 14 - Borescope port plug 15 - N R magnetic sensor 16 - Upper casing (light alloy) 17 - Swashplate balljoint guide 18 - S elf-lubricating adhesive tape 19 - Stationary swashplate 20 - Rotating swashplate 21 - Pitch change rod

14 10

13

ˇ 

12

R O T O R MAST C hip detector

11

P P11 ˇ 

CHIP MG B

P P12

MGB C hip detector C e document est la propriété d'E UR O C O PT E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'E UR O C O PT E R et son contenu ne peut être divulgué. This document is the property of E UR O C O PT E R ; no part of it shall be reproduced or transmitted without the express prior written authorization of E UR O C O PT E R and its contents shall not be disclosed. © E UR O C O PT E R 1998.

4.5

T HM

4.2.4. M AIN R O T O R S H A F T/M G B C O U P LIN G 1 2 4 3

17 5 16

6

15 7 14

8

13

10

11

12

9

1 - Lip se al 2 - B e aring cup lock bolt 3 - Plug for checking oil le akage from lip se al (1) 4 - Roller be aring 5 - Slotted (phonic) whe el 6 - O il slinger for be arings (4) & (9) 7 - E lectric "metal chip" detector 8 - B e aring housing 9 - Thrust be aring (4-contact) 10 - C hip collector 11 - Planet ge ar carrier/mast assembly 12 - Oil scavenge bowl 13 - Planet ge ar 14 - Air vent 15 - Plug for borescope inspection 16 - N R magnetic sensor 17 - Light alloy upper casing

4.2.5. S WA S H P L AT E A S S E M B LY

7 9

11

8 10

A

7

1

Two ball sockets (1), made of self-lubricating material, allow the swashplate assembly to oscillate on balljoint (2). The 4-contact be aring (3) is lubricated by gre ase nipple (4). Protectors (5, 11) ke ep out rain and dust. A tapped hole (10) on e ach arm of the rotating star is used to fit struts for flight control rigging. A pulse-generating tab (6) integral with the rotating star synchroniz es the strobe light flashes in blade tracking checks. The rods have 2 end-fittings (7) with opposite-hand threads for blade pitch adjustment by rotating rod body (8) (with locknuts (9) unscrewed). Turning the rod in the direction marked "+" on the rod body incre ases the blade pitch: a rotation of one flat on the rod body changes the blade track by approximately 6 mm.

2 6

5

4

3

A : Laminated shim for adjusting play of ball sockets (1)

4.6

D O N O T A DJUST TH E L E N G TH O F Y E LL O W PIT C H C H A N G E R O D A S IT IS TH E D ATUM R O D


T HM

4.3 - M AIN R O T O R H U B (MR H) 4.3.1. " S TA R F L E X " R O T O R H U B The basic component of the rotor is the S TA R with its 3 arms F L E Xible in the flapping direction (hence its name " Starflex"). O n the Starflex rotor hub, rigid sle eves join the blades to the star arms so that the hub performs the following functions WIT H O U T B E A RIN G S:

- F LA P PIN G, D R A G, PIT C H C H A N G E The sle eve must also transmit the blade centrifugal loads to the rigid center part of the star. F or this purpose, flexible couplings are fitted betwe en the sle eve (3) and the star arm (2), i.e.: - a laminated spherical stop (1) (sandwich structure of ste el cups and thin elastomer she ets). - elastomer blocks (4), called frequency adapters. Positive flapping Manufacturing coning Theoretical plane of rotation N egative flapping

1

2

3

4

O nly parts required for the functional explanation are shown or outlined

1 - L a min a t e d sph eric al stop, which is fle xible in torsion, flapping and drag but rigid in compression. It is the "he art" of the hub as it absorbs all the loads and displacements. 2 - Star arm (star made of "glass resin" laminate). F abrics molded and oven-cured. 1

2

3 - Sle eve (glass resin yarn roving). 4 - E la stom er blocks distorting sh e arwis e (in-pla n e dragwise damping and stiffness). 5 - S elf-lubricating balljoint, centering the sle eve at the end of the star arm.

3

4

5

BLA D E

Some advantages of the Starflex hub compared to the hinged rotor hub: - Practically maintenance-fre e (hingeless, gre aseless, etc.). - F ail-safe design through the use of composite materials (any damage evolves very slowly and is visible).

- O n-condition maintenance (No overhauls). - Modular design with all parts bolted together for e asy replacement of critical elements (spherical stop, elastomer blocks). - Low weight of 55 kg (In comparison, the Alouette 3 MR H weighs 105 kg).


4.7

T HM

4.3.2. R O T O R H E A D D Y N A MIC S The Starflex rotor hub is comparable to a hinged rotor, with elastic return in the flapping and drag directions (the star arms and elastomer blocks act as springs). F LA P PIN G F U N C TIO N

The star arms are flexible in flapping and are bent upward or downward by the flapping forces...

ˇ

...causing the blade/sle eve assembly to flap about the center O of the laminated spherical stop, which distorts elastically.

IN-PLA N E D R A G F U N C TIO N

The star arms are rigid in-plane (dragwise).

U n d e r th e a ctio n of the drag forces...

ˇ the elastomer blocks deform in she ar...

. . a n d th e bl a d e /sl e e v e a s s e m bly pivots a bout th e c e ntre " O " of th e l a m i n a t e d s p h e ri c a l s t o p , w h i c h deforms elastically.

4.8

The elastomer blocks provide: - both stiffness to adjust the natural frequency - and damping to limit the oscillation amplitude.


T HM

4.3.2. R O T O R H U B D Y N A MIC S (C o nt.) PIT C H C H A N G E

The star arms are rigid in torsion

Actuated by the blade horn...

ˇ

...the laminated spherical stops deform in T O R SIO N...

ˇ

...and the sle eve rotates about an axis going through the laminated spherical stop center O and the balljoint centre O'.

ˇ N O T E : Since the end of the blade control horn (E) is directly opposite the spherical stop center O , there is no geometric pitch/flapping coupling (no K-link)



R E A C TIN G T H E C E N T RIF U G AL L O A D S

The centrifugal loads are re acted via the sle eve by the laminated spherical stop. The stop is stiff in compression and transmits the centrifugal loads to the thick center section of the star where they balance e ach other out. The star arms are thus not stressed.

Fc


4.9

T HM

4.3.3. M R H C O M P O N E N T S All the rotor hub parts are either perfectly symmetrical or foolproofed :

1 - Star (glass-resin) 2 - Spherical stop (laminated elastomer) 3 - Sle eve flange (glass-resin) 4 - Frequency adapter (3 elastomer layers) 5 - Blade attach pin 6 - Light alloy washers (replaced by balance weights, if necessary) 7 - S elf-lubricating balljoint centered in bush 8 - Blade horn lever 9 - Thrust fitting (droop restrainer) 10 - Droop restraining ring 11 - Hub locating boss 2

1

N O E RR O R IS P O SSIB L E IN DIS A SS EMB LY/R E A SS EMB LY

5

4

3

11 7

6

Location for balancing plates

8 10

9 Tungsten carbide coating Bonded bush with m e ch a nic a l locking Teflon coating 1

R O T O R H U B IN S TALLATIO N O N R O T O R MA S T

2 11

3 4

1 - Star attach bolt 2 - Flanged ring 3 - Anti-corrosion washer 4 - Bush 5 - Ring nut 6 - R etaining ring for nuts (5) 7 - Droop restrainer ring 8 - C lamp for stirrups (9) 9 - Stirrup for retaining ring (7) 10 - Stud for sle eve electrical bonding braid 11 - Bolt attaching star and stirrup (9)

4.10

5

10

6

7

9


8

T HM

4.4 - M AIN R O T O R B L A D E S C onstruction ................................. composite materials W eight ............................................................... 33.9 kg Airfoil .................................................................. O A 209 Chord ................................................................ 350 mm

n AIR F OIL O A 2 X X O N E R A.

Type 2

Thick./ chord ratio

e = n% of C

C = 350 mm

Polyurethane protector on underside

Le ading edge protector

Bonding braid (polyurethane coated)

C enter of gravity mark Blade folding prop position marks

5th and 6th tab set at 0°, can be cambered for blade adjustment on MR H

First 4 tabs are c a mb ere d during dyn a mic b a l a ncing

Blade attach pin bushings

Static and dynamic blade balance weights

Glass roving tape wound around attach inserts and forming the le ading edge spar and the trailing edge ledge

Tracking finger for blade tracking flag check

Stainless ste el cuff

Glass fabric layup forming blade skin

Blade strobe-tracking target mounting screw

Roving spar

Polyurethane strip integrated in airfoil

Spar box structure (gla ssfib er)

Glass fabric skin

F oam core


Roving trailing edge ledge

4.11

T HM

4.5 - R O T O R S P E E D M O NIT O RIN G 4.5.1. R O T O R R PM (N R) D E T E C TIO N The pilot's instrument panel includes a triple rpm indicator displaying the main rotor spe ed (N R) and the fre e turbine spe ed for e ach engine (N F 1-N F 2)*. The copilot's instrument panel includes a single pointer N R indicator. An aural alarm sounds when the rotor spe ed is outside the minimum or maximum rpm limits. A test light confirms proper operation of the electronic circuitry. * N F is the rpm of the generator fre e turbine.

3 4

5

NR

1 - Slotted phonic whe el on main rotor shaft 2 - Magnetic sensor 3 - Pilot's triple rpm indicator (N R - N F 1 - N F 2) 4 -Indicator light 5 - Horn 6 - E lectronic detection unit 7 - C opilot's N R indicator

1

FRE QUENCY C OMPARATO R

2

6 7 P P13 NR

( 1 ) O p eratin g prin ciple of pilot's s elf-c o ntain e d N R in dic ator C opilot's N R indicator

1 2

FRE QUENCY/ V O LTA G E C ONVERTER

F

The phonic whe el (1) is driven by the main rotor shaft. As e ach tooth passes in front of sensor (2), it induces an alternating electric current whose frequency is proportional to N R. The frequency signal (F) is applied to a frequency/voltage converter, which supplies an output current with a voltage (U) proportional to the rotor spe ed.

NR G ALVAN OME T E R P O W E R SUPPLY

G

This voltage is transmitted via a power supply circuit to a galvanometer that controls the rpm indicator display. T H E S E L F-C O N TAIN E D TA C H O M E T E R IN DIC AT O R WILL DIS PLAY T H E R O T O R R PM E V E N IN T H E E V E N T O F A T OTAL AIR C R A F T E L E C T RIC P O W E R S Y S T E M FAILU R E .

( 2 ) O p eratin g prin ciple of c o pilot's a u xiliary N R in dic ator

1

FRE QUENCY/ V O LTA G E C ONVERTER

A

F

M

2 B

The rpm sensor (2) is not powerful enough to drive 2 selfcontained indicators.

4.12

MO T O R SLAVIN G C IR C UIT

P O W E R S U P PLY

P P13

Since the copilot's N R indicator is only fed a we ak signal from the second winding (B), it requires external slaving power.


T HM

4.5.2. N R MIN/M A X A U R A L A L A RM S Y S T E M The N R min/max aural alarm system warms the pilot when the rotor is overspe ed above the maximum limit (410 rpm) or underspe ed below the minimum limit (360 rpm), corresponding to the rotor's mechanical and a erodynamic rotor limits. ( 1 ) N orm al o p eratio n SL O T T E D WHE EL

FAILU R E W/PA N E L 4

SENSOR

HORN

NR "HORN" pushbutton 15

30 A

N R alarm printed circuit

P P11 B C

10 P P12

A - Horn light ground B - N R MA X (overspe ed) detection C - N R MIN (underspe ed) detection (horn)

The frequency of the current induced in the double sensor windings is transmitted to the N R indicator and to the electronic N R MIN/MA X detection unit. D epending on the sensor's output frequencies, the detection unit triggers the (2)

horn in the following rpm ranges: - 250 rpm < N R < 360 rpm (continuous audio signal) - N R > 410 rpm (intermittent audio signal)

O p eratio n s elf-te st SL O T T E D WHE EL


SENSOR

HORN


30 N R alarm printed circuit

A P P11 B C

10

A - Horn light ground B - N R MA X (overspe ed) detection C - N R MIN (underspe ed) detection (horn)

P P12

O v ers p e e d d ete ctor o p eratin g te st T h e syst e m runs a s e lf-t e st of th e ov ersp e e d a nd underspe ed alarm electrical circuits as the engine accelerates after starting with the " H O R N " switch off, but without re aching the overspe ed rating (410 rpm).

When the " H O R N " pushbutton is off, oscillator (B) in the detection unit is connected to the " H O R N " light causing it to flash betwe en 250 and 360 rpm inste ad of 410 rpm.


4.13

T HM

4.5.2. N R MIN/M A X A U R A L A L A RM S Y S T E M ( C o nt.) (3)

Dro p of N R b etw e e n 360 a n d 250 rp m SL O T T E D WHE EL


SENSOR

HORN


30 A

N R alarm printed circuit

P P11 B C

10 P P12

A - " H O R N " light ground B - N R MA X (overspe ed) detection C - N R MIN (underspe ed) detection (horn)

In this rpm range with the " H O R N " pushbutton O N, the detection unit directly energiz es the audio alarm via the busbars P P11 and P P12. T h e s o u n d is c o ntin u o u s.

( 4 ) O v ers p e e d c o nfig uratio n (N R > 410 rp m) SL O T T E D WHE EL


SENSOR

HORN

NR "HORN" P ushbutton 15

30 N R alarm printed circuit

A P P11 B C

10

A - H O R N light ground B - N R MA X (overspe ed) detection C - N R MIN (underspe ed) detection (horn)

P P12

The frequency of the induced current corresponds to an overspe ed condition, causing the detection unit oscillator to energiz e the horn, which s o u n d s intermitte ntly.

4.14


T HM

4.5.2. N R MIN/M A X A U R A L A L A RM S Y S T E M ( C o nt.) ( 2 ) In dic atin g lo gic a n d h orn o p eratio n

• " H O R N " lig ht s e q u e n c e d urin g o p eratin g te st

NR

ˇ ˇˇ 

ˇ 

HORN

ˇˇ  ˇ 

ˇˇ  ˇˇ 

HORN

ˇ 

HORN

The illumination sequence of the " H O R N " light indicates: - the horn is not active - the alarm circuit test is O K.

Light flashes from 250 to 360 rpm

• H orn o p eratio n (" H O R N " switch O N)

NR

Intermitte nt o v ers p e e d w arnin g above 410 rpm ˇ ˇˇ 

ˇ  ˇˇ  ˇ 

ˇˇ  ˇˇ 

ˇ 

C o ntin u o u s u n d ers p e e d w arnin g from 250 to 360 rpm C e document est la propriété d'E UR O C O PT E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'E UR O C O PT E R et son contenu ne peut être divulgué. This document is the property of E UR O C O PT E R ; no part of it shall be reproduced or transmitted without the express prior written authorization of E UR O C O PT E R and its contents shall not be disclosed. © E UR O C O PT E R 1998.

4.15

T HM

4.5.3. C O M P O N E N T L O C ATI O N S

Magnetic sensor

N R MIN/MA X alarm printed circuit (on 30D)



ˇ   





Horn pushbutton

   ˇ 

   ˇ 

 ˇˇ 

 ˇ 

 

ˇ  





 ˇ

ˇ 

HORN 

   ˇ

ˇ ˇ ˇ

 ˇˇ ˇ  ˇ ˇ

ˇ ˇ 

C O PIL O T'S N R IN DIC AT O R

4.16



PIL O T'S N R-N F 1-N F 2 IN DIC AT O R


Horn

T HM

4.6 - VIB R ATIO N A B S O R B E R S 4.6.1 G E N E R A L As you know, periodic cyclic loads act on the blades about the flapping and in-plane drag axes. These loads induce stresses and re actions at the rotor hub, i.e.: - bending and torsion moments on the rotor shaft, - she ar loads on the shaft. The rotor hub cyclic stresses and re actions are repe ated regularly every revolution and on e ach blade. Their frequency is 3 since there are 3 blades with an angular velocity of , The rotor hub re actions are transmitted through the rotor mast, suspension bars and M G B housing and generate vertical and horizontal vibrations that propagate through the airframe.

These vibrations are felt in the cockpit (particularly the vertical component which is the most troublesome), i.e. in the very place where a comfortable environment is essential. ALWAY S B E A R IN MIN D that these 3 vibrations are perfectly normal and are due to the operating principle of the rotor; moreover, they are in no way related to the static and a erodynamic balance. In other words, we either have to live with them or try and attenuate them. W e have alre ady se en that the M G B bidirectional suspension is designed to filter out the vibration but some always "gets through". W e have therefore attempted to further improve the vibration level by me ans of vibration absorbers based on the resonator principle.

( 1 ) R e s o n ator prin ciple F1

The dynamic behaviour of the airframe can be represented by a spring K and a weight M suspended from the rotor, which excites the airframe by a dynamic load F 0 at frequency of 3 . The response of the weight M to this excitation (load F 1) varies with M and with the natural frequency of the spring K/weight M system (a function of M and the spring stiffness). Thus depending on the airframe dynamics (M and K), the vibrations will either be amplified or attenuated but they will always be present. If a weight m is now added via a spring k to weight M (m < M), the vibration characteristics are altered (such a system is called a resonator). W eight m is excited by weight M but it counteracts and tends to reduce the excitation load F 0; it can even cancel it out if the resonator's natural frequency is equal to the 3 excitation (the resonator natural frequency = k/m). In other words if the resonator frequency is equal to the excitation frequency, the airframe does not respond since the weight M does not vibrate, i.e. th e re s o n ator c a nc els o ut th e vibratio n s.

R esponse of weight M

K

M

F0

K F2

M k

m

O bviously, such a simple system does not exist. From the dynamic point of view, the structure consists of a series of dissimilar weights (like M) and springs (like K); thus, to filter out all the vibrations, it would be necessary to provide a resonator for every "M/K " system, which of course is not fe asible. However what can be done is to limit the number of reso-

3 w rotor excitation

if

k m

=3

.... F 2 = F 0 and F 1 = 0 F0

nators by locating them so that they minimiz e the vertical vibration component in the cabin. The 3 resonators on the E cureuil are therefore are installed : - under the pilot and copilot se ats to make the cabin a "calm" are a. - on the main rotor hub at the source of the excitation loads.


4.17

T HM

4.6.1

G E N E R A L (C o nt.)

( 2 ) Prin ciple of th e c a bin re s o n ators The figure gives you an ide a of how the vertical vibration amplitude varies when there are no cabin resonators. The amplitude curve is se en to include anti-nodes (high vibration) and nodes (zero vibration). You can also se e that the vibration level in the cabin is high. The cabin resonators (a weight m at the end of a flexible ste el blade k) are therefore located under the pilot's and copilot's se ats; since the resonator is tuned to the 3 frequency, it cancels out the vibration a t th e a tt a chm e nt point of spring k , thereby generating a node under the pilot's and copilot's se ats and reducing the vibration level in the cabin.

A nti-nod e

N od e

Node fixed by resonator

The weight m vibrates in a ne arly vertical plane

m

k

( 3 ) Prin ciple of th e rotor h u b vibratio n a b s orb er Main rotor hub axis

In this case, the resonator acts on the excitation loads themselves. A weight m is located on the rotor hub axis and is held by 3 springs k allowing it to flap (to vibrate) in the horizontal plane and in the other directions. The weight m/springs k system is excited by the periodic cyclic loads on the rotor hub, and responds at the excitation frequency by counteracting the excitation loads.

k k m

1

2

3 k

7

6

4 5

4.18

123456-

Vibration absorber fairing C oil spring (3 springs) Vibrating weight C ylinder centering and retaining balljoint (5) B alljoint, guiding weight (3) in horizontal plane Protective boot ke eping out external agents (e.g. dust, rain, etc.) 7 - Rotor hub star


T HM

4.6.2 C A BIN R E S O N AT O R S

5

1

4

2

1 - Bottom structure be am 2 - Attachment backing plate 3 - Attachment plate 4 - F lexible ste el blade 5 - Resonator weights

Chamfers for movement of blade (4). C omply with installation direction.

3

The helicopter vibration level can be enhanced by moving the resonator weights on the ste el blades as specified in the Maintenance Manual instructions.

4.6.3 R O T O R H U B S P RIN G T Y P E VIB R ATIO N A B S O R B E R

1

2

3 4 9 8

123456-

F airing Upper flange W eight Mount assembly Lower flange C enter rod holding weight in horizontal plane 7 - B alljoint 8 - E xterior stop of spring (9) 9 - Spring C e document est la propriété d'E UR O C O PT E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'E UR O C O PT E R et son contenu ne peut être divulgué. This document is the property of E UR O C O PT E R ; no part of it shall be reproduced or transmitted without the express prior written authorization of E UR O C O PT E R and its contents shall not be disclosed. © E UR O C O PT E R 1998.

5

6

7

4.19

T HM

5 TAIL R O T O R DRIV E SYST EM

5.1 -

FROM THE MG B TO THE TG B

5.2 -

TAIL R O T O R D RIV E S Y S T E M

5.3 -

TAIL G E A R B O X

5.3.1.

T G B C O MP O N E N T S A N D M O U N TIN G

5.3.2.

PIT C H C H A N G E S PID E R A N D H U B

5.3.3.

TAIL R O T O R D RIV E C O MP O N E N T S


5 .1

T HM

5.1 - F R O M T H E M G B T O T H E T G B 2090 rpm

The tail rotor is driven from the M G B by: • The M G B T G B coupling shafts • The tail ge arbox (T G B)

6125 rpm

5.2 - TAIL R O T O R D RIV E S Y S T E M The system comprises 4 drive shafts: a stainless ste el forward shaft (1), a fan drive shaft (2) riding in 2 ball be arings (3), an intermediate shaft (4), and a very long re ar shaft (5) riding in 6 ball be arings (6), mounted in elastomer bushes to absorb the assembly vibration. All the shafts are connected by flexible couplings (7). The forward and re ar shafts (1, 5) have splined end fittings (8), which slide in the coupling flanges (9) for e asy removal of the drive shafts.

TGB

7 5 9

8

7 6

4

6 be arings along tail boom

2

7 3

1 7

B e aring (stainless ste el) 9

E la stom er bush E la stom er sle e v e

8 TGB

Driv e shaft

B all be aring B e aring support bra ck e t

Access panel to re ar flex coupling on shaft (1) for installation, inspection and balancing.

5 .2


T HM

5.3 - TAIL G E A R B O X (T G B) The T G B is basically an angle reduction ge ar (spiral bevel ge ar) mounted in and protected by a light alloy casing. The bevel ge ar shafts rotate in standard Timken tapered roller be arings which absorb the radial loads and axial thrust. Both the bevel ge ar and the other ge ars are splashlubricated. T h e h e a t g e n era t e d by th e g e arbox in op era tion is completely dissipated by radiation from the casing.

Hub attachment Tapered roller b e arings

Power takeoff

Tapered roller b e arings

" Gle ason" spiral bevel ge ar

Velocity ratio:

44 = 2.93 15

5.3.1. T G B C O MP O N E N T S A N D M O U N TIN G

3

The condition of the bevel ge ar can be checked using a borescope inserted through the filler neck (strainer removed).

4

1

2

F ORWARD MOUNTS

1 - O-ring 2 - O il level sight (Pyrex glass) 3 - O il filler cap (elastomer) 4 - Strainer (perforated brass she et) 5 - G asket 6 - Drain plug and magnetic element

5

6

REAR MOUNTS

P P11

TGB CHIP

P P12


ˇ 

5 .3

T HM

5.3.2. PIT C H C H A N G E S PID E R A N D H U B

1

2

3

4

5

6

The rotating plate (4) is driven by the rotor via 2 pitch change links (5) and is fre e to slide along the rotor shaft (7). The stationary plate (2) is actuated by a pitch change bellcrank (1) hinged on the T G B casing. It is fre e to slide axially and hence moves the rotating plate but it is prevented from rotating by the bellcrank. The stationary and rotating plates are separated a ball be aring. The figure shows the pitch linkage movements to incre ase the pitch angle . The directions are reversed to decre ase the pitch angle.

7

1 - Pitch change bellcrank 2 - Stationary plate 3 - B all be aring 4 - Rotating plate 5 - Pitch change link 6 - Hub 7 - Rotor shaft

Sliding motion on self-lubricating bushes Life-lubric ate d b e aring

S elf-lubric ating b a lljoint

S elf-lubric ating b a lljoint

5 .4

Yaw control

The maintenance of the control assembly has been minimiz ed. Apart from the standard visual inspections, no routine maintenance is required. There are no lubrication points thanks to the use of selflubricating balljoints, a life-lubricated be aring and self-lubricating sliding be arings.


T HM

5.3.3. TAIL R O T O R D RIV E C O MP O N E N T S 1

1 - Rotor mounting bolt 2 - Hub 3 - S elf-lubricating balljoint 4 - Pitch change link 5 - Dust protector wiper se als 6 - S elf-lubricating friction bushes 7 - Hinge on shock mounts 8 - B e aring protective baffles (grease-filled) 9 - Rotor shaft (ste el) 10 - V-ring dust protector 11 - Thre aded baffle joint 12 - Timken tapered roller be arings 13 - T G B casing 14 - B evel ring ge ar (case-hardened ste el) 15 - T G B cover (light alloy) 16 - B evel pinion (case-hardened ste el) 17 - V ented plug 18 - Magnetic se al 19 - B e aring spacer 20 - Pitch change bellcrank 21 - E xpansible bolt 22 - Nut joining stationary/rotating plates 23 - Stationary plate (light alloy) 24 - D e ep groove ball be aring 25 - Rotating plate (light alloy)

2

3 4

5 6 25

7

24 23

8

22 21 5

20

9 10

19

11 12

18

13 14 17 16

12 12 A

B

C

D

15

E

IN S TALLATIO N A N D O P E R ATIN G P RIN CIPL E O F T H E MA G N E TIC S E AL

T h e c arbon s e a ling ring (D) is h e ld by th e rotating bush (E). The ring is magnetically attracted onto magnetic bush (A), which is integral with nonmagnetic se al holder (C), itself held by lock ring (B). C e document est la propriété d'E UR O C O PT E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'E UR O C O PT E R et son contenu ne peut être divulgué. This document is the property of E UR O C O PT E R ; no part of it shall be reproduced or transmitted without the express prior written authorization of E UR O C O PT E R and its contents shall not be disclosed. © E UR O C O PT E R 1998.

5 .5

T HM

6 TAIL R O T O R

6.1 -

G ENERAL

6.2 -

TAIL R O T O R D E SIG N P RIN CIP L E S

6.3 -

TAIL R O T O R F U N C TIO N A L A N D S C H E M ATIC D E S C RIP TIO N

6.3.1.

PIT C H C H A N G E

6.3.2.

BLA D E C O NIN G A N G L E

6.3.3.

PIT C H/F LA P PIN G C O U PLIN G (K LIN K)

6.3.4.

