V2500

Training Manual B 737-300/400/500 737-300/400/500 ATA 49 APS 2000 ATA 104 Level 3

Book Book No: No:

B737 B737-3 -3 49 49 L3 L3 E APS APS

Lufthansa Technical Training GmbH Lufthansa Base

For Training Purposes Only Lufthansa

!

For training purposes and internal use only. Copyright by Lufthansa Technical Training GmbH. All rights reserved. No parts of this training manual may be sold or reproduced in any any form without permission of:

Lufthansa Technical Training GmbH Lufthansa Base Frankfurt D-60546 Frankfurt/Main Tel. +49 +49 69 / 696 41 41 78 Fax +49 69 / 696 63 84 84 Lufthansa Base Hamburg Weg beim Jäger 193 D-22335 Hamburg Tel. +49 40 / 5070 24 13 Fax +49 40 / 5070 47 46

TABLE OF CONTENTS

ATA 49 APU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APS 2000 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . PANEL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ACCESS DOOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APU DRAINS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AIR INLET DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . APU AIR INLET ADJUSTMENTS . . . . . . . . . . . . . . . . . . . . BOROSCOPE INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . APU LUBRICATION SYSTEM . . . . . . . . . . . . . . . . . . . . . . . OIL TANK DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . COMPONENT DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . OIL TANK SERVICING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OIL SYSTEM SCHEMATIC DESCRIPTION . . . . . . . . . . . APU FUEL SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APU FUEL SHUTOFF VALVE . . . . . . . . . . . . . . . . . . . . . . . FUEL HEATER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ELECTR ELECTRONI ONIC C FUEL FUEL CONTRO CONTROL L AND PUMP PUMP ASSEMB ASSEMBL LY START PURGE VALVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FUEL SYSTEM OPERATION . . . . . . . . . . . . . . . . . . . . . . . DRY MOTOR THE APU . . . . . . . . . . . . . . . . . . . . . . . . . . . . WET MOTOR THE APU . . . . . . . . . . . . . . . . . . . . . . . . . . . . LOW PRESSURE BLEED . . . . . . . . . . . . . . . . . . . . . . . . . . APU AIR SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APU BLEED BLEED AIR VALVE . . . . . . . . . . . . . . . . . . . . . BLEED AIR VALVE OPERATION . . . . . . . . . . . . . . . . . . . . APU COOLING AIR SYSTEM . . . . . . . . . . . . . . . . . . . . . . . APU COOLING AIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . COOLING FAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IGNITION AND START SYSTEM . . . . . . . . . . . . . . . . . . . . IGNITION COMPONENT DESCRIPTION . . . . . . . . . . . . . STARTING COMPONENT DESCRIPTION . . . . . . . . . . . . STARTING COMPONENT DESCRIPTION . . . . . . . . . . . . APU CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APU CONTROL UNIT/FADEC DE DESCRIPTION . . . . . . . .

1 2 4 6 8 10 12 14 16 18 20 22 24 26 28 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68

FADEC DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . AMBIENT PRESSURE TRANSDUCER . . . . . . . . . . . . . . . SPEED SENSOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APU START SEQUENCE . . . . . . . . . . . . . . . . . . . . . . . . . . . APU SHUT DOWNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E. G. T. INDICATING SYSTEM. . . . . . . . . . . . . . . . . . . . . . THERMOCOUPLES ( 2 ) . . . . . . . . . . . . . . . . . . . . . . . . . . . EGT BALANCING RESISTOR . . . . . . . . . . . . . . . . . . . . . . . ID-MODULE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FADEC BITE CODES AND LIGHTS. . . . . . . . . . . . . . . . . . MCDU, APU DATA PAGES. . . . . . . . . . . . . . . . . . . . . . . . . . TROUBLE SHOOTING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . APU OPERATION LIMITS AND PARAMETERS . . . . . . . APU OPERATION TEST . . . . . . . . . . . . . . . . . . . . . . . . . . .

70 72 74 76 78 80 82 86 88 90 92 94 97 98

TABLE OF FIGURES Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 Figure 20 Figure 21 Figure 22 Figure 23 Figure 24 Figure 25 Figure 26 Figure 27 Figure 28 Figure 29 Figure 30 Figure 31 Figure 32 Figure 33 Figure 34 Figure 35

APS 2000 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APU Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APU Access Door and Shroud. . . . . . . . . . . . . . . . . . . . . . . Shroud Drains. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APU Air Inlet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APU Air Inlet Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . Boroscope Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lubrication Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lubrication System Components . . . . . . . . . . . . . . . . . . . . Lubrication System Components . . . . . . . . . . . . . . . . . . . Oil Tank Servicing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Oil Servicing System Schematic . . . . . . . . . . . . . . . . . . . . Fuel System Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . APU Fuel Shutoff Valve and DC Fuel Boost Pump . . . . APU Fuel Shutoff Valve Control . . . . . . . . . . . . . . . . . . . . DC Fuel Boost Pump Control . . . . . . . . . . . . . . . . . . . . . . Fuel Heater and Flow Control Valve . . . . . . . . . . . . . . . . Fuel Control and Pump Assembly . . . . . . . . . . . . . . . . . . Fuel System Components . . . . . . . . . . . . . . . . . . . . . . . . . APU-MAX. EGT CHART . . . . . . . . . . . . . . . . . . . . . . . . . . APU Dry Motoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APU Wet Motoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Low Pressure Bleed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bleed Air Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APU Bleed Air Components . . . . . . . . . . . . . . . . . . . . . . . APU Bleed Air Valve Schematic . . . . . . . . . . . . . . . . . . . . APU Cooling Air Schematic . . . . . . . . . . . . . . . . . . . . . . . . Cooling Air Components . . . . . . . . . . . . . . . . . . . . . . . . . . Cooling Air Shutoff Valve . . . . . . . . . . . . . . . . . . . . . . . . . . Ignition / Starting Schematic . . . . . . . . . . . . . . . . . . . . . . . Ignition Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Start Relay Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Starter Motor and Shaft Assembly . . . . . . . . . . . . . . . . . . APU Control Sytem Schematic . . . . . . . . . . . . . . . . . . . . . APU Control Unit and FADEC Component . . . . . . . . . . .

3 5 7 9 11 13 15 17 19 21 23 25 27 29 30 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69

Figure 36 Figure 37 Figure 38 Figure 39 Figure 40 Figure 41 Figure 42 Figure 43 Figure 44 Figure 45 Figure 46 Figure 47 Figure 48 Figure 49

FADEC Component . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Amb. Press. Transducer and Amb. Temp. Sensor . . . . Speed Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . APU Start Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Normal/Auto Shut Down . . . . . . . . . . . . . . . . . . . . . . . . . . EGT Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thermocouples and Event Monitoring Unit. . . . . . . . . . . APU E. G. T . System Schematic . . . . . . . . . . . . . . . . . . EGT Balancing Resistor and Indicator . . . . . . . . . . . . . . ID-Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LOP FADEC Bite Code Indication. . . . . . . . . . . . . . . . . . . MCDU APU DATA Display . . . . . . . . . . . . . . . . . . . . . . . . LOP FADEC BITE Code Shown . . . . . . . . . . . . . . . . . . . . LOP FADEC BITE Code Shown . . . . . . . . . . . . . . . . . . . .

71 73 75 77 79 81 83 85 87 89 91 93 95 96

g n i n i a r T l a c i n h c e T a s n a h t f u L

AIRBORNE AUXILIARY POWER GENERAL

B737-300/400/500 49

ATA 49 APU FWD

APS 2000

y l n O s e s o p r u P g n i n i a r T r o F



49-00 APS 2000 INTRODUCTION The APS 2000 auxillary power unit (APU) supplies electrical and pneumatic power to other airplane systems. This permits these airplane systems to operate without the use of ground power sources or the engines. The APU can also supply electrical and pneumatic power in the air. Altitude Operational Limits The APU can supply:  55 KVA electrical power on ground  45 KVA electrical power up to 37,000 feet (11,277 meters)  Electrical and pneumatic power is available at the same time up to 10,000 feet (3,048 meters).  Pneumatic power alone is available up to 17,000 feet (5,183 meters).  The APU can be started at 37,000 feet or below. Model Designation:  Manufacturer: Sundstrand Power System, San Diego, USA.


B737-300/400/500

Ratings at SL:  ROTOR SPEED  OVERSPEED  OUTPUT SPEED  BLEED AIR FLOW  BLEED AIR PRESSURE  BLEED AIR TEMP  FUEL FLOW  MAX CONTINUOUS EGT  Max EGT

45,225 RPM steady state 105% / 47,486 6000 RPM at Generator Drive 193 lbs/min at no electrical load 45 PSIG 209C 200 kg/h during max load at standard day 702"C 730"C

Abreviations and Acronyms APU . . . . . . . . . . . . . . . . . . . . . . . . . . . . Auxilary Power Unit ARINC . . . . . . . . . . . . . . . . . . . . . . . Aeronautical Radio Inc. BATT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Battery BITE . . . . . . . . . . . . . . . . . . . . . . . . . Built in Test Equipment C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Degrees/Celsius CB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Circuit Breaker DC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Direct Current DMU . . . . . . . . . . . . . . . . . . . . . . . . . Data Managment Unit EGT . . . . . . . . . . . . . . . . . . . . . . Exhaust Gas Temperature EMU . . . . . . . . . . . . . . . . . . . . . . . . . . Event Monitoring Unit FADEC . . . . . . Full Authority Digital Electronic Controller LBS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pounds HZ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hertz KG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Kilogram KVA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Kilo Volt Ampere KW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Kilowatt LCD . . . . . . . . . . . . . . . . . . . . . . . . . . Liquid Crystal Display LRU . . . . . . . . . . . . . . . . . . . . . . . . . . Line Replaceable Unit MCDU . . . . . . . . . . . . . Multi Purpose Control Display Unit PPH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pounds Per Hour PSI . . . . . . . . . . . . . . . . . . . . . . . . . Punds Per Square Inch PSIA . . . . . . . . . . . . . . . Punds Per Square Inch Absolute PSID . . . . . . . . . . . . . Punds Per Square Inch Differential PSIG . . . . . . . . . . . . . . . . . . Punds Per Square Inch Gage RPM . . . . . . . . . . . . . . . . . . . . . . . . . Revolutions Per Minute RTD . . . . . . . . . . . . . . . . . Resistive Temperature Detector SHP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Shaft Horsepower SW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Switch V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Volts



B737-300/400/500 49-00


Figure 1

APS 2000



49-00 PANEL DESCRIPTION MAINTENANCE LIGHT ( blue ) ON- Identifies an APU Warning. An Electrical fault has occured , or an APU Oil Servicing is required . See MCDU Multi purpuse Control Display Unit or FADEC Fault Display for Maintenance Light Reason. LOW OIL PRESSURE LIGHT (amber)  ON- APU oil pressure is low, causing the APU to initiate an automatic shutdown (after the start cycle is complete).  Light is illuminated during start until APU oil pressure is normal.  Light is armed only when APU switch is not in OFF. FAULT LIGHT (amber)  ON- Identifies an Automatic Shutdown of the APU. See MCDU Multi purpuse Control Display Unit or FADEC Fault Display for Fault Light Reason.APU oil temperature is excessive, causing APU to initiate an automatic shutdown.  Light is armed only when APU switch is not in OFF. OVERSPEED LIGHT (amber)  ON - APU speed excessive causing APU to initiate an automatic shutdown. Note: MASTER CAUTION light and the APU annunciator will illuminate together with any of the above described amber caution lights (Exception: Low oil pressure light during APU start)


B737-300/400/500

APU GENERATOR AC AMMETER  Display APU generator load current. APU MASTER CONTROL SWITCH  OFF- Normal position when APU is not running.  OFF- when APU is running initiates normal shutdown.  ON - Normal position with APU running.  START (Momentary) - When APU switch is moved from OFF to START and released to ON, causes automatic start sequence to be initiated. EXHAUST TEMPERATURE INDICATOR  Displays APU exhaust gas temperature.

APU BLEED AIR SWITCH  ON -Opens the APU Bleed Air Valve if the APU is Operating.  OFF- Closes the APU Bleed Air Valve.