E F F E C T O F T H E B O S S (" C HIN E S E ") W EIG H T S

6.4 -

TAIL R O T O R C H A R A C T E RIS TIC S

6.5 -

TAIL R O T O R C O MP O N E N T S


6 .1

T HM

6.1 - G E N E R A L The tail rotor controls the helicopter about its yaw axis. The forces acting are the main rotor's counter torque (Cr), a nd th e t a il rotor thrust (Ty) with a mom e nt M = L.Ty about the c.g. The tail rotor is a flexible se esaw type, mainly constructed of composites (carbon, K evlar etc.) with only a few metal connecting parts. The conventional pitch and flapping hinges have be en eliminated and, with them, the maintenance-intensive be arings. In fact, the tail rotor offers the same advantages as the main rotor (described in § 4.3.1.), i.e. almost maintenance-fre e, fail-safe design, on-condition maintenance, etc.

L . T y > Cr Cr G L

Ty

L . Ty > Cr

• L . Ty = Cr, the helicopter is in equilibrium • L . Ty < Cr, the helicopter turns to the left • L . Ty > Cr, the helicopter turns to the right.

6.2 - TAIL R O T O R D E SIG N P RIN CIP L E S The basic rotor component is a glass-resin roving spar on which the 2 blades are molded. The spar is clamped (at its center) betwe en 2 half shells. O ne of the shells has a hole for se esaw-mounting the blade assembly on the rotor shaft hub yoke.

S e esaw b olt H alf-shells

T H E S PA R IS A T HIN BLA D E T H AT IS

...fl e xibl e in th e bl a d e thrust (Ty) direction. This fl e xibilit y a b s orb s t h e thrust-induc e d b e nding loads.

Sp ar Bla d e

...torsionally flexible over its central portion. This flexibility acts as the pitch change hinge (thrust control).

Yok e

Bla d e

Ty

Ty

R etre ating blade

0.29 R Twisting are a

S e esaw a xis

C oning

The se esaw mounting performs the flapping function. The blade assembly pivots about the seesaw bolt and "balances itself" every half revolution, i.e. when the advancing blade lifts above the plane of rotation, the retre ating blade drops below this plane. N.B. The flapping motion compensates for the thrust asymmetry betwe en the advancing and the retre ating blade.

FWD A dv a ncing bl a d e F la pping

6 .2


T HM

6.3 - TAIL R O T O R F U N C TIO N A L A N D S C H E M ATIC D E S C RIP TIO N The glass fabric blade skin (1) blends into the le ading edge of the spar (8) over the main non-twisting section. The core (2) betwe en the spar and skin is filled with synthetic alkyd isocyanate foam. The skin is secured by a light alloy flanged ring (4) on the blade shank. The ring supports the blade control horn (7), connected to the tail rotor pitch change link, and 2 large boss-type weights (9) (also called " C hinese " weights). The spar is

clamped betwe en 2 metal half-shells (6) on the se esaw axis. The half-shells and ring are separated by 2 laminated, natural rubber/metal half-be arings (5) that deform in torsion and she ar. In the twisting are a, a cavity (3) in the foam filler allows the fre e spar to distort.

3 1

2

5

4

8

7 T WIS TIN G A R E A (Initial twist = 10°)

9

6.3.1. PIT C H C H A N G E

K link

5

7

When actuated by a pilot input, the blade control horn (7) rotates the blade shank flanged ring about the laminated half-be arings (5) which distort in torsion. The pitch change load is transmitted from the flanged ring to the blade's main non-twisting section and then on to the spar's torsion section, which twists to incre ase or decre ase the pitch.

6

10°

Blade axis

Spar centerline at clamp

Incre a sing pitch

6.3.2. B L A D E C O NIN G A N G L E The spar bending loads are picked up in the clamping are a by the 2 laminated half-be arings, which locate the coning axis and limit the coning angle. The arrows in the figure show the directions of the loads exerted on the be arings, which are stiff in compression but flexible in she ar. C oning axis C e document est la propriété d'E UR O C O PT E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'E UR O C O PT E R et son contenu ne peut être divulgué. This document is the property of E UR O C O PT E R ; no part of it shall be reproduced or transmitted without the express prior written authorization of E UR O C O PT E R and its contents shall not be disclosed. © E UR O C O PT E R 1998.

6 .3

T HM

6.3.3. PIT C H/F L A P PIN G C O U P LIN G (K LIN K) Since the blade horn is offset from the seesaw axis (flapping axis), flapping and pitch will couple with e ach other. Blade flapping causes the blade horn to move out of the plane of rotation (which contains the flapping axis) and to change the pitch of: - the advancing blade, which lifts and its pitch decre ases, - the retre ating blade, which drops and its pitch incre ases. The K link has the same a erodynamic effect as blade flapping (R efer to the theory of the helicopter) and therefore tends to stabiliz e it.

6.3.4. E F F E C T O F T H E B O S S ( " C HIN E S E " ) W EIG HTS These weights balance out the z ero pitch return moment of the blades and reduce the pitch control loads; this is particularly useful in case of failure of the tail rotor servo actuator, which le aves the pilot without hydraulic power assistance. E X PLA N ATIO N O F BLA D E Z E R O PIT C H R E T U R N M O M E N T

C onsider 2 blade elements A and B , e ach of mass m, in the same airfoil section. They are roughly at the same distance r from the center of rotation O . The centrifugal FC

F1

F0

FC

K link K link FWD S e esaw a xis

K link d e cre a s e s pitch

A dv a ncing bl a d e

F la pping a ngl e

force F c (F c = m 2r) acting on elements A and B can be resolved into 2 components A et B: - F o, parallel to the blade spanwise axis, - F 1, perpendicular to this axis. The F o components have no effect on the airfoil position, but the F1 components generate a moment about the blade hinge line that tends to return the blade to its flat or z ero pitch ( = 0) position. When the blade is flat, the moment generated by these forces is z ero.

O

A

A F1

B

F0

K link incre a s e s pitch

R etre ating bl a d e

r

B F1

F1 Hinge line

E F F E C T O F T H E B O S S W EIG H T S

The purpose of the boss weights, located perpendicular to the airfoil, is to generate a moment counteracting the blade z ero pitch return moment so that the airfoil is stabi-

liz ed at all pitch angles . The figures show cle arly that the effect of the boss weights is to counteract the blade z ero pitch return moment. FC

Boss weights

F1

F0 O

F0 FC

6 .4

F1


T HM

6.4 - TAIL R O T O R C H A R A C T E RIS TIC S Rotor diameter .................................................... 1.86 m W eight ................................................................. 4.6 kg Airfoil ......................................... symmetric N A C A 00.12

185 mm chord, extended by a trailing edge tab D esign twist .............................................................. 0° Spar in twist are a preset to ...................................... 10°

6.5 - TAIL R O T O R C O MP O N E N T S T h e construction of th e tail rotor bla d e s is similar to th at of the main rotor blades, i.e.: - glass roving spar (longitudinal roving layup) - foam core - glass fabric skin laid at ± 45° (2 layers). The blade assembly is molded and then hot-cured. 4

2

Blade cuff - R einforced twist are a (glass fabric under skin) 5

6

3

1

4

5

C 6

A 0 & B 0 : Attachment points of the rotor hub chordwise balancing weights. C : Attachment point of the spanwise balancing weights.

1 - Impact finger 2 - O utboard rib 3 - Spanwise balancing weights 4 - Lower surface protection - polyurethane she et 5 - Skin (2 glass fabric layers) 6 - Leading edge protection (bonded stainless steel) 7 - Glass roving spar 8 - Alkyd isocyanate foam 9 - Mounting plate for blade assembly balance weights 10 - Blade control horn 11 - Boss weights 12 - Tab

12

8

7

B0

10

9

11

11 10

A0


6 .5

T HM

6.5 - TAIL R O T O R C O MP O N E N T S (C o nt.)

A S S E MBLY O F TAIL R O T O R

Laminated taper be arings B alljoint

6

7

8

9

10

11

12

Ste el insert

E la stom er

3

1

1 2 3 4 5 6 7 8

9 10 11 12

6 .6

-

S e esaw half-shell Blade root ring with boss weights Laminated half-be aring Blade spar S e esaw clamp Blade control horn S e esaw bolt (rotor attachment) Tight-fit, laminated taper be aring. Inner ring is made integral with the rotor by bolt (7). The be aring is designed to attenuate blade swinging. - Hub yoke Woodruff key - Rotor shaft - Pitch change link

5

4


2

T HM

7 F LIG HT C O NTR O LS

7.1 -

O P E R ATIN G P RIN CIP L E O F T H E F LIG H T C O N T R O L S

7.2 -

MAIN R O T O R C O NTR O LS

7.2.1.

G E N E R AL D E S C RIP TIO N

7.2.2.

O P E R ATIO N O F T H E MAIN R O T O R C O N T R O LS

7.2.3.

MAIN R O T O R C O N T R O L C O MP O N E N T S

7.2.4.

MAIN R O T O R C O N T R O L RIG GIN G P R O C E D U R E

7.3 -

TAIL R O T O R C O N T R O L

7.3.1.

G E N E R AL D E S C RIP TIO N A N D O P E R ATIO N

7.3.2.

TAIL R O T O R C O N T R O L RIG GIN G P R O C E D U R E


7 .1

T HM

7.1 - O P E R ATIN G P RIN CIP L E O F T H E F LIG H T C O N T R O L S FN

The flight controls modify the pitch angle of the main and tail rotors so that the pilot can control the helicopter's attitude, velocity and he ading. The collective pitch lever (1) controls the main rotor lift F N by collectively varying the pitch. F N can be resolved into a "lift" vector S and an " airspe ed" vector V, whose direction and amplitude are controlled by the cyclic pitch stick (2). The cyclic stick tilts the rotor disk (cyclic pitch variation).

S

V

The yaw control pedals (3) modify the tail rotor thrust Ty , i.e. the helicopter he ading.

( 1 ) A ctio n of th e m ain rotor c o ntrols • Mo vin g th e c y clic stic k fore or aft drives a pitch linkage controlling the helicopter about its pitch axis via point B on the swashplate. F or instance, moving the stick forward causes point B to move down but points A a n d C re m ain e d fix e d. The resulting cyclic pitch change tilts the rotor forwards. • Mo vin g th e c y clic stic k laterally drives two roll linkages controlling the helicopter about its roll axis via points A and C on the swashplate. F or instance, moving the stick to the right causes point A to move down and point C to move up through equal distances. Point B re m ain s fix e d. The resulting cyclic pitch change tilts the rotor to the right.

• Mo ving th e c olle ctiv e pitc h le v er displaces the 3 points A , B and C simultaneously through the same distance, F or instance, pulling the lever up to incre ase the collective pitch will cause these 3 points to move up. H igh pitch

• Moving the collective pitch lever actuates the swashplate at A, B and C so that it moves parallel to itself without changing the cyclic pitch.

Low pitch

Pitch axis X Swashplate

• Moving the stick fore or aft actuates the swashplate at B so that it rotates about the X axis. • Moving the stick laterally actuates the swashplate symmetrically at A and C so that it rotates about the Y axis.

A

Y

60°

FWD

FWD

S w a shpla t e hinge line in roll control

Roll axis 30°

B

90°

C Swashplate hinge line in pitch control

( 2 ) A ctio n of th e tail rotor c o ntrol In this case the control action is simpler, i.e. pushing the R H pedal forward increases the tail rotor pitc h a n d h e n c e th e thru st Ty; p u s hin g th e L H pedal forward has the opposite effect.

7 .2

S ervo actuator


Ty

T HM

7.2 - M AIN R O T O R C O N T R O L S 7.2.1. G E N E R A L D E S C RIP TIO N 1

The control linkages betwe en the cyclic stick (10), collective pitch lever (11) and swashplate (1) consist of rigid rods interconnected by bellcranks and reversing levers. E ach control linkage acts on the swashplate through a hydraulic servo actuator (2, 3, 15) that exerts the necessary control forces. The standard version of the helicopter is fitted with single-action controls without an autopilot (dual action controls and an autopilot are options).

Pitch control linkage Roll control linkage C ollective pitch control. Downstre am of the mixing unit, the collective control utiliz es the roll and pitch linkages (the collective pitch lever moves e ach of the 3 linkages equally).

2

15

3

14

13

4

12

11 10

T h e la t era l b e llcra nk is a rock er arm a ss e mbly th at reverses the movement of the LH and R H roll systems.

5

RH control

LH control

1 - Swashplate 2 - LH roll servo actuator 3 - Pitch servo actuator 4 - Mixing unit 5 - " Quick fit" copilot collective pitch lever (dual controls) 6 - C ollective pitch levers torque tube 7 - " Q uick fit" copilot cyclic pitch stick 8 - C yclic pitch sticks torque tube 9 - Lateral bellcrank 10 - Pilot cyclic pitch stick 11 - Pilot collective pitch lever 12 - R eversing levers of cyclic pitch linkages 13 - " C ollective pitch/engine governor" coupling (se e C hapter 12) 14 - S ervo actuator input rods (stainless ste el) 15 - R H roll servo actuator

9

8

7

6

T h e m i x i n g u n it is th e int erf a c e for th e cyclic a nd colle ctiv e pitch controls. It e n a ble s th e m to op erate independently of e ach other without mutual coupling, i.e. a change in collective pitch does not modify the swashplate tilt and hence the cyclic pitch is not altered; conversely, moving the cyclic stick does not affect the collective pitch (the swashplate tilts but its height is unaltered).


7 .3

T HM

7.2.2. O P E R ATIO N O F T H E M AIN R O T O R C O N T R O L S The simplified schematic of the linkages cle arly illustrates the effect of moving the cyclic stick and the collective lever. E XAMPLE S:

Y

( 1 ) L ateral m o v e m e nt of th e c y clic stic k Moving the stick to the right displaces both the roll linkages by the same amount but in opposite directions; the swashplate therefore tilts to the right about the Y axis (which passes through the pitch servo actuator). ( 2 ) F ore/aft (lo n gitu din al) m o v e m e nt of th e c y clic stic k Moving the stick forward causes the pitch linkage to tilt the swashplate forward about the X axis (which passes through the 2 roll servo actuators).

X

AV

( 3 ) Mo v e m e nt of th e c olle ctiv e pitc h le v er Pulling the collective lever up (i.e. increasing pitch) causes the pitch and roll linkages downstre am of the mixing unit to move through equal distances in the same direction. This moves the swashplate upwards parallel to itself.

O P E R ATIO N O F T H E MIXIN G U NIT

C yclic stick to right

C yclic stick forward

C ollective pitch lever up

R

The roll bellcrank pivots about the colle ctiv e pitch b ellcra nk which is fixed. This motion is reversed on the other bellcrank.

7 .4

The pitch bellcrank pivots about the collective pitch bellcrank which is fixed.

The mixing unit shaft and the collective bellcranks rotate, displacing the pitch and roll bellcranks through the same distance.


T HM

7.2.3. M AIN R O T O R C O N T R O L C O MP O N E N T S ( 1 ) C y clic pitc h stic k

F RIC TIO N M E C H A NISM 1

The cyclic stick fe atures an adjustable friction mechanism, allowing the pilot to modify the load required on the control (It should be noted that the hydraulic power system eliminates the control loads).

2 3 4

N O T E : O n helicopters fitted with an autopilot, the friction is rele ased. 1 - Friction adjusting nut 2 - Elastomer spring washer 3 - Friction cap 4 - Moving cup 5 -Inner cup 6 - Threaded sleeve 7 - R etaining nut of cup (5) 8 - Lock ring of nut (7) 9 - Lock bolt of sle eve (6) 10 - F ixed friction cup

5 6

7 8 10

9

(2)

F ore/aft (lo n gitu din al) c o ntrol

13

12

3

1

2

3

4

10 5

11

6 9 8 7

1 - Stick lateral pivot bolt 2 - Yoke 3 - B all be arings 4 - Trim unit bellcrank (A P option) 5 - F ore/aft torque tube 6 - F ore/aft bellcrank 7 - Lateral link rod for 2 sticks

8 - C yclic stick lever end 9 - Rod 10 - Intermediate bellcrank 11 - C ollective pitch tube 12 - Rigging hole 13 - Adjustable stops


7 .5

T HM

7.2.3. M AIN R O T O R C O N T R O L C O MP O N E N T S (C o nt.) ( 3 ) L ateral b ellcra n k

1

3

2

1 - B ellcrank mount 2 - B ellcrank pivot tube 3 - Rigging holes 4 - Bush-type be aring (Ertacetal) 5 - Lateral bellcrank 6 - Adjustable stop assembly on 2 sides of bellcrank

4

5

6

( 4 ) C olle ctiv e pitc h le v er Note the friction adjusting grip (2) and the "low pitch lock" strip (14).

1 - C ollective pitch lever 2 - Friction adjusting grip 3 - Elastomer spring washer, compressed by grip (2) to generate frictional pressure 4 - Friction pad assy with 2 pads rubbing on (9) 5 - C over strip 6 - C over strip retention spring 7 - Rigging hole 8 - Lever control end with bellcrank 9 - Friction plate 10 - Rigging hole 11 - C ompensating spring 12 - C opilot's lever control end 13 - Adjustable stop for low pitch 14 - Lock strip

1 2 3 4 5 6 7 8

9 10

11 12

14 13

7 .6


T HM

7.2.3. M AIN R O T O R C O N T R O L C O MP O N E N T S (C o nt.) ( 5 ) Mixin g u nit a n d re v ersin g le v ers u n d er pilot's flo or MIXIN G U NIT

1 - Summing bellcranks 2 - R H lateral bellcrank 3 - Pivot be arings (Ertacetal) 4 - F ore/aft bellcrank 5 - LH lateral bellcrank 6 - B all be aring 7 - C ollective pitch lever 8 - Mixing unit torque tube

2

1

3

4 8

6

5 3

7

1

1 3

6 LAT E R AL R E V E R SIN G L E V E R S 11

10 9

9

9

9 - Pivot be arings (Ertacetal) 10 - LH lateral reversing levers 11 - R H lateral reversing levers

F O R E/A F T R E V E R SIN G L E V E R S

12 12

12

14 13

12 - Pivot be arings (Ertacetal) 13 - F ore/aft reversing lever 14 - F ore/aft rigging hole


7 .7

T HM

7.2.4. M AIN R O T O R C O N T R O L RIG GIN G P R O C E D U R E RIG GIN G : " T H E P O SITI O N S O F T H E C O N T R O L S A N D O F T H E S WA S H PLAT E " • D atu m s ettin g s of c o ntrol lin k a g e s : O ne rigging pin per control linkage. With the rigging pins fitted, the cyclic stick is in the neutral position and the collective lever at mid-travel (50 %). • D atu m s ettin g s of s w a s h plate : a special fixture locks the swashplate in its datum position (i.e. perpendicular to the rotor shaft, servo actuator at mid-travel). E ach servo actuator input lever is centered betwe en its stops by a rigging pin. • Rig gin g p oints: - the 3 pitch control rods - the 3 servo actuator input rods • Rigging: - betwe en the swashplate and rotor: fit the tool shim betwe en the star and sle eve upper flange (se e figure) and adjust the pitch control rods to an angle setting given by the tool shim. - betwe en control linkage and servo actuator: adjust the length of the servo actuator input rods so that they can be connected without forcing.

C O N T R O L T R AV E L A DJU S TM E N T

This adjustment ensures the minimum and maximum pitch angles are actually achieved when the controls are on their travel limit stops. • D atu m p oints : two fixed index marks on the M G B ring gear opposite the forward and LH servo actuator input rods. • A dju stm e nt p oints: C ontrol travel limit stops. • A dju stm e nt: Adjust the stop screws with e ach control at its travel limit to obtain the travel X (and hence the pitch), as specified in the Maintenance Manual for this control position.

S ervo actuator rigging pins (input rod centered betwe en its stops)

Swashplate locking fixture Adjustable rods

C ollective pitch rigging pin

C ollective control stops

X

F ore/aft cyclic stops

Ind e x m ark Lateral cyclic rigging pin

The control linkage rigging pins fit in clo s e-tolera n c e holes in the structure and control component. With the pin inserted, the control is secured to the structure and hence fixed.

7 .8

F ore/aft cyclic rigging pin Lateral cyclic stops


T HM

7.2.4. M AIN R O T O R C O N T R O L RIG GIN G P R O C E D U R E (C o nt.)

Swashplate locking fixture

IN S TALLIN G T O O L S HIM

Travel X

A DJU S TIN G C O N T R O L T R AV E L C e document est la propriété d'E UR O C O PT E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'E UR O C O PT E R et son contenu ne peut être divulgué. This document is the property of E UR O C O PT E R ; no part of it shall be reproduced or transmitted without the express prior written authorization of E UR O C O PT E R and its contents shall not be disclosed. © E UR O C O PT E R 1998.

7 .9

T HM

7.3 - TAIL R O T O R C O N T R O L 7.3.1. G E N E R A L D E S C RIP TIO N A N D O P E R ATIO N The tail rotor control pedals (1) are interconnected by a rocker arm (2) so that when one pedal moves forward the other moves backward. Downline of the rocker arm, the control linkage includes: a control rod (3), a bellcrank (4), a flexible ball-type sliding control (5) and, at the servo output (7), a rod (9) actuating bellcrank (10) on the tail rotor pitch change spider.

The load compensator (8) is connected in parallel with the input rod (9) to reduce the control loads that the pilot has to apply in case of hydraulic pressure loss. N ote: The operation of the load compensator is explained in chapter 9.7.

2

1

10 9

5 4 3

7 6

8

1 - Tail rotor control pedals 2 - Rocker arm 3 - Rod 4 - B ellcrank 5 - F lexible ball-type sliding control 6 - Dual control installation (option) 7 - S ervo actuator 8 - Load compensator 9 -Input rod to bellcrank (10) 10 - C ontrol bellcrank 11 - Engine governor/yaw pedal coupling potentiometer (se e chap. 12)

7 .10

11

- When the R H pedal is pushed forward (as shown), the tail rotor pitch change spider is moved closer to the fuselage by bellcrank (10) : the tail rotor blade pitch therefore incre ases. - C onversely when the LH pedal is pushed forward, the pitch change unit moves away from the fuselage and the blade pitch decre ases.


T HM

7.3.2. TAIL R O T O R C O N T R O L RIG GIN G P R O C E D U R E RIG GIN G T H E P O SITIO N S O F T H E P E D ALS A N D O F T H E PIT C H C H A N G E S PID E R

C O N T R O L T R AV E L A DJU S TM E N T (W H E N R E Q UIR E D)

• P e d al d atu m s ettin g : The pedals are aligned and secured at mid (50%) travel (i.e. medium pitch) using the special fixture (Make sure the load compensator accumulator is discharged). • Pitc h c h a n g e s pid er d atu m s ettin g : The tail rotor blades are locked in the medium pitch position by a special fixture. This blade angle of attack corresponds to one position of the pitch change spider. The servo actuator is pinned (input lever centered between its stops) as per the type of servo actuator. • A dju stm e nt p oint: A single point on the end-fitting of the flexible ball sliding control attached to the servo actuator. • A dju stm e nt: With the pedals and tail rotor blades locked by their fixtures (as above) and the servo actuator pinned, the adjustment is limited to screwing or unscrewing the flexible control end-fitting until it can be connected without forcing to the servo actuator input lever.

This adjustment ensures that the low and high pitch angles are actually re ached when the pedals are on their travel stops. • D atu m p oint: dimension M is me asured betwe en the pitch change spider and the T G B. • A dju stm e nt p oint: stops on bellcrank. These stops are fixed since misadjustment is highly improbable. • A dju stm e nt: Push the LH and R H pedals in turn onto their forward stops and me asure dimension M (S e e Maintenance Manual) in e ach position. If M is out of tolerance, the stops must be re adjusted.

A djust a ble end-fitting

Fixed stops S ervo actuator rigging pin (if servo has no mechanical locking system) Special fixture (P edals at 50%) C h e ck dim e nsion

Special fixture (Tail rotor blades at medium pitch)


7 .11

T HM

8 HYDR A ULIC SYST EMS

8.1 - HYDR A ULIC SYST EM F UN C TIO N A L O R G A NIZ ATIO N 8.2 - HYDR A ULIC SYST EM C OMP O N E NTS 8.3 - HYDR A ULIC SYST EM O P E R ATIO N


8. 1

T HM 8.1 - H Y D R A U LIC S Y S T E M F U N C TIO N A L O R G A NIZ ATIO N Two hydraulic systems supply hydraulic power to the servo actuators.

LH S Y S T E M

• T h e L H s y ste m supplies the upper cylinders of the main rotor servo actuators. The pump (2), driven by the M G B LH intermediate pinion, draws hydraulic fluid from reservoir (1).

RH SYSTEM

1

3

2

• T h e R H s y ste m supplies the lower cylinders of the main rotor servo actuators and the single-cylinder tail rotor servo actuator. Hydraulic fluid from reservoir (3) is pressuriz ed by pump (4), driven by the M G B R H intermediate pinion. Solenoid valve (5) remains open during normal operation. If the tail servo actuator distributor seiz es, the pilot will notice incre ased pedal loads; he must then energiz e the solenoid valve which isolates the servo actuator.

4

MAIN R O T O R S E RV O A C T U AT O R S Upper cyl Low er cyl Upper cyl Low er cyl

5

Upper cyl Low er cyl Tail servo act.

C ompensator

7

8 1

2

6

3 5

4

N ote: The LH hydraulic system pipes have protective fireresistant sle eving.

8 .2

1 - R H hydraulic unit 2 - R H system reservoir 3 - R H system pump 4 - LH system reservoir 5 - LH system pump 6 - LH hydraulic unit 7 - Main rotor servo actuators 8 - Tail rotor servo actuator (with compensation system)


T HM

8.2 - H Y D R A U LIC S Y S T E M C O MP O N E N T S LH S Y S T E M

RH SYSTEM P P11

P P12 1

1

HYD.

2

6 l/min

2

3

6 l/min

3 LIMIT

4

4

6 35 b ar

P <24

SERVO

6

P <24

35 b ar

5

5 UPPER LOWER C YLIN D E R C YLIN D E R

UPPER LOWER C YLIN D E R C YLIN D E R P P13 UPPER LOWER C YLIN D E R C YLIN D E R P P11 15

7

8

17 C O PIL O T

PILO T

P P12 9

TAIL S E RV O 13

10 11

1 - Hydraulic reservoir 2 - Strainer on pump inlet and magnetic drain plug 3 - C onstant displacement ge ar pump 4 - Filter 5 - Pressure switch connected to " H Y D " indicator light 6 - Regulating valve 7 - Tail rotor isolation solenoid valve 8 - Tail rotor hydraulic cutoff switches (on collective levers)

12

14

15 16

9 - C onnecting rod 10 - C ompensator bellcrank 11 - C ompensator actuator 12 - Accumulator 13 - C alibrated orifice 14 - C heck valve 15 - Pressure relief valve (55 bar) 16 - Accumulator discharge solenoid valve 17 - " A C C " pushbutton


8. 3

T HM

8.2 - H Y D R A U LIC S Y S T E M C O MP O N E N T S (C o nt.) ( 1 ) L H a n d R H h y dra ulic u nits LH

RH

1

1

2

4

3

1 - Regulating valve 2 - Filter 3 - Pressure switch

3

2

1 - Regulating valve 2 - Tail servo isolating solenoid valve 3 - Pressure switch 4 - Filter

( 2 ) H y dra ulic s y ste m c o ntrols a n d m o nitorin g 4

3 1

HYD 2

1 - " A C C " pushbutton (compensator accumulator discharge) 2 - " H Y D " warning light 3 - C ollective pitch lever grip 4 - Tail rotor and compensator hydraulic cutoff switch

8 .4


T HM

8.3 - H Y D R A U LIC S Y S T E M O P E R ATIO N ( 1 ) N orm al o p eratio n Both hydraulic systems are pressuriz ed and the " H Y D " warning light is off. The 3 main rotor servo actuators and the tail rotor servo actuator are supplied at a pressure of 35 bar.