B737-300/400/500 49-00

MAINTENANCE LIGHT

LOW OIL PRESSURE LIGHT FAULT LIGHT

OVERSPEED LIGHT RECIRC FAN OFF

DUCT PRESSURE INDICATOR

NORMAL 40

60 OVHT 80 PSI

0

APU GENERATOR AC METER

TEST L PACK OFF AUTO HIGH

FORWARD OVERHEAD PANEL, P5 y l n O s e s o p r u P g n i n i a r T r o F

APU

WING ANTI ICE

OFF

100

OFF AUTO AUTO HIGH

PACK TRIP OFF

OPEN

WING-BODY

APU MASTER CONTOL SWITCH

R PACK

ISOLATION VALVE CLOSE

TRIP

OVERHEAT

WING ANTI ICE

PACK TRIP OFF WING-BODY OVERHEAT BLEED TRIP OFF

BLEED TRIP OFF

APU BLEED AIR SWITCH

RESET

ON OFF

OFF

ON

START

1

ON APU

2 BLEED

APU EXHAUST GAS TEMPERATURE INDICATOR

FORWARD OVERHEAD PANEL, P5

Figure 2

APU Panel


AIRBORNE AUXILIARY POWER POWER PLANT

49-10 ACCESS DOOR Access to the APU is through an access door, completely enclosing the APU compartment. The access door is hinged on the right side and latched on the left side. It consists of skin, ribs and stringers forming the outside contour of the fuselage. On the inside are two door open holding rods, two drain cups and cooling air exhaust. On the outside, is a drain mast connected to the drain cups. The door can be opened for normal APU servicing, or it can be removed by unlatching the hinges on the right side. The drain cups should be inspected periodically for cleanliness. The exhaust ducting is cooled by four air inlets around the aft end of the exhaust fairing. SHROUD The APU shroud is a titanium compartment that fully protects the APU power plant. The APU shroud gives the protection from an APU fire and decrease the noise from the APU power plant. The APU shroud includes the upper shroud and the lower shroud. The upper shroud attaches to the airplane structure and holds the forward end of the APU exhaust duct. The upper shroud and the lower shroud connect to one another with the shroud latches on the lower shroud.


737-300/400/500

Upper Shroud The upper shroud is installed in the APU compartment. When the APU is removed from the airplane, the upper shroud will stay in the APU compartment. The upper shroud has openings for the fuel lines, air inlet ducts and bleed air duct. Three mounting brackets for the APU engine attach to the shroud rings. Lower Shroud The lower shroud attaches to the upper shroud with ten shroud latches. The lower shroud has the openings to the filler port for the oil tank and to the overboard exhaust for the APU cooling air. Also, there is an access panel that is removed to read the elapsed time indicator. When the lower shroud is removed, you can get access to do maintenance on the APU.



737-300/400/500 49-10

EXHAUST DUCT

UPPER SHROUD

APU DOOR HINGE ( 2 LOCATIONS )


DRAIN SEAL PLATES

APU SHROUD LATCH ( 10 LOCATIONS )

DOOR SUPPORT RODS (STOWED POSITION)

DRAIN HOLES

FWD

DRAIN LINE

COOLING AIR EXHAUST

LOWER SHROUD

APU ACCESS DOOR APU COOLING AIR EXHAUST DUCT

TO DRAIN MAST

APU DOOR LATCH (3 PLACES)

Figure 3

DRAIN FITTING

APU Access Door and Shroud.

FWD


AIRBORNE AUXILIARY POWER APU POWER PLANT

49-10 APU DRAINS The APU drains provide means for draining unburned fuel from the engine and for draining fuel or oil from the shroud in event of leakage inside the shroud. At the aft end of the shroud, a drain cup with stand-pipe picks up unburned fuel discharged through the turbine exhaust port. Two fuel drain lines are manifolded into a fitting on the engine. This fitting mates with a drain cup in the drain line. The drain line terminates at a fitting at the forward end of the shroud. Adjacent to the drain line terminal end fitting is another fitting. Through this fitting fuel or oil is drained from the shroud. Both fittings at the forward end of the shroud mate with drain cups in the APU compartment access door. The drain cups in the access door are connected to a drain mast. Drain Valve The drain valve is a spring- loaded ball device. The drain valve permits fuel that collects in the combustor to flow to the APU drain mast. The drain valve is located at the lowest point in the combustor plenum. This permits complete drainage prior to another attempted start. The drain valve is spring-Ioaded open until the APU reaches approximately 15 percent RPM. At 15 % RPM APU combustor pressure closes the drain valve.


B737-330/430/530


AIRBORNE AUXILIARY POWER APU POWER PLANT

B737-330/430/530 49-10

APU ENGINE

FWD TURBINE EXHAUSTEND DRAIN

DRAIN CHECK VALVE LOWER SHROUD DRAIN RESERVIOR

TURBINE EXHAUST END DRAIN CUP

SHROUD DRAIN SHROUD DRAIN CUP DRAIN CUP y l n O s e s o p r u P g n i n i a r T r o F

APU ACCESS DOOR

APU DRAIN MAST

A0 96 73

Figure 4

Shroud Drains.

9 10 61


AIRBORNE AUXILIARY POWER APU AIR INLET

49-15 AIR INLET DESCRIPTION The air supply for the APU engine operation and accessories cooling is through a door installed in the air inlet duct. The air inlet consists of a door with a vortex generator and flap, actuator, door position switch and ducting. Access to the actuator and door position switch is through an access door on the left side of the fuselage, forward of the APU compartment. Operation When the actuator is powered, the pushrods move the door to the open position. Movement of the door deflects the flap on the vortex generator for improvement of air flow into the inlet. When the door is fully open, the door switch operates. The switch actuation is part of the APU start cycle.


B737-300/400/500



B737-300/400/500 49-15 APU COMPARTMENT STRUCTURE

TORQUE BOX

AIR DIFFUSER DUCT VORTEX GENERATOR

COMPRESSOR AIR DUCT COOLING AIR DUCT

AIR INLET DOOR

AIR INLET DOOR


INLET DOOR POSITION SWITCH

FWD

AIR DIFFUSER DUCT

AIR INLET DOOR ACTUATOR

FWD

ACTUATOR ARM

767244 767245

Figure 5

APU Air Inlet



49-15 APU AIR INLET ADJUSTMENTS Maintenance Practices The APU air inlet has three adjustments:

 Air Inlet Door Adjustment . Door alignment. Adjustment is made by varying the length of the two actuator push rods.

 Air Inlet Door Position Switch Adjustment. Door open switch, door full open position. Adjustment is made by two nuts on the switch.

 Vortex Generator

Flap Adjustment .

Flap deflection with door open. Adjustment is made by varying the length of the control rod and the adjustable flap stop.


B737-300/400/500



B737-300/400/500 49-15

AIR INLET DOOR (CLOSED POSITION)

AIR INLET DOOR (OPEN POSITION) SET SCREW (DOOR OPEN)

VORTEX GENERATOR FLAP

VORTEX GENERATOR STOP 3 FLAP (DOOR CLOSED POSITION)

3 PUSHROD

FLAP STOP (DOOR OPEN POSITION)

FWD

INBD DOOR CLOSE

BARREL FITTING

NUT NO. 1 NUT NO. 2 AIR INLET DOOR - CLOSED POSITION


DOOR OPEN AIR INLET DOOR ACTUATOR

1

AI R I NL ET DO OR

PUSHROD BEARING END

AIR DIFFUSER DUCT

NUT

2 DOOR POSITION SWITCH

Figure 6

APU Air Inlet Adjustments



AIRBORNE AUXILIARY POWER ENGINE

B737-300/400/500 49-20

BOROSCOPE INSPECTION The following components of the turbine assembly may be inspected by the use of a boroscope: Turbine Blade Tips Combustion Chamber Turbine Nozzle Vanes Turbine Wheel Blades Compressor Wheel Blades Compressor Diffuser Legend: 4. BLADES OF THE COMPRESSOR WHEEL 5. LEADlNG EDGE OF THE COMPRESSOR WHEEL 6. EXHAUST SECTlON 7. BLADES AND VANES OF THE TURBlNE WHEEL 8. LEADlNG EDGE OF THE TURBlNE WHEEL (3 LOCATlONS) 9. COMBUSTION CHAMBER (4 LOCATlONS) 10.HAND-CRANK PROVlSlONS (LOCATED ON THE COOLlNG FAN)


AIRBORNE AUXILIARY POWER ENGINE

B737-300/400/500 49-20

946555

TURBINE NOZZLE

COMPRESSOR WHEEL

FWD

FWD

3 4

BOROSCOPE PLUG

COVER PLATE

COMPRESSOR PLENUM

IGNITER PLUG 6 5

1 2

COMPRESSOR DIFFUSER

HAND-CRANK PROVISIONS

TURBINE WHEEL

COMBUSTION CHAMBER

______ LEGEND: COVER


BOLT

COOLING AIR FAN

MANUAL DRIVE

945054

1

BLADES OF THE COMPRESSOR WHEEL

2

LEADING EDGE OF THE COMPRESSOR WHEEL

3

EXHAUST SECTION

4

BLADES AND VANES OF THE TURBINE WHEEL

5

LEADING EDGE OF THE TURBINE WHEEL (3 LOCATIONS)

6

COMBUSTION

833716

Figure 7

Boroscope Inspection

CHAMBER


AIRBORNE AUXILIARY POWER OIL

49-90 APU LUBRICATION SYSTEM The APS 2000 is lubricated by a self-contained, wet sump system that is integral with the gearbox. The oil system provides a pressurized supply of oil that lubricates and cools all the gears and bearings in the gearbox and engine rotor assembly. Operation Before the APU is started, the de-prime valve is energized to the open position. This stops the supply of oil to the oil pump. When the APU accelerates to 55% service speed, the de-prime valve is de-energized to the closed position. The oil pump pulls the oil from the oil tank and sends the oil to the oil filter element. If the oil filter element is clogged, the bypass valve opens to permit the oil fiow to continue. From the oil filter element, the oil goes through the oil cooler. If the oil cooler is clogged, the bypass valve for the oil cooler opens. From the oil cooler, the oil goes to the gearbox assembly and the gears and bearings of the APU engine. In the gears and bearings of the APU engine, an airloil mixture is made. The air/oil mixture is divided when the gearshaft turns. The air is sent to the turbine exhaust port through a gearbox case vent. The oil returns to the oil tank by gravity. The Iube service panel replenishes the oil tank with the oil. The ADD Iight (amber Iight) on the Iube service panei comes on when the oil quantity in the oil tank is 1 .6 U,S quarts (l .5 Iiters). When the ADD Iight is on, a solenoid valve opens to Iet the oil enter the oil tank from the pressure fiII connection. The FULL Iight (green Iight) comes on when the oil quantity in the oil tank is 2.6 U.S quarts (2.5 Iiters). The solenoid valve wiII close when the FULL Iight is on. The solenoid valve closes so the oil tank wiII receive the correct amount of oil.


B737-300/400/500

Gearbox oil distribution Oil is drawn from the gearbox sump by the oil pump mounted on the front of the gearbox. The oil is filtered prior to leaving the pump and then fiows through the oil cooler. The cooled oil is returned to the gearbox oil passages and jets to provide Iubrication and cooling of the gears, shafts and bearings. During operation of the gear system, an oil/air mist is created inside the gearbox. The oil and air are separated by the action of a mechanical separator that is part of the generator gear shaft. Oil is returned by gravity to the gearbox oil sump and the air is vented to the APU exhaust through the gearbox vent system.



B737-300/400/500 49-90 GEARBOX LUBE

OIL PRESSURE SWITCH

OIL TANK VENT LINE TO APU EXHAUST

< 20 PSI ON > 26 PSI OFF

ROTOR ASSEMBLY RELIEF VALVE 45 PSID

OIL COOLER BYPASS VALVE 25-45 PSID

OIL COOLER

COOLING AIR FAN

AIR/OIL MIST TURBINE ASSEMBLY FORWARD OVERHEAD PANEL, P5 HIGHOIL TEMP. SW.

OIL FILTER AND PUMP ASSEMBLY

135  C

FADEC AFT CARGO CPTM

GEARBOX OIL FILTER BYPASS VALVE 40-45 PSID

DE-PRIME VALVE S

FILLER CAP FROM FADEC SIGHT GLASS

FULL

ADD


APU OIL TANK OIL TYPE

APU OIL QTY MODULE

OIL PUMP TO DE-PRIME VALVE < 55 % OP EN > 55% CLOSE

S

60 PSI

OIL FILTER OIL FILTER CLOGGING IND. 30-35 PSID

OILTANK OIL LEVEL SENSOR

MAGNETIC DRAIN PLUG

FILL

WHEN AMBER LIGHT IS ON

OILTANK SOLENOID VALVE

LEGEND OIL SUCTION

LUBE SERVICING PANEL

PRESS. FILL CONNECTION

OIL PRESSURE OIL PRESS. FILLING 833776

795131

OIL TANK VENT LINE

830931

Figure 8

Lubrication Schematic



49-90 OIL TANK DESCRIPTION Oil Tank The oil tank is part of the gearbox assembly. The oil tank hold the supply of oil for the APU Iubrication system. The oil is removed from the oil tank by the oil pump. The oil goes through the oil filter element and oil cooler to the gearbox assembly and the APU engine. The oil flows back from the APU engine to the oil tank by gravity. The air in the oil goes out the turbine exhaust port.The oil tank has a filler port with a filIer cap and dipstick. The oil can be added to the oil tank through the filIer port. Also, the oil tank has a sight glass to do a check on the oil level. Magnetic Drain Plug The magnetic drain plug is installed at the bottom of the oil tank. The magnetic drain plug has a magnetic element and a plug. When the oil tank is serviced, the magnetic element is removed to make sure no metal particles are in the oil. If the oil has metal particles, an investigation of damage to the APU engine is necessary. The magnetic element can be removed without the plug. When the plug and the magnetic element are removed together, the oil will drain from the oil tank. Oil Level Sensor The oil level sensor transmits a signal through the FADEC to show the APU oil quantity. The FADEC sends the signal to the MAINT Iight on the forward overhead panel and to the lube service panel. The oil level sensor has a tube, float and microswitch. The microswitch has two circuits that are operated by the fioat. The oil level sensor is installed on the bottom of the APU oil tank.


B737-300/400/500



B737-300/400/500 49-90

FWD

FILLER PORT FOR THE OIL TANK

OIL FILLER CAP y l n O s e s o p r u P g n i n i a r T r o F

MAGNETIC DRAIN PLUG CHECK VALVE

OIL LEVEL SIGHT GLASS FWD

OIL LEVEL SENSOR GEARBOX (WITH INTEGRATED OIL TANK OILTANK) PRESSURE FILL LINE

803803

833776

Figure 9

Lubrication System Components

DIPSTICK




B737-300/400/500 49-90

COMPONENT DESCRIPTION Oil Cooler The oiI cooler is installed on the APU below the APU electrical generator. The oiI cooler is a rectangular unit made of aiuminum tubes. The oiI cooler receives the oil from the oiI pump. In the oil cooler the oil moves through the tubes where it is cooled by air from the cooling tan assembly. The oil tIows from the oil cooler to the gearbox assembly and the gears and bearings ot the APU engine. The oil cooler has a bypass valve that opens if the oil cooler is clogged. The bypass valve opens when the differentia! pressure across the oii cooler is 25 to 35 psig . The bypass valve is tu!Iy open when the differential pressure is 45 psig .

Oil Pressure Relief Valve The pressure relief valve is installed in the lower part of the gearbox housing. The pressure relief valve keeps the oil pump pressure below 40 to 45 psig. If the pressure relief valve opens, the oil wilI flow back to the oil tank.

Oil Pump and Filter Assembly The oil pump and filter assembly is installed on the gearbox assembly. The oil pump and filter assembly has the oil pump, oil filter element, filter bypass valve, differential pressure indicator, oil temperature switch and de-prime valve. A shaft that connects to the gearbox assembly drives the oil pump and filter assembly. The oil pump gets the oil from the oil tank. The oil pump moves the oil under pressure through the oil cooler to the gears and bearings of the APU. The oil filter assembly has an oil filter element. The oil filter element keeps alI unwanted material in the oil out of the oil pump. The oil filter element is a 2O micron fiIter that can not be cleaned. The oil filter element must be replaced. The oil filter element is installed on the oil pump and filter assembly. The filter bypass valve opens at 40-45 psig when the oil filter element is clogged this permits unfiltered oil to enter the oil pump. A filter clogging indicator (red ) extends when the differential pressure across the oil filter element is 30 to 35 psig .

High Oil Temperature Switch The oil temperature switch is found on the front of the oil pump and filter assembly. The oil temperature switch automatically stops the APU when the APU oil temperature is greater than 135 +/- 5 C The signal from the oil temperature switch is monitored by the FADEC and the airplane electronics in the control cabin.

De-Prime Valve The de-prime valve is energized open when the APU is started . When the APU accelerates to 55% service speed, the de-prime valve is de-energized to the closed position. This will permit the oil pump to produce oil pressure. When the APU is stopped the de-prime valve is energized to the open position to stop the supply of oil to the oil pump. The oil that stays in the APU wiIl drain to the oil tank. After 5 minutes APU stop the de-prime valve is de-energized to the close position.The de-prime valve is installed on the oil pump and filter assembly. The de-prime valve operates with a solenoid.

OiI Pressure Switch The oil pressure switch is installed on the gearbox assembly or on the oil cooler The oil pressure switch stops the APU when the APU oil pressure decreases to 20+/-2 psig . The signal from the oil pressure switch is monitored by the FADEC and the airplane electronics in the control cabin.



B737-300/400/500 49-90 COOLING AIR FAN FLAME ARRESTOR

GENERATOR

GEARBOX OIL VENT TO APU EXHAUST OIL COOLER

OIL PRESSURE SWITCH

FWD

FWD OIL PUMP AND FILTER ASSEMBLY DE-PRIME VALVE OIL FILTER BYPASS VALVE

OIL FILTER CLOGGING IND. (RED)


OIL PRESSURE RELIEF VALVE HIGH OIL TEMP. SWITCH

CARBON SEAL DRAIN

WHITNESS PORT DO NOT PLUG

GEARBOX OIL FILTER

997146

803403

Figure 10

Lubrication System Components

830947



49-90 OIL TANK SERVICING Servicing of the oil sump is accomplished by opening the APU access door. The oil level is checked by removing the filIer cap and using the dipstick. If the oil level is below the FULL mark, add oil until the Ievel is at the FULL mark on the dipstick. To assist in observing the servicing during the addition of oil, a Iine of sight access door is used. The Ievel of oil can be observed through this access during servicing. A hole drilled through the fiIler tube prevents overfilIing of the sump by allowing excess oil to drain out of the fill tube and into the APU lower shroud. REMOTE OIL SERVICING The external service panel provides a means of replenishing the oil supply for the APU oil tank. Power Power for the system is 28 volts dc from the battery bus,switched hot bat bus or APU G.C.U. Maintenance Practices The oil tank is replenished by connecting the oil supply to the pressure fill connection and pumping oil into the tank until the green light ilIuminates. Required oil supply pressure is 35 psi.


B737-300/400/500



B737-300/400/500 49-90

FULL

GREEN LIGHT

ADD

AMBER LIGHT

STABILIZER COMPARTMENT ACCESS DOOR

OIL TANK SOLENOID VALVE

APU OIL QTY MODULE M 925

PRESSURE FILL LINE TO OIL TANK

APU OIL TANK

DOOR OPEN SWITCH

OIL TYPE FWD

STABILIZER COMPARTMENT

FILL

BULKHEAD

PRESSURE FILL CONNECTION

WHEN AMBER LIGHT IS ON


LUBE SERVICE ACCESS DOOR DOOR OPEN SWITCH ACTUATING MAGNET

LUBE SERVICE PANEL

991803

Figure 11

Oil Tank Servicing




B737-300/400/500 49-90

OIL SYSTEM SCHEMATIC DESCRIPTION Operation When the access door to the re-oil system is opened, 28 volts dc is supplied to Module M925. If the oil quantity is more than 2.6 U.S. quarts in the tank, the FULL switch provides a ground for the green (FULL) light, relay R253 and oil tank’ solenoid valve remains de-energized. If the oil quantity is less than 1.6 U.S. quarts in the tank, the ADD switch provides a ground for the amber (ADD) light, relay R253 and oil tank solenoid valve are energized. Adding oil to the tank opens the ADD switch and when tank has 2.6 U.S. quarts the FULL switch operates de-energizing R253 and solenoid valve.



B737-300/400/500 49-90

TO APU CONT

LOW OIL QUANTITY MCDU

OFF

BITECODE

ON START APU PANEL

TO APU CONT

MAINT

ADD B

< 5% RPM

APU MASTER CONTR. SW. (P5) FADEC AFT CARGO CPTM

CLOSE FULL G OPEN DOOR OPEN SWITCH

APU CONTROL UNIT M280 ( E3-3 )

WHEN OIL LEVEL”ADD” ADD

A

SIGNAL TO FADEC DURING APU START AND SHUTDOWN.

28V DC SWITCHED HOT BAT BUS


APU CONT

CIRCUIT BREAKER PANEL ( P6 -5 )

FULL OIL TANK SOLENOID VALVE

ADD

28V DC

OIL QTY RELAY R 253

SWITCHED

OIL LEVEL SENSOR

HOT BAT BUS M 925 APU OIL QTY MODULE APU GENERATOR CONTROL UNIT ( P6 )

Figure 12

Oil Servicing System Schematic

APU OIL TANK

LOQ


AIRBORNE AUXILIARY POWER ENGINE FUEL AND CONTROL

49-30 APU FUEL SYSTEM Purpose The APU fuel system receives fuel from the airplane wing tanks through a shrouded line. The system then pressurizes, filters, and meters fuel for combustion. The primary components are the fuel control and pump assembly. low and high pressure filters, a start fuel purge solenoid valve, start and main fuel manifolds, and nozzles. The APU is a constant speed engine. Speed control is accomplished automatically by the FADEC through torquemotor inputs to the fuel control and pump assembly, resulting in fuel flow regulation. Fuel Control and Pump Assembly This assembly accomplishes all pressurizing, filtering, and metering for the APU. Electrical connections include the servo valve, the start fuel solenoid valve, and the main fuel solenoid valve. SYSTEM OPERATION


B737-300/400/500

Starting Placing the APU switch to START and ON, opens the APU fuel shutoff valve and the inlet door begins to open. When the inlet door is full open,the FADEC activates the starter and energizes the start fuel solenoid valve to open. The start fuel solenoid valve is located on the fuel control and pump assembly. The APU fuel control and pump assembly then receives fuel from the airplane tanks through the APU fuel line. A low pressure centrifugal pump pressurizes the fuel and delivers it to the high pressure gear pump through the external low pressure fuel fitter. Unmetered fuel flows through the start fuel solenoid valve, through the start manifold and through the 4 start nozzles into the combustor. The FADEC energizes the ignition exciter one second after the starter is energized. The FADEC energizes the main fuel solenoid valve to open when the APU reaches 5% RPM with an increase of 28  C EGT. This permits metered fuel to flow through the in-line filter, through the check valve to the 14 main fuel nozzles. When the APU reaches 55% RPM, the FADEC deenergizes the starter and ignition exciter. At 70% RPM the FADEC de-energizes the start fuel solenoid valve to the close position and energizes the start purge solenoid valve to the open position for 60 seconds. This removes fuel from the start fuel manifold and nozzles. The FADEC monitors APU the EGT during starting. The FADEC sends electrical control signals to the servo valve to meter the fuel flow.

Running (APU RPM Above 98 Percent) The FADEC receives APU RPM, EGT, inlet temperature and inlet pressure signals from APU sensors. The FADEC sends electrical control signals to the servo valve to meter fuel flow to the main fuel nozzles. This keeps the APU at a constant speed with the APU supplying electrical and/or pneumatic loads or with the APU unloaded. Shutdown Placing the APU switch to off position : The fuel shutoff valve closed. The air inlet door closed. The main fuel solenoid valve de-energized to the close position. The fuel servo valve deenergized. The start purge valve energized to the open position for 30 seconds. Remaining fuel in the APU combustor drains through a drain valve into the lower shroud drain Iine. The de-prime valve energized to the open position. The anti-surge bleed valve energized to the closed position. The hour meter and start counter off.



B737-300/400/500 49-30

OPEN: RPM >70% FOR 60 SEC. AND APU SHUT DOWN FOR 30 SEC.

OPEN: AFTER STARTER CUT IN OR (>2% RPM) CLOSED: RPM >70%

APU BLEED AIR DUCT

MAIN CHECK VALVE

FROM APU

FADEC MODULATED POSITION

FILTER

MAIN FUEL MANIFOLD

OPEN: RPM 5% AND EGT RISE >28 C

START PURGE VALVE S

FADEC

M

APU FUEL DC BOOST PUMP

APU FUEL FUEL HEATER SHUTOFF CHECK VALVE VALVE FUEL M HEATER FUEL SHROUD

LP-FUEL PUMP

START FUEL MANIFOLD

OIL TANK VENT LINE

NOZZLES

START FUEL SOLENOID VALVE S

MAIN FUEL SOLENOID VALVE S

TO DRAIN CHECK VALVE

GEARBOX

FLAME ARRESTOR IGNITOR (2)

FUEL SERVO VALVE COMBUSTER

M

DRAIN

AC FUEL BOOST PUMP FUEL TANK 1


40 PSI

FLOW CONTROL VALVE <18 o C A PU B LE ED A IR CHECK VALVE

LOW FUEL PRESSURE

640 PSID

FUEL

EXHAUST

HP FUEL PUMP

600 PSI

200 PSID

CONTROL / PUMP ASSEMBLY SEAL DRAIN

APUBLEED AIR

BYPASS VALVE

LEGEND

RELIEF VALVE

DIFF. PRESS VALVE

...