LH S Y S T E M

RH SYSTEM P P11

P P12

HYD.

6 l/min

6 l/min

LIMIT

SERVO 35 b ar

35 b ar

UPPER LOWER C YLIN D E R C YLIN D E R


C O PIL O T

PILO T

P P12 TAIL S E RV O


8. 5

T HM

8.3 - H Y D R A U LIC S Y S T E M O P E R ATIO N (C o nt.) ( 2 ) D e pre s s uriz atio n of L H h y dra ulic s y ste m T h e 3 w a rnin g lig h t s ( " H Y D " , " LIMI T " a n d " S E R V O " ) illuminate, telling the pilot that the LH hydraulic system has failed.

LH S Y S T E M

RH SYSTEM P P11

P P12

HYD.

6 l/min

6 l/min

LIMIT

SERVO 35 b ar

35 b ar



C O PIL O T

PILO T

P P12 TAIL S E RV O

8 .6


T HM

8.3 - H Y D R A U LIC S Y S T E M O P E R ATIO N (C o nt.) ( 3 ) D e pre s s uriz atio n of R H h y dra ulic s y ste m The " H Y D " and " S E R V O " lights illuminate. When the "LIMIT " light is off, this indicates the R H system has failed. The load compensator system is isolated by check valve (14) and remains active. The pedal actuating load incre ases slightly.

LH S Y S T E M

RH SYSTEM P P11

P P12

HYD.

6 l/min

6 l/min

LIMIT

SERVO 35 b ar

35 b ar



C O PIL O T

PILO T

P P12 TAIL S E RV O 14


8. 7

T HM

8.3 - H Y D R A U LIC S Y S T E M O P E R ATIO N (C o nt.) ( 4 ) Tail s erv o a ctu ator m alfu n ctio n The pilot is warned of a tail servo actuator malfunction by increased pedal control loads. H e should then cut off the pressure by tripping switch (8), which energiz es solenoid valve (7).

LH S Y S T E M

RH SYSTEM P P11

P P12

HYD.

6 l/min

6 l/min

LIMIT

SERVO 35 b ar

35 b ar


UPPER LOWER C YLIN D E R C YLIN D E R P P13 UPPER LOWER C YLIN D E R C YLIN D E R P P11 15 8 C O PIL O T

7 PILO T

P P12 TAIL S E RV O

8 .8


T HM

8.3 - H Y D R A U LIC S Y S T E M O P E R ATIO N (C o nt.) ( 5 ) Dis c h argin g th e lo a d c o m p e n s ator a c c u m ulator (after e a c h flig ht) Pressing the " A C C " pushbutton (17) energiz es and opens solenoid valve (16). The accumulator is discharged, depressurizing the load compensator system.

Note: In the event of a RH hydraulic system failure in flight, do not press the " A C C " pushbutton as this would incre ase the pedal control loads (especially on the R H pedal).

LH S Y S T E M

RH SYSTEM P P11

P P12

HYD.

6 l/mIn

6 l/min

LIMIT

SERVO 35 b ar

35 b ar


LOWER UPPER C YLIN D E R C YLIN D E R P P13 LOWER UPPER C YLIN D E R C YLIN D E R P P11 15 17 C O PIL O T

PILO T

P P12 TAIL S E RV O

16


8. 9

T HM

9 S E RV O A C TU ATO RS

9.1 -

T H E N E E D F O R S E RV O A C T U AT O R S

9.2 -

S A MM M AIN R O T O R S E RV O A C T U AT O R S

9.2.1.

MAIN C O MP O N E N T S A N D S P E CIFIC ATIO N S

9.2.2.

MAIN R O T O R S E R V O A C T U AT O R O P E R ATIO N

9.2.3.

D O U BL E DIS T RIB U T O R VALV E - A S A F E T Y F E AT U R E

9.2.4.

D E T E C TIO N O F DIS T RIB U T O R VALV E S EIZ U R E

9.3 -

AIR-E Q UIP E M E N T M AIN R O T O R S E RV O A C T U AT O R S

9.3.1.


9.3.2.

MAIN R O T O R S E R V O A C T U AT O R O P E R ATIO N

9.3.3.

D O U BL E DIS T RIB U T O R VALV E - A S A F E T Y F E AT U R E

9.3.4.

D E T E C TIO N O F DIS T RIB U T O R VALV E S EIZ U R E

9.4 -

IN DIC ATIO N O F S E RV O A C T U AT O R DIS T RIB U T O R VA LV E S EIZ U R E

9.4.1.

IN DIC ATIN G P RIN CIPL E O F S E RV O A C T U AT O R DIS T RIB U T O R VALV E S EIZ U R E

9.4.2.

C O MP O N E N T L O C ATIO N

9.5 -

L O A D S E N S O R A N D " LIMIT " WA R NIN G LIG H T

9.5.1.

D E T E C TIO N A N D IN DIC ATIN G P RIN CIPL E

9.5.2.

"LIMIT " LIG H T L O C ATIO N

9.6 -

S A MM TAIL R O T O R S E RV O A C T U AT O R

9.6.1.


9.6.2.

TAIL R O T O R S E RV O A C T U AT O R O P E R ATIO N

9.7 -

YAW L O A D C OMP E NS AT O R


9.1

T HM

9.1 - T H E N E E D F O R S E R V O A C T U AT O R S F light control operating loads are assisted by hydraulic servo actuators to allow the pilot to control the helicopter effortlessly and accurately. MAIN R O T O R S E RV O A C T U AT O R S

The main servo actuators are a tandem-cylinder design. The upper cylinder is supplied by the LH hydraulic system, the lower cylinder by the RH hydraulic system. Therefore, if one of the hydraulic systems fails, the servo actuator cylinder remaining under pressure is sufficient to operate the swashplate in all flight configurations.

TAIL R O T O R S E RV O A C T U AT O R A N D L O A D C O MP E N S AT O R

The tail rotor can be controlled without hydraulic assistance. The tail servo actuator is thus a single-cylinder unit supplied by the R H hydraulic system. N evertheless a load compensator system is fitted in parallel with the servo actuator to reduce the pilot's muscular effort in the event of loss of hydraulic pressure.

1 "single-cylinder" tail rotor servo actuator

3 "tandem-cylinder" main rotor servo actuators

Load compensator

SAMM S E RV O A C TU AT O R

AIR-E Q UIP E M E N T S E RV O A C T UAT O R

T W O T Y P E S O F MAIN R O T O R S E RV O A C T U AT O R

The AS 355 can be equipped with Samm or Air-Equipement main servo actuators which have the same main characteristics.

9.2


T HM

9.2 - " S A MM " M AIN R O T O R S E R V O A C T U AT O R S 9.2.1. M AIN C O MP O N E N T S & S P E CIFIC ATIO N S Tandem-cylinder servo actuator: The casing moves and drives the swashplate. The piston is anchored on the M G B casing and is therefore stationary. The piston and cylinder together form a double-action hydraulic actuator controlled by two double rotary distributor valves (one per cylinder). The double distributor valve prevents the flight con-

trol from being jammed in the event of valve seizure and continues to supply the servo actuator with hydraulic power. The operation of the valve and the seizure indicating system will be discussed later. The R H servo actuator is equipped with an overload sensor (refer to chapter 9.5).

11

1

1

8 12

5 6 2

2

7

13

Pilot input 10

B

3

3

8 8

4 9

9 A

10 O P E R ATIO N O F C O A XIAL DIS T RIB U T O R VALVE

1 - Upper cylinder 2 - Input lever & stop (pilot control) 3 - Lower cylinder 4 - E lectrical receptacle 5 - Distributor seizure alarm unit 6 - Rigging hole for Input lever (2) (mechanical z ero) 7 - Distributor control link 8 - Double rotary distributor valve 9 - Filter (105µ) 10 - Piston 11 - O verload sensor (R H servo only) 12 - Liner (equaliz es cross-sectional are as in both cylinders) 13 - C entral be aring

- Normal operation: Distributor A rotates inside distributor B. - With A seiz ed: Distributors A and B rotate together inside the casing. Hydraulic fluid is distributed by B. S P E CIFIC ATIO N S

Effective travel ........................................................................ 128 mm Piston stop-to-stop travel ....................................................... 130 mm Input lever & stop travel .......................................................... + 3 mm Distributor opening angle ................................................................ 6° E xtension force (2 cylinders at 35 bar) ................................... 350 daN R etraction force (2 cylinders at 35 bar) .................................. 217 daN Input load with hydraulic power ......................................... < 0.25 da N Ste ady-state hydraulic fluid flow (normal operation) .............. 0.3 l/min.


9.3

T HM

9.2.2. M AIN R O T O R S E RV O A C T U AT O R O P E R ATIO N The figure below shows a servo actuator during retraction. The pilot's control input moves the input lever downward through an angle of - , causing the distributor valves to rotate in direction - C hambers A in e ach cylinder are open to hydraulic pressure and chambers B to the return line. T h e s erv o a ctu ator retra cts. It continues to retract as long as the pilot acts on the servo actuator input lever. This is the principle which slaves the servo actuator output motion to the input action (pilot's command): A S L O N G A S T H E IN P U T L E V E R IS IN M O TIO N, T H E

S E RV O C YLIN D E R F O LL O W S IT. W H E N T H E L E V E R S T O P S, T H E S E RV O C YLIN D E R " C AT C H E S U P " WIT H T H E L E V E R , R E C E N T E RIN G T H E DIS T RIB U T O R VALV E S IN T H E H Y D R A ULIC Z E R O C O N FIG U R ATIO N. T H E S E RV O A C T U AT O R T H E N S T O P S M O VIN G. Similarly, moving the input lever in direction + causes the servo actuator to extend. The distributor valve opening angle ± depends on the rate of the pilot's action on the collective lever or cyclic stick, and determines the servo actuator displacement rate.

R UA

H y dra ulic z ero = servo actuator immobiliz ed

B

UB

-

P

P

-

A UA

UB

Stops + R UA

UB

B

Input lever travel range

-

P

P A

-

UA

UB

Pilot's input

R

P: R: A: B:

9.4

Pressure Return R etraction chambers E xtension chambers


T HM

9.2.3. D O U B L E DIS T RIB U T O R VA LV E - A S A F E T Y F E AT U R E If no safety provision were included, the seizing of a distributor valve would jam the corresponding flight control linkage and make the rotors almost impossible to control. The double distributor valve prevents the control from jamming and continues to supply the servocontrol in the event of a valve seizing







1

2

ˇ

The unit comprises two coaxial rotary valves : - the main distributor valve (1) - and the secondary valve (2) (B ack-up distributor valve)

ˇ  

( 1 ) N orm al o p eratio n The main distributor valve is driven by the input lever (5) and rotates fre ely inside the back-up distributor valve. The back-up valve is secured by thre e balls (3) held in their recesses by a coil spring (4) .As long as the force F 1 exerted on the input lever does not exce ed the locking spring force F 2, the main distributor rotates inside the back-up valve and supplies the servo-control. This is the normal operating mode.

ˇ

ˇ˛

( 2 ) S eizin g of th e m ain distrib utor v alv e If the main distributor valve seiz es inside the back-up distributor, the coaxial valve acts as a single unit and the input lever force (F'1 overcomes F 2) pushes locking balls out of their recesses. Both distributors then rotate together, and the relevant servo-control cylinder is supplied via the back-up valve. If the main distributor valve seiz es "closed", the servo-control operates normally. If the main distributor valve seiz es "open" the servocontrol is still supplied but the hydraulic z ero, hence the balance position, is offset (when the servo-control is shut down, the stop bellcrank is no longer exactly centered with respect to its stops) This results in an asymmetrical supply to chambers A and B of e ach cylinder



 ˇ 





Main distributor valve seiz ed "opened"

1

2

ˇ˝˛



ˇ

4

3

5









ˇ

ˇ  



Main distributor valve seiz ed "closed"


9.5

T HM

9.2.4. D E T E C TIO N O F DIS T RIB U T O R VA LV E S EIZ U R E 2

1

3

4

( 1 ) S eiz ure d ete ctio n & a uto m atic te st fe ature Pressure

5

The double distributor valve mechanism has a seizure indicator system consisting of the following on e ach distributor unit:

6

1 - Automatic test plunger 2 - G uide plate retaining the locking balls 3 - Rocker lever 4 - Thre e balls locking the backup valve 5 - Actuator of microswitch (7) 6 - Locking spring 7 - Indicator microswitch 8 - B ackup distributor valve 9 - Main distributor valve 10 - Test lever integral with backup valve

10 To distributor v alv e

7 9

8

O P E R ATIO N N O RMAL O P E R ATIO N

AUT OMATIC T E ST R

P =0

O n th e ground, hydra ulic pressure = z ero (before engines are started) 8

To distributor v alv e

P

1

SERVO

SERVO

ˇ˛

6

8

In the absence of hydraulic pressure, spring (R) extends test plunger (1) which rotates backup valve (8). The balls are unse ated, moving the rocker lever and tripping the microswitch: the S E R V O light comes on.

The hydraulic pressure retracts the test plunger. The backup distributor valve returns to its normal configuration, lock e d by th e 3 b alls h eld by spring (6). T h e microswitch contacts are open and the S E R V O light is off.

S EIZ U R E O F A DIS T RIB U T O R VALV E

The main and backup distributor valves now act as a single unit. Any movement of the input lever causes the backup valve to rotate: the microswitch is tripped and the S E R V O light comes on. N ote: The light goes out when the control returns to the position where seizure occurred, since in this position the balls are se ated in the locking retainer.

9.6


SERVO

T HM

9.3 - AIR-E Q UIP E M E N T M AIN R O T O R S E RV O A C T U AT O R S 9.3.1. M AIN C O MP O N E N T S A N D S P E CIFIC ATIO N S Tandem-cylinder servo actuator: The casing moves and drives the swashplate. The piston is anchored on the M G B casing and is therefore stationary. The piston and cylinder together form a double-action hydraulic actuator controlled by two coaxial spool distributor valves (one per cylinder). The double distributor valve prevents the flight control from being jammed in the event of valve seizure

and continues to supply the servo actuator with hydraulic power. The operation of the valve and the seizure indicating system will be discussed later. The R H servo actuator is equipped with an overload sensor that triggers the LIMIT warning light (refer to chapter 9.5).

1

C C

D

2

D B

A

5

3

4

O P E R ATIO N O F C O A XIAL S P O O L DIS T RIB U T O R VALV E

- N orm al op eration: Distributor A slid e s in distributor B. - With A seiz ed: A and B slide together and B distributes the hydraulic fluid.

MAIN S P E CIFIC ATIO N S

Effective travel ....................................................... 128 mm Piston stop-to-stop travel ...................................... 130 mm E xtension force (2 cylinders at 35 bar) ................ 350 daN R etraction force (2 cylinders at 35 bar) ................ 210 daN

1 - Load sensor (R H servo only) 2 - Upper cylinder 3 - Lower cylinder 4 - E lectrical receptacle 5 - Input lever and stop (pilot control) C - Rigging hole D - Mechanical stop adjusting slot


9.7

T HM

9.3.2. M AIN R O T O R S E RV O A C T U AT O R O P E R ATIO N The figure below shows a servo actuator during retraction. The pilot's control input moves the input lever downward through an angle of - , causing the distributor valves to slide C hambers A in e ach cylinder are open to hydraulic pressure and chambers B to the return line. T h e s erv o a ctu ator retra cts. It continues to retract as long as the pilot acts on the servo actuator input lever. This is the principle which slaves the servo actuator output motion to the input action (pilot's command):

A S L O N G A S T H E IN P U T L E V E R IS IN M O TIO N, T H E S E RV O C YLIN D E R F O LL O W S IT. W H E N T H E L E V E R S T O P S, T H E S E RV O C YLIN D E R " C AT C H E S U P " WIT H T H E L E V E R , R E C E N T E RIN G T H E DIS T RIB U T O R VALV E S IN T H E H Y D R A ULIC Z E R O C O N FIG U R ATIO N. T H E S E RV O A C T U AT O R T H E N S T O P S M O VIN G. Similarly, moving the input lever in direction + causes the servo actuator to extend. The distributor valve opening angle ± depends on the rate of the pilot's action on the collective lever or cyclic stick, and determines the servo actuator displacement rate.

R eturn

B

Pressure

A

+ Input lever mov e m e nt

B

R eturn

A Pressure Pilot input

A - R etraction chambers B - E xtension chambers

9.8


T HM

9.3.3. D O U B L E DIS T RIB U T O R VA LV E - A S A F E T Y F E AT U R E If no safety provision were included, seizure of a distributor valve would jam the corresponding flight control linkage, making the main rotor almost impossible to control. The double distributor valve prevents control jamming and continues to supply the servo actuator in the event of seizure.

The unit comprises two coaxial valves: - the main distributor valve (2) - the backup valve (3).

N O RMAL O P E R ATIO N

S EIZ U R E O F MAIN DIS T RIB U T O R VALV E

F

1

2

F'

F

R eturn

3 4 F1

F1

5

F2 6 7 Pressure

The main distributor (2) is controlled by input lever (1) and slides fre ely in backup distributor (3). The backup distributor is held in neutral position by the movement of test piston assembly (7) and caps (5, 6) when the hydraulic system is pressuriz ed. Spring (4) se ats the backup distributor on cap (5). During operation: F < F 1 or F 2.

If the main distributor seiz es in the backup distributor, both the distributors form a single unit. In the example shown, force F' applied by the input lever exce eds the spring force F 1 . Both distributors slide and the backup distributor now controls the supply to the corresponding servo actuator cylinder.


9.9

T HM

9.3.4. D E T E C TIO N O F DIS T RIB U T O R VA LV E S EIZ U R E P RIN CIPL E O F S EIZ U R E D E T E C TIO N

The double distributor mechanism also includes a seizure indicating system. O n e ach distributor unit, a microswitch, connected to a single " S E R V O " indicator light, detects any backup distributor movement.

N O RMAL O P E R ATIO N

SERVO The pressure pushes up t e s t p i s t o n (3) . T h e backup distributor is held in neutral position by 2 opposing springs (1 and 2). The microswitch is open and the " S E R V O " light is not lit. The main distributor slides freely.

SERVO

1 2 3

S EIZ U R E O F A DIS T RIB U T O R VALV E

SERVO

A U T O MATIC T E S T O F T H E B A C K U P DIS T RIB U T O R

SERVO W h e n th ere is no pre ssure , t e st piston (3) is push e d down by th e backup distributor under the action of spring (1), which extends. T h e b a ckup distributor mov e s from th e n e utral position and actuates the microswitch. The "S E RV O " light comes on.

The main and backup distributors form a single unit. Input lever operation causes the backup distributor to slide and compress spring (1). The microswitch closes and the " S E R V O " light com e s on. N O T E : A n input l e v er movement in the opposite dir e ctio n c o m pr e s s e s spring (2).

1 1

3

2

9.10


T HM

9.4 - IN DIC ATIO N O F S E RV O A C T U AT O R DIS T RIB U T O R VA LV E S EIZ U R E 9.4.1. IN DIC ATIN G P RIN CIP L E O F S E RV O A C T U AT O R DIS T RIB U T O R VA LV E S EIZ U R E The seizure detector microswitches (2 per servo actuator) are connected in series to form a monitoring loop: - when the monitoring loop closes via the ground, transistor (1) is no longer biased and the " S E R V O " light is off.

- when the monitoring loop is open, the z ener diode (2) voltage is re ached and transistor (1) is biased and conducts: the " S E R V O " light comes on.

( 1 ) O n th e gro u n d b efore th e h y dra ulic s y ste m s are pre s s uriz e d Microswitches on main rotor servo actuator

1

SERVO 2

P P11

RH P P12

3

30

LH

F WD

SERVO Test

All the microswitches are in their make position (the backup distributors have turned, pushed by the test pistons). The monitoring loop is open and the indicator light is lit. ( 2 ) Te st b efore th e h y dra ulic s y ste m s are pre s s uriz e d 1

SERVO 2

P P11

RH P P12

3

30

F WD

LH

SERVO Test

Pressing test pushbutton (3) once closes the monitoring loop: the light should go out to indicate that: - all the microswitches are in their make position - the monitoring circuit is correct (all connectors plugged in, no bre aks). ( 3 ) T h e h y dra ulic s y ste m s are pre s s uriz e d 1

SERVO 2

P P11

RH P P12 30

3

F WD

LH

SERVO Test

All the microswitches bre ak contact (the test pistons retract under the hydraulic pressure and the backup distributor valves return to the neutral position). The monitoring loop is closed and the indicator light goes out. C e document est la propriété d'E UR O C O PT E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'E UR O C O PT E R et son contenu ne peut être divulgué. This document is the property of E UR O C O PT E R ; no part of it shall be reproduced or transmitted without the express prior written authorization of E UR O C O PT E R and its contents shall not be disclosed. © E UR O C O PT E R 1998.

9.11

T HM

9.4.1. IN DIC ATIN G P RIN CIP L E O F S E RV O A C T U AT O R DIS T RIB U T O R VA LV E S EIZ U R E (C o nt.) ( 4 ) Te st with th e h y dra ulic s y ste m s pre s s uriz e d 1

SERVO 2

P P11

RH P P12

3

30

LH

F WD

SERVO Test

Pressing test pushbutton (3) once causes the monitoring loop to loop back on itself (the ground is lost) and the indicator light comes on. This test checks there is no short circuit in the line. If there is a short circuit (as shown above), the indicator light remains off. 5) S eiz ure of a distrib utor v alv e 1

SERVO 2

P P11

RH P P12 30

LH

F WD

SERVO

3

Test

If one of the distributor valves seiz es, the related microswitch makes contact and the monitoring loop goes open circuit: the indicator light comes on. N O T E : The " S E R V O " light also comes on for a drop in the LH or R H system hydraulic pressure.

9.4.2. C O M P O N E N T L O C ATI O N    ˇ  



   ˇ  



 

 

 

 









ˇ  







"S E RV O T E ST" pushbutton

9.12




 ˇ

T HM

9.5 - L O A D S E N S O R A N D " LIMIT " WA R NIN G LIG H T In highspe ed flight, tight small radius maneuvers generate high structural stresses capable of causing damage if the permissible load factors are exce eded. The loads on the main rotor incre ase with the load factor, and are partially transmitted to the control channels - especially the R H roll channel, which is the most he avily loaded. To warn

the pilot that the helicopter is at its maneuverability limit, a load sensor is mounted on the R H roll servo actuator. When the load on the servo actuator re aches the permissible threshold, a "LIMIT " light illuminates on the instrument panel to warn the pilot either to reduce the pitch or "open out" the maneuver.

9.5.1. D E T E C TIO N A N D IN DIC ATIN G P RIN CIP L E The servo actuator rod end consists of an actuator (1) supplied by the LH hydraulic system. In flight when the load (F) on the servo actuator is below the permissible value, the higher pressure (P) ke eps the piston se ated on the upper stop. Microswitch (2) is in its bre ak position. If the load (F) on the servo actuator exce eds the limit threshold, microswitch makes contact and the light comes on. Note: When the unbiased transistor T is saturated, the "LIMIT " light is off. A restrictor (3) damps out any pressure drops caused by rapid servo actuator movements. The charging time of capacitor (C) delays the illumination of the "LIMIT " light in response to small dynamic spikes.

SAMM

AIR-E Q UIP E M E N T

F P P12

P P11

LIMIT 1 30 T

Z

P

2

C

3

9.5.2. " LIMIT " LIG H T L O C ATIO N

   ˇ  

   ˇ  



 

 

 

 












 ˇ

9.13

T HM

9.6 - S A MM TAIL R O T O R S E RV O A C T U AT O R 9.6.1. M AIN C O MP O N E N T S A N D S P E CIFIC ATIO N S S P E CIFIC ATIO N S

Maximum stroke ............................................... 100 mm E ffective stroke ................................................. 84 mm S ervo force at 32 bar ........................................ 146 daN Bypass operation: P incre asing for unlocking ............................... 6 bar P decre asing for locking ................................ 14 bar

The servo actuator has a single cylinder (the tail rotor can be controlled without hydraulic assistance by me ans of the load compensator). The piston rod (1) is secured to the structure, and the mobile cylinder (3) is equipped with a long rod (4) to operate the tail rotor pitch change spider.

3

4

2

1 Lo a d comp e ns ator

Without hydraulic pressure, input lever (2) is locked.

R

1 - Input lever (connected to pedals) 2 - Distributor slide valve 3 - Bypass spring 4 - Bypass valve 5 - S ervo actuator cylinder 6 - Piston rod 7 - Lever (1) travel stop 8 - Input lever locking pin A - C ompression chamber B - E xtension chamber P - Pressure line R - R eturn line

P 2

1 3 4

8

7

9.14

A

B

6

5


T HM

9.6.2. TAIL S E R V O A C T U AT O R O P E R ATIO N ( 1 ) N orm al o p eratio n 1

8

R

A

P

The diagram shows the servo actuator compressed. When over 6 bar, the hydraulic pressure moves the bypass valve, which closes off the line interconnecting chambers A and B and unlocks input lever (1). Pilot action on the input lever, within the limits imposed by stop (8), moves distributor (2) which connects: - chamber A to the pressure line, - and chamber B to the return line. The servo actuator cylinder moves and tends to bring the input lever back into the neutral position while the pilot's control tends to move it away. When the pilot's control action stops, the input lever remains in place and the servo cylinder returns the input lever to neutral: the servo actuator then stops.

2

B

( 2 ) L o s s of h y dra ulic pre s s ure If the pressure drops below 14 bar, the spring pushes back the bypass valve and pin (7) locks the input lever in neutral. Chambers A and B are now interconnected. The servo actuator then acts as a simple rod transmitting movement.

( 3 ) P e d al " stiffe nin g " In hydraulic mode, if the pilot fe els that pedal operation is stiff (probably indicating excessive friction in the distributor), he must operate one of the switches (1 or 2) to close solenoid valve (3). With the solenoid valve closed, the pressure drops and the bypass valve interconnects chamber A and B.

7

B

A

P 3

1

2

P P11

P P12


9.15

T HM

9.7 - YAW L O A D C O MP E N S AT O R Moving the yaw pedals from stop to stop varies the pitch of the tail rotor blades from - 8° to + 23°. In flight when the rotor thrust is non-z ero (i.e. the pitch is not 0°), the z ero pitch return moment of the blades (partly compensated by the boss-type " C hinese " weights) tends to bring the pitch back to z ero. The servo actuator hydraulic pressure overcomes the rotor's z ero pitch return moment and cancels out the control reversal. Without any hydraulic pressure, the pedal operating force is very high. This is why a hydraulic device or "load compensator" has be en mounted in parallel with the tail rotor servo actuator.