EXH. DRAIN

SPEED SENSOR (2)

DRAIN CHECK VALVE

T AMB P AMB

10 PSID

FILTER HIGH FUEL PRESSURE

FILTER CLOGGING INDICATOR 6 PSID

EGT PROBE (2) FROM START PURGE VALVE

TO DRAIN MAST

REGULATED FUEL PRESSURE APU BLEED AIR

TO FADEC

OIL TANK VENT AIR 55700 946555

Figure 13

Fuel System Schematic



49-30 APU FUEL SHUTOFF VALVE The valve allows fuel supply from the tank to the APU engine. Physical Description The valve consists of an actuator assembly and valve body assembly. The actuator is motor operated with a manual override. Power The valve motor utilizes 28 volt dc power. Control The valve operation is controlled by the APU switch on P5 panel and by protection circuits in module M280, APU control unit. The valve is installed on the rear spar of No.1 fuel tank in the Ieft main wheel welI. Operation. The valve is opened by placing the APU switch to the ON position. The valve can be closed by the switch placed to the OFF position or automaticalIy by fire detection or operation of fire handle. The valve can be operated manually without electrical power by the override handle. Maintenance Practices The valve actuator assembly can be removed separately from the valve body. The removal of the valve body requires No. 1 tank entry.


B737-300/400/500

APU FUEL DC BOOST PUMP The pump supplies pressurized fuel during starting of the APU. Physical Description The pump consists of a motor driven vanes, bypass valve, inlet and outlet ports. It is held in position by four boats through fianges on pump body. Power The pump utilizes 28 volt dc power. Control The pump operation is controlled by the APU switch and main tank No. 1 boost pump switches on P5 panel. The pump is mounted on the wing bottom skin aft of the rear spar. Operation The pump operates only during APU start if:  the APU Master Switch is in ”ON” and  Boost Pump relays from tank #1 are ”OFF” and  APU RPM is below 98%. When the APU reaches 98% RPM during the start cycle, the APU pump is automatically de-energized.



B737-300/400/500 49-30

LEFT REAR WING SPAR

APU DC BOOST PUMP FUEL OUTLET


APU FUEL SHUTOFF VALVE FUEL INLET MANUAL OVERRIDE LEVER

FWD

INBD LEFT LOWER INBOARD TRAILING EDGE PANEL

INBD

FWD

ATA28.190608

997665

Figure 14

APU Fuel Shutoff Valve and DC Fuel Boost Pump



B737-300/400/500 49-30

START

APU START CIRCUIT

NC

ON NORMAL SHUTDOWN

OFF

APU AIR INLET DOOR

APU MASTER CONTR. SW. (P5) 28V DC NORM DISCH

FIRE

DOOR NOT FULLY OPEN

NC CLOSE

CLOSE APU FIRE HANDLE

M

M

FULL OPEN

R

OPEN

NORM

NC

FIRE

APU REMOTE CONTROL PANEL


OPEN

APU FUEL SHUTOFF VALVE FIRE RELAY

FIRE DETECTION MODULE M 279

DOOR OPEN SWITCH

APU AIR INLET DOOR ACTUATOR

28V DC


APU MONITOR

APU GENERATOR CONTROL UNIT ( P6 ) APU SHUTDOWN SIGNAL 28V DC SWITCHED HOT BAT BUS

POWER SUPPLY APU CONT

APU CONTROL UNIT

M 280

CIRCUIT BREAKER PANEL ( P6 -5 )

FADEC M 3056

Figure 15

APU Fuel Shutoff Valve Control

FADEC

AFT



B737-300/400/500 49-30

START

BAT BUS

NC APU FUEL BOOST PUMP

M

CIRCUIT BREAKER PANEL ( P6 )

ON

APU FUEL

NC

OFF

BOOST PUMP

R 155 APU FUEL BOOST PUMP RELAY

APU MASTER CONTROL SWITCH APU SPEED > 98% RPM NC

R 18 TANK 1 AFT FUEL BOOST PUMP RELAY

R 191 BOOST PUMP SHUT-OFF RELAY

NC R 19 TANK 1 FWD FUEL BOOST PUMP RELAY P 6 LOAD CONTROL CENTER - R y l n O s e s o p r u P g n i n i a r T r o F


APU MONITOR

APU GCU ( P6 )

28V DC

POWER SUPPLY APUCONT APU CONTROL UNIT M280


( E3-3 ) CIRCUIT BREAKER PANEL ( P6 )

FADEC M 3056 AFT CARGO CPTM

Figure 16

DC Fuel Boost Pump Control



49-30 FUEL HEATER The fuel heater is used to prevent ice from blocking the fuel filter. The heater is a tubular fuel / air heat exchanger. The control valve has a bimetallic element for sensing the fuel temperature and allowing bleed air to pass through the heater. The fuel heater and control valve with a temperature sensor are attached to the inside surface of the upper shroud. FIow Control Valve When the fuel temperature passing through the valve decreases to 3C (37 F), the valve modulates to full open. This allows hot air from the APU bleed duct to pass through the heater and dumps into the shroud. When fuel temperature increases to 18 C (64F), the valve closes. FueI Heater Check Valve A check valve is installed in the fuel Iine upstream of the heater to retain fuel in the pump. This ensures a positive prime for starting. FIow Control Check Valve A check valve is instalIed in the air line to prevent fuel entering the bleed air duct.


B737-300/400/500



B737-300/400/500 49-30

FUEL HEATER CHECK VALVE

UPPER SHROUD FUEL HEATER

OVERBOARD DUMP LINE FOR THE BLEED AIR

FLOW CONTROL VALVE

INLET LINE FOR THE BLEED AIR


PRESSURE LINE TO PNEUMATIC ACTUATOR

FWD

FUEL INLET LINE FLOW CONTROL CHECK VALVE

FUEL HOSE

APU BLEED AIR DUCT 997661

Figure 17

Fuel Heater and Flow Control Valve



49-30 ELECTRONIC FUEL CONTROL AND PUMP ASSEMBLY The fuel control and pump assembly supplies high pressure fuel to the start fuel manifold and high pressure, metered fuel to the main fuel manifold. It is mounted to the front face of the accessory gearbox with a quick attach/detach clamp. The fuel control and pump assembly consists of the following components:  Centrifugal Pump  Gear Pump  High Pressure Relief Valve  Start Fuel Solenoid Valve  Main Fuel Solenoid Valve  Differential Pressure Valve  Fuel Servo Valve Centrifugal Pump  rise up the Fuel Pressure to 40 PSIG.  Protects the Gear Pump against cavitation. Gear Pump  rise up the fuel pressure (100% RPM) to 600 PSID with a fuel flow of max 646 kg/h High Pressure Relief Valve The high pressure relief valve protects the fuel system against overpressurization. It has a crack point pressure of 640 psid.


B737-300/400/500

Start Fuel Solenoid Valve The start fuel solenoid gets a signal from the FADEC to permits unmetered fuel flow through the start fuel nozzles.  opens, after start circuit aktivation. Software Conf.15 or  opens, if RPM > 2% Software Conf.16 ( FF ca 10 kg/h)  closes, if RPM > 70%.

Main Fuel Solenoid Valve The main fuel solenoid valve permits metered fuel to flow through the main fuel manifold to the main fuel nozzles. It is energized open during APU start, if  RPM > 5% and  EGT rise >28 C. It closes during APU shutdown. Differential Pressure Valve The differetial pressure valve holds a constant differential pressure of 200 PSID across the fuel servo valve. This differential pressure creates a linear relationship between fuel flow and torquemotor current. Fuel Servo Valve The servo valve controls the fuel flow output from the fuel control and pump assembly. The servo valve is a torquemotor operated flapper type valve. The valve’s position is electrically controlled by the FADEC and has a regulating range from 7 to 250 kg/h. The servo valve current is a function of APU speed, inlet temperature and pressure; and is EGT limited.



B737-300/400/500 49-30

GEARBOX

FWD

START FUEL SOLENOID VALVE

FUEL PUMP

FUEL SERVO VALVE MAIN FUEL SOLENOID VALVE y l n O s e s o p r u P g n i n i a r T r o F

FUEL CONTROL AND PUMP ASSEMBLY

FUEL DRAIN TUBE

FWD DIFFERENTIAL PRESSURE VALVE

Figure 18

Fuel Control and Pump Assembly



49-30 START PURGE VALVE The start fuel purge solenoid va!ve allows APU compressor discharge air to remove remaining fuel in the start fuel manifold and nozzles. This prevents coking of the start fuel nozzles. The start fuel purge solenoid valve is a normally closed shutoff valve. The FADEC energizes the solenoid for 60 seconds to open when the APU reaches 70% RPM. This permits compressor discharge air to purge the start manifold and nozzles of remaining fuel. When the APU Master switch is placed to OFF; the start fuel purge solenoid valve is energized to the open position for 30 seconds and then deenergized to the closed position, The start fuel purge solenoid valve is Iocated on the left side of the APU just aft of the ignition exciter. it is located in the high pressure start fuel Iine between the fuel control and pump assembly and the start fuel nozzles. Start Fuel Manifold The start fuel manifold and four start nozzles along with the main fuel manifold and fourteen fuel nozzles deliver fuel to the combustion chamber for APU operation. Start Fuel Nozzles ( 4 ) four start nozzles deliver fuel to the combustion chamber for APU operation. Main Fuel Manifold The main fuel manifold attaches to the main fuel nozzles ( 14 ). The main fuel nozzles bolt to the combustor housing. Air in the combustor atomizes the fuel through a slot in the fuel nozzles.


B737-300/400/500

Main Fuel Nozzles ( 14 ) Fourteen fuel nozzles deliver fuel to the combustion chamber for APU operation.The main fuel nozzles supply fuel to the combustor at 550 pph.Air in the combustor atomizes the fuel through a slot in the fuel nozzles. besteht aus: Fuel Filter  protects the fuel Gear Stage against contamination. Filter Bypass  Filter Bypass, opens at 10 PSID .

Filter Clogging Indicator  Filter Clogging Indicator ( Red ) , is shown at 6 PSID. Indicates a clogged fuel filter. is resettable. Fuel Filter Fitting  protects the 14 Main Fuel Nozzles against contamination. Main Check Valve  closes when APU is Shutdown. Drain Check Valve  opens after APU Shutdown, drains the unburned fuel of the Combustion Chamber, connects the Drain Lines to the Drain Mast .  closes when the Combustion Discharge Presssure ( CDP ) increases (15% APU RPM )  drains fuel from Start Fuel Nozzles and Start Fuel Manifold during - APU Start > 70% APU RPM and - during every APU Shutdown when the Start Purge Valve opens,  drains fuel to the Drain Mast (13 ccm Drain Fuel ).



B737-300/400/500 49-30

START FUEL MANIFOLD IGNITOR MAIN FUEL MANIFOLD MAIN FUEL NOZZLE ( 14 ) COMBUSTION CHAMBER

FWD

START FUEL NOZZLE

START PURGE VALVE

START FUEL MANIFOLD DRA IN L INE TO DRAIN CHECK VALVE

FILTER CLOGGING INDICATOR

FUEL FILTER ASSEMBLY y l n O s e s o p r u P g n i n i a r T r o F

(4)

FUEL FILTER 803431

DRAIN CHECK VALVE FUEL FILTER FITTING

MAIN CHECK VALVE

MAIN FUEL MANIFOLD

Figure 19

Fuel System Components

COMBUSTION CHAMBER DRAIN LINE

997645




B737-300/400/500 49-30

FUEL SYSTEM OPERATION Starting The APU start sequence is controlled by the FADEC.  After the start relay is energized (Software version 15) or  After 3% RPM (Software version 16), the fuel solenoid energizes and opens. (At 2% RPM ignition is activated) Unregulated fuel from the high pressure fuel pump is supplied to the start fuel manifold. It enters the combustion chamber via 4 start nozzles. After 1 second ignition is activated (Software version 15).  At a speed of 5% RPM and a minor of 28 C EGT rise, the main fuel solenoid valve opens. The fuel servo valve starts controlling the fuel flow. The magnitude of the regulating fuel flow depends upon RPM, EGT, T-amb and P-amb. Control is provided by the temperature control circuit within the FADEC. At this point the fuel flow is approximately 25 kg/h and will continuosly increase. Regulated high-pressure fuel goes into the main fuel manifold, from where it leaves through 14 main fuel nozzles for combustion.  At 55% RPM ignition is deenergized.  At 70% RPM the start fuel solenoid valve closes and the start purge valve energized open for 60 sec. CDP air enters the 4 start fuel nozzles in order to blow out the remaining fuel from the start fuel manifold.  At 80% RPM the temperature control circuit is turned off and the speed control circuit will now control the fuel flow. Running Speed > 98% 2 sec after 98% RPM load can be applied. The fuel servo valve, controlled by the FADEC, coverns the fuel flow to keep the APU-speed at 100% at all normal loads. The max. load factor is limited by the EGT-set point. The EGT-set point is variable and is computed by the FADEC. The set point depends upon T-amb and P-amb (see EGT-Chart). The max. EGT is slightly higher than the EGT-set point. An exceedance of max. EGT will cause an APU Auto Shut Down.

Shutdown When the APU Master Control Switch is put to OFF following fuel valves will close:  Main Fuel Solenoid Valve  Fuel Servo Valve and  APU Fuel Shutoff Valve  Start Purge Valve opens for 30 sec. and closes again.



B737-300/400/500 49-30

49

38 ) C ( F O E R U T A R E P M E T T N E I B M A

27

16

4

-7

-18

-29 y l n O s e s o p r u P g n i n i a r T r o F

-40 710

715

720

725

730

735

740

MAXIMUM EGT C EGT Limit - APU Speed more than 98%

Figure 20

APU-MAX. EGT CHART




B737-330/430/530 49-10

DRY MOTOR THE APU General: You dry motor the APU to operate the APU without fuel to the start fuel nozzles. Procedure Set the switch and the circuit breaker:  Set the APU master switch on the P5 forward overhead panel to the OFF position and attach a DO-NOT-OPERATE tag.  Open this circuit breaker and attach a DO-NOT-CLOSE tag:  APU Control Unit, E3-3 Electrical Shelf,  Put the container below the start fuel manifold.  Disconnect the fuel line for the start fuel manifold from the start purge valve.  Connect the fuel hose to the start purge valve.  Put the end of the fuel hose into the container.  Set these circuit breakers and these switches:  Remove the DO-NOT-CLOSE tag and close this circuit breaker:  APU Control Unit, E3-3 Electrical Shelf,  Remove the DO-NOT-OPERATE tag from the APU master switch on the P5 forward overhead panel.  Set the BAT switch on the P5 forward overhead panel to the ON position. Make sure this circuit breaker is closed:  DC BOOST PUMP. on the P6-5 Load Control Center Assembly.  Set the APU master switch on the P5 forward overhead panel to the START position and release it to the ON position.  Permit the APU engine to motor until the APU has an automatic shutdown. Make sure the FAULT light comes on. NOTE: The FAULT light is on the P5 forward overhead panel.  Make sure the FADEC has a ”LITE” BITE code shown.  Set the APU master switch on the P5 forward overhead panel to the OFF position and attach a DO-NOT-OPERATE tag.



B737-330/430/530 49-10

START PURGE VALVE FUEL LINE FOR START FUEL MANIFOLD ON

P5 FWD OVERHEAD PANEL

OFF

IGNITION EXCITER FUEL HOSE

FWD

CIRCUIT BREAKER

APU MASTER CONTROL SWITCH

CONTAINER

APU CONTROL UNIT E3-3

FAULT DISPLAY SWITCH

APU CONTROL UNIT

ON BAT

TR NO.3

3

APU FUEL BAT BOOST BUS PUMP

50

OFF y l n O s e s o p r u P g n i n i a r T r o F

CIRCUIT BREAKER

FAULT DISPLAY

LITE

5 P6-5

P 5 FWD OVERHEADPANEL CIRCUIT BREAKER

P 5 FWD OVERHEADPANEL

START ON

APU MASTER CONTROL SWITCH FADEC

769273

995421

991836

Figure 21

APU Dry Motoring

992794




B737-330/430/530 49-10

WET MOTOR THE APU General: You wet motor the APU to operate the APU without ignition. Procedure Set the switch and the circuit breaker:  Set the APU master switch on the P5 forward overhead panel to the OFF position and attach a DO-NOT-OPERATE tag.  Open this circuit breaker and attach a DO-NOT-CLOSE tag:  APU Control Unit, E3-3 Electrical Shelf.  Put the container below the combustor drain. WARNING: DO NOT TOUCH THE IGNITION COMPONENTS UNTIL YOU DO THESE STEPS. THESE STEPS WILL RELEASE THE HIGH VOLTAGE FROM THE IGNITION EXCITER. IF YOU DO NOT OBEY THIS PROCEDURE, INJURY TO PERSONS CAN OCCUR. Do these steps to release the high voltage from the ignition exiter:  Make sure 5 minutes have gone by since the last APU start.  Disconnect the igniter cables from the igniter plugs.  Ground the igniter cables to the APU.  Disconnect the electrical connector from the ignition exciter.  Set these circuit breakers and these switches: Remove the DO-NOT-CLOSE tag and close this circuit breaker:  APU Control Unit, E3-3 Electrical Shelf.  Remove the DO-NOT-OPERATE tag from the APU master switch on the P5 forward overhead panel.  Set the BAT switch on the P5 forward overhead panel to the ON position. Make sure this circuit breaker is closed:  DC BOOST PUMP, P6-5 Load Control Center Assembly.  Set the APU master switch on the P5 forward overhead panel to the START position and release it to the ON position.  Permit the APU engine to motor until the APU has an automatic Shutdown.  Make sure the FAULT light comes on. NOTE: The FAULT light is on the P5 forward overhead panel.

 Make sure the FADEC has a ” LITE ” BITE code shown.  Set the APU master switch on the P5 forward overhead panel to the OFF position and attach a DO-NOT-OPERATE tag.



B737-330/430/530 49-10

ON


OFF

ELECTRICAL CONNECTOR CIRCUIT BREAKER

IGNITION EXCITER


APU CONTROL UNIT E3-3

FUEL FILTER

ON BAT y l n O s e s o p r u P g n i n i a r T r o F

FAULT DISPLAY

FAULT DISPLAY SWITCH

APU CONTROL UNIT

CIRCUIT BREAKER

TR NO.3

3

APU FUEL BAT BOOST BUS PUMP

50

LITE

5

OFF

P6-5


CIRCUIT BREAKER


START ON

APU MASTER CONTROL SWITCH FADEC

769273

995592

991836

Figure 22

APU Wet Motoring

992794




B737-330/430/530 49-30

LOW PRESSURE BLEED The low pressure bleed makes sure the air is removed from the fuel line to the fuel control and pump assembly. Procedure Set the switch and these circuit breakers  Set the APU master switch on the P5 forward overhead panel to the OFF position and attach a DO-NOT-OPERATE tag . Remove the DO-NOT-CLOSE tag and close this circuit breaker:  DC BOOST PUMP, on the P6-5 Load Control Center Assembly.  Bleed the fuel supply hose to the fuel control and pump assembly.  Put the container below the fuel control and pump assembly. Remove the DO-NOT-CLOSE tag and close this circuit breaker:  APU Control Unit, E3-3 Electrical Shelf. Remove the DO-NOT-OPERATE tag from the APU master switch and set the APU master switch to the ON position. NOTE: The APU master switch is on the P5 forward overhead panel. Do not move the APU master switch to the START position. It is not necessary to start the APU.  Loosen the fuel supply hose from the inlet fuel tube for the fuel control and pump assembly. NOTE: Do not remove the fuel supply hose.  Permit the fuel in the inlet fuel line to drain into the container.  Tighten the fuel supply hose to the inlet fuel tube for the fuel control and pump assembly.  Set the APU master switch on the P5 forward overhead panel to the OFF position and attach a DO-NOT-OPERATE tag. HIGH PRESSURE BLEED GeneraL The high pressure bleed makes sure the air is removed from the fuel line to the start fuel manifold. Do the APU dry motoring to bleed the fuel line to the start fuel manifold (AMM 49-11-00/201).



B737-330/430/530 49-30

APU CONTROL UNIT

TR NO.3

ON

OFF



3

APU FUEL BAT BOOST BUS PUMP 5

50

P6-5 CIRCUIT BREAKER CIRCUIT BREAKER

FUEL SUPPLY HOSE TO THE FUEL CONTROL AND PUMP ASSEMPLY P 5 FWD OVERHEADPANEL

P 5 FWD OVERHEADPANEL INLET FUEL TUBE

ON BAT y l n O s e s o p r u P g n i n i a r T r o F

OFF

ON

APU MASTER CONTROL SWITCH FWD

Figure 23

Low Pressure Bleed



AIRBORNE AUXILIARY POWER AIR

B737-300/400/500 49-50

APU AIR SYSTEM The bleed air system of the APU supplies compressed air for the air conditioning system, engine start system and other pneumatic components of the airplane. It also stops compressor surge during alI APU starts and during the normal operation of the APU. The APU Bleed Air System supply air to the - Air Condition System, - Engine Start System, - Wing Anti-Ice System, - Water and Hydraulic Tank pressurization. The bleed air system for the APU has a  bleed air valve  and a bleed servo valve



B737-300/400/500 49-50

ON

S BLEED SERVO VALVE

OFF APU BLEED 28 AIR SWITCH VDC P 5 FWD OVERHEAD M280 APU PANEL CONTROL UNIT E3-2

ACTUATOR APU BLEED AIR VALVE

CLOSED

REG

OPEN

FILTER

VENT

APU BLEED AIR DUCT

M 27 8 M IS C SWITCHING MODULE E3-2 MAIN ENGINE START ( GRD )

TO DUAL BLEED BLEED LIGHT

98% RPM AND 2 SEC

TO FUEL HEATER CHECK VALVE

AIR INLET

OPEN SIGNAL RPM

FILTER

T AMB P AMB COOLING AIR SHUTOFF VALVE

EGT

FADEC A FT CARG O CPMT


CHECK VALVE

ACTUATOR

GENERATOR

LEGEND COOLING FAN BLEED AIR SYSTEM

OIL COOLER COOLING AIR SYSTEM A56082

Figure 24

Bleed Air Schematic

GEARBOX

AIR INLET HOUSING

COMBUSTOR HOUSING



49-50 APU BLEED BLEED AIR VALVE The bleed air valve is used to control the bleed air flow from the APU to the airplane pneumatic system. The valve consists of a butterfly valve, actuator, rate control valve, switcher valve and solenoid. The valve is solenoid controlled, pneumaticalIy operated, shutoff and modulating type. The valve is controlled by the APU bleed valve switch on the P5 panel and the bleed servo valve. The FADEC controls the bleed servo valve. Valve operating pressure is supplied from pneumatic duct through a differential air pressure regulator. Differential Air Pressure Regulator The differential air pressure regulator provides constant pressure air supply for operation of the bleed valve. The regulator consists of an air inlet, filter, spring- loaded diaphragm assembly, metering and relief valves. The regulating pressure is set at 19 psig. The APU compressor discharge pressure is supplied to the regulator. The metering valve restricts the output to 19 psig independent of ambient conditions. Bleed Servo Valve The bleed servo valve changes the control air pressure to the bleed valve. This permits the bleed valve to modulate. The FADEC controls the bleed servo valve. The bleed servo valve is Iocated above and inboard of the oil filler neck on the APU. The bleed servo valve is a pneumatic valve that is electrically controlled.


B737-300/400/500

Operation When the APU is operating above 98% RPM and the APU bleed air switch is ’ON’, the bleed servo valve changes control pressure to the APU bleed valve. The FADEC controls the bleed servo valve as a function of APU EGT. When APU EGT Iimits are approached, the FADEC signals the bleed servo valve to vent control pressure. This modulates the APU bleed valve closed.



B737-300/400/500 49-50

UPPER SHROUD

CONTROL AIR LINE TO BLEED SERVO VALVE BLEED SERVO VALVE

APU BLEED AIR DUCT

ELECTRICAL CONNECTOR

TURBINE PLENUM

FWD

FWD

BLEED AIR VALVE SOLENOID POSITION SWITCH

CONTROL AIR LINE

CONTROL AIR PRESSURE TEST PLUG

APU BLEED AIR DUCT y l n O s e s o p r u P g n i n i a r T r o F

BLEED AIR VALVE

INBD

AIR FILTER

FWD

PRESSURE REGULATOR 833545

Figure 25

APU Bleed Air Components




B737-300/400/500 49-50

BLEED AIR VALVE OPERATION When the solenoid is energized, air upstream of the butterfly valve passes through the filter and regulator assembly and switcher valve to chamber C of the valve. Chamber D is vented through the switcher valve. As the butterfly valve opens, upstream pressure decreases, chamber B pressure decreases faster than chamber A pressure by virtue of the restrictor. The differential pressure acts on the diaphragm and opens the rate control valve. This partially vents chamber C, thus decreasing the opening rate of the valve. If high EGT occurs, the bleed servo valve vents chamber C and the valve modulates towards the closed position. When the solenoid is de-energized, control pressure is supplied to chamber D, chamber C is vented and the butterfly closes. Two switches are operated by the bleed valve.  One is for the amber DUAL BLEED light on the P5 panel ( ATA Chapter 36)  and the other goes to the FADEC. The FADEC (Sunstrand) does not use this signal.



B737-300/400/500 49-50

OFF VENT ON SERVO VALVE

APU BLEED AIR SWITCH P5-10 AIR COND. MODULE (P5) 28 V DC

RATE CONTROL VALVE

SOLENOID

RATE ADJUST

A MAIN ENGINE START ( GRD )

SWITCHER VALVE

VENT ENGINE START RELAY

1

B

M280 APU CONTROL UNIT (E3-3)

VENT POPPET VALVE

C

PNEUMATIC ACTUATOR

D

NC TO PNEUMATIC SYSTEM ENGINE START INTERLOCK RELAY

FILTER PRESSURE REGULATOR

M278 MISC SWITCHING MODULE (E3-2)

OPEN

TO DUAL BLEED LIGHT CIRCUIT

CLOSED

APU BLEED AIR VALVE 98% AND

RPM

RPM

AIR INLET

2 SEC T AMB


OPEN SIGNAL TO BLEED SERVO VALVE

FILTER

COOLING AIR SHUTOFF VALVE

P AMB EGT

GENERATOR

M3056 FADEC (AFT CARGO CPTM)

COOLING FAN

1

TO FUEL HEATER

AIRPLANES WITH ENGINE STARTER INTERLOCK PROTECTION.