C omp e ns ator le v er

C ontrol rod

C omp e ns ator connecting link S ervo actuator

S ole noid v alv e A ccumulator

P RIN CIPL E O F YAW L O A D C O MP E N S AT O R

7

1

5 6 2

3

4

Mo vin g to lo w pitc h

Pilot-applied force

Z ero pitch return force

In flight the helicopter's R H hydraulic system charges an accumulator (3) and an actuator (5). Any pedal movement acts on the servo actuator. In case of hydraulic failure (pump inoperative, le akage, etc.), the accumulator is kept charged by: - non-return valve (4) in the pressure circuit - pressure relief valve (2) set at 55 bar (N.B. The system's operating pressure is 40 bar) - solenoid valve (1), which is always closed and opened by the pilot. Mo vin g to hig h pitc h

Z ero pitch return force

C omp e ns ator force

A ccumulator pre ssure

Pilot-applied force

C omp e ns ator force

A ccumulator pre ssure

The total force applied by the pilot and by the compensator actuator is equal to the z ero pitch return force

9.16


T HM

10 F U E L SYST EM

10.1 -

O N E F U E L TA N K P E R E N GIN E

10.2 -

E SS E NTIA L F UN C TIO NS

10.3 -

F U E L TA N K FIL LIN G A N D V E N TIN G

10.4 -

F U E L S Y S T E M F U N C TIO N S

10.4.1.

F O RW A R D F U E L TA N K

10.4.2.

R E A R F U E L TA N K

10.4.3.

F U E L TA N K C R O S S F E E D

10.5 -

SIMP LIFIE D DIA G R A M O F T H E F U E L S Y S T E M

10.6 -

F U E L SYST EM C OMP O N E NTS

10.6.1.

E Q UIPM E N T O N M O U N TIN G PLAT E S

10.6.2.

E Q UIPM E N T O F E N GIN E F U E L S U P PLY S Y S T E M

10.7 -

F U E L S Y S T E M C O N T R O L S A N D M O NIT O RIN G


10 .1

T HM

10.1 - O N E F U E L TA N K P E R E N GIN E There are two fuel tanks, one per engine. The fuel tanks are structural units and are tandem-mounted below the M G B transmission deck, aft of the cabin bulkhe ad betwe en the baggage compartments. This ensures the centre of gravity (c.g.) of the fuel is below the aircraft's theoretical c.g.

E N GIN E 1

E N GIN E 2

F orward fuel tank capacity ................................... 330 l R e ar fuel tank capacity ........................................ 400 l Unusable fuel in forward tank ................................ 3.5 l Unusable fuel in re ar tank ..................................... 3.2 l

10.2 - E S S E N TIA L F U N C TIO N S ( 1 ) In d e p e n d e nt e n gin e fu el s y ste m s • The forward tank supplies engine 1 (LH engine). • The re ar tank supplies engine 2 (R H engine). ( 2 ) F u el cro s sfe e d fro m o n e ta n k to th e oth er A solenoid valve controls the transfer of fuel by gravity from one tank to the other. In flight, the fuel level in the two tanks can therefore be balanced; in particular with one engine inoperative, the crossfe ed enables all the fuel to be used.

Suction of E N GIN E 2

To E N GIN E 1

FWD

REAR

( 3 ) B o o ster p u m p failure The booster pump includes a bypass line with an inlet strainer. If one booster pump fails, fuel is drawn out of the tank via the strainer by the engine low-pressure pump. The strainer includes a non return valve to prevent the booster pump from discharging fuel back through the strainer into the tank in normal operation. Strainer with

Strainer with

non return valve

non return valve

Booster pump

10.3 - F U E L TA N K FIL LIN G A N D V E N TIN G

C rossf e e d

Booster pump

solenoid valve

The filler necks are located on the LH wall of e ach fuel tank and provide an expansion volume when the tanks are filled to the top. The air vent lines are routed to prevent fuel spillage if the helicopter were to roll over on its side.

10 .2


T HM

10.4 - F U E L S Y S T E M F U N C TIO N S 10.4.1. F O RWA R D F U E L TA N K F U N C TIO N S E N GIN E 1

• F u el s u p ply to L H e n gin e b y a b o o ster p u m p : This pump maintains the pressure at the engine pump input and ble eds the entire fuel system before starting. N O T E : If a booster pump fails during a mission, the pilot can continue the flight normally. Max. level

• F u el c o nte nts d ete ctio n : The fuel quantity in the tank is me asured by a capacitive fuel content gauge connected to an indicator graduated in percentage of the total capacity of both tanks.

FUEL

• " L o w le v el " in dic atio n : When the fuel quantity drops to 6 % of the total capacity of the fuel tanks, a thermistor detector illuminates a " F U E L" light to indicate 18 minutes of level flight remain. 40 l

10.4.2. R E A R F U E L TA N K It performs the same functions as the forward fuel tank.

10.4.3. F U E L TA N K C R O S S F E E D F uel is only cross-fed betwe en the tanks if one engine fails so that the maximum quantity of fuel in the tanks can be used. A " C/F E E D" pushbutton energizes the solenoid valve, which when fully open illuminates a light in the pushbutton. C A U TIO N: The different capacities of the 2 tanks and their relative positions require that certain precautions be taken when operating the crossfe ed valve. • If the tanks are full, the crossfe ed valve must not be opened, otherwise the forward tank would overflow via the air vent line. • When the re ar tank is full, the forward tank fuel contents re ading on the tank's indicator must be less than 40 % to balance the fuel levels. • When e ach tank contains less than 20 % fuel, level balancing results in a re ading difference of about 4 % higher for the forward tank.

330 LIT E R S

400 LIT E R S


10 .3

T HM 10.5 - SIMP LIFIE D DIA G R A M O F T H E F U E L S Y S T E M 1

1 2

2

3

P2 4

LH FILTER

RH FILTER

6

6

5

P1

E N GIN E 1

7

E N GIN E 2 10

8

4

5

P1

7

3

P2

10

8

13

FUEL

9

9 11

11

14

12

15

12

14

F ORWARD

R E AR

15

16

20

19

18

18

19

20

17

1 - Flowmeter transmitter (optional) 2 - High pressure fuel pump 3 - F ilter bypass with clogging indicator 4 - F uel filter 5 - Differential pressure switch ( P = P1 - P2) 6 - " F ilter pre-clogging" indicator light 7 - Low pressure fuel pump 8 - C alibrated orifice 9 - F uel pressure transmitter 10 - F uel pressure indicator 11 - F uel shutoff valve 12 - F uel shutoff valve control lever

10 .4

13 14 15 16 17 18 19 20

- F orward and re ar tank low level indicator flight - F uel contents indicator - F uel gauge transmitter - Pushbutton control of solenoid valve (17) - Crossfe ed solenoid valve - Booster pump - Strainer with non return valve - Pushbutton control of booster pump (18) Booster pump maximum flowrate ....................... 900 l/hr "Low level" indicator light comes on at ..................... 6% F ilter indicator light comes on at .................. P 1.2 bar F ilter bypass opens at ................................. P 2.2 bar


T HM

10.6 - F U E L S Y S T E M C O MP O N E N T S 10.6.1. E Q UIPM E N T O N M O U N TIN G P L AT E S ( 1 ) B o o ster p u m p 3

4

5

2 1

6

5

6 8 7

9

B O O S T E R P UMP D ATA

- C entrifugal pump (bladed rotor) - E xplosion-proof motor with R FI filter - R ated delivery 600 l/hr at 0.8 bar pressure A 400 l/hr flow through the non-operating pump results in a pressure drop of less than 60 mbar. F O R R E F E R E N C E:

TM319 consumption at M CrP ............... 127 l/hr approx. Maximum consumption at MT O P ......... 157 l/hr approx.

1 - Ble ed valve 2 - F uel crossfe ed connection 3 - F uel jettison provision 4 - F uel contents gauge 5 - E ngine fuel supply line 6 - Booster pump 7 - Pump drain 8 - Non return valve 9 - Strainer

( 2 ) C a p a citiv e fu el c o nte nts s y ste m A

B

A capacitive fuel contents system offers more reliable fuel contents me asurements and makes the "low level" alarm independent of the me asurement. This system provides operators having to work with low fuel levels (e.g. hoist operations) with fully redundant data.

C

2

FUEL 1 3

A m plifier

A m plifier

Power supply

F U EL C O NT E NTS G AU G E The fuel probe unit consists of 2 concentric electroplated tubes (A and C) forming the plates of a capacitor with either the fuel (below fuel level) or air (above fuel level) forming the dielectric (B). Since the dielectric constant of fuel is twice that of air, it is cle ar that the probe capacitance will vary with the fuel level; in fact, tubes A and C are electroplated so that the capacitance is proportional to the fuel level. The me asured signal is sent to the fuel contents indicator via an amplifier. A thermistor "fuel level low" detector (3) connected to another amplifier illuminates the " F U E L" light on failure warning panel 4 when there is 6 % of fuel remaining. The system is D C-powered and internally generates the A C power ne eded for its operation.

1 - F uel 2 - F uel contents gauge 3 - Level low sensor C e document est la propriété d'E UR O C O PT E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'E UR O C O PT E R et son contenu ne peut être divulgué. This document is the property of E UR O C O PT E R ; no part of it shall be reproduced or transmitted without the express prior written authorization of E UR O C O PT E R and its contents shall not be disclosed. © E UR O C O PT E R 1998.

10 .5

T HM

10.6.1. E Q UIPM E N T O N M O U N TIN G P L AT E (C o nt'd) ( 3 ) B le e d s y ste m

P ull knob

R eturn spring V alv e

The two ble ed valves are installed at the low point of e ach tank and are operated by a cable-controlled mechanism. The pull knobs are accessible on the LH side of the helicopter.

10.6.2. E Q UIPM E N T O F E N GIN E F U E L S U P P LY S Y S T E M ( 1 ) F u el s h utoff v alv e s E N GIN E

3

2 1

The operating levers (3) of the fuel shutoff valve (4) are installed in the M G B compartment and are connected to their control levers (1) by ball-flex cables (2).

Visual clogging indic ator

4

( 2 ) F ilter 6

7

5

ˇ 

8

10

11

4

3 2 1

9

10 .6

1 - F uel outlet 2 - F uel inlet 3 - E ngine oil inlet (fuel he ating system) 4 - Le aktight he at exchanger shell 5 - Filter cartridge 6 - Visual filter clogging indicator (magnetically attracted to bypass valve) 7 - Bypass valve (opening P bar) 8 - E ngine oil outlet (fuel he ating system) 9 - F uel drain orifice 10 - F uel/oil filter unit 11 - F uel filter pre-clogging differential pressure switch


T HM

10.6.2. E N GIN E F U E L S U P P LY S Y S T E M E Q UIPM E N T (C o nt'd) ( 2 ) F ilter F U EL FILT E R PR E-CLO G GIN G When P (P1-P2) re aches 1.2 bar, the differential pressure switch illuminates the " FILT E R " pre-clogging warning light on the failure warning panel. When this occurs, the pilot must apply the instructions specified in the Flight Manual.

RH FILTER

P2

P1

E N GIN E 2

F U EL FILT E R CLO G GIN G 3

2

ˇ



1

When P re aches 2.2 bar, the fuel pressure from the engine low-pressure pump forces the bypass valve (3) downward to open the filter bypass orifices (1) and thus supply the engine with unfiltered fuel. The top-to-bottom displacement of valve (3) bre aks the magnetic force attracting it to visual indicator (2); the indicator is thus rele ased and pushed upward by its spring so that its top part protrudes out of the filter unit. When the engine is shut down, the return spring pushes bypass valve (3) back to its top position. The clogging indicator (2) remains extended as it is beyond the magnetic attraction (incre ased distance from valve + effect of its spring). It must be pressed in by hand to bring it back into magnetic retention. When the indicator is out and visible, it indicates the engine has be en operated with unfiltered fuel. In this case refer to the engine manufacturer's documentation for the proper procedure. To fuel filter unit

( 3 ) F u el pre s s ure in dic atin g A pie zo-resistive pressure sensor (9) transmits a signal depending on the system pressure to the electronic unit (10), which converts the signal and outputs it to the fuel pressure indicator. N.B. The electronic unit delivers a calibrated current to power the sensor.

E N GIN E 2

9 10


10 .7

T HM

10.6.2. E Q UIPM E N T O F E N GIN E F U E L S U P P LY S Y S T E M (C o nt'd) ( 4 ) Pre s s ure tra n s mitter a n d differe ntial pre s s ure s witc h The fuel pressure transmitter (2) and the differential pressure switch (1) are mounted on the accessory drive housing on the LH side of the engines. 1

The pressure transmitter electronic units are located behind and at the bottom of the re ar cabin bulkhe ad. 2

10.7 - F U E L S Y S T E M C O N T R O L S A N D M O NIT O RIN G F uel crossfe ed pushbutton with integrated light

LH fuel shutoff lever

LH engine pump

R H fuel shutoff lever 

ˇ 

ˇ  









 

R H engine pump 

C O NTR OL PUSHBUTT O N PAN ELS F U EL C O NT E NTS INDIC AT O RS 45%

Tanks full

55%

FAILU R E WA R NIN G PA N E L

 

ˇ 





 

 

 ˇ 

 ˇ 

 

10 .8

 

 

 



 

ˇ  

ˇ 



 F U EL PR E SSUR E INDIC AT O RS


T HM

11 E L E C TRIC P O W E R

11.1 -

D C P O W E R G E N E R ATIN G S Y S T E M (28V)

11.1.1.

O V E R VIE W

11.1.2.

D C P O W E R S Y S T E M O R G A NIZ ATIO N A N D F U N C TIO N S

11.1.3.

D C P O W E R S Y S T E M C O MP O N E N T S

11.1.4.

D C P O W E R S Y S T E M O P E R ATIO N

11.1.5.

D C P O W E R DIS T RIB U TIO N

11.2 -

SIN G L E-P H A S E A C P O W E R G E N E R ATIN G S Y S T E M (26V A N D 115V, 400H Z)

11.2.1.

O P E R ATIN G P RIN CIPL E

11.2.2.

A C P O W E R S Y S T E M C O MP O N E N T S

11.2.3.

A C P O W E R S Y S T E M O P E R ATIO N

11.2.4.

A C P O W E R DIS T RIB U TIO N

11.2.5.

L O C ATIO N O F A C P O W E R S Y S T E M C O MP O N E N T S


11 .1

T HM

11.1 - D C P O W E R G E N E R ATIN G S Y S T E M (28V) 11.1.1. O V E R VIE W ( 1 ) B a sic prin ciple s of th e re d u n d a nt p o w er g e n eratin g a n d distrib utio n s y ste m

U 1+2

U1

Two distribution systems (1 & 2) are supplied via two busbars (1 & 2) from two power generating systems (1 & 2). The utiliz ation circuits are connected to the distribution buses: • U1 = utiliz ation circuits supplied by system 1, • U2 = utiliz ation circuits supplied by system 2, • U1 +2 = utiliz ation circuits with dual supply, • U3 = utiliz ation circuits with dual supply (supplied by both systems) and load shedding provision, Dual supply users are the essential consumers that are vital for in-flight safety. The single supply users are secondary consumers.

SYSTEM 2

SYSTEM 1

U2

U3

BUS 1

BUS 3

G E N E R AT O R 1

BUS 2

G E N E R AT O R 2

BATT E RY

C O NS E Q U E NTLY: • If one power generating system fails, the remaining generator is capable of supplying both distribution systems (U1 & U2). A number of particularly important safety-related utiliz ation circuits (e.g. fire extinguisher system) are provided with a redundant power supply from the aircraft battery (via the direct battery bus) and from power system 1 or 2. These circuits therefore remain operational even in the event of the failure of both power generating systems. ( 2 ) P o w er s o urc e s The aircraft is supplied with D C power from the following sources: - two starter-generators G 1 & G 2 (one per engine) when the engines are running, - the aircraft battery or a ground power unit when the engines are shut down. This is for starting the engines and performing checks and electrical tests.

U1 + B AT T

B AT T. B U S BUS 1

BUS 2

G E N E R AT O R 1

B attery

U2 + B AT T

E xt. power receptacle

G E N E R AT O R 2

G2

BASIC SP E CIFIC ATIO NS G E N E RAT O R O utput voltage regulated at ....................... 28.5 V R ated current .............................................. 150 A BATT E RY Voltage ......................................................... 24 V C apacity ................................................... 16 A-hr The standard helicopter has 1 battery Two batteries (option) may be fitted for cold weather starting.

11 .2


G1

T HM

11.1.2. D C P O W E R S Y S T E M O R G A NIZ ATIO N A N D F U N C TIO N S ( 1 ) G e n erators a n d c o u plin g d e vic e s Direct battery circuits

ˇ˛˝˝

 LH utiliz ation circuits

R H utiliz ation circuits









 

 





Load-shedding circuits









• The battery is connected to busbars PP8 and PP9 across two battery contactors 19P1 and 19P2. • Bus P P10 is connected to the system via two load-shedding contactors 23P1 and 23P2. • G enerators G 1 and G 2 are connected in parallel to the buses via generator contactors 22P1 & 22P2 and battery contactors 19P1 & 19P2. • Direct battery bus P P21 is connected to the battery positive terminal via contactor 35P. • The external power receptacle 8P supplies buses P P8, P P9 and P P10 via external power contactor 20P and contactors 23P1, 23P2.

R EM EMB E R When power is supplied via the external power receptacle, battery contactors 19P1, 19P2 and generator contactors 22P1, 22P2 are automatically open to isolate the helicopter generators from the ground power unit. Load-shedding contactors 23P1, 23P2 also act as bus coupling (tie) contactors, and are automatically closed when: - power is supplied from the external power receptacle, - power is supplied from the helicopter battery, - power is supplied from the helicopter generators. In flight the direct battery utiliz ation circuits are connected to the battery by the commanded closure of contactor 35P. This prevents the battery from being discharged after a flight by a utiliz ation circuit that was not switched off (e.g. cabin dome lights).


11 .3

T HM

11.1.2. D C P O W E R S Y S T E M O R G A NIZ ATIO N A N D F U N C TIO N S (C o nt.) ( 2 ) C ontrols The pilot has two types of controls: • G e n erator c o u plin g a n d is olatio n c o ntrols, c o n sistin g of " Push-on/push-off" switches. - a DIR E C T-BATT pushbutton (1) controlling contactor 35P. - a LH E XT PWR/BATT pushbutton (2) and a RH E XT PWR/ BATT pushbutton (3) controlling contactors 19P1 and 19P2, or contactor 20P when external power is supplied. - a G E N 1 pushbutton (4) and a G E N 2 pushbutton (7) controlling contactors 22P1 and 22P2. • E m erg e n c y c o ntrols - a LH B U S S H E D pushbutton (5) and a R H B U S S H E D pushbutton (6) which are normally pushed off: when either of these switches is pushed "on", the corresponding contactor 23P is tripped open, allowing bus P P10 to be isolated. - a G E N R E S E T pushbutton (10). - Two coupled E M E R G C U T O F F pushbuttons (8 and 9). When pressed "on", they open all the contactors except for 35P.

 1 ˇˇ˛˝

2

3

ˇ˛˝

˝ 

˝ 

ˇ˝ 

ˇˇ

ˇ˝ 

ˇˇ˝

ˇˇ ˝ 

4

˝ 

5

6

8

9

˝ 

˝ 

˝ 

˛  10

7

( 3 ) In dic ators 9

BAT 8

1 ˇˇ˛˝

7

2

ˇ˛˝

˝ 

˝ 

4

5 ˇˇ

ˇˇ˝

ˇ˝ 

ˇˇ

ˇ˝ 

˝ 

˝ 

6

3 ˝ 

˝ 

˝ 

˛  U. SHED U. R H E S S.

I L H G E N.

U. L H E S S.

I R H G E N.

In the normal flight configuration, all the warning lights are off. Illumination of a warning light indicates a fault condition in the corresponding circuit. • C uto ut w arnin g lig hts (1 thro u g h 7) E ach contactor is monitored by a warning light which operates as follows: - C ontactor closed: light off. - C ontactor open: light on. • B attery fu s e w arnin g lig ht (8) This light illuminates if the battery fuse blows. • B attery te m p erature w arnin g lig ht (9) This light illuminates if the battery temperature exce eds 71°C . The pilot must then isolate the battery by switching "off" the E X T P W R/B AT T pushbutton . • G e n erator v olta g e a n d c urre nt m o nitorin g A voltmeter (11) indicates the voltage of the generator connected to the primary busbars as chosen by selector (10). A z ero-center ammeter (12) is controlled by the same selector: the pointer deviates to the left to indicate the power consumption during engine starting, generator power output causes the pointer to deviate to the right.

10

11

11 .4

ˇ



12


T HM

11.1.2. D C P O W E R S Y S T E M O R G A NIZ ATIO N A N D F U N C TIO N S (C o nt.) ( 4 ) Prote ctio n circ uitry • Prim ary b u s a n d wirin g s h ort-circ uit prote ctio n. The system is designed to make short-circuits highly improbable: - Electrical master unit components are installed in he avyduty insulated shells. - E lectrical le ads to and from the master units are protected in vibration-, abrasion- and he at-resistant she aths.

BAT

To secondary buses

ˇˇ˛˝

To secondary buses

T HIS IS PA S SIV E P R O T E C TIO N

- S econdary bus fe eders le ading to the cockpit are protected by circuit-bre akers (D). T HIS IS A C TIV E P R O T E C TIO N



ˇˇ

ˇˇ˝ 

˝  LH E L E C T RIC MA S T E R U NIT

ˇˇ





To secondary buses

˛  RH E L E C T RI C MA S T E R U NIT

• B attery fe e d er s h ort-circ uit prote ctio n

BATT. FUS.

BAT F

• Dire ct b attery b u s s h ort circ uit prote ctio n A 30 amp circuit-bre aker (D) in the battery positive le ad protects the fe eder and bus P P21 against short circuits.

A 400-amp fuse (F) in the battery negative le ad isolates the battery to protect against current overloads caused by short-circuits on the battery fe eder or betwe en battery cells. The direct battery bus P P21 is then no longer supplied. The fuse controls a detection circuit which illuminates a B AT T F U S E light if the fuse blows. When the light comes on, the pilot must switch off both B AT T switches. The direct battery bus P P21 is then no longer supplied, but the circuits connected to it have redundant power supplies and continue to operate.

BAT ˇˇ˛˝ 

To electrical master unit C e document est la propriété d'E UR O C O PT E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'E UR O C O PT E R et son contenu ne peut être divulgué. This document is the property of E UR O C O PT E R ; no part of it shall be reproduced or transmitted without the express prior written authorization of E UR O C O PT E R and its contents shall not be disclosed. © E UR O C O PT E R 1998.

11 .5

T HM

11.1.2. D C P O W E R S Y S T E M O R G A NIZ ATIO N A N D F U N C TIO N S (C o nt.) ( 5 ) A uto m atic fu n ctio n s • E xtern al p o w er re c e pta cle prote ctio n - G enerator isolation: when power is supplied via the external power receptacle, two auxiliary external power relays RL4 & RL8 cut off the supply to battery contactors (19P1, 19P2) and to generator cut-in/cut-out contactors (22P1, 22P2). Load-shedding contactors (23P1, 23P2) act as bus coupling contactors. - O vervoltage protection: if the external power supply voltage exce eds 32 V, a fuse (9P) and related z ener diode cut off the excitation circuits of the external power contactor and auxiliary relays. - Polarity reversal protection: a series-connected diode in the control circuit prevents the auxiliary relays from closing if the polarity is incorrect.

 ˇˇ˛˝ ˇ˛˝

˝ 

˝  ˝ 

ˇˇ˝

ˇˇ ˇ˝ 

˝ 

ˇˇ ˇ˝ 

˝ 

AUX R E LAY

A U X ˝ R E LAY



˝ 

˝ 



˛  ˇ 



• B u s c o u plin g In normal operation, whenever a primary bus is energiz ed via the battery or generator contactor, the corresponding load-shedding contactor closes.

ˇˇ˛˝ ˇ˛˝

˝ 

˝  ˝ 

ˇˇ˝

ˇˇ ˇ˝ 

• G e n erator c o u plin g a n d is olatio n - The generators are coupled to their distribution buses when the generated output voltage exce eds their coupling bus voltage by 0.5 V. - The generators are isolated when a reverse current of 8 ± 2 amps is detected from the battery to the generator.

ˇˇ ˇ˝ 

˝ 

 ˇˇ˛˝

• Volta g e re g ulatio n a n d o v erv olta g e prote ctio n E ach generator is monitored by electronic voltage regulation and protection P C Bs performing the following functions: - Voltage regulation at 28.5 ± 0.5 V by modulating the excitation current - System overvoltage protection by cutting off the generator excitation and the generator contactor supply when the voltage (U) exce eds 31.5 V - P arallel coupling of the two generators by balancing their outputs within 10%; the generators are interconnected via a balancing circuit that detects any load imbalance betwe en them.

ˇ˛˝

˝ 

˝ 

ˇˇ˝

ˇˇ ˇ˝ 

ˇˇ ˇ˝ 

˝  ˝ 

B ala ncing

˝ 

˝ 

˝ 

R egul.

R egul.

Module

Module

˛ 

E xcitation

11 .6


T HM

11.1.2. D C P O W E R S Y S T E M O R G A NIZ ATIO N A N D F U N C TIO N S (C o nt.) ( 6 ) Dire ct b attery in dic atin g circ uit lo gic • S y ste m d e-e n ergiz e d Buses PP21, PP8 and PP9 are not energized: the DIR E C T B AT T light in pushbutton (3) is off.

 ˇˇ˛˝

3

ˇ˛˝

˝ 

ˇ 

˝ 

ˇˇ

ˇˇ

2

1

R H E X T P W R/ BATT

LH E X T P W R/ BATT

• B u s e s P P8 a n d P P9 e n ergiz e d  ˇˇ˛˝ ˇ˛˝

˝ 

ˇ 

˝ 

ˇˇ

3

ˇˇ

Power is supplied to primary buses P P8 and P P9 by energizing relays 19P1 and 19P2, which are controlled by the B AT T switches (1 and 2). The DIR E C T B AT T light (3) is illuminated to indicate that bus P P21 is not supplied since relay 35P is still in its bre ak position. In normal flight configuration, pressing the DIR E C T B AT T pushbutton (3) supplies power to bus P P21 by closing contactor 35P, which switches off the DIR E C T B AT T light.

2

1 LH E X T P W R/ BATT

R H E X T P W R/ BATT



• " DIR E C T-B ATT " pushbutton set to " O N " If the BATT1 and BATT2 switches are off, the DIR E C T BATT light (3) illuminates to indicate that bus P P21 is energiz ed.