OIL COOLER

Figure 26

APU Bleed Air Valve Schematic

GEARBOX

AIR INLET HOUSING

COMBUSTOR HOUSING



49-50 APU COOLING AIR SYSTEM The Cooling Air System consists:  Cooling Air Duct  Cooling Air Pneumatic Actuator  Cooling Air Shutoff Valve  Cooling Air Fan Cooling Air Inlet Duct The cooling air duct supplies the stable air to the cooling fan when the airplane is on the ground. When the airplane is in flight, the cooling air duct supplies the ram air to the cooling fan. The cooling air duct is Iocated between the torque box and the inlet flange of the cooling fan. A cooling fan inlet screen attaches to the cooling fan inlet. An inspection tube and a cap assembly are attached to the cooling air duct for the inspection of the fan inlet screen. The inspection tube goes through a Iightening hole in the horizontal web above the upper shroud. Pneumatlc Actuator The pneumatic actuator controls the shutoff valve. The pneumatic actuator has a cylinder, piston and rod assembly, spring and cap. The pneumatic actuator is installed on the fIange of the cooling air duct. The pneumatic actuator rod extends when the pneumatic pressure from the bleed air duct is greater than the spring force. A filter in the pneumatic Iine seals the pneumatic actuator from contaminants. The filter can be one that is used again or one that is discarded.


B737-300/400/500

Cooling Air Shutoff Valve The shutoff valve stops the airflow through the cooling air duct when the APU is stopped. AIso, the shutoff valve wiII keep aII flames inside the APU shroud if an APU fire occurs. The shutoff valve has a butterfiy mounted on a shaft. The butterfiy is installed in the cooling air duct. The pneumatic actuator controls the shutoff valve.



B737-300/400/500 49-50

APU BLEED AIR DUCT

CONDITION: APU RUNNING.

AIR INLET

ACTUATOR

CHECK VALVE

FILTER


GENERATOR

COOLING AIR INLET DUCT

COOLING FAN


GEARBOX

AIR INLET

COMBUSTOR

HOUSING

HOUSING

OIL COOLER

Figure 27

APU Cooling Air Schematic

S




B737-300/400/500 49-50

APU COOLING AIR



B737-300/400/500 49-50

PRESSURE LINE TO THE PNEUMATIC ACTUATOR

UPPER SHROUD PNEUMATIC LINE FILTER AND CHECK VALVE

COOLING AIR INLET PRESSURE LINE TO THE PNEUMATIC ACTUATOR

CHECK VALVE (TO FUEL HEATER)


FWD

APU BLEED AIR DUCT APU BLEED AIR VALVE

767835

Figure 28

Cooling Air Components



49-50 COOLING FAN The cooling fan supplies a positive, cool airflow through the oil cooler and the APU electrical generator. The cooling fan is a gear-driven, mixed flow fan. The cooling fan has a shaft impeller that is installed in a shroud. A housing holds the baiI bearing for the impeller shaft. The housing also moves the air to and from the shaft impeller. The cooling fan inlet duct and the exhaust scroll for the cooling fan move the air into and out of the cooling fan assembly. The fan inlet screen stops aII unwanted materials before they go into the components of the cooling fan that turn. Cooling Fan Duct The airflow from the cooling fan moves through the cooling fan duct to the oil cooler and APU electrical generator. Operation When the APU operates, the cooling fan supplies the cooling air. The gearbox accessory drive turns the cooling fan. The cooling fan supplies stable air while the airplane is on the ground. When the airplane is in flight, the cooling fan supplies ram air. The pneumatic actuator receives the pneumatic pressure from the bleed air duct to hold the shutoff valve open. The cooling air from the cooling fan is supplied to the APU electrical generator and the oil cooler. To get to the APU shroud, the cooling air moves through the cooling fan duct. In the APU shroud, the cooling air keeps the APU temperature Iow. From the APU shroud, the cooling air goes out through the APU exhaust system. When the APU is stopped, the pneumatic actuator close the shutoff valve. When the shutoff valve closes, it wiII keep aII f!ames from an APU fire in the APU shroud.


B737-300/400/500



B737-300/400/500 49-50

COOLING FAN INLET SCREEN INSPECTION TUBE PNEUMATIC ACTUATOR

COOLING AIR SHUTOFF VALVE PNEUMATIC ACTUATOR

PRESSURE LINE STABILIZER COMPARTMENT AREA


ACTUATOR RETRACTED COOLING AIR DUCT COOLING AIRFLOW

FWD

UPPER SHROUD

COOLING FAN INLET SCREEN PRESSURE LINE INLET

APU GEARBOX DRIVEN

COOLING FAN


CLOSED POSITION

ACTUATOR EXTENDED

OPEN POSITION COVER AND LOCATION TO MANUALLY TURN THE APU

COOLING AIRFLOW TO GENERATOR AND OIL COOLER

COOLING AIR SHUTOFF VALVE TEST 767825

Figure 29

Cooling Air Shutoff Valve

767831

767832


AIRBORNE AUXILIARY POWER IGNITION / STARTING

49-40 IGNITION AND START SYSTEM The APU ignition and starting system provides the means of rotating the APU engine to starting speed and for igniting the fuel-air mixture in the combustion chamber. System Description The system consists of a starter, start relay, ignition exciter, igniter plug, and control circuits. Component Location The starter, ignition exciter, ignition leads and igniter plugs are located on the APU engine. The start relay is located in the electronic equipment compartment right outboard side of the E3 rack. System Interfaces The start system interfaces with the full authority digital electronic control (FADEC), APU control unit and APU switch. Operation During APU start, the starter is energized and the APU rotates. The ignition exciter is energized by the action of the FADEC. The starter and ignition circuits are de-energized by the action of the FADEC during APU engine acceleration. During normal engine operation, the exciter remains de-energized.


B737-300/400/500



B737-300/400/500 49-40

START RELAY R5

START

APU

BATTERY 28 V DC

NC

STARTER

ON

OFF

IGNITION EXCITER

TD 1 SEC

APU MASTER CONTROL SWITCH ( P5 )

IGNITER PLUG IGNITER PLUG

FULL OPEN AIR INLET DOOR POSITION SWITCH

> = 55 % RPM

NO FADEC FAULT SIGNAL

28V DC y l n O s e s o p r u P g n i n i a r T r o F

28V DC SWITCHED HOT BAT BUS APU MONITOR

APU GENERATOR CONTROL UNIT( P6 ) 28V DC SWITCHED HOT BAT BUS

POWER SUPPLY

APU CONT

APU CONTROL UNIT M280

( E3-3 )

APU GENERATOR CONTROL UNIT ( P6 )

FADEC M 3056 AFT CARGO CPTM

Figure 30

Ignition / Starting Schematic



49-40 IGNITION COMPONENT DESCRIPTION Purpose The purpose of the ignition system is to provide the spark necessary to ignite the fuel and air mixture for APU operation. Ignition Exiter ( 1 ) The ignition exciter supplies the high voltage current necessary to cause the igniter plugs to make the sparks. The ignition exciter has a transformer, inverter, rectifier, booster coil and capacitors. These components are hermetically sealed in a metal container on the APU. The ignition unit is an LRU. Igniter Plugs ( 2 ) The ignition system has two igniter plugs, left and right. The igniter plugs have an outer casing, center electrode and ceramic insulator. The igniters screw into mounting bosses on the combustor case. The igniters are LRU’S. WARNING:


B737-300/400/500

MAKE SURE YOU REMOVE THE ELECTRICAL POWER FROM THE IGNITION AND START SYSTEM. LET 5 MINUTES GO BY BEFORE YOU REMOVE THE IGNITER CABLE. GROUND THE IGNITER CABLE AGAINST THE SHELL OF THE IGNITER PLUG BEFORE YOU REMOVE THE IGNITER CABLE. MAKE SURE THAT THE IGNITION EXITER IS FREE FROM ELECTRICAL POWER BEFORE YOU REMOVE THE IGNITER CABLE. THE ELECTRICAL POWER TO THE IGNITION AND START SYSTEM IS AT A VERY HIGH VOLTAGE. THE ELECTRICAL POWER TO THE IGNITION AND START SYSTEM CAN CAUSE INJURY TO OR KILL PERSONS.



B737-300/400/500 49-40

COMBUSTION CHAMBER HOUSING

FWD

IGNITER PLUG

ELECTRICAL CONNECTOR IGNITER CABLE IGNITION EXCITER


IGNITER CABLE S 768571

Figure 31

Ignition Components




B737-300/400/500 49-40

STARTING COMPONENT DESCRIPTION Start Relay R5 Connects the Battery Power 28 V DC to the Starter. energized when:  APU Master Switch „START“,  Air Inlet Door Full Open.  FADEC NO FAULT, de-energized when :  APU RPM > 55%. or:  FADEC detects FAULT. Location:  Right Side Electronic Compartment.



B737-300/400/500 49-40

START RELAY R5


FWD

803778

Figure 32

Start Relay Location



49-40 STARTING COMPONENT DESCRIPTION Purpose The starter provides initial power for rotating the APU engine compressor, turbine, and engine-driven accessories to a speed high enough to obtain good airflow for combustion. Location The starter is mounted on the accessory drive section. Physical Description The starter consists of an electric motor, a starter motor shaft assembly with an internal sprag clutch. Power The power supply to the starter is 28 volt dc from the battery or external dc power connection. Operation The starter is energized by the action of the APU switch. !t wiIl continue to drive the APU until 55% RPM. The power supply to the starter is controlled by the FADEC. The starter brushwear switch is located inside the starter. This switch is Iocated inside the starter. This switch electrically signals the FADEC when 75% brushwear occurs. Monitor The starter operation is monitored by the dc ammeter on the P5 panel in the flight compartment and the FADEC located in the aft cargo compartment.


B737-300/400/500

Starter Motor Duty Cycle APU Start Mode 3 consecutive starts or tries (Maximum) ( NO EGT Increase during the APU starts or tries ) (30 minutes cooldown time).



B737-300/400/500 49-40

FWD

FWD GEARBOX SPRAG PAWL

WASHER

V-BAND CLAMP

SCREW PACKING

APU

”ENGAGED”

RETAINING RING OUTER RACE INNER RACE

STARTER MOTOR SHAFT ASSEMBLY ( CLUTCH ) y l n O s e s o p r u P g n i n i a r T r o F

CAUTION: THE SHAFT ASSEMBLY MUST BE PULLED OUT FROM THE GARBOX ASSEMBLY IN A STRAIGHT DIRECTION. DO NOT TWIST THE SHAFT ASSEMBLY FROM SIDE TO SIDE. THE SHAFT ASSEMBLY CAN BE DAMAGED OR COME APART.

STARTER

APU

SPRAG PAWL ”DISENGAGED”

STARTER

SHAFT SHAFT ASS ASSEMB EMBL LY ( CLUTC CLUTCH H ) OPERA OPERATIO TION N

Figu Figure re 33

Star Starte terr Mot Motor or and and Sha Shaft ft Ass Assem embl bly y


ENGINE CONTROLS APU CONTROLS

49-60 APU CONTROLS The APU control system consists of manual and automatic controls for  Start Sequence.  Speed Governing.  Load Control.  Shutdown.  Fault Detection and Indication.  Fault History and Memory. APU control during all phases of operation is primarily the function of the FADEC, however, other components are also active in controlling operation. System Description The primary APU control system consists of the following: -Full Authority Digital Electronic Control (FADEC) -APU Control Unit ( M28O Module ) -Speed Sensors (2) -Ambient Temperature Sensor -Ambient Pressure Sensor


B737-300/400/500



B737-300/400/500 49-60

LOW OIL PRESS. SWITCH

HIGH OIL TEMP. SWITCH

OIL LEVEL

STARTER

SENSOR

BRUSH IND APU CONTROL UNIT FWD OVERH OVERHEAD EAD PANEL ANEL P 5

EGT SENSOR NO.1 / 2

RPM SENSOR NO.1 / 2

AMB. TEMP. SENSOR

AMB. PRESS. SENSOR

EMU

FLIGHT DATA AQUSITION UNIT ( FDAU )

AIR /GRD APU CONTROL

FADEC

28V DC SW. HOT BAT BUS MISCELLANE0US SWITCHING MODULE


ON

OFF FWD OVERHEAD PANEL P5

STARTI ARTING NG

IGNI IGNITI TION ON

START FUEL SOLENOID VALVE

Figu Figure re 34

START PURGE VALVE

MAIN F FU UEL SOLENOID VALVE

FUEL SERVO VALVE

APU APU Cont Contro roll Syte Sytem m Sche Schema mati tic c

BLEED BLEED AIR VALVE SOLENOID

BLEED SERVO VALVE

DE-PRIME VALVE




B737-300/400/500 49-60

APU CONTROL UNIT/FADEC DESCRIPTION APU Control Unit The APU Control Unit ( M 280 ) is used in conjunction with the FADEC for Starting, operation, and shutdown of the APU. The Unit contains switches and relays. On the front is a circuit breaker for overcurrent protection. The Unit contains a 300sec. time delay relay to switch off the APU Indication after the APU switch is placed to off. The power supply is 28 v dc batt bus, APU Generator Control Unit and 28 vdc switched hot batt. bus. The APU Control Unit ( M 280 ) location is in the electronic copartment, E3-3. FADEC ( Full Authority Digital Electronic Controller ). The Full Authority Digital Electronic Control (FADEC) is a microprocessorbased system. The FADEC controls the following activities::  Start Sequence.  Speed Governing.  Load Control.  Shutdown.  Fault Detection, Protection and Indication.  Fault History. Recording of engine operating history and provisions for communicating the engine functional status, fault assessment, and operating history to the Digital Flight Data Acquisition Unit. The DFDAU compiles this information and then sends it to the flight recorder. The power supply is 28 v dc batt bus, and 28 vdc from the switched hot batt. bus. The FADEC location is in the aft cargo compartment .

START/STOP

START SEQUENCING SYSTEM

FIRE PROTECTION

SPEED CONTROL SYSTEM

BLEED VALVE INTERFACE

AIRFLOW CONTROL SYSTEM

COCKPIT INTERFACE

PROTECTIVE SHUT DOWN SYSTEM

FADEC WIRING INTERFACE

SELF TEST


FADEC M3056



B737-300/400/500 49-60

AFT CARGO E 3 ELECTRONIC ELECTRONIC SHELF

DOOR

AFT CARGO COMPARTMENT


CIRCUIT BREAKER


769273

Figur Figure e 35

APU APU Contr Control ol Unit Unit and and FADE FADEC C Comp Compone onent nt

FADEC M3056



49-60 FADEC DESCRIPTION The FADEC will conduct a self-test and initialization procedure. Following a successful self-test, the FADEC wilI enter into a watch state in which it monitors APU startup and continuous operation. If a component fails, depending on the severity of the situation, the FADEC will either shutdown the APU with a FAULT FAULT light displayed on the overhead P5 or illuminate a MAlNT light also on the P5, but continue to operate. LED Display Faults and warnings are displayed on the alpha numeric display on the front of the FADEC. Faults/warnings are displayed in the order of occurrence with critical faults taking precedence over warnings. This data is just for the present APU cycle. Historical data can be accessed via the Fault Data switch. The fault indication will be cleared once the fault condition has been corrected and a new APU cycle is initiated. It is not until the FADEC senses the fault again, that it will display it on the LED. For the situation in which a fault occurs, and power is removed from the airplane (Bat switch is placed to the OFF position), the FADEC will retain the fault(s).


B737-300/400/500

FADEC BITE Test Procedure  Set the APU Master switch to the OFF position.  Set the BAT switch switch to the ON position.  Push the FAULT DISPLAY switch on the FADEC. The fault display on the FADEC will show firstly the APU Identification Number ( ENID ). Then the fault display will show the FADEC BITE code (s) of the given faults of the last APU auto shutdown or maintenance data ( first history record ) or OK if there were no FADEC BITE code (s) found by the FADEC. Following comes 11 history records (second history records ), a FADEC BITE code or maintenance data or OK will show for five seconds. After one compled cycle the FADEC BITE code ( first hystory record ) from the last APU auto shutdown or maintenance data or OK will show again for 10-15 seconds. After 10-15 seconds the fault display go out of view. Power Up Self Test. When you move the APU Master switch from OFF to ON, the FAULT DISPLAY DISPLAY will show the result of the power-up self-test of the FADEC. lf you move the APU master switch from ON to OFF and you did not move it to START, START, the result of the power-up self-test for the FADEC will show for 5 minutes then go out

of view. You can then push the FAULT DlSPLAY switch on the FADEC and still see the FADEC BITE code for the last auto shutdown. Start Prepare Test. When you move the APU master switch from ON to START then to ON, the fault display will show the result of the start prepare test. When the APU operates, the fault display will show the condition of the APU system continuously. continuously. If the airplane is on the ground and the APU does not start or has an automatic shutdown, do not try a subsequent start until you look at the FADEC. FADEC. When you move the APU master switch to the OFF position and then to START START, the FADEC BITE code from the last auto shutdown will not show. The problem from the first start can possibly not occur again on the subsequent start. You must have the APU Master switch in the OFF position to make the FADEC BITE code from the last last auto shutdown show. show. Nonvolatile Memory Five categories of data will be transmitted to the DFDAU as part of the APU condition monitoring. These are: CATE CATEGO GORY RY Life Cy Cycle Data Real Time Operating Param aramet eter ers s

PARAM ARAMET ETER ER Engine I. I.D. Nu Number Hours of Operation Number of Starts

EGT Speed Fuel uel Flow Flow Inlet Pressure Inlet Temperature Real Time 3 Fault Codes Fault Data 12 History The ARlNC 429 transmission take place in the continuous broadcast mode mode and shall commence when the FADEC is powered up through the APU switch or the display power switch.



B737-300/400/500 49-60

ACCL ACFT AMBP AMBT ASVL BLD ECU EMU EXCT FSRV GDOV HOT LITE LOP LOQ MFVL OPSW OTMP OVSP PWRF SFVL SPD1 SPD2 SPVL SRVB STRT TC1 TC2 UNSP

FAIL TO ACCEL FIRE/DOOR NOT OPEN/ BATTERY SW OFF

FAULT DISPLAY

AMBIENT PRESSURE SENSING SYSTEM AMBIENT TEMP SENSING SYSTEM ANTI SURGE VALVE SYSTEM A/C BLEED VALVE SYSTEM ELECTRONIC CONTROL UNIT SYSTEM EVENT MONITOR UNIT SYSTEM IGNITION SYSTEM FUEL SERVO SYSTEM GEARBOX DE-OILING VALVE SYSTEM HIGH OIL TEMPERATURE FAIL TO LITE LOW OIL PRESSURE LOW OIL QUANTITY MAIN FUEL VALVE SYSTEM OIL PRESSURE SWITCH SYSTEM OVERTEMP OVERSPEED ELECTRICAL POWER SYSTEM START FUEL VALVE SYSTEM SPEED SENSING SYSTEM 1 SYSTEM SPEED SENSING SYSTEM 2 SYSTEM START PURGE VALVE SYSTEM BLEED SERVO SYSTEM STARTER SYSTEM EGT SYSTEM 1 SYSTEM EGT SYSTEM 2 SYSTEM UNDERSPEED

AFT CARGO DOOR

ENID 1

AFT CARGO COMPARTMENT

FADEC BITE CODE ( S ) OF THE GIVEN FAULTS AND MAINTENANCE DATA OF THE LAST APU SHUTDOWN ( FIRST HISTORY RECORD ) 2

HIST

FAULT DISPLAY SWITCH FAULT DISPLAY

FIRST FADEC BITE CODE OF THE FIRST HISTORY RECORD

RN 11 3

END

RN 10

RN 01

RN 09

RN 02

RN 08

RN 03

RN 07

RN 04

RN 06

RN 05

FADEC BITE CODE DECCODING LABEL FADEC IDENTIFICATION PLATE


FADEC DATA CONNECTOR

FADEC M3056 FADEC DISPLAY SEQENCE WHEN FAULT DISPLAY SWITCH IS PUSHED. 1 2 3 a53173

Figu Figure re 36

THE FAULT DISPLAY WILL SHOW THE LAST FOUR NUMBERS OF THE IDENTIFICATION NUMBER ( ENIT ) THE FAULT DISPLAY WILL SHOW ”OK ” WHEN NO FAULTS OR MAINTENANCE DATA ARE IN MEMORY. THIS IS THE SECOND HISTORY ( RN ) RECORD. UP TO 11 HISTORY RECORDS ARE POSSIBLE. THE FAULT DISPLAY WILL SHOW ”N/A” WHEN NO HISTORY RECORDS ARE IN MEMORY.

FADEC ADEC Comp Compon onen entt



49-60 AMBIENT PRESSURE TRANSDUCER The ambient pressure sensor senses inlet air pressure to the compressor. The pressure sensor is mounted on the Ieft side of the air inlet muff above the temperature sensor. The pressure sensor measures inlet air pressure and sends that signal to the FADEC for fuel flow scheduling and operation of the anti-surge bleed valve. Ambient Temperature Sensor The Ambient Temperature Sensor senses air inlet temperature to the compressor. The temperature sensor is mounted on the left side of the air inlet muff below the pressure sensor. The temperature sensor measures inlet air temperature and sends the signal to the FADEC for fuel flow scheduling.


B737-300/400/500



B737-300/400/500 49-60

MOUNTING FLANGE

FWD

AMBIENT PRESSURE TRANSDUCER

MOUNTING FLANGE


FILLER PORT FOR THE OIL TANK

833587

AMBIENT TEMPERATURE SENSOR FWD

833686

Figure 37

Amb. Press. Transducer and Amb. Temp. Sensor




B737-300/400/500 49-60

SPEED SENSOR Speed Sensor ( 2 ) The two speed sensors deliver analog signals to the FADEC for speed sensing. The FADEC uses this information to operate start sequencing, condition monitoring and provides overspeed and underspeed control. The speed sensors are located inside of the engine air intake muff and are mounted on the intake-housing. The magnetic probe of each sensor extends through the housing and aligns with the Iobes on the oil impeller. As the turbine/compressor shaft rotates, the Iobes on the oil impeller pass by a magnetic probe on each speed sensor. This generates a sinusoidal output signal which is then sent to the FADEC. The loss of speed sensor will signal the FADEC to give a MAINT light on the P5 panel. The loss of both speed sensors will result in an automatic shutdown and a FAULT light.



B737-300/400/500 49-60

APU AIR INLET HOUSING

PACKING

FWD

SPEED SENSOR PROBE NO. 1

BOLT ELECTRICAL CONNECTOR

AIR INLET MUFF

AIR INLET HOUSING y l n O s e s o p r u P g n i n i a r T r o F

SPEED SENSOR PROBE

OIL IMPELLER LOBES SPEED SENSOR PROBE NO. 2 APU COMPRESSOR AIR INTAKE SCREEN

833716

Figure 38

Speed Sensor




B737/300/400/500 49-60

APU START SEQUENCE 1. BATTERY SWITCH 0N. 2. APU MASTER CONTROL SWITCH TO THE START MOMENTARILY AND TO THE ON POSITION.  APU CONTROL UNIT AND FADEC ELECTRICAL POWERED.  FADEC INITIATES ELECTRICAL POWER FOR SELF TEST INITIALIZATION.  FADEC SELF TEST INITIALIZATION PROCEDURE COMPLETED, WHEN NO FAULTS, FADEC GOES TO WATCH STATE.  TIME DELAY RELAY ACTIVATES EGT AND FADEC FAULT DISPLAY.  DE-PRIME VALVE OPEN.  DC FUEL PUMP ON.  LOW OIL PRESSURE LIGHT ON.  APU FUEL SHUT OFF VALVE OPENS, WHEN OPEN:  APU AIR INLET DOOR OPENS ( CA 15 SEC, MAX ALLOWABLE 30 SEC) NOTE: IF APU MASTER CONTROL SWITCH IS PLACED TO THE ON POSITION : SAME ACTIONS AS ABOVE. THE APU MASTER CONTROL SWITCH THEN SELECTED TO START : APU START SEQUENCE CONTINIUE 3. WHEN APU AIR INLET DOOR FULL OPEN APU ENGINE STARTS:  STARTER RELAY ENERGIZED  START FUEL SOLENOID VALVE OPEN.  + TD1 SEC. IGNITION EXCITER ENERGIZED. 4. APU ENGINE AT 5% SPEED  MAIN FUEL VALVE OPENS WHEN EGT RISE > 28 C.  FUEL SERVO VALVE MODULATES.  FADEC ACTIVATES TEMPERATURE CONTROL CIRCUIT.  HOUR METER ON.  START COUNTER PULSE.

5.   

APU ENGINE AT 55% SPEED STARTER RELAY DE-ENERGIZED IGNITION EXCITER DE-ENERGIZED. DE-PRIME VALVE CLOSE. APU ENGINE AT 70% SPEED START FUEL SHUT OFF VALVE DE-ENERGIZED TO CLOSE. START PURGE VALVE ENERGIZED TO OPEN FOR 60 SEC. LOW OIL PRESSURE LIGHT OFF, WHEN OIL PRESS. > 26 PSI. APU ENGINE AT 80% SPEED

6.    7.  FADEC: DE- ACTIVATES TEMPERATURE CONTROL CIRCUIT.  FADEC: ACTIVATES SPEED SPEED CONTROL CIRCUIT. 8. APU ENGINE AT 98% SPEED  DC FUEL PUMP OFF.  + TD 2 SEC, READY TO LOAD ( RTL ) SIGNAL, FOR APU BLEED AIR VALVE,  GEN. BUS OFF LIGHT ILLUMINATES.  LOW OIL PRESS. AUTO SHUTDOWN CIRCUIT ACTIVATED. 9. APU ENGINE AT 100% SPEED  FADEC SPEED CONTOLLED. NORMAL RUNNING SPEED.