ˇˇ˛˝ ˇ˛˝

˝ 

ˇˇ

1 LH E X T P W R BATT

3

ˇ 

˝ 

ˇˇ

2 RH EXT PWR BATT


11 .7

T HM

11.1.2. D C P O W E R S Y S T E M O R G A NIZ ATIO N A N D F U N C TIO N S (C o nt.) ( 7 ) D u al b attery in stallatio n In order to incre ase the available electric power, the electrical system may be equipped with a second battery having the same specifications as the standard battery. The addition of a 2nd battery permits:

- self-contained engine starting in cold we ather, - extended range in IF R conditions after the loss of both generators (one generator cut out and failure of the opposite engine).

B A SIC DIA G R AM O F D U AL B AT T E RY S Y S T E M BATT FUSE

˛ 

˝ 



BATT TEMP

ˇˇ˛˝ B AT G.

B AT D.

˝ ˇ˝

ˇ 

˝ ˇ˛

ˇˇ

ˇˇ˝ ˛ ˇ˝

ˇˇ ˛ ˇ

˛ ˇ˛

ˇ  ˛˛ˇ˝

˝ 

E ach battery is connected to the helicopter's electrical system via its respective battery contactor. The batteries are coupled by closing the load-shedding contactors. With this arrangement, a defective battery (overhe ating, short-circuit, etc.) can be isolated and the remaining "valid" battery kept connected to the system. Note that direct battery bus (P P21) is still supplied by the original equipment battery. In this installation, the generator balancing circuit is only monitored with load-shedding contactors energiz ed (se e page 11.21/22).

11 .8

˛˛ˇ˛

˛ 

The system indicator lights have the same functions as in the single-battery version but the procedures are not identical: - If the BATT F US E light illuminates, set both BATT switches to O F F and then back O N: the contactor for the faulty battery will not close and its light will remain on. - If the B AT T T E MP light illuminates, set both B AT T switches to O F F and wait until the B AT T T E MP light goes out. C ut e ach battery back into the system again and check the generators' current flows using the ammeter. The higher current on battery coupling can give an indication of the fault condition of the battery.


THM 11.1.3. DC POWER SYSTEM COMPONENTS GEN. LH

1P -- Battery m3P --LH starter generator m4P --RH starter generator 5PaU-6PaU --Single battery installation shunt terminals 8P --External power receptacle 19P1-19P2 --Battery contactors 20P --External power contactor 21P1-21P2 --Starting contactors 22P1-22P2 --Generator contactors 23P1-23P2 --Bus coupling or load-shedding contactors 28P1-28P2 --RFI filters 29P --Battery detecting fuse 35P --Direct battery contactor RL2-RL5 --Generator excitation relays RL3-RL7 --Bistable overvoltage/reset relays RL4-RL8 --Auxiliary external power relays PP8 --RH primary bus PP9 --LH primary bus PP10 --Load-shedding primary bus 1 --Direct battery switch 2 --LH bus load-shedding switch 3 --RH bus load-shedding switch 4 --Voltmeter (measuring volts on each primary bus) 5 --Selector (2 stages, 5 positions) 6 --Ammeter (measuring current in starter & generator modes) CRP1-CRP2 --Regulation and protection PCBs.

LH BUS SHED

PP11 PP12

BAT. LH

BAT. TEMP.

PP11 PP12

BAT. FUSE

DIRECT. BAT.

BAT. RH

PP11 PP12

PP11 PP12

RH BUS SHED

GEN. RH

PP11 PP12

1P

PP11 PP12

PP21 1

29P

35P F15

19P1

PP9

PP10 23P1

10P1

F13

PP19

F16

PP11

F1 5PaU 6PaU

PP13

Voltmeter

Voltmeter

8P

PP11 PP12

PP8 23P2

12P1 12P2

F5

2

19P2

START 1

10P2

3

PP14

F4

F2

PP12

20P

RL7

RL3

AUX START 1

RL2

AUX START 1

CRANK 1

CRANK 2 LH EXT PWR BAT

RH EXT PWR BAT

21P2

21P1 RL4

RL8

F14

9P

Voltmeter

START 2

EMERGENCY CUT-OFF RL5

F6

PP20

F3

START START

22P1

22P2

PP10 5

PP8

G1

PP9

F17

G2

F11

U +1V

V

A

4

6

REV. CURR.

REGUL

REGUL U>31.5V

GEN RESET

RESET

28P1

U>31.5V

U>32V

U +1V REV. CURR.

RESET

CRP1

CRP2 + GEN 1

28P2

+ GEN 2

m3P

m4P

G1


G2

11.9 /10

THM 11.1.4. DC POWER SYSTEM OPERATION This selection covers the main functional configurations:

GEN . LH

- power supply by external power receptacle, - power supply from the helicopter battery,

LH BUS SHED

PP11 PP12

BAT. LH

BAT. TEMP.

PP11 PP12

BAT. FUSE

DIRECT. BAT. PP11 PP12

PP11 PP12

- power supply from the generators. The starting function is described in chapter 12 "Engine Installation".

GEN. RH PP11 PP12

PP21

29P

( 1 ) Power supply via external power receptacle

35P F15

19P1

BAT 1

RH BUS SHED

PP11 PP12

1P

BAT

BAT. RH

F1 5PaU 6PaU

19P2

BAT 2 8P

PP9 F13

L/SHED PP9

PP19

PP10

PP10

10P1 F16

23P1

PP13

Voltmeter

PP8

Voltmeter

PP8

12P1 12P2

F5

PP11

PP11 PP12

START 1

10P2

23P2

PP14

F4

F2

PP12

GEN 1

9P

Voltmeter

START 2

20P


F6

PP20

RL7

RL3

RL2

GEN 2

G1

G2 AUX START 1

SYSTEM CONFIGURATION Energizing the external power receptacle has the following effects: • Via the small positive pin: - Relay RL4 is energized if the voltage is less than 32V and if the Battery/Ext. power switches are ON and the emergency cutoff switch is not set. • Via the large positive pin:

CRANK 1

• Pressing the EMERG. CUTOFF push-button de-energizes the external power priority relays RL4 and RL8, causing relay 20P to trip open. • The system is protected against an external power overvoltage exceeding 32V by fuse 9P and a zener diode. • The external power supply configuration is standard for ground test-

21P2

RL4

RL8

F14

F3

START START

22P1

22P2

F17 F11

U +1V

- Buses PP8, PP10, PP9 are supplied.

THE GROUND POWER UNIT HAS PRIORITY

RH EXT PWR BAT

21P1

- Bus coupling is ensured by load-shedding contactors 23P2, then 23P1 via the auxiliary contact of contactor 20P.

REMARKS • In the external power configuration, the battery and the generators are isolated:


- RL8 is energized by RL4 which makes contact. • After relay RL8 closes: - External power relay 20P is energized via contactors 22P1, 19P1, 19P2, 22P2 which break contact.

AUX START 1

REV. CURR.

REGUL U>31.5V

REGUL GEN RESET

RESET

28P1

U>31.5V

U>32V

U +1V REV. CURR.

RESET

CRP1

CRP2 + GEN 1

28P2

+ GEN 2

m3P

m4P

G1

G2

ing and for engine starting (when a ground power unit is available). The standard procedure is as follows: Power supply via the external power receptacle → Pre-starting checks and tests → Engine starting→ "Disconnection" of the ground power unit → Automatic generator coupling (the helicopter is now electrically self-sustaining and ready for flight). Ce document est la propriété d'EUROCOPTER ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'EUROCOPTER et son contenu ne peut être divulgué. This document is the property of EUROCOPTER ; no part of it shall be reproduced or transmitted without the express prior written authorization of EUROCOPTER and its contents shall not be disclosed. © EUROCOPTER 1998.

11.15 /16

THM 11.1.4. DC POWER SYSTEM OPERATION (Cont.) ( 2 ) Power supply from battery

GEN. 1

BAT

DELEST. BUS G.

PP11 PP12

BAT T. 1

T° BATT.

PP11 PP12

FUS. BATT.

DIRECT. BATT. PP11 PP12

PP11 PP12

DELEST. BUS D

GEN. 2

PP11 PP12

1P

BAT 1

BATT. 2

PP11 PP12

PP21

BAT 2 29P

35P

L/SHED PP9

1

F15

19P1

PP10

G1

GEN 2

PP10 23P1

10P1

F13

F16

PP19

PP11

G2

PP13

Voltmètre

Voltmètre

8P

PP8 23P2

12P1 12P2

F5

1

19 P2

PP11 PP12

2 PP9

GEN 1

F1 5PaU 6PaU

PP8

PP14

DEM.1

10P2

2

F4

F2

PP1 2

PP20 9P

Voltmètre

DEM.2

20 P

COUPE-TOUT RL5

F6

RL7

RL3

RL2

SYSTEM CONFIGURATION Both load-shedding switches (1 - 2) are tripped. The two Battery/Ext. power switches are ON: Battery contactors 19P1 & 19P2 close, buses PP8 & PP9 are supplied from the battery and the BATT lights are out. The bus coupling function between PP8 and PP9 via PP10 is performed by the closures of load-shedding contactors 23P1 and 23P2, energized by their respective primary buses. The GEN lights are illuminated.

GEN.1

AUX DEM.1

AUX DEM. 2

VENTIL.1

VENTIL.2 BATT PARC G

GEN. 2

BATT PARC D

21P2

21P1

F14

RL4

RL8

F3

DEM

REMARKS 22P1

• When in the normal position, the EMERG. CUTOFF switch allows the battery relays to be energized. • The battery supply configuration is the standard for ground testing and engine starting when no ground power unit is available. The standard procedure is as follows: Power supply from battery → Pre-starting checks and tests → Engine starting → Generator coupling after starting the 2nd engine. NOTE: If the battery charge is insufficient to start the 2nd engine while complying with the limitations, cut in the generator of the 1st engine before starting the second engine.

DEM

22P2

F17 F11

U +1V CONJ.

REGUL U>31.5V

REGUL REARM. GEN

REARM

28 P1

U>31.5V

U>32V

U +1V CONJ.

REARM

CRP1

CRP2 + GEN 1

28P2

+ GEN 2

m3P

m4P

G1


G2

11.17 /18

THM 11.1.4. DC POWER SYSTEM OPERATION (Cont.) ( 3 ) Power supply from helicopter generators, Coupling of 1st generator

GEN. LH

LH BUS SHED

PP11 PP12

BAT. LH

BAT. TEMP.

PP11 PP12

BAT. FUSE

DI RECT. BAT.

BAT. RH

PP11 PP12

PP11 PP12

RH BUS SHED

GEN. RH

PP11 PP12

1P

PP11 PP12

PP21

BAT 29P

BAT 1

BAT 2

35P F15

19P1

F1 5PaU 6PaU

L/SHED PP9

PP10

PP8

8P

PP9 PP19

G1

GEN 2

PP10 23P1

10P1

F13

GEN 1

19P2

F16

PP13

Voltmeter

Voltmeter

PP8 23P2

12P1 12P2

F5

PP11

PP11 PP12

START 1

PP14

10P2

F4

F2

PP12

F6

PP20 9P

Voltmeter

START 2

G2 20P


RL7

RL3

RL2

ASSUMPTIONS • The system is initially in the battery power configuration. • The RH engine is not running. • The LH engine is starting.

AUX START 1 CRANK 1

SYSTEM CONFIGURATION • The GEN 1 & GEN 2 switches are ON. • Excitation relays RL5 & RL2 make contact: the excitation and regulation circuits of the generators are active. • When generator 1 voltage exceeds the battery voltage by 0.5V, the cut-in system grounds line contactor 22P1.

AUX START 1 CRANK 2 LH EXT PWR BAT

RH EXT PWR BAT

21P2

21P1 RL4

RL8

F14

F3

START

• Generator 1 is coupled to bus PP9 and to bus PP8 via the 2 battery contactors 19P1 & 19P2.

START

22P1

22P2

• The bus coupling function with PP10 is ensured by loadshedding contactors 23P1 & 23P2. • The GEN1 light goes out.

F17 F11

U +1V

REMARKS • As soon as one generator is coupled, the battery becomes a consumer, i.e. reverts to charging mode.

REV. CURR.

• The voltage on all the system buses is equal to the generator G1 output voltage of 28 ± 0.5V.

REGUL

REGUL U>31.5V

GEN RESET

RESET

28P1

U>31.5V

U>32V

U +1V REV. CURR.

RESET

CRP1

CRP2 + GEN 1

28P2

+ GEN 2

m3P

m4P

G1


G2

11.19 /20

THM 11.1.4. DC POWER SYSTEM OPERATION (Cont.) ( 4 ) Power supply from helicopter generators, Coupling of 2nd generator

GEN. LH PP11 PP12

BAT

BAT 1

LH BUS SH ED

BAT. LH

BAT. TEMP.

PP11 PP12

BA T. FUSE

DIRECT. BAT.

BAT. RH

PP11 PP12

PP11 PP12

GEN. RH

PP11 PP12

1P

BAT 2

RH BUS SHED PP11 PP12

PP21

29P

35P

PP9

PP10

F15

19P1

L/SHED

F1

19P2

5PaU 6PaU

PP8 8P

PP11 PP12

PP9 F16

PP19

GEN 1 G1

GEN 2

PP10

10P1

F13

PP8

12P1 12P2

23P1 PP11

PP13

Voltmeter

Voltmeter

10P2

23P2

F5

START 1

F4

F6

F2

PP14

PP12

PP20 Voltmeter

START 2

9P

G2 20P


ASSUMPTIONS

RL7

RL3

RL2

Generator 1 is coupled and supplying the 3 buses PP8, PP9 and PP10. Engine 2 is driving generator 2, which is not energized. AUX START 1

SYSTEM CONFIGURATION Pressing the "GEN 2" switch activates the excitation and regulation circuits of generator 2, by closing excitation relay RL2. For the cut-in system to detect a generator 2 overvoltage of at least 0.5V, an additional "U + 1 volt" circuit offsets the voltage regulation threshold while line contactor 22P2 is in break position. Generator 2 is coupled into the system. All the indicator lights are off. • The voltmeter reading is the same in with the reading selector set to RH PRIMARY, LH PRIMARY, L/SHED because the generators are coupled.

CR ANK 1 RH EXT PWR BAT

21P2

21P1 F14

RL4

RL8

F3

START START 22P1

22P2

F17 F11

U +1V REV. CURR.

REMARKS

• When the generator's second contactor is in make position, the balancing system cut-in system is grounded via the auxiliary contacts of the system contactors. The balancing line controls the voltage regulating circuits to balance the generator outputs within ± 10%.


• The ammeter indicates the load current of each generator when the selector is set to LH GEN, RH GEN.

• If a generator fails, the cut-in system opens when the reverse (bus to generator) current exceeds 8 ± 2 A. When the coupling conditions are realized again, the generator is automatically recoupled.

AUX START 1

REGU L

REGUL U >31.5V

U >31.5V

GEN RESET

RESET

28P1

REV. CURR.

RESET

CRP1

CRP2 + GEN 1

G1

28P2

+ GEN 2

U. SHED

m3P

U>32V

U +1V

m4P

U. RH PRIM

LH GEN

U. LH PRIM

RH GEN

V


G2

A

11.21 /22

T HM

11.1.3. D C P O W E R S Y S T E M C O MP O N E N T S (C o nt.) ( 1 ) C o ntrol a n d m o nitorin g O V E R H E A D PA N E L P U S H B U T T O N S

1 - G enerator 1 contactor pushbutton 2 - B attery 1 contactor pushbutton 3 - Voltmeter/ammeter selector 4 - Direct battery contact pushbutton with built-in indicator light 5 - B attery 2 contactor pushbutton 6 - G enerator 2 contactor pushbutton 7 - Voltmeter 8 - Ammeter

8

7 

ˇ 

ˇ  









 

1



2

3

5

4

6

P U S H B U T T O N PA N E L LH-RH GEN RESET

EMERGENCY CUT-OFF

1

2

RH BUS SHED.

3

LH BUS SHED.

4

1 - G enerator reset pushbutton 2 - R H load-shedding contactor pushbutton with built-in indicator light 3 - LH load-shedding contactor pushbutton with built-in indicator light 4 - C oupled LH-R H system emergency cutoff pushbutton

ˇ    ˇ 

 

 



 

 

 

 

 



 

ˇ    



 

 

 

 











 

 

 

 





  





FAILU R E WA R NIN G PA N E L C e document est la propriété d'E UR O C O PT E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'E UR O C O PT E R et son contenu ne peut être divulgué. This document is the property of E UR O C O PT E R ; no part of it shall be reproduced or transmitted without the express prior written authorization of E UR O C O PT E R and its contents shall not be disclosed. © E UR O C O PT E R 1998.

11 .11

T HM

11.1.3. D C P O W E R S Y S T E M C O MP O N E N T S (C o nt.)

E xternal power receptacle

G enerator

B attery detecting fuse

BATT E RY

11 .12

E L E C T RIC AL MA S T E R U NIT S


T HM

11.1.3. D C P O W E R S Y S T E M C O MP O N E N T S (C o nt.)

E L E C T RIC AL MA S T E R U NIT S

O V E RV OLTA G E T E ST PUSHBUTTON

G E N E R AT O R V OLTA G E A DJU S TM E N T

RETURN CURRENT TEST PUSHBUTTON

+ G E N E R AT O R V OLTA G E JA C K C ONNE CTOR

N E G ATIV E JA C K C ONNE CTOR + B ALA N CIN G JA C K C ONNE CTOR

ˇ˛˝ ˇ  ˇ ˝ ˝ 

ˇ ˝



 ˇ

 

ˇ  ˇ ˝

B ALA N CIN G A DJU S TM E N T

 ˛

ˇ

ˇ  ˇ

ˇ˝ 

ˇ 

RH MA ST E R UNIT

ˇ ˝ˇ



˝  ˇ ˝

 

˝ 

˛ 

 ˇ 

ˇ ˝



ˇ 

 

ˇ  ˛ ˇ ˝ˇ ˝ˇ 

ˇ˛  ˇ˝ˇ 

ˇ ˝ˇ

 ˇ 



ˇ ˝

ˇ   ˇ

ˇ 

ˇˇ 

N E G ATIV E JA C K C ONNE CTOR   ˇ    ˇ

 



+ G E N E R AT O R V OLTA G E JA C K C ONNE CTOR



+ B ALA N CIN G JA C K C ONNE CTOR

ˇ 

ˇ 

LH MA ST E R UNIT ˝ˇ 

B ALA N CIN G A DJU S TM E N T

 



RETURN O V E RV OLTA G E T E ST CURRENT TEST PUSHBUTTON PUSHBUTTON

G E N E R AT O R V O LTA G E A DJU S TM E N T


11 .13 /14

T HM

11.1.4. D C P O W E R S Y S T E M O P E R ATIO N (C o nt.) ( 5 ) P o w er s u p ply fro m aircraft g e n erators : d e-e n ergizin g a n d re s ettin g + (P P9) 

ˇ 

ˇ 



ˇ ˇ 

ˇ

 ˇ 

 ˇ 

ˇ 









ˇ˛˝¸ ˇˇ¸ 

ˇ 



 

ˇ 

ˇ˛˝¸



˛ 

The system is shown in self-contained reset configuration



¸ 

Without going into unnecessary detail about relatively complex operation of the voltage regulator, it is important to know that excitation relay RL5 is controlled by a bistable relay RL7 and the E M E R G E N C Y C U T O F F switch. R elay RL5 bre aks the generator excitation circuit: - if an overvoltage exce eding 31.5 V is detected, - or if the pilot actuates the E M E R G C U T O F F switch. D E-E N E R GIZIN G C O NDITIO NS • O v erv olta g e If the voltage exce eds 31.5 V, an electronic circuit causes bistable relay RL7 to trip: - Line contactor 22P1 opens - E xcitation relay RL5 opens. • E m erg e n c y c utoff When the E M E R G C U T O F F switch is tripped open: - E xcitation relay RL5 opens. - Line contactor 22P1 opens.

R E S E TTIN G A " G E N R E S E T' pushbutton activates an electronic circuit shared with the self-contained reset function to reset the bistable relay and thus restore the generator excitation current. R esetting is possible even if the primary bus is de-energiz ed (self-contained reset). S ELF-C O NTAIN E D R E S E T F UN C TIO N In the event of a generator fault with loss of voltage on the primary bus, this circuit uses the generator remanence to supply a current pulse to the excitation circuit via the bre ak contact of relay RL5. When the generator voltage is high enough, bistable relay RL7 is supplied together with excitation relay RL5. Line contactor 22P1 closes, and the generator is coupled to the system. N O T E that the G E N 1 switch remains "on" throughout this procedure.


11 .23

T HM

11.1.5. D C P O W E R DIS T RIB U TIO N ( 1 ) Prin ciple

Primary bus (generation)



The utiliz ation circuits, protected by fuses, are supplied from a distribution bus which in turn is supplied from the primary power buses. The distribution buses and fuses are located on distribution panels on the cockpit ceiling and console.

Supply cable Distribution bus

Utiliz ation circuits

B us e s P P 8 a nd P P 9 supply bus e s P P12, P P20 and P P11, P P19 respectively for the essential utiliz ation circuits. All these utiliz ation circuits have redundant (dual) power supplies. Bus P P10 supplies buses P P13, P P14, whose secondary utiliz ation circuits are located on two panels (pilot's and copilot's circuits) and may be shed from the system in flight. Safety-related utilization circuits (e.g. fire extinguishing) are supplied from the "direct battery" bus P P21.





ˇ ˇ ˇ

16



( 2 ) Distrib utio n s y ste m org a niz atio n



DIR E C T BATT E RY

ˇ˛˝

LH MAST E R U NIT

ˇˇ ˛

R H MA S T E R U NIT

ˇˇ˝

ˇˇ˛

ˇ ˝ˇ

ˇ ˝ˇ

˛

7

ˇ ˝

7

ˇˇ˛

ˇˇ˛

10 SE C ONDARY utiliz ation circuits ( C opilot)

ˇˇ˛˛

ˇ ˝



SE C ONDARY utiliz ation circuits (Pilot)

ˇˇ˛

8 ˇˇ˛˝

ˇˇ

ˇˇ 

E S S E N TIAL utiliz ation circuits (R edundant supply)

( 3 ) F u s e p a n el lo c atio n 7 1 V ertic al Spare fuses 7 1 Horizontal

8

+ 7 2 V ertical

7 2 H oriz ontal 10

11 .24

16

Direct battery panel


T HM

11.2 - SIN G L E-P H A S E A C P O W E R G E N E R ATIN G S Y S T E M (26 V A N D 115 V, 400 H z) 11.2.1. O P E R ATIN G P RIN CIP L E Two static inverters supplied by the D C power system each generate: - single-phase 26 VA C - single-phase 115 VA C E ach inverter is connected to a separate distribution system supplying radionavigation equipment requiring A C power. Both inverters are powered in normal operation. If one inverter fails, the remaining inverter is capable of supplying both systems: the systems transfer function is automatic. The system may be equipped with an optional manual transfer provision.

STATIC IN V E R T E R 2

STATIC IN V E R T E R 1

26 V

26 V

115 V

115 V SYSTEM 2

SYSTEM 1

Inverter transfer options are indicated by broken lines.

11.2.2. A C P O W E R S Y S T E M C O MP O N E N T S LH INV P P19

1

2 LH INV

5

1X P10 A

115V 26V

3

4

U<60V

U<14V

1X P11 A 6 T

K1

K2 7

26V 115 V

8

115 V

3

1

P P20

U<60V

RH INV

4 U<14V

K1

T

K2

26V

6 2X P11 A

26V 115V

2

RH INV

1 - Inverter control switches 2 - Static inverters 3 - 115 V undervoltage detector 4 - 26 V undervoltage detector 5 - Inverter failure warning lights

2X P10 A 5

6 - R elay K1 time delay 7 - Voltmeter (26 V and 115 V re adings) 8 - Voltmeter selector K1 - Protection relay K2 - Transfer relay


11 .25

T HM

11.2.3. A C P O W E R S Y S T E M O P E R ATIO N ( 1 ) N orm al o p eratio n LH INV P P19

LH INV

115V 26V

U<60V

U<14V T

T U<60V P P20

K1

K1

K2

K2

26V

115V

115V 26V

U<14V

26V

RH INV

115V

RH INV

Both switches are O N. Both inverters are supplied with D C power and produce 115 VA C and 26 VA C outputs to their respective distribution systems.

The undervoltage detectors are not active, and the protection relays K1 are de-energiz ed. R elays K2 are energiz ed, and couple the A C buses to the corresponding inverter.

( 2 ) F ailure of o n e static in v erter LH INV P P19

LH INV

115V 26V

U<60V

U<14V T

T U<60V P P20

K1

K2

K2

26V

115V

115V 26V

U<14V

26V

RH INV

115V

The figure shows a failure of the 115 VA C output from the R H inverter

RH INV

The 115 V output drops below 60 V: the undervoltage detector makes the power supply circuit to protection relay K1.

11 .26

K1

Transfer relay K2 is de-energiz ed, allowing the R H A C buses to be supplied from the LH A C buses. The " R H IN V " light illuminates.


T HM

11.2.3. A C P O W E R S Y S T E M O P E R ATIO N (C o nt.) ( 3 ) S h ort-circ uit o n R H 115 VA C b u s

F

LH INV P P19

LH INV

115V 26V

U<60V

U<14V T

Inhibiting lin e s

K1

K1

T U<60V

K2

K2

26V

115V

115V 26V

U<14V

26V

P P20

RH INV

115V

RH INV

Initially, the 115 V undervoltage detector for the R H inverter is activated and energizes protection relay K1. Transfer relay K2 is de-energiz ed, illuminating the " R H IN V " light and allowing the short-circuit to be supplied from the LH inverter. A s a re s ult, the 115 V undervoltage detector for the LH inverter is activated and relay K1 is energiz ed. R elay K2

remains energiz ed, however, since it is grounded via the de-energized contacts of the RH inverter transfer relay (the "inhibiting line "). The LH inverter thus continues to fe ed the short-circuit for approximately 35 ms until the fuse (F) blows: this occurs before the internal inverter protection circuits operate. The 115 VA C supply on the R H bus is then definitively cut off.

11.2.4. A C P O W E R DIS T RIB U TIO N 2X P11 A

1X P11 A

2X1

2X2 2X P10 A

1X P10 A 26V

115 V

LH INV

26V

115 V

TRANSF ER

RH INV

E ach static inverter receives a single D C power supply input. All A C utiliz ation circuits are supplied from the pilot's fuse panel 2 x 2. The copilot's fuse panel 2 x 1 includes only fuses for the LH power system.

P P20

P P19

8


11 .27

T HM

11.2.5. L O C ATIO N O F A C P O W E R S Y S T E M C O MP O N E N T S

S TATIC IN V E RT E R S P E CIFIC ATIO N S

Total power rating ....................................... 300 VA Distributed power rating 115 VA C ............... 150 VA 26 VA C .............. 150 VA Power input ................................................ 28 VD C C urrent draw at maximum load .................... 16.3 A O utput frequency ........................................ 400 H z  

R H inverter



ˇ

AC voltm eter

LH inverter F use panel 2 X1 & undervoltage detectors



ˇ 

ˇ  









 



LH static inverter control pushbutton

F use panel 2 X 2 & undervoltage detectors

ˇ    ˇ 

 



 

 

 

 

11 .28

 

 



 

ˇ    



 

R H static inverter control pushbutton S elector 115V / 26V

 

 

 











 

 

 

 





  






T HM

12 E N GIN E IN S T A L L A TIO N

12.1 -

D E S C RIP TIO N O F T H E E N GIN E S

12.1.1.

O V E R VIE W O F T H E E N GIN E S

12.1.2.

SIMPLIFIE D E N GIN E S C H E MA TIC A N D S P E CIFIC A TIO N D A T A

12.2 -

E N GIN E L U B RIC A TIO N S Y S T E MS

12.2.1.

P RIN CIPL E O F E N GIN E LU B RIC A TIO N

12.2.2.

L O C A TIO N O F E N GIN E LU B RIC A TIO N S Y S T E M C O MP O N E N T S

12.3 -

A U T O M A TIC G O V E R NIN G S Y S T E M

12.3.1.

E L E C T RIC AL E N GIN E G O V E R N O R M O NIT O RIN G

12.3.2.

E N GIN E C O N T R O L WIT H V A RIA BL E N1

12.3.3

E N GIN E M O NIT O RIN G

12.3.4.

M E C H A NIC AL F U E L F L O W C O N T R O LS

12.4 -

E N GIN E S T A R TIN G C O N T R O L S

12.4.1.

G E N E R AL

12.4.2.

S T A R TIN G S Y S T E M F U N C TIO N AL CIR C UIT DIA G R AM

12.4.3.

O P E R A TIO N O F S T A R TIN G S Y S T E M

12.4.4.

L O C A TIO N O F S T A R TIN G S Y S T E M C O MP O N E N T S

12.5 -

E N GIN E P O W E R M O NIT O RIN G

12.5.1.

G A S G E N E R A T O R R O T A TIO N S P E E D (N1)

12.5.2.

F R E E T U R BIN E R O T A TIO N S P E E D (N2)

12.5.3.

E X H A U S T G A S T E MP E R A T U R E (T4)

12.5.4.

E N GIN E T O R Q U E (C)

12.5.5.

L O C A TIO N O F E N GIN E M O NIT O RIN G C O MP O N E N T S

C e document est la propriété d'E U R O C O P T E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation pré alable écrite d'E U R O C O P T E R et son contenu ne peut être divulgué. This document is the property of E U R O C O P T E R ; no part of it shall be reproduced or transmitted without the express prior written authoriz ation of E U R O C O P T E R and its contents shall not be disclosed. © E U R O C O P T E R 1998.

12 .1

T HM

12.1 - D E S C RIP TIO N O F T H E E N GIN E S 12.1.1. O V E R VIE W O F T H E E N GIN E S The helicopter is powered by two TM 319 " A R RIU S " turboshaft engines. T h e t e c h n o l o g i c a l a n d f u n c ti o n a l a s p e c t s o f t h e powerplant are described in the E N GIN E manufacturer's documentation. O nly the E N GIN E installation on the helicopter will be covered here. The fre e power turbine engines are installed aft of the Main G e arbox (M G B), in separate ventilated, drained, fireproof bays. The two engines are identical and interchange able. O n the helicopter: • the LH E N GIN E is E N GIN E 1 • the R H E N GIN E is E N GIN E 2 F uel and oil lines, E N GIN E controls and electrical wiring are all either fire-resistant or fireproof. All firewalls (bulkhe ads) are made of titanium. The digital governor computers are located in the re ar baggage compartment.

N o. 2

MG B

N o. 1

E N GIN E B A Y LA Y O U T

A R RIU S E N GIN E S

E N GIN E G O V E R N O R DIGIT AL C O MP U T E R S

(E N GIN E control and monitoring)

12 .2


T HM

12.1.1. O V E R VIE W O F T H E E N GIN E S (C o nt.) E N GIN E M O U N T S E N GIN E lug attachment flange D amper protective shell

Elastomer damper

E ach E N GIN E is coupled to the M G B combiner ge arbox by a connecting housing and a gimbal ring (C hapter 3.2), and is secured to a damper mount (A) in the E N GIN E bay.

D amper mount

12.1.2. SIMP LIFIE D E N GIN E S C H E M A TIC A N D S P E CIFIC A TIO N D A T A C entrifugal compressor

Air intake

R everse-flow combustion chamber

Starter-generator drive coupling

Power turbine

R eduction ge ar

Power transmission shaft

• Fre e-turbine turboshaft E N GIN E : coaxial independent gas generator shaft and power turbine shaft. • Annular reverse-flow combustion chamber with pre-vaporiz ed fuel injection.

G as generator turbine

• C onstant fre e turbine rotation spe ed (N2) maintained by full-authority digital governing system; manual fuel flow control available in case of governor failure. • S elf-contained lubrication system.

S P E CIFIC A TIO N D A T A

E N GIN E weight without starter, exhaust noz zle and air intake plenum ............................................... 92 Kg G as generator rotation spe ed (100% N1) .................................... 54,117 rpm Fre e turbine rotation spe ed (constant N2) ................................... 45,438 rpm Power takeoff rotation spe ed (reduction ge ar output) ..................... 6016 rpm Maximum takeoff power rating (MT O P) ............................................ 340 K W Maximum contingency power rating (M C P) ...................................... 380 K W C e document est la propriété d'E U R O C O P T E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation pré alable écrite d'E U R O C O P T E R et son contenu ne peut être divulgué. This document is the property of E U R O C O P T E R ; no part of it shall be reproduced or transmitted without the express prior written authoriz ation of E U R O C O P T E R and its contents shall not be disclosed. © E U R O C O P T E R 1998.

12 .3

T HM

12.2 - E N GIN E L U B RIC A TIO N S Y S T E MS 12.2.1. P RIN CIP L E O F E N GIN E L U B RIC A TIO N Hot oil from the engines is recycled through a cooling system. E ach E N GIN E has a separate, opposite handed cooling system. Prin ciple : Hot oil is forced by the E N GIN E scavenge pumps (16) through a he at exchanger (cooler) (20) across which fresh air is drawn by fans to cool the oil. From the cooler outlet, the oil returns to the reservoir (1) from which it is drawn by the E N GIN E oil pump (17). A thermostatic ally controlle d v alv e (19) byp a ss e s th e E N GIN E oil cooler to ensure quick warm-up after starting. LU B RIC A TIO N S Y S T E M M O NIT O RIN G

E ach oil system includes the following monitoring provisions: - O il pre s s ure indicator (11) - O il te m p erature indicator (4) - Ma g n etic c hip detector warning light (12) - O il filter clo g gin g via the failure annunciator - O il pre s s ure dro p warning light (8)

F U N C TIO N AL S P E CIFIC A TIO N S

O il pressure:

Max ........................................ 10 bar Min (N1>70%) ....................... 1.7 bar Normal in flight ............. 1.7 to 10 bar O il temperature maximum in operation .............. 107°C Bypass valve setting ................................ P = 2.2 bar Pressure relief valve setting ............................... 10 bar Pre-clogging valve setting ........................ P = 1.2 bar Thermostatic valve set points F ully open ................................ < 96°C F ully closed .............................. 106°C O il flow rate in lubrication system ..................... 800 l/h Lubrication system capacity ............................ 4.8 liters

ENG. P

4

to failure annunciator

1

11

12

8 10

7 6 3

20

CHIPS LH ENG.

9

5

2 18 LH E N GIN E

17 19 15

16

14

1 - O il reservoir 2 - Magnetic plug 3 - T emperature probe 4 - O il temperature indicator 5 - O il/fuel filter unit 6 - F ilter pre-clogging magnetic contactor 7 - Low oil pressure switch 8 - Low oil pressure warning light (shared by 2 engines) 9 - O il pressure transmitter 10 - O il pressure electronic unit

12 .4

11 12 13 14 15 16 17 18 19 20

13

- O il pressure indicator - E N GIN E chip detection warning light - Strainer - C hip detector - Strainer & chip detector - Scavenge pumps - Pressurizing pump - Pressure relief valve - Thermostatic valve - O il cooler


T HM

12.2.2. L O C A TIO N O F E N GIN E L U B RIC A TIO N S Y S T E M C O MP O N E N T S

3

7 6

2

1

8

4

5

9

10

12

11

1 - E N GIN E oil reservoir 2 - O il level sight 3 - F iller spout strainer 4 - T emperature probe 5 - Magnetic plug 6 - Two-stage oil cooling fan

7 8 9 10 11 12

- M G B oil cooler - E N GIN E oil cooler - Thermostatic valve - O il cooler air intake scre en - Magnetic plug in re ar be aring oil return line - Magnetic plug with electrical chip detector on reduction ge ar casing


12 .5

T HM

12.2.2. L O C A TIO N O F E N GIN E L U B RIC A TIO N S Y S T E M C O MP O N E N T S (C o nt.)

ˇˇ 

1



 ˇ

 







ˇˇ

 ˇ 

2

 

ˇ ˇ

 



1 warning light for both engines 5 3 4

1 2 3 4 5

- O il filter pre-clogging magnetic contactor - O il low pressure switch - O il pressure transmitter - E lectric chip detector - F ailure annunciator (oil filter pre-clogging) E N GIN E OIL P R E S S U R E IN DIC A T O R S

Oil pressure electronic units

12 .6

E N GIN E OIL T E MP E R A T U R E IN DIC A T O R S C e document est la propriété d'E U R O C O P T E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation pré alable écrite d'E U R O C O P T E R et son contenu ne peut être divulgué. This document is the property of E U R O C O P T E R ; no part of it shall be reproduced or transmitted without the express prior written authoriz ation of E U R O C O P T E R and its contents shall not be disclosed. © E U R O C O P T E R 1998.

T HM

12.3 - A U T O M A TIC G O V E R NIN G S Y S T E M E N GIN E governing consists in regulating the fre e turbine spe ed to a virtually constant value irrespective of the E N GIN E power demand by adjusting the gas generator spe ed as necessary. A full-authority digital governor is used for this purpose. The governing system comprises: - an electrically controlled hydromechanical unit - an electronic unit to analyse the E N GIN E and flight con-

P1 T2

trol parameters. The electronic unit implements the following functions: - optimum automatic E N GIN E starting - N2 regulation - overspe ed protection - sensor and computer self-monitoring

N1

P3

N2 T4.5

E L E C T R O NIC G OVERNOR U NIT

Pitch/throttle coupling

Y aw axis coupling

Stepper motor from H P fuel pump Metering unit

to fuel injectors

Hydromechanical Unit N2 (and therefore N R) governing may be described simply as follows: In response to E N GIN E load variations, the computer analyz es the input parameters (P1 - T2 - N1 - P3 - N2 T4.5 as well as the collective pitch/yaw coupling) to proc-

ess an N1 setpoint value, which is compared with the actual N1 value; the computer then uses a proportional function to determine a new position command for the metering unit that is transmitted to the stepper motor to restore N2 to its setpoint.


12 .7

T HM

12.3.1. E L E C T RIC A L E N GIN E G O V E R N O R M O NIT O RIN G ( 1 ) F u n ctio n al dia gra m

M C P/IC P control

P P21

P P21 C ollective pitch

P P13

P P14

coupling

E N GIN E 1 alternator

LH E N GIN E G OVERNOR

A N TICIP A T O R U NIT T/rotor pitch coupling

R H E N GIN E G OVERNOR

E N GIN E 2 alternator

DIGIT AL C O MP U T E R

DIGIT AL C O MP U T E R

Mutual monitoring (overspe ed) N R fine adjustment

O verspe ed

O verspe ed

B alancing trims

( 2 ) Pitc h/throttle a n d y a w a xis a nticip ators Anticipator unit (50K) (in re ar compartment above R H footstep)

28 K 1 28 K 2

PIT C H/T H R O T TL E C O U PLIN G

YAW AXIS C O UPLIN G

(behind cabin bulkhe ad on R H side of mixing unit)

(in re ar compartment under LH E N GIN E deck)

Two-track potentiometer (1 track per E N GIN E); voltage Uv incre ases with pitch, and is supplied to the computer via anticipator unit (50 K) to incre ase the rotor spe ed.

Two-track potentiometer (1 track per E N GIN E); voltage Uv varies when yaw pedal motion exceeds 70% of full scale travel; the variation is applied to the computer via anticipator unit (50 K) to increase the rotor speed.

12 .8


T HM

12.3.1. E L E C T RIC A L E N GIN E G O V E R N O R M O NIT O RIN G (C o nt.) ( 3 ) Trim c o ntrol A rotary contactor (3) on the instrument panel supplies the computer Trim inputs with a command to trim one E N GIN E rating upward, and to derate the other E N GIN E (2 track potentiometer). This fe atures allows the pilot to precisely balance the engines if necessary using another parameter (T4.5 or torque) inste ad of N1, used for automatic balancing by the governing system. A second potentiometer (4) for fine adjustment of the rotor spe ed is used only for maintenance purposes (screwdriver adjustable).

1

1-2 - S elector switch used for failure annunciator 3 - Rotary T RIM control 4 - Rotor rpm (N R) fine adjustment potentiometer (maintenance)



ˇ  

2

4

3



ˇ 

 ˇˇ







( 4 ) Ma n u al g o v ernin g The governing selector can be used to simulate a failure of the governing system (R efer to the F light Manual for the conditions). S election of MA N U AL governing switches the digital computer to dormant status. The metering unit will then stay in the position it was at failure or simulated failure. The red " G O V " warning light and the fuel flow light for the inoperative E N GIN E come on . The pilot must then use the fuel control lever to vary the fuel flow. During a simulated failure, it is possible at any time to switch back to automatic governing by: - moving th e fu el control le v er into th e norm al flight detent, - moving the governing selector to " A U T O ". The red " G O V " light and the fuel control light then go out. A U T O MA TIC/MA N U AL governing selector C e document est la propriété d'E U R O C O P T E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation pré alable écrite d'E U R O C O P T E R et son contenu ne peut être divulgué. This document is the property of E U R O C O P T E R ; no part of it shall be reproduced or transmitted without the express prior written authoriz ation of E U R O C O P T E R and its contents shall not be disclosed. © E U R O C O P T E R 1998.

12 .9

T HM

12.3.2. E N GIN E C O N T R O L WIT H V A RIA B L E N1 The gas generator spe ed (rpm) varies with the power demand, i.e. with the collective pitch. The generator spe ed is therefore related to the developed power. It is thus possible to determine the profile of the operating spe eds

which must be observed in flight to avoid premature damage to the E N GIN E .

( 1 ) N orm al flig ht C H A R A C T E RIS TIC P OIN T

• M C rP Maximum continuous (cruise) rating: maximum power available for unlimited duration. • MT O P Maximum takeoff rating: maximum power available for the takeoff phases (limited to 5 minutes of continuous operation). • M C P Maximum contingency rating: maximum O EI power rating (limited to 2.5 minutes) • IC P Interm e diate conting e ncy rating b etw e e n M C P and MT O P. The pilot selects the IC P rating with M C P/I C P (conting e ncy) pushbutton on the collective lever.

In normal flight the N1 indicator informs the pilot of the available power margin during takeoff and in cruising flight. The power margin is converted into a percentage re ading on the indicator: • The maximum takeoff rating corresponds to an indicator re ading of 0%. • The maximum continuous rating of -2.6%. ˇ

N1



ˇ

ˇ˛

Light illuminates if IC P rating is enabled

+2.7%

Indicator

B efore AMS 2158 and T U 70 C Light flashes after 2.5 minutes





 ˇ

LIMIT

 



ˇ

Power

0%

ˇ

ˇ ˇ

MT O P 5 min max.

MCP 2 min 30 max.

IC P

+1.1%

-2.6% M CrP

N O RMAL F LIG H T

O N E E N GIN E IN O P E R A TIV E

Time O N E E N GIN E IN O P E R A TIV E In the event of a single-E N GIN E failure, the maximum contingency rating (M C P) is immediately available for a duration of up to 2.5 minutes. The "LIMIT " light illuminates on the failure warning panel as soon as the N1 indicator pointer moves above 0%. The M C P rating limitation is indicated on the N1 indicator by a red line at +2.7%. By pressing the M C P/IC P contingency push-button on the collective lever, the pilot selects the intermediate contingency rating. The computer IC P input is activated: the E N GIN E is derated and automatically limited to the IC P rating.

12 .10

The IC P light illuminates on the N1 indicator. The IC P limitation is indicated on the N1 indicator by a yellow line at + 1.1%. The IC P rating protects the E N GIN E and fre es the pilot from the obligation to monitor the M C P limitation. N O T E : If flight conditions are satisfactory, the pilot may cut off the maximum contingency rating before re aching the 2.5 minute limit. If ne ed be, the pilot can revert to the M C P rating by pressing the M C P/IC P contingency push-button. R efer to the manufacturer's E N GIN E documentation, for the maximum cumulated flight time authoriz ed in maximum contingency power betwe en two E N GIN E overhauls.


T HM

12.3.2. E N GIN E C O N T R O L WIT H V A RIA B L E N1 (C o nt.) ( 2 ) Trainin g F lig ht

ˇ



ˇ

Power

ˇ

Light illuminates if IC P rating is enable

MT O P 5 min max.

Indicator





ˇ ˇ

0%



N1

ˇ

TRNG

 





ˇ ˇ

-1%

-2.6%

-2.6%

TRNG MCP 2.5 min max

M Cruise P

T R N G IC P

T R AININ G M O D E F LIG H T

N O RMAL F LIG H T

Time The training mode is designed to allow training in O EI procedures by limiting the operating E N GIN E to damage-fre e ratings (refer to the F light Manual for training mode limitations). The training M C P rating is betwe en the MT O P rating limited to 5 minutes and the continuous M CrP rating: use of the training M C P rating for 2.5 minutes has no adverse effect on the E N GIN E condition. The training mode is selected in flight by setting the O F F/ T R N G/F LT selector to the " T R N G " position. The corresponding E N GIN E is throttled down to an idle rating equivalent to a rotor spe ed of 355 N2. The amber

" T R N G " light illuminates on the failure warning panel. The operating E N GIN E is derated by the digital computer: the M C P, IC P and N1 laws are reduced by 3.7% by reducing the maximal fuel flow to switch to training mode. The training M C P (TrN G M C P) and the training IC P (TrN G IC P) have the same time limitations as the normal flight M C P and IC P ratings. In training mode, the N1 indicator is artificially offset by 3.7% by the computer in order to indicate the same values of M C P and IC P as in actual mode.

A F E W V ALU E S

ˇ˛˝¸˚˙˘¯ ¯˘˝˘ ˛

ˇ˛˝ ˛˝ ˇ˝ ˇ˛˝ ˇ˛˝˛˝

˝˚¯¸˘ ¯˚˙˘˘¯

N1

˛ ˛

˝˘˝˛

¯˚¯¯

˛ ˛

˛˘¯ ˚˙

¯˚¯¯


12 .11

T HM

12.3.2. E N GIN E C O N T R O L WIT H V A RIA B L E N1 (C o nt.) ( 3 ) C o ntrols a n d in dic ators • T h e N1 d e viatio n in dic ator ( N1) is a flight control instrument designed to display the E N GIN E limitations and power margins throughout the flight envelope. The pilot does not have to make allowance for ambient conditions; all that is necessary is to maintain the N1 indicator pointers below the mark corresponding to the limit of the current flight envelope. O P E R A TIN G P RIN CIPL E The E N GIN E digital governor computer generates an error signal converted into % N1: N1 = N1 max MT O P - N1 true. The z ero 0 reference point on the N1 indicator corresponds to the maximum takeoff power (MT O P). N O T E : The digital governor computer also implements a maximum fuel flow law to protect the transmission system components from overtorque.

• M C P/IC P C o ntrol In the event of a single-E N GIN E failure in flight, maximum contingency power is available for 2.5 minutes to correct the aircraft flight path and for manoeuvring. As soon as stable flight conditions are restored, the pilot may select the intermediate contingency power (IC P) rating even before the 2.5 minute limit has expired in order to protect the E N GIN E . Pressing push-button (1) or (2) activates the computer IC P input via remote contactor 31 K. The E N GIN E is derated from the M C P to the IC P rating. The IC P light on the indicator illuminates.

1

M C rP (-2.6%)

ˇ

IC P (+1.1%)

 

ˇ

2 1

N1

ˇ ˇ

ˇ˛

1 - R H E N GIN E pointer 2 - LH E N GIN E pointer 3 - IC P light (on when IC P enabled)

The M C P/IC P rating limits are guarante ed by the computer when the corresponding function is engaged: • In IC P rating, the light on the N1 indicator illuminates. • In M C P rating , the light on the N1 indicator is off. • The N1 indicator activates the "LIMIT " light when the N1 deviation for the operating E N GIN E exce eds 0%. N O T E : O n power-up, M C P is selected.

LIMIT from torquemeter E N GIN E 1 C O MP U T E R ˇ

ˇ

ˇ ˇ

E N GIN E 2 C O MP U T E R

 

N1

 

 ˇ

ˇ˛

Pilot collective grip

M C P/IC P push-button

12 .12

P P11



 ˇ

C omputer 2 logic ground

3





 ˇ

ˇ

2



31 K C omputer 1 logic ground

MCP (+2.7%)



ˇ ˇ

R emote contactor

Pilot collective grip

P P14 (7 2)

MT O P (0%)


P P12

T HM

12.3.3 E N GIN E M O NIT O RIN G ( 1 ) In dic atin g a n d alarm s The red and amber " G O V " lights and the " T R N G " light on the failure warning panel are shared by both engines. E ach cockpit fuel flow control lever includes a separate red warning light to ensure the pilot e asily identifies the E N GIN E requiring adjustment.

2

3

1

F uel flow control in-flight detent ENG 1 G OVERNOR C O MP U T E R

4 4

Major failure input

GOV 5

Minor failure input

GOV

Training input

TRNG

7 F uel flow control grip

6

To E N G 2 governor computer

(10 ) P P11

1 - Microswitch of fuel flow control in flight detent 2 - Manual fuel flow control travel 3 - C ockpit fuel flow control lever 4 - R ed " G O V " light indicating major governor failures • R e d " G O V " lig ht: Major g o v ern or failure The red " G O V " light illuminates in the event of a governor failure or seizure of the metering unit. In the event of a major fault condition, the computer grounds its major failure input (0V). The red " G O V " light and the fuel flow control lever light illuminate. • A m b er " G O V " lig ht: Min or g o v ern or failure The amber " G O V " light illuminates ste adily in case of loss of one of the following signals: P1, T2, P3, pitch and trim potentiometers, and fuel flow control not in flight detent. O utside normal spe eds (acceleration and deceleration), the amber " G O V " light flashes to indicate loss of one of the following signals: one N1 channel, one N2 channel, or one power system (alternator or helicopter power). F or these minor governor failures, the warning light stays unlit at normal spe ed.

P P12

P P14 (7 )

5 - Amber " G O V " light indicating minor governor failures 6 - Amber " T R N G " indicator light 7 - R ed warning light on fuel flow control lever In the event of a minor failure, the computer activates its minor failure input: the amber " G O V " light is grounded via the computer and illuminates. In the fuel flow control is out of the in-flight detent, the " G O V " light is grounded via the lever safety microswitch (1) and illuminates together with warning light (7), even though the computer minor failure input is not activated. • A m b er " T R N G " lig ht If one E N GIN E is set to the Training mode using the starting selector, the computer governing the other E N GIN E causes the " T R N G " light to illuminate. The E N GIN E whose selector is set to " T R N G " is governed at the idle rating (N2 = 355 rpm at no-load power). The other E N GIN E is limited to the training IC P or M C P N1. F ailure of the operating E N GIN E , or a drop in N2/N1 below 355 rpm will cause the idling E N GIN E to develop power.


12 .13

T HM

12.3.3 E N GIN E M O NIT O RIN G (C o nt.) ( 2 ) F re e turbin e o v ers p e e d s afety s y ste m The overspe ed safety system protects the fre e turbine if its rotation spe ed exce eds a threshold considered as m e ch a nic ally d a ng erous. T his function a utom atic ally shuts down the E N GIN E if the specified N2 threshold is exce eded.

The phonic whe el signals are supplied to a computer analog processing board, which automatically shuts down the E N GIN E when the fre e turbine spe ed re aches 112 ± 3%. At the same time, a mutually exclusive interlock circuit prevents the other E N GIN E from being shut down: this is the only interconnection betwe en the two computers. E N GIN E 2

N1 A N D F AILU R E A N N U N CIA T O R S

Mode selector

N G

P R M T R

T E S T

P A N N E M E M O

T R IM M O T G .

M O T D .

F uel pressure shutoff solenoid valve

D E F IL .

N1 A N D F AILU R E E L E C T R O NIC U NIT

E N GIN E 1 G OVERNOR C O MP U T E R

M O T . G A R M

T E S T

A R M A R R E T T E S T

E N GIN E 2 G OVERNOR

M O T . D A R M

T E S T

The E N GIN E is shut down by opening the fuel system shutoff solenoid valve and the red " T E S T " light on the control panel in the re ar compartment comes on. The four rightmost digits on the failure annunciator re ad " O V S P " if the mode selector is set to " F AIL". F or maintenance purposes, a 3-position (spring-loaded) switch is provided for e ach E N GIN E in the compartment above the LH computer, to allow periodic testing of the overspe ed logic circuitry:

O verspe ed shutdown interlock circuit

C O MP U T E R to N2 indicator

- Unstable (spring-loaded) " T E S T " position: simulates input frequencies to trip and globally operate the overspe ed safety circuit (Amber " S E T " light goes out and red " T E S T " light comes on). - Stable " O F F " position: no effect on overspe ed logic circuitry. - Unstable " S E T " position: cle ars the overspe ed operating memory for future initiation (amber " S E T " light comes on).

O verspe ed unit

12 .14

N2 D etectors

Annunciators


T HM

12.3.3 E N GIN E M O NIT O RIN G (C o nt.) ( 3 ) F ailure a n n u n ciator • F u n ctio n s ele ctor (2) T E S T F U N C TIO N (Unstable position) The annunciators display the following information in 3second sequences: - F irst sequence: all display segments illuminate - S econd sequence: both displays re ad "355" - Third sequence: E N G 1 on upper display, E N G 2 on lower display (display connection test). " S C R O LL" F U N C TIO N (Stable position) S etting the selector to the " S C R O LL" position causes the parameter values to scroll when the rotary mode selector (1) is set to "M E M O " or " P RMT R ". • Mo d e s ele ctor (1) " N G " M O D E (normal in-flight position): displays the N1 value in tenths of a percent and refreshes the value at 1second intervals; this display is used for monitoring N1 during engine starting. The leftmost digit shows the letter " S " when the overspe ed system is not enabled. O n engine start-up, the pilot checks the " S " disappe ars (overspe ed enabling)

when N2 re aches approximately 25%. If the " S " persists, this may indicate that the overspe ed system has not be en reset on the unit in the baggage compartment. In flight, N1 monitoring is control with N1. " F AILU R E " M O D E : this mode displays the codes corresponding to any fault conditions detected on the engine a n d g o v e rnin g s y st e m; f a ult c o d e s a r e dis pl a y e d sequentially at 3-second intervals. "M E M O R Y " M O D E : all fault conditions occurring in flight are stored in nonvolatile memory. After landing, this mode is used to scroll through the fault codes with the function selector (2) set to " S C R O LL". " P A R AM E T E R " M O D E : this mode is used to detect existing failures or for adjustment purposes. It may be used on the ground, with the engines shut down or running, or during check-out flights. P arameter codes are scrolled on the display when the function selector (2) is set to " S C R O LL". N O T E : R efer to the F light Manual for a list of fault and parameter codes.