B737/300/400/500 49-60

100%

9

98%

8

90% 80%

7

70%

6

60%

APU MOTOR RPM%

55%

5

50% 40% 30% 20% 10%


4

5%

1

2

3

TIME

83952

Figure 39

APU Start Sequence




B737/300/400/500 49-60

APU SHUT DOWNS APU NORMAL SHUTDOWN DESCRIPTION 1. APU MASTER CONTROL SWITCH TO OFF POSITION.  REMOVES READY TO LOAD SIGNAL, DISABLE BLEED AIR VALVE, GEN BUS OFF.  MAIN FUEL SOLENOID VALVE DE-ENERGIZED TO CLOSE  MAIN FUEL SERVO VALVE DE-ENERGIZED  START PURGE VALVE ENERGIZED TO THE OPEN POSITION FOR 30 SEC ,THEN DE-ENERGIZED TO THE CLOSE POSITION.  DE-PRIME VALVE ENERGIZED TO THE OPEN POSITION.  APU FUEL SHUT OFF VALVE CLOSE  APU AIR INLET DOOR CLOSE.  HOUR METER OFF. APU AUTO SHUTDOWN DESCRIPTION 2. AUTO SHUTDOWN ACTIVATED.  REMOVES READY TO LOAD SIGNAL, DISABLE BLEED AIR VALVE, GEN BUS OFF.  MAIN FUEL SOLENOID VALVE DE-ENERGIZED TO CLOSE  MAIN FUEL SERVO VALVE DE-ENERGIZED  START PURGE VALVE ENERGIZED TO THE OPEN POSITION FOR 30 SEC ,THEN DE-ENERGIZED TO THE CLOSE POSITION.  DE-PRIME VALVE ENERGIZED TO THE OPEN POSITION.  START FUEL SOLENOID VALVE DE-ENERGIZED( DEPENDS ON RPM )  STARTER RELAY DE-ENERGIZED( DEPENDS ON RPM )  APU FUEL SHUT OFF VALVE CLOSE.( ONLY WHEN : FIRE DETECTION.)  APU AIR INLET DOOR CLOSE. ( ONLY WHEN : FIRE DETECTION ).  HOUR METER OFF APU MASTER CONTROL SWITCH TO OFF POSITION + 5 MINUTES.  TIME DELAY RELAY SWITCHES OFF EGT INDICATION AND FADEC FAULT DISPLAY.



B737/300/400/500 49-60

1

100%

MASTER CONTROL SWITCH OFF OR AUTO SHUT DOWN

98% 90% 80% 70% 60%

APU MOTOR RPM%

55% 50% 40% 30% 20% 10% 5% y l n O s e s o p r u P g n i n i a r T r o F

2 TIME

83952

Figure 40

Normal/Auto Shut Down



INDICATING EXHAUST GAS TEMPERATURE INDICATING SYSTEM E. G. T. INDICATING SYSTEM. EGT Indication provides a means of monitoring the efficiency of the APU during Startup, run (Ioaded or unloaded) and shutdown. The EGT Indicating system consists of:  2 Thermocouples, located in the exhaust duct.  Event Monitoring Unit, mounted on the cooling air duct.  FADEC, mounted in the aft cargo compartment.  Balancing Resistor, located in the forward right sidewall of the flight deck. .  EGT Indicator, mounted in the P5 panel on the flight deck. Once the APU switch has been placed to the START position, 28v dc is provided to the FADEC, which will then allow an EGT signal to be sent to the indicator on the flight deck. Indication wilI continue during operation and until five minutes after shutdown. At this time, the time delay will prevent 28v dc to the FADEC. The thermocouples sense the exhaust gas temperature and convert it to an electrical signal. This signal is sent to the Event Monitoring Unit (EMU), and then to the FADEC. The FADEC uses EGT to modify fuel scheduling and modulate the Bleed Air Valve. The signal is also sent through a balancing resistor to the EGT indicator on the PS panel.

B737-300/400/500 49-70


INDICATING EXHAUST GAS TEMPERATURE INDICATING SYSTEM

B737-300/400/500 49-70

EGT INDICATOR COCKPIT P5 O/H PANEL COCKPIT

EGT THERMOCOUPLE 1

BALANCING RESISTOR COCKPIT

APU EXHAUST

EGT THERMOCOUPLE SIGNALS 1/2 TO APU START COUNTER AND APU HOUR METER

EVENT MONITORING UNIT ( EMU ) y l n O s e s o p r u P g n i n i a r T r o F

EGT THERMOCOUPLE 2

FADEC

Figure 41

EGT Schematic


INDICATING EXHAUST GAS TEMPERATURE INDICATING SYSTEM THERMOCOUPLES ( 2 ) The chromel / alumel thermocouples extend into the exhaust stream to sense APU exhaust gas temperature. The milli-volt output of the thermocouple is transmitted to the FADEC which analyzes the signal for appropriate scheduling of fuel and control of bleed air. Event Monitoring Unit ( EMU ). The Event Monitoring Unit (EMU) houses the resistive temperature detector and also provides indication of APU hours and starts. The EMU is located on the cooling air duct forward of the cooling fan. EGT signals are sent to the EMU before going to the FADEC. The resistive temperature detector in the EMU provides cold junction compensation for the EGT thermocouples. Displayed on the EMU are the number of APU hours and starts. Hours are not recorded until 98% RPM is accomplished. FADEC EGT input to the FADEC affects fuel scheduling. The EGT signal is also provided through a balancing resistor to the flight deck.


B737-300/400/500 49-70



B737-300/400/500 49-70

FWD

FWD

COOLING AIR DUCT


EVENT MONITORING UNIT

THERMOCOUPLES

833726

Figure 42

01901

03688

STARTS

HOURS

Thermocouples and Event Monitoring Unit.

803964



THIS PAGE INTENTIONALLY LEFT BLANK


B737-300/400/500 49-70



B737-300/400/500 49-70

P5 FORWARD OVERHEAD PANEL

CONSTANTAN

EGT INDICATOR PLUG SPRING

1

A

B

B

COPPER

ARMATURE COIL SPRING

A

CALIBRATING RESISTOR

EGT INDICATOR

2

0.05Q

0.05Q 7

A9 SPOOOL 0.05Q 0.15Q

0.15Q

0.15Q

0.15Q

B8

6

B9

18

D1

THERMOCOUPLE CH

39

4

C1

20

5

D2

38

12

C2

22

D3

40

6

C3

21

7

1

1

2 E1

AL

3

EGT RESISTOR

THERMOCOUPLE


STATION 851

AIRPLANE WIRING

795321

APU E. G. T . System Schematic

CH

1

EVENT MONITORING UNIT

FADEC

Figure 43

3

2

APU ENGINE HARNESS

AL

2


INDICATING EXHAUST GAS TEMPERATURE INDICATING SYSTEM EGT BALANCING RESISTOR  receive the EGT Signal from the FADEC  is installed between FADEC and EGT Indicator.  allows Adjustment of the EGT Systems with vernier und coarse Coil.  is located in the cockpit right side below the window No #3 .

EGT Indicator  shows the APU Exhaust Gas Temperature in  Celsius  compensates and correct cockpit temperature changes.  is located in the Cockpit P5 Overhead Panel


B737-300/400/500 49-70



B737-300/400/500 49-70

FLIGHT COMPARTMENT

APU EGT BALANCING RESISTOR

FWD

RESISTANCE WIRE


SPARE SPOOL

EGT RESISTOR (WITH THE COVER REMOVED)

RESISTANCE WIRE SPOOL

VERNIER ADJUST B3 .05 /STEPS

COARSE ADJUST .15 /STEPS A3

B2

A4

A2

A5 B1

A1

INCREASE

INCREASE VERNIER ADJUSTMENT TERMINAL

AIRPLANE LEADS

Figure 44

COURSE ADJUSTMENT TERMINAL

APU EGT INDICATOR

EGT Balancing Resistor and Indicator

EGT


INDICATING ID-MODULE

49-70 ID-MODULE The Engine Identification Module is installed on the APU and provides a resistance value to a microprocessor. The microprocessor interprets this value and enables the FADEC to identify the APU by a number from 0 to 2047. The Engine Identiflcation Module can be physicalIy altered to select a desired ID number. This is accomplished by removing the ID module protective cover exposing a small printed wiring assembly. By cutting one or more copper clad circuits, resistance is modified, which represents a number and is assigned to that particular APU. Location The Engine Identification Module is installed on the left side of the APU below the ignition exciter.


B737-300/400/500

Example The engine identification number can be represented from 0 to 2047 by physically cutting the appropriate copper clad circuits. The values are as follows:  W1 =1  W2 =2  W3 =4  W4 =8  W5 =16  W6 =32  W7 =64  W8 =128  W9 =256  W10 =512  W11 =1024 APU SN Nr. 296 is installed  Cut W9 = 256  Cut W6 = 32  Cut W4 = 8


INDICATING ID-MODULE

B737-300/400/500 49-70 ELECTRICAL CONNECTOR PRINTED WIRING BOARD PAD

CUT ZONE

ELECTRICAL CONNECTOR y l n O s e s o p r u P g n i n i a r T r o F

Figure 45

REMOVABLE PROTECTOR COVER

ID-Module


AIRBORNE AUXILIARY POWER INDICATING

49-70 FADEC BITE CODES AND LIGHTS. Auto Shut Down with FAULT Light IIlumination. Fadec Bite Code:  ACCL  ACFT  ECU  FSRV  HOT  LITE  MFVL ( ELECTRICAL FAULT )  OPSW  OTMP  OTSP  PWRF  STRT  UNSP Auto Shut Down with OVERSPEED Light Illumination. Fadec Bite Code:  ECU ( = FADEC )  OVSP Auto Shut Down with LOW OIL PRESSURE LIght Illumination.


B737-300/400/500

Fadec Bite Code:  LOP

No Auto Shut Down. Illumination of the MAINT Light. Fadec Bite Code:  ECU ( FADEC SPEED CHANNEL 1 OR 2 FAULT )  LOQ  MFVL ( MECHANICAL FAULT )  SPD 1  SPD 2  TC 1  TC2 No Auto Shut Down, No Light Illumination . Fadec Bite Code:  AMBP  AMPT  ASVL  BLD  EMU  EXCT  GDOV  SFVL  SPVL  SRVB  STRT


AIRBORNE AUXILIARY POWER INDICATING

B737-300/400/500 49-70

RELATED APU INDICATING LIGHT

TROUBLE SHOOTING FAULT INDEX AMM 49-00-00 PAGE 108 TABLE 101 FADEC BITE CODE

MCDU DISPLAY

APU DATA APU AC TUAL BITE LOW OIL PRESSURE

2/5

ACCL

FAULT

See Fig. 101

ACFT AMBP AMBT

FAULT

See Fig. 102

ANTI SURGE VALVE FAIL

ASVL BLD

FADEC FAILURE

MCDU DISPLAY

EMU EXCT FSRV GDOV HOT LITE

LOW OIL PRESSURE FAULT DISPLAY FADEC BITE DECODING LABEL


LOP

LOW OIL QUANTITY MAIN FUEL VALVE FAILURE OIL PRESSURE SWITCH FAIL OVER TEMPERATURE OVER TEMPERATURE AT START

LOP

OVERSPEED ELECTRICAL POWER FAULT START FUEL SOV FAIL N SENSOR 1 FAIL N SENSOR 2 FAIL START PURGE SOV FAIL BLEED SERVO VALVE FAIL STARTER WARNING OR FAIL TO START EGT PROBE 1 FAIL EGT PROBE 2 FAIL UNDERSPEED

FADEC

*(1) IF BOTH SPD1 AND SPD2 ARE SET, THE FAULT LIGHT WILL SHOW. MCDU DISPLAY: BOTH N SENSORS FAIL

Figure 46

FAULT or OVERSPEED

ECU

EMU FAIL EXCITER FAILURE FUEL SERVO VALVE GBX DE-OILING VALVE FAIL HIGH OIL TEMPERATURE FAIL TO LIGHT

PRINT >

< RETURN

CORRECTIVE ACTION

FAIL TO ACCELERATE A/C FAULT P1 SENSOR FAIL T1 SENSOR FAIL A/C BLEED FAIL

DATE FLIGHTMODE UTC 01 13MAY96 094656

RELATED APU INDICATING LIGHT

LOQ MFVL OPSW OTMP OTST

MAINT FAULT FAULT LOW OIL PRESSURE MAINT FAULT or MAINT FAULT FAULT FAULT

See Fig. 103 See Fig. 104 See Fig. 105 See Fig. 106 REPLACE THE FADEC