L E F T E N GIN E E N GIN E 1 G OVERNOR C O MP U T E R

OIL FILT E R P R E-C L O G GIN G NG

E ngine 1 re ad-out

P P13 P P14

N1 A N D F AILU R E E L E C T R O NIC U NIT

N G

P R M T R

T E S T

P A N N E M E M O

T R IM M O T G .

M O T D .

D E F IL .

1

2

E ngine 2 re ad-out

R H governor and engine

N1 and failure electronic unit


12 .15

T HM

12.3.4. M E C H A NIC A L F U E L F L O W C O N T R O L S ( 1 ) F u n ctio n of fu el flo w c o ntrols Both engines on this helicopter include an automatic starting and governing system. The fuel flow control lever (9) is therefore used only in emergency mode in the event of automatic governing failure. The fuel flow control lever

actuates an emergency valve (7) to bypass the fuel metering unit (5) in the event of a governor metering seizure.

2 1

4

3 8

5 7

9

6

1 - C ockpit fuel flow control lever gate 2 - B all-slider control 3 - E mergency fuel flow valve control lever 4 - G overnor metering unit stepper motor (computer-driven) 5 - G overnor metering unit 6 - F uel bypass line (in case of governor failure) 7 - Manually actuated emergency fuel flow control valve 8 - F uel system high-pressure pump 9 - E mergency cockpit fuel flow control lever 10 - R etractable stop (30° re arward)

C O N T R O L L E V E R P O SITIO N S

F ORWARD C 1

N N-C N-A B

: : : :

Normal in-flight detent: 0° on engine quadrant scale Manual fuel governing range (spe ed incre ase) Manual fuel governing range (spe ed reduction) R etractable stop located 30° forward of minimum stop position; allows pilot to move fuel flow lever quickly aft without danger of flame-out.

N

B

10

R etractable stop (retracted)

A AFT

12 .16


T HM

12.3.4. M E C H A NIC A L F U E L F L O W C O N T R O L S (C o nt.) ( 2 ) C o m p o n e nt lo c atio n s

R etractable stops



ˇ

" E M E R G E N C Y " fuel flow control levers



Graduated quadrant



ˇ



V alve control lever

 







E ach fuel flow control lever has a red warning light: • In normal flight, if the fuel flow control lever is not in the in-flight detent, the amber " G O V " light illuminates on the failure warning panel, together with the warning light on the lever itself. • A total failure of the digital governor for one engine causes the red " G O V " light and the warning light on the corresponding lever to illuminate. Illumination of the red warning light on the fuel flow control lever allows the pilot to identify the faulty engine quickly and unambiguously.


12 .17

T HM

12.4 - E N GIN E S T A R TIN G C O N T R O L S 12.4.1. G E N E R A L The A R RIU S engines include an automatic starting system with digital governing. A s a re sult, th e e ngin e st arting control is a simpl e electrical selector with 3 stable positions (O F F/T R N G/ F LT) selector.

• Startin g s e q u e n c e S elector on T R N G or F LT: - the solenoid valve (14) closes - the contactor energizing starter (3) closes - the injector solenoid valve opens - the igniters (5) are supplied

• Startin g S ele ctor F u n ctio n s In the " O F F " position: • Initiates the computer self-test when the Direct B attery power comes on. • Allows the engine to be shut down by moving the selector from " F LT " or " T R N G " to " O F F ".

When N1 = 50%, the starting components are cut off and the computer takes over engine governing by the fuel metering (10). Solenoid valve (14) does not open until th e e n gin e is s h ut d o w n or th e c o m p ut e r d e t e cts overspe ed. 1 2 3 4 5 6 7 8 9 10 11 12 13 14

In the " T R N G " position: • Starts the engine and stabiliz es the engine spe ed at idle rating. • Actuates the " T R N G " input of the computer governing the other engine. In the " F LT " position : • E xecutes the engine starting sequence and accelerates the engine to its nominal rating. This is the normal flight position.

NG

NF

- Manual/Automatic governing selector - Starting selector (O F F - T R N G - F LT) - Starter-generator -Ignition unit - High-energy igniters (2 per engine) - Starting solenoid valve - Starting fuel injectors (4 off) - Main fuel injectors (10 off) - Level valve (set at 6 bar) - Stepper motor (controlling fuel metering unit) - E mergency manual fuel flow control valve - High-pressure fuel pump - C ockpit fuel flow control lever - F uel shutoff solenoid valve

B attery or external power unit

T4

3



1

 

5

N1 > 50%

G OVERNOR C O MP U T E R

4

ˇ 

6

2

7

10 FWD 9

12 13

11

AFT

8 14 E N GIN E

12 .18


T HM

12.4.2. S T A R TIN G S Y S T E M F U N C TIO N A L CIR C UIT DIA G R A M N O T E : F or clarity, only the R H engine starting system is described here. The LH engine system is identical. " Direct battery" indicating

9P

1

35P

P P10

P P8

P P14 (7 2)

(16 )

P P21

20P

23P2

21P2

P P13 (7 1)

m P4 53 K

to LH eng. starting system

R L5

2

R L6 From generator excitation

3

26 K 2 27 K 2 34N

23 K 2

AUTO

to 30K1

FLT TRNG

56 K 2

MAN.

R eturn to LP pump

34N

F uel pressure inlet

OFF

F

33N

S T A R TIN G O

N1>50% 14 Q 2 30 K 2

13 Q 2 To main injectors

To starting injectors

O verspe ed protection

1 - " DIR E C T B A T T E R Y " push-button 2 - " E N G C R A N K " push-button on overhe ad panel 5 2 3 - " Rotor brake rele ased" safety microswitch 7 2 - R H fuse panel supplied from load-shedding secondary bus P P14 16 - Direct battery fuse panel supplied from bus P P21 P P8 - Main busbar in electrical master unit mP4 - Starter-generator RL5 - G enerator excitation relay in electrical master unit RL6 - Auxiliary starting relay in electrical master unit 23K2 - High-energy igniter unit 26K2 - 3-position starting selector (O F F/T R N G/F LT) 27K2 - 2-position engine governor selector (AUT O/MANUAL)

30K2 - R H engine electronic governor computer 53K - Starting relay on external power connection (switching of direct battery) 56K2 - Starting inhibit relay 33N - C omputer 30K1 logic ground 34N - C omputer 30K2 logic ground 20P - E xternal power contactor 21P2 - Starting contactor 23P2 - Shedding bar contactor 35P - " DIR E C T B A T T E R Y " contactor 13 Q 2 - Starting solenoid valve (injector fuel supply) 14 Q 2 - F uel pressure opening/closing solenoid valve (bistable)


12 .19

T HM

12.4.3. O P E R A TIO N O F S T A R TIN G S Y S T E M ( 1 ) P u s h-b utto n " DIR E C T B A T " s witc h e d o n • Starting selector on " O F F " • G overnor selector on " A U T O " " Direct battery" indicating

9P

1

35P

P P10

P P8

P P14 (7 2)

(16 )

P P21

20P

23P2

21P2

P P13 (7 1)

m P4 53 K to LH eng. starting system

R L5

2

R L6 From generator excitation

3

26 K 2 27 K 2 34N

23 K 2

AUTO

to 30K1

FLT TRNG

56 K 2

MAN.

R eturn to LP pump

34N


OFF

F

33N

S T A R TIN G O

N1>50% 14 Q 2 30 K 2

To main injectors



The direct battery bus (P P21) is energiz ed. Power is supplied to the computer from P P21 via a bre ak contact of relay 53K, and the self-test routine lasting about 10 seconds is initiated. In the " O F F " position, the starting selector (26K2) : - Activates the engine " O F F " (shutdown) input to the computer by setting it to logic ground. - Supplies +28 V D C power from bus P P14 to the " O P E N " winding of the main solenoid valve (14 Q 2) : the fuel return line to the low-pressure pump is open.-

12 .20

13 Q 2

Auxiliary starting relay RL6 is not grounded by the computer : the relay remains de-energiz ed. NOTE : During the computer self-test sequence, the " T R N G ", amber " G O V" and "M C P/IC P" rating lights are illuminated. The red " G O V " and the red lights on the fuel flow control levers flash five times. O n the N1 indicator the two pointers move to 0 then go back to neutral. At the end of the test, all lights go out.


T HM

12.4.3. O P E R A TIO N O F S T A R TIN G S Y S T E M (C o nt.) ( 2 ) Startin g s ele ctor " F L T " (startin g in " pro gre s s " u ntil 50% N1)

• With external power unit • G overnor selector on " A U T O "

" Direct battery" indicating

from battery

1

35P

P P10

20P

23P2 P P8

P P14 (7 2)

(16 )

P P21

9P

21P2

P P13 (7 1)

m P4 53 K


R L5

2

R L6 3

26 K 2

From generator excitation

27 K 2 34N

23 K 2

AUTO

to 30K1

FLT TRNG

56 K 2

MAN.

R eturn to LP pump

34N


OFF

F

33N

S T A R TIN G O

N1>50% 14 Q 2 30 K 2




N O T E : R elay 53K switches the " Direct B attery" electric power of the starting components onto the external power unit. The relay is energiz ed by the " Direct B attery" pushbutton on panel 14 . In the " F LT " position, the starting selector: - D e-energiz es the " O P E N " winding of the main solenoid valve (14 Q 2). - Actuates the governor " F LT " input. The computer grounds the auxiliary starting relay (RL6) via the "rotor brake rele ased" microswitch (3) and the " A U T O " position of the governor mode selector (27K2).

In make position, relay RL6 activates the starter contactor (21P2), the " C L O S E " winding of the main solenoid valve, the injector solenoid valve (13 Q 2) and the highenergy ignition units. The starter-generator is supplied from bus P P8. The automatic starting sequence is performed by the computer up to 50% N1. At that spe ed, the computer cuts off the ground of the auxiliary relay, which bre aks contact. The starter, the solenoid valves and igniters are no longer supplied.


12 .21

T HM

12.4.3. O P E R A TIO N O F S T A R TIN G S Y S T E M (C o nt.) ( 3 ) P h a s e 3 : N1 > 50% a c c eleratio n • G overnor selector on " A U T O " • B attery powered


9P

+ generator

35P

P P10

P P8

P P14 (7 2)

(16 )

P P21

20P

23P2

21P2

P P13 (7 1)

m P4 53 K


R L5 R L6 From generator excitation

26 K 2 27 K 2 34N

23 K 2

AUTO

to 30K1

FLT TRNG

56 K 2

MAN.

R eturn to LP pump

34N


OFF

F

33N

S T A R TIN G O

N1>50% 14 Q 2 30 K 2

To main injectors



The computer accelerates the engine to its rated spe ed and ensures N2 governing. When N1 equals 50%, the starting inhibit relay (56K2) is energiz ed and its bre ak contact cuts off power to the auxiliary starting relay. In " T R AININ G " mode, the computer limits the idle spe ed to 68% N1 (corresponding to 355 rpm N2).

12 .22

13 Q 2

• O v ers p e e d prote ctio n The computer also provides for overspe ed protection. If N2 exce eds 112 ± 3%, the computer supplies a +28 V D C signal to the main solenoid valve " O P E N " winding, causing the valve to return the pressuriz ed fuel to the LP pump.


T HM

12.4.3. O P E R A TIO N O F S T A R TIN G S Y S T E M (C o nt.) ( 4 ) E n gin e cra n kin g


9P

35P

P P10

P P8

P P14 (7 2)

(16 )

P P21

20P

23P2

21P2

P P13 (7 1)

m P4 53 K


R L5 1 R L6 From generator excitation

26 K 2 27 K 2 34N

23 K 2

AUTO

to 30K1

FLT TRNG

56 K 2

MAN.

R eturn to LP pump

34N


OFF

F

33N

S T A R TIN G O

N1>50% 14 Q 2 30 K 2




Cranking is controlled by push-button (1) on overhe ad panel 5 . When pressed, it grounds the starting contactor (21P2) via the de-energiz ed generator excitation relay (RL5). The starter is supplied from bus P P8 and drives the engine. The main solenoid valve (14 Q 2) " O P E N " winding is energiz ed from P P14 via the " O F F " position of the starting selector: the fuel pressure is returned to the engine LP pump.

( 5 ) Ma n u al g o v ernin g G overnor selector (27K2) can be used to simulate a governor failure, in which case starting is no longer possible.


12 .23

T HM

12.4.4. L O C A TIO N O F S T A R TIN G S Y S T E M C O MP O N E N T S

Microswitch of Static Braking (starting inhibited)



ˇ



G overnor computers + relays 53K and 56K



ˇ



 







Starting selectors (O F F - T R AININ G - F LIG H T)

Starter-generator

Starting solenoid valve

Starting fuel injectors (4 off)

Manifold for main injectors (10 off) Metering unit with built-in high-pressure fuel pump

12 .24

High-energy igniters (2 off)


T HM

12.5 - E N GIN E P O W E R M O NIT O RIN G N1

T4.5

G as generator rotation spe ed

E xhaust gas temperature

N2

Fre e power turbine rotation spe ed

Cm

E ngine torque

12.5.1. G A S G E N E R A T O R R O T A TIO N S P E E D (N1) Me a s ure m e nt prin ciple The gas generator spe ed is me asured by an electromagnetic sensor opposite a slotted (phonic) whe el) driven by the rotating assembly whose spe ed is to be me asured. As the te eth move past the sensor they modify the magnetic field, inducing an alternating current in the coil, with a frequency proportional to the rotation spe ed. (The principle is the same for N R me asurement). O n this type of engine, the gas generator spe ed is me asured using 3 phonic whe els and a triple sensor. The

phonic whe els are mounted on the starter drive shaft. Two signals are transmitted to the computer, and a third to the N1 indicator via the electronic failure analysis unit. The N1 indicator includes two 5-digit displays (1 for e ach engine). The four right-hand digits display the N1 value in tenths of a percent; the leftmost digit re ads " S " when the overspe ed protection system is not enabled.

Phonic whe el/ electromagnetic sensor assembly for one engine N1 signal from second engine

N1 signal N1 A N D F AILU R E E L E C T R O NIC U NIT



Mode selector

ˇ  



ˇ

 ˇˇ





E L E C T R O NIC G O V E R NIN G U NIT




12 .25

T HM

12.5.2. F R E E T U R BIN E R O T A TIO N S P E E D (N2) The principle is the same as that used for N1 me asurement.

The N2 signal is received from a set of 3 phonic whe els and 2 triple sensors mounted on the end of the fre e turbine shaft.

P P14

P P13

N2 detector    ˇ

ˇ ˇ ˇ

 ˇˇ

P P13

P P14

ˇ 

E N GIN E 1 E L E C T R O NIC G O V E R NIN G C O MP U T E R

ˇ ˇ

ˇ ˇ

NF2 Index

NF1 Index

NR Pointer

Triple in dic ator (N F + N R) In normal operation, the N F 1 and N F 2 indexes are always superposed and aligned (synchroniz ed) with the N R pointer, even if the engine power varies. An engine remains synchroniz ed despite engine power variations, i.e. N2 R E MAIN S C O N S T A N T A N D O NLY T H E E N GIN E T O R Q U E V A RIE S.

E N GIN E 1 E L E C T R O NIC G O V E R NIN G C O MP U T E R





from engine-driven alternator

In the event of an engine power failure, its N2 value will obviously drop out of synchronisation. D esynchroniz ation may also occur in the unlikely event of failure of the engine/M G B coupling shaft: the fre e turbine would then no longer be under load, and its spe ed would incre ase until the overspe ed safety.

12.5.3. E X H A U S T G A S T E MP E R A T U R E (T4.5) The true temperature value from e ach thermocouple circuit is corrected by balancing resistors (R) installed by the engine manufacturer in the junction box.

The current produced by the thermocouples (4 sensors for T4.5 indicator + 4 sensors for computer) inserted in the gas stre am is applied to the T4 indicator; the current voltage is proportional to the T4.5 temperature T4.5 signal to computer 2

R H E N GIN E

D O U BL E T4 IN DIC A T O R

T4.5 signal to computer 1

LH E N GIN E

˛˛

ˇ˛˛

˛˛

R

˛˛

˛˛

 ˛˛

P P13

12 .26



P P12

R

˛

P P11


T HM

12.5.4. E N GIN E T O R Q U E (C) ( 1 ) T orq u e m eter o p eratin g prin ciple The engine torque (C m) represents the mechanical load applied to the drive shafts and ge ars. As the rotor rotation spe ed is roughly constant, it is also representative of the power W furnished by the engine (W = C ). This is an important flight control parameter since the mechanical power transmission components are subject to stress limitations, and the torquemeter allows the pilot to avoid exce eding the permissible limits. The engine torque is me asured at the reduction ge ar intermediate pinion. The helical ge ar te eth are subjected to axial thrust (P A) from the opposing effects of engine torque and rotor drive resistance. Oil from the engine lubrication system enters the torquemeter me asurement chamber (A) and flows out by throttling action. The thrust shaft, which is integral with the reducing ge ar intermediate pinion, moves axially and modifies the flow cross section of the oilway le ading from me asurement chamber A into the shaft. • If the engine torque C m incre ases, the axial thrust (P A) also incre ases, limiting the flow cross section and causing the oil pressure to rise in the me asurement chamber (A). The torquemeter transmits this variation to the torque indicator. • The opposite occurs if the engine torque decre ases.

Axial thrust

O il pressure inlet

PA

Transmitter

C hamber A

Thrust shaft

( 2 ) T orq u e m e a s ure m e nt s y ste m s E ach engine includes a pie zo-resistive pressure transmitter (1). The instrument panel indicator (2) comprises two galvanometers, e ach slaved to one of the transmitters. The resistance of the pie zo-resistive pressure transmitter varies with the pressure variations in chamber (A),

modifying the position of the corresponding torque indicator pointer accordingly. When the sum of the E ngine 1 + E ngine 2 torque values re aches 160%, the "LIMIT " light illuminates on the failure warning panel.

LIMIT R H E N GIN E

LH E N GIN E

P O W E R S U P PLY S/P R O C E S SIN G SLA VIN G

1

Pressure in chamber A

M

P P11

2

P O W E R S U P PLY S/P R O C E S SIN G SLA VIN G

1

Pressure in chamber A

M

P P12


12 .27

T HM

12.5.5. L O C A TIO N O F E N GIN E M O NIT O RIN G C O MP O N E N T S T4.5 T E MP E R A T U R E M O NIT O RIN G

N1 sensor

Junction box N2 sensors

Torque transmitter Thermocouples

T RIPL E IN DIC A T O R NR - NF1 - NF2

N1 IN DIC A T O R S

  ˇ 

ˇ ˇ ˇ

ˇ ˇ ˇ  ˇ ˇ

ˇ ˇ 

NR Pointer

NF1 Index

E ngine 2  ˇ 



E ngine 1

 





E ngine 2

  



E ngine 1 T4 IN DIC A T O R

12 .28

T O R Q U E IN DIC A T O R




NF2 Index

T HM

13 FIR E PR O T E C TIO N

13.1 -

MO NIT O R E D A ND PR O T E C T E D A R E A S

13.2 -

FIR E D E T E C T O RS

13.3 -

MG B C OMPA RTM E NT FIR E D E T E C TIO N SYST EM

13.3.1.

O P E R ATIO N O F M G B FIR E D E T E C TIO N

13.3.2.

L O C ATIO N O F M G B FIR E D E T E C TIO N S Y S T E M C O MP O N E N T S

13.4 -

E N GIN E FIR E D E T E C TIO N SY ST EM

13.4.1.

E N GIN E FIR E D E T E C TIO N S Y S T E M C O MP O N E N T S

13.4.2.

E N GIN E FIR E D E T E C TIO N S Y S T E M O P E R ATIO N

13.5 -

E N GIN E FIR E E X TIN G UIS HIN G S Y S T E M

13.5.1.

FIR E E X TIN G UIS HIN G S Y S T E M C O MP O N E N T S

13.5.2.

FIR E E X TIN G UIS HIN G DIS T RIB U TIO N S Y S T E M

13.5.3.

FIR E E X TIN G UIS H E R U NIT

13.5.4.

E N GIN E FIR E E X TIN G UIS HIN G S Y S T E M O P E R ATIO N

13.5.5.

E N GIN E FIR E E X TIN G UIS HIN G S Y S T E M C O MP O N E N T S


13 .1

T HM

13.1 - M O NIT O R E D A N D P R O T E C T E D A R E A S

MG B C OMPARTME NT 1 fire detection circuit

E N GIN E C O MPA RTM E N T 1 fire detection circuit per engine 1 fire extinguishing system per engine

C A BIN 1 portable fire extinguisher

13.2 - FIR E D E T E C T O R S The fire detectors are bimetallic-strip temperature sensors located at critical points in the engine and M G B compartments. D E T E C TO R O P E RATIO N • Slo w te m p erature ris e Both bimetallic strips (2, 7) distort in the same way. When the detection threshold is re ached, insulated strip (7) re aches the stop (1) while bare strip (2) continues to distort: the contacts separate and the detection circuit is broken. • F a st te m p erature ris e The bare metal strip (2) he ats faster than the insulated strip (7) and thus distorts more quickly. C ontact is broken when the detection threshold is re ached.

1

2

3

4

9

8

7

6

5

1 - Adjustable temperature threshold stop 2 - Q uick-distorting bare bimetallic strip 3 - Insulator 4-5 - Terminals 6 - G lass fabric 7 - Slow-distorting insulated bimetallic strip 8 - Low-temperature stop 9 - Bimetallic strip contacts

13.3 - M G B C O MPA R TM E N T FIR E D E T E C TIO N S Y S T E M M G B C ompartment

FIR E warning light

Direct b attery bus

13 .2

D etectors

Two detectors are installed close to e ach other, and thus open simultaneously when the temperature exceeds 160°C in the MG B compartment. As long as one of the detectors remains closed, the FIR E warning light is shortcircuited. This provision is designed to prevent possible illumination of the warning light due to accidental operation of one detector.


T HM

13.3.1. O P E R ATIO N O F M G B FIR E D E T E C TIO N S Y S T E M ( 1 ) Mo nitorin g circ uit e n ergiz e d

P P21

R elays K1 and K2 are de-energiz ed; the current passes through detectors D1 and D2 which are closed and to the ground through resistor R1. Light (2), which is short-circuited, is out.

1

K1

K2

1 - T E S T pushbutton 2 - M G B FIR E warning light R1 - R esistor D1-D2 - F ire detectors (set at 160°C) K1-K2 - R elays for simulating detectors "open" for the test function

2

R1 D1

D2

P P21

1

K1

K2

( 2 ) Te m p erature > 160°C Simultaneous opening of both detectors D1 and D2 illuminates the warning light (2) via the break contacts of relays K1 and K2.

2

R1 D1

D2

P P21

( 3 ) O n e d ete ctor o p e n or lin e c o ntin uity fa ult 1

K1

K2

• Momentary opening of one detector The warning light remains short-circuited by the second closed detector, and therefore does not illuminate unnecessarily. • Line continuity fault (as shown in the F igure) The result is the same as above, but this condition is detected by the system test function.

2

Line bre ak

R1 D1

D2


13 .3

T HM

13.3.1. O P E R ATIO N O F M G B FIR E D E T E C TIO N S Y S T E M (C o nt.) P P21

K1

( 4 ) S y ste m te st Pressing the T E S T pushbutton (1) energiz es relays K1 and K2, and thus bre aks the short-circuits inhibiting the warning light (2). The light illuminates, since all of the detection loops are energiz ed: any dormant system faults are detected in this way.

K2

1

2

R1 D1

D2

13.3.2. L O C ATIO N O F M G B FIR E D E T E C TIO N S Y S T E M C O MP O N E N T S E ngine/M G B FIR E test pushbutton

ˇ  

ˇ  

ˇ  

  ˇ

   

 



16 DIR E C T B AT T E RY

M O NIT O RIN G U NIT

DETE CTORS

13 .4




T HM

13.4 - E N GIN E FIR E D E T E C TIO N S Y S T E M 13.4.1. E N GIN E FIR E D E T E C TIO N S Y S T E M C O MP O N E N T S M O NIT O R E D P OIN T S

Pushbutton for M G B + E N G 1 & 2 fire test

A ˇ  

ˇ  

ˇ  

 ˇ 

   

  



B 

Two separate but identical detection systems each include: - 4 temperature sensors - a relay unit - a FIR E warning light - a T E S T pushbutton used to check the system by simulating fire conditions

The 2 sensors in the front zone are set at 200°C . The 2 sensors in the re ar zone are set at 400° C . These sensors monitor the ventilation airflow around the engine and in zones where a flammable liquid le akage ha z ard exists.

13.4.2. E N GIN E FIR E D E T E C TIO N S Y S T E M O P E R ATIO N P P11 P P12

P P11

T E MP E R AT U R E < 200°C

P P12

T E MP E R AT U R E > 200°C

FIRE ENG. LH

FIRE ENG.LH

3 1

3

2 4

The system is shown in normal operating condition: T° < 200°C , monitoring relay (2) energiz ed FIR E light (3) off. T E S T F U N C TIO N : Pressing pushbutton (4) simulates opening of a temperature sensor to check operation of the engine and M G B fire detection systems.

1

2 4

The detector opens and the monitoring relay (2) is deenergiz ed the FIR E light (3) illuminates. 1 - Polariz ed capacitor (prevents accidental illumination of the FIR E warning light) 2 - Monitoring relay 3 - FIR E indicating light 4 - Pushbutton for testing the M G B and engine fire detection systems


13 .5

T HM 13.5 - E N GIN E FIR E E X TIN G UIS HIN G S Y S T E M 13.5.1. FIR E E X TIN G UIS HIN G S Y S T E M C O MP O N E N T S The fire extinguishing system includes: - Two freon fire extinguishers and their distribution lines le ading to a spray noz zle in e ach engine compartment. - a discriminating electric percussion circuit.

E ach fire extinguisher can be discharged into either engine compartment as selected by the pilot (direct or crossfeed delivery).

R H extinguisher

R H engine e xtinguishing

RH

ˇ

ENGINE



MGB LH engine e xtinguishing

C OMPARTMENT LH



ENGINE

ˇ C OMPARTMENT

LH extinguisher

13.5.2. FIR E E X TIN G UIS HIN G DIS T RIB U TIO N S Y S T E M

RH ENG 1

LH ENG 2 EXT 2

R H E N GIN E 1

2

3

LH E N GIN E

RH ENG 2

LH ENG 1

EXT 1

4

A pressure gauge (4) is provided to check the freon pressure before flight.

13 .6

E ach fire extinguisher is equipped with two electric pyrotechnical cartridge percussion he ads (1). When power is supplied to the he ad resistor, the percussion of the cartridge bre aks a rupture disk (2) and rele ases pressuriz ed freon. E ach freon distribution system to the engine bay spray noz zles is connected to one percussion he ad of e ach fire extinguisher by pipes with two non-return valves (3) that isolate the extinguishers from e ach other. Schematically, here is how the system works: • LH engine, first percussion: Pressing pushbutton "LH E N G 1" guisher 1 into the LH engine bay. • LH engine, second percussion: Pressing pushbutton "LH E N G 2" guisher 2 into the LH engine bay. • R H engine, first percussion: Pressing pushbutton " R H E N G 1" guisher 2 into the R H engine bay. • R H engine, second percussion: Pressing pushbutton " R H E N G 2" guisher 1 into the R H engine bay.

discharges extin-

discharges extin-

discharges extin-

discharges extin-


T HM

13.5.3. FIR E E X TIN G UIS H E R U NIT

1 - Pressure gauge 2 - Pressure-temperature correspondence chart 3 - P ercussion he ads 4 - C harging valve with pressure-relief rupture disk 5 - Pyrotechnical cartridges

1

4

SP E CIFIC ATIO NS Tank volume .................................................. 0.983 dm3 W eight of freon 13B1 gas ................................. 0.620 kg Charging pressure ................................................ 45 bar Rupture disk bursting pressure ..................... P > 91 bar C artridge-priming resistor rating ............... 1.15 ± 0.25

Threads

2

3

5

Bayonet

The pyrotechnical cartridges are color-coded to prevent assembly errors.

13.5.4. E N GIN E FIR E E X TIN G UIS HIN G S Y S T E M O P E R ATIO N E x a m ple s h o w n, a fire in th e L H e n gin e b a y persists after the LH extinguisher is fired (1st percussion); the pilot therefore fires the second extinguisher (2nd percussion). LH E N GIN E

R H E N GIN E

P P21 (B AT) EXT 2 LH ENG

EXT 1 LH ENG

EXT 1 RH ENG

EXT 2 RH ENG

P P12 P P11

C urrent-limiting resistors in case of short-circuit after firing (wiring protection)

LH engine bay

R H engine bay


13 .7

T HM

13.5.5. E N GIN E FIR E E X TIN G UIS HIN G S Y S T E M C O MP O N E N T S

E N G. 1 FIR E E X TIN G UIS HIN G PUSHBUTTONS

E N G. 2 FIR E E X TIN G UIS HIN G PUSHBUTTONS

1 st percussion

1 st percussion

2 nd percussion

2 nd percussion



ˇ 

ˇ  









 



1

1 - Fire extinguishers 2 - Spray noz zles 3 - D elivery lines 4 - Non-return valves

13 .8

4

3

2


T HM

14 H E ATIN G A ND V E NTIL ATIO N

14.1 -

H E ATIN G A N D D E MIS TIN G S Y S T E M

14.2 -

C A BIN V E NTIL ATIO N


14 .1

T HM

14.1 - H E ATIN G A N D D E MIS TIN G S Y S T E M Hot air bled from the centrifugal compressor outlets of e ach engine (T1, T2) is mixed with outside air drawn in through two induction noz zles (2, 7) underne ath the cabin floor and diffused inside the cabin via : - 2 he ating outlets (3) - 2 windshield demisting diffusers (1) The hot compressor ble ed air flows are adjusted by two valves (4, 8) located next to the pilot's se at. C alibrated orifice plates (5) limit the maximum compressor ble ed air flow to 2.25 % of the total compressor air flow. The engines are isolated from one another by non-return valves (6).

3

1

T1

5

2

4

8

7

T2 1

3

6

5

T1 P2

T2

P2 airflow acceleration cre ates suction pressure that draws in cabin air 8 7 9 5

4

1

3 2

6

1 - D emisting diffuser (1 on e ach side) 2 - D emisting induction noz zle 3 - H e ating outlet (1 bene ath e ach front se at) 4 - D emisting control valve 5 - H e ating control valve

14 .2

5

4

6 - H e ating induction noz zle 7 - Dual non-return valve to isolate engines from e ach other 8 - Hot air ble ed line with orifice plate (1 for e ach engine) 9 - P2 air ble ed for option


T HM

14.2 - C A BIN V E N TIL ATIO N C abin ventilation is ensured by outside air entering the cabin : - at fro nt through a scre ened airscoop (10): the air flow rate is controlled by a flap actuated by a pull-knob (13) bene ath the pilot's instrument panel. - o n th e c a bin c eilin g through a ram airscoop (1). The ventilation air flows betwe en the polycarbonate skin panels of the cabin roof to swiveling, adjustable-flow and closable ventilation outlets (5, 6).

The ram airscoop (1) is equipped with water separators (2) to drain off most of the water outside the aircraft. The airscoop includes a summer/winter air flow adjustment provision: rotating the condensation water bowl (4) opens or closes air le akage slots (3).

1

2

5 3

Summer position: slots open 6

9

8

Winter position: slots clos e d 13

4

W ater

7

10

13 11

12

1 - R am airscoop 2 - W ater separator 3 - Air le akage slot 4 - Rotating water condensation bowl 5 - C enter vent diffuser and light fixture 6 - Side-mounted vent diffuser 7 - Front airscoop flow regulating flap 8 - Diffuser 9 - F lap (7) control cable 10 - V entilation airscoop 11 - Protection scre en 12 - W ater drain 13 - F lap (7) control pull-knob


14/4.3

T HM

15 PIT O T-STATIC SYST EM A ND INSTRUME NTS

15.1 -

D E S C RIP TIO N O F PIT O T-S TATIC S Y S T E M A N D IN S T R UM E N T S

15.1.1.

O P E R ATIN G P RIN CIPL E

15.1.2.

PIT O T-S TATIC S Y S T E M C O MP O N E N T S

15.1.3.

L O C ATIO N O F PIT O T-S TATIC S Y S T E M C O MP O N E N T S

15.1.4.

D E S C RIP TIO N O F PIT O T-S TATIC S Y S T E M C O MP O N E N T S

15.2 -

PIT O T H E ATIN G S Y S T E M

15.2.1.

PIT O T H E ATIN G S Y S T E M C O N T R O LS A N D M O NIT O RIN G

15.2.2.

C O MP O N E N T L O C ATIO N


15. 1

T HM

15.1 - D E S C RIP TIO N O F PIT O T-S TATIC S Y S T E M A N D IN S T R UM E N T S 15.1.1. O P E R ATIN G P RIN CIP L E

AIR S P E E D IN DIC AT O R

The pitot-static system instruments indicate: - the helicopter's altitude on the ALTIM E T E R - the helicopter's spe ed relative to the air on the AIRSP E E D INDIC AT O R - the helicopter's rate of climb or descent on the V E RTIC AL SP E E D INDIC AT O R The operating principles of these instruments are illustrated in the figure opposite. - the airspe ed indicator me asures the dynamic pressure of the air P D = P T - P S - the altimeter me asures the static pressure P S - the vertical spe ed indicator me asures the pressure difference P S - P S1 , a function of the helicopter's rate of climb or descent.

ALTIME T E R

V E R TIC AL S P E E D IN DIC AT O R

ˇ

PS

PS

P S1 PS

P artial vacuum

PT

C apillary tube

Pitot he ad

Static pressure port

P T : Total pressure P S : Static pressure P S1 : Static pressure with lag induced by capillary tube

15.1.2. PIT O T-S TATI C S Y S T E M C O M P O N E N T S 4

2

5

3

Total pressure copilot's system

PIL O T'S S Y S T E M

1

6 7

2 2 Total pressure pilot's system

1

3 5

8

2 2

4

Note: The pilot he ad is mounted on the left of the helicopter centerline where the airflow perturbations are the le ast.

15 .2

AUXILIARY SYST EM (C O PILO T) 1 - Pitot he ad 2 - Drains (for condensation) 3 - V ertical spe ed indicator 4 - Airspe ed indicator 5 - Altimeter 6 - Pilot's standby static valve 7 - Static pressure port 8 - A P air data system


T HM

15.1.3. L O C ATIO N O F PIT O T-S TATIC S Y S T E M C O MP O N E N T S

1

2

1

2

3

3

5

6

8

7

1 - Airspe ed indicator 2 - Altimeter 3 - V ertical spe ed indicator 4 - Pilot's standby static valve 5 - Total pressure line 6 - Pitot he ads 7 - Static pressure line 8 - Static ports

4

15.1.4. D E S C RIP TIO N O F PIT O T-S TATIC S Y S T E M C O MP O N E N T S PIT O T H E AD • Electrical resistance he ating (anti-icing provision) • R esistor power rating: 35W-55W

1

1 - Mounting bracket (positions the Pitot he ad parallel to the airstre am deflected by the aircraft nose) 2 - E lectrical le ad 3 - Hose fitting 4 - Pitot (total pressure) tube 5 - H e ating resistor with mica insulator 2

5

4 C e document est la propriété d'E UR O C O PT E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'E UR O C O PT E R et son contenu ne peut être divulgué. This document is the property of E UR O C O PT E R ; no part of it shall be reproduced or transmitted without the express prior written authorization of E UR O C O PT E R and its contents shall not be disclosed. © E UR O C O PT E R 1998.

3

15. 3

T HM

15.2 - PIT O T H E ATIN G S Y S T E M D E S C RIP TIO N 15.2.1. PIT O T H E ATIN G S Y S T E M C O N T R O L S A N D M O NIT O RIN G The projecting Pitot tubes are highly susceptible to icing. To prevent any risk of icing which would cause immediate loss of airspe ed information, the Pitot he ads are equipped with a he ating resistor. A warning light illuminates to indicate a resistor power supply fault.

E X PLA N ATIO N O F CIR C UIT DIA G R AM

PIL O T'S PIT O T H E A D: The PIT O T switch (1) is "on", resistor (3.1) is supplied, monitoring relay (2.1) is energiz ed and the PIL PIT O T warning light is off. C O PIL O T'S PIT O T H E A D: Power supply fault in circuit to resistor (3.2), relay (2.2) is de-energiz ed and A U X PIT O T light is illuminated.

P P12

P P11

PIL. PITOT

P P20

P P19

1

AUX. PITOT 2.2

2.1

Lin e continuity fault

3.1

Note the redundant power supply to the pilot's Pitot he ating resistor. PIL O T'S PIT O T H E A D

3.2

AUXILIARY PIT O T H E A D

15.2.2. C O M P O N E N T L O C ATI O N

1

  

ˇ   ˇ   

  ˇ   



 

 

 

 

ˇ

ˇ







2

 

 ˇ 



3

1 - A U X PIT O T fuses 2 - Pitot he ating push-button 3 - PIL PIT O T fuses

15 .4


T HM

16

INT E RIO R A ND E XT E RIO R LIG HTIN G

16.1 -

IN T E RIO R LIG H TIN G

16.1.1.

IN T E RIO R LIG H TIN G S Y S T E MS

16.1.2.

O V E R H E A D LIG H TIN G

16.1.3.

P RIN CIPL E O F LIG H T G E N E R AT O R A N D LIG H T DIF F U SIO N

16.1.4.

PIL O T'S IN S T R UM E N T PA N E L A N D O V E R H E A D PA N E L LIG H TIN G

16.1.5.

C O PIL O T'S IN S T R UM E N T PA N E L LIG H TIN G

16.1.6.

C O MP O N E N T L O C ATIO N S

16.2 -

E X T E RIO R LIG H TIN G

16.2.1.

P O SITIO N LIG H T S

16.2.2.

C O LLISIO N LIG H T

O N IN S T R UM E N T PA N E L

16.2.3.

PA R KIN G LIG H T

16.2.4.

LA N DIN G LIG H T


16 .1

T HM

16.1 - IN T E RIO R LIG H TIN G 16.1.1. IN T E RIO R LIG H TIN G S Y S T E MS The interior lighting consists of 4 separate systems: - pilots and passengers overhe ad lighting - copilot's instrument panel lighting - pilot's instrument panel lighting - overhe ad panel, console, compass and thermometer lighting.

O verhe ad p a n els

Instrument panel - pilot - copilot

C onsole

16.1.2. O V E R H E A D LIG H TIN G E ach dome unit has 2 swivelling lamp-holder/light diffusers, e ach light being individually controlled. E ach light in the pilot's dome unit is individually controlled by a switch and a dimmer. N.B. The pilot's lighting is maintained in the event of failure of the generator or battery contactor.

P P21 P P13

DIR E C T BAT. PILO TS O V E R H E A D LIG H T

PA S S E N G E R S OVERHEAD LIG H T

16.1.3. P RIN CIP L E O F LIG H T G E N E R AT O R A N D LIG H T DIF F U SIO N O N IN S T R UM E N T PA N E L The light from a 70 W iodine light, reflected by reflector (1) is picked up by cone (2) linked to an optical glass fiber loom (3). E a ch ele m e nt of this loom termin ate s in a

4 1

2

3

5

16 .2

plexiglas light-diffuser (4) mounted on the instrument panel (5) ne ar the instrument to be lit .

Light propagation through the black-painted glass fiber (the light is captive within the fiber)

Diffusion of light


T HM

16.1.4. PIL O T'S IN S T R UM E N T PA N E L A N D O V E R H E A D PA N E L LIG H TIN G ( 1 ) N orm al o p eratio n The overhe ad panels, console and O AT indicator are lit when switch (1) is set to on. The brightness is adjusted by potentiometer (P1) which controls dimmer (3).

The pilot's instrument panel and compass lighting is controlled with switch (2). Potentiometer (P2) controls dimmer (4). P P20

P P14

1

P1

3

2

F1

P2

4

F2

C omp a ss

OVERHEAD PA N E L

to radion a vig ation T h ermom et er (O AT)

C ONSOLE

Light generator

( 2 ) B u s P P14 failure If the power supply from P P14 is lost, the overhe ad panel, console and O AT indicator lighting goes out. The pilot must set the switch of the failed circuit to " O F F " (in this example, switch 1) so that the system can now be supplied from bus P P20.

The brightness of all the lighting is now controlled by potentiometer (P2). Note that fuses F 1 and F 2 protect against short-circuits in the failed system. P P20

P P14

2

1

P2

P1

3

F1

F2 4

C omp a ss OVERHEAD PA N E L

C ONSOLE

to radion a vig ation T h ermom eter (O AT) Light generator C e document est la propriété d'E UR O C O PT E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'E UR O C O PT E R et son contenu ne peut être divulgué. This document is the property of E UR O C O PT E R ; no part of it shall be reproduced or transmitted without the express prior written authorization of E UR O C O PT E R and its contents shall not be disclosed. © E UR O C O PT E R 1998.

16 .3

T HM

16.1.5. C O PIL O T'S IN S T R UM E N T PA N E L LIG H TIN G P P 13

Note the single power supply to the light generator Potentiometer

1

1 - Switch 2 - Dimmer 3 - Fuse

2 Light generator

3

16.1.6. C O M P O N E N T L O C ATI O N S

C opilot's instr./panel lighting pushbutton

C onsole lighting pushbutton

Pilot's instr.panel lighting pushbutton U L/S H E D U 115V U 26V

LH

U 26V U 115 V

LH

RH

I. LH G E N.

U RH E SS

RH

I. RH G E N.

U LH E SS

LIG HTIN G C opilot I/panel

C o ns ol e

C opilot's instrument panel lighting pote ntiom eter

Pilot I/panel

Pilot's instrument panel lighting pote ntiom eter C onsole lighting pote ntiom eter

Pilot's light g e n erator

C opilot's light g e n erator Pilot's dimmer

16 .4

C opilot's dimmer


T HM

16.2 - E X T E RIO R LIG H TIN G 16.2.1. P O SITI O N LI G H T S 2



ˇ 

ˇ  









 

3

4



1

5

6

8

7

P P11

1

P P12

1 - C ontrol pushbutton 2 - R e ar light support 3 - G lobe gasket 4 - Globe-lamp assembly 5 - Clamp 6 - G lobe gasket 7 - Side light globe-lamp assembly 8 - Cover C e document est la propriété d'E UR O C O PT E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'E UR O C O PT E R et son contenu ne peut être divulgué. This document is the property of E UR O C O PT E R ; no part of it shall be reproduced or transmitted without the express prior written authorization of E UR O C O PT E R and its contents shall not be disclosed. © E UR O C O PT E R 1998.

16 .5

T HM

16.2.2. C O L LISIO N LIG H T Night or day, the collision light indicates the aircraft's presence at a gre at distance. The unit emits flashes of red light which draw attention much better than a fixed light. The xenon gas tube is supplied from a flashing unit (2). The light is controlled by pushbutton (1).

45 flashes per min. visible over 360°

3

4 5 6 7 8

2 

ˇ 

ˇ  









 



P P14

1 - C ontrol pushbutton 2 - High voltage generator 3 - G lobe made of he at resistant glass 4 - F araday shield 5 - X enon tube 6 - Printed circuit 7 - Seal 8 - Mount

1

HV G ENERATOR

58 L

O p eratio n of th e hig h v olta g e (H V) g e n erator: the H V generator supplies the lamp via an electronic circuit. The electronic circuit transforms the 28 V input voltage into high voltage and charges the capacitors.

16 .6

When the capacitors are charged, a timer controls ioniz ation of the xenon and discharge of the capacitors 45 times per minute.


T HM

16.2.3. PA R KIN G LIG H T A fixed light is installed under the structure on the LH side of the aircraft. The be am from the light illuminates a wide zone in front of the aircraft. The light is equipped with a 150 watt iodine lamp which projects an elliptical be am 40° wide in a zimuth and 10° wide in elevation. The be am axis is positioned at -8° relative to the helicopter's horizontal datum line.

ˇ  







P P13 

16.2.4. L A N DIN G LIG H T A fixed landing light is installed under the structure on the R H side of the aircraft and equipped with a 450 W iodine lamp. The conical be am of this light is positioned at -23° relative to the helicopter's horizontal datum line. This light is controlled by switch (1) on the pilot's and copilot's collective lever grips.

P P19

1

P P20

P P11

1

1

P P12


16 .7

T HM

17 WINDSHIE LD WIP E RS

17.1 -

WIN D S HIE L D WIP E R S

17.2 -

WIN D S HIE L D WIP E R C O N T R O L S

17.3 -

F U N C TIO N A L DIA G R A M O F WIN D S HIE L D WIP E R C O N T R O L CIR C UIT


17 .1

T HM

17.1 - WIN D S HIE L D WIP E R S The windshield wiper installation improves visibility in rainy we ather by wiping the two front windshields . The wiper arms (1) are driven by electric motors (3) whose rotary motion is converted into reciprocating motion by a rod and crank mechanism (2).

WIP E R D RIV E LIN K A G E

1 Wiper pivot

2

R od

Motor driv e

3 C ra nk

17.2 - WIN D S HIE L D WIP E R C O N T R O L S

1

2



ˇ 

ˇ  









 



1 - Pilot's windshield wiper arming pushbutton 2 - C opilot's windshield wiper arming pushbutton 3 - C ontrol pushbutton

17 .2

3


T HM

17.3 - F U N C TIO N A L DIA G R A M O F WIN D S HIE L D WIP E R C O N T R O L CIR C UIT The pilot's and copilot's installations are identical. The copilot's circuit has a single power supply.

PILO T

C O PIL O T

2.1

1.1

1.2

2.2 3.1

4.1

4.2

3.2

F

F 5.1

5.2

6.1

6.2 S

S

5 6 F S

1 - C ontrol circuit arming pushbutton 2 - C ontrol switch 3 - Power relay control relay 4 - Power relay

- Motor stop microswitch - Motor fitted with a stop cam - Motor power supply: fast - Motor power supply : slow

1) S witc hin g o n th e win d s hield wip er With arming pushbutton (1) and switch (2) set to " O N ", relays (3) and (4) are energiz ed; the motor (6) is supplied by the high spe ed winding. Microswitch (5) operated at e ach rotation by the cam has no effect. 3

2

1

4 F 5 6 S

( 2 ) Sto p pin g th e win d s hield wip er

3 2

4

S etting control switch (2) to " O F F " de-energiz es relays (3 and 4). The motor is supplied by the low spe ed winding until the motor cam opens microswitch (5). This system stops the windshield wiper straightaway in the "park" position.

1

F 5 6 S C e document est la propriété d'E UR O C O PT E R ; il ne peut être communiqué à des tiers et/ou reproduit sans l'autorisation préalable écrite d'E UR O C O PT E R et son contenu ne peut être divulgué. This document is the property of E UR O C O PT E R ; no part of it shall be reproduced or transmitted without the express prior written authorization of E UR O C O PT E R and its contents shall not be disclosed. © E UR O C O PT E R 1998.

17 .3

T HM

18 A UT O PIL O T

18.1 -

O V E R VIE W O F A U T O PIL O T

18.2 -

A U T O PIL O T F LIG H T C O N T R O L C O MP O N E N T S

18.2.1.

C Y C LIC C H A N N E LS

18.2.2.

YAW C H A N N E L

18.2.3.

C O LL E C TIV E PIT C H/YAW M E C H A NIC AL C O U PLIN G

18.3 -

A U T O PIL O T D E T E C TIO N A N D A MP LIFIC ATIO N U NIT S

18.4 -

A U T O PIL O T C O N T R O L S A N D M O NIT O RIN G


18 .1

T HM

18.1 - O V E R VIE W O F A U T O PIL O T The autopilot (A P) is designed to replace the human pilot in controlling the helicopter on the 3 flight control axes (pitch, roll and yaw). It ensures the following primary functions based on pilotselected references values: - attitude and he ading hold, - altitude hold, - airspe ed hold, - coordin a t e d turns (no sid e slip, with sid e slip b a ll centered). When coupled to certain radionavigation systems, it performs automatic capture and tracking of radio guidance beacons. The A P includes fly-through control provisions that allow the pilot to resume flight control and override the system.

Prin ciple s of th e A uto m atic Pilot (A P) The A P transmits electrical signals to electric control actuators series-mounted in the flight control linkage. The control actuators are supplied directly by the A P computer. The pitch and roll channels also include parallelmounted actuators, called " T RIM A C T U AT O R S " and connected to the A P computer via an actuator control unit. These trim actuators move the anchoring point of the pilot's cyclic stick to enhance the limited action of the control actuators.

A U T O PIL O T

MAIN R O T O R S E RV O A C T U AT O R S

Control unit A C TU AT O R S

Position sensor Coupled radionavigation systems

Computer

Coupler

P RIN CIPL E O F A P " F E E D B A C K L O O P "

Actuator control unit

H/copter deviates from its theoretical position

Position s ensor

E lectric order to cancel deviation

Deviation signal C omput er

18 .2

L A T E R

TRIM

TRIM

Yaw actr.

TAIL R O T O R S E RV O A C TUAT O R

The control channel is actuated to cancel the deviation

S ervo actuator

L O N G

N O T E : The system uses the S FIM autopilot with only one control lane. In the IF R version a failure monitoring unit ensures surveillance. • The sensor me asures the deviation direction, amplitude and rate, and outputs a deviation signal. Sensors include: gyroscope (attitude deviation), compass (he ading deviation), air data module (altitude deviation). • The computer processes the deviation signal and generates an electric signal to cancel the deviation.


T HM

18.2 - A U T O PIL O T F LIG H T C O N T R O L C O MP O N E N T S 18.2.1. C Y C LIC C H A N N E L S R O LL C H A N N E L Trim actuator with anchoring system

Roll actuator PIT C H C H A N N E L Trim actuator with anchoring system

Pitch actuator

18.2.2. YAW C H A N N E L P e d al motion sensor

Spring rod

Yaw control actuator

C ollective pitch/yaw coupler Friction system


18 .3

T HM

18.2 - A U T O PIL O T F LIG H T C O MP O N E N T S (C o nt.) 18.2.3. C O L L E C TIV E PIT C H/YAW M E C H A NIC A L C O U P LIN G The tail rotor blade incidence varies with the collective pitch setting. Main rotor counter torque variations are compensated at all times by a mechanical coupling betwe en the collective pitch channel and the yaw channel. C oupling with the collective pitch is via a summing crank lever (1) that pivots on a bellcrank (2) secured to a torque shaft (3). This shaft is connected to the collective pitch bellcrank by a spring rod (4), which allows collective lever operation if the yaw control seiz es.

Tail servo 2

3 1 4

Pedals

To mixing unit P E D AL IN P U T WIT H C O LL E C TIV E L E V E R S TATIO N A RY

B e ll cr a n k ( C ), c o n tr o l l e d b y the collective lev e r, i s f i x e d . Crank lever (1) rotates about (A) and transmits pedal movement to the tail servo actuator.

1

C O LL E C TIV E L E V E R IN P U T WIT H P E D ALS S TATIO N A RY

Point (D) is fixed. B e llcra nk ( C ) is D moved by the coll e ctiv e l e v e r. Crank lever (1) rotates about (B) and transmits a movement proportional to that of the collective lever to the output rod.

C

A

1 B C

18.3 - A U T O PIL O T D E T E C TIO N A N D A MP LIFIC ATIO N U NIT S F ailure monitoring unit

Dire ction al gyro

F lux v alv e

Sid e slip detector C D V 85 coupler

C omput er

Trim control unit

18 .4

Air data unit


V ertical gyro

T HM

18.4 - A U T O PIL O T C O N T R O L S A N D M O NIT O RIN G Trim artificial fe el rele a s e/e ng a g e m e nt

Trim actuator O N/O F F

Trim actuator O N/O F F 

ˇ 

ˇ  









 

A N N U N CIAT O R PA N E L ROLL

PITCH

G alv a nom eters indicating position of control actuators

YAW

ˇ ˇ

 









 



ˇ



 

  

C h ann el dis eng a ge d indicator lights

ˇ

 



ˇ 

 

ˇ 



ADI RADIO ALTIME T E R

(Hover transition)

ˇ

























 ˇ

 



ˇ 

 ˇ

ˇ˛˝¸ 





ˇ 



ˇ 



ˇ 

 ˇ









A P A N D F D C C O N T R O L PA N E L

(O n console)

H SI


18 .5

T HM

18.4. A U T O PIL O T C O N T R O L S A N D M O NIT O RIN G (C o nt.)

Illuminates when mode is enabled

A U T O PIL O T & F LIG H T DIR E C T O R C O U PL E R C O N T R O L PA N E L

ˇ

























 ˇ

 



ARM CAP

ˇ 

ˇ 

ˇ˛˝¸ 



ˇ 



ˇ 



ˇ 



ˇ 





Illuminates on capture of guid a nc e b e a m

 

A N N U N CIAT O R PA N E L

(IF R version) ˇ ˇ









 

 



ˇ





IN T H E V F R V E R SIO N O NLY T H E A P- T RIM - ALT - H D G - A S A N N U N CIAT O R S A R E IN C LU D E D



  



ˇ 



ˇ 

 ˇ



C O LL E C TIV E L E V E R G RIP

C Y C LIC S TIC K G RIP 4 position b e e p-trim switch



A P rele ase

Trim rele ase

C oupler rele ase (IF R version)

G O - AROUND E ng a g e/Dis e ng a g e

18 .6


AS355N - Training Manual (1998)

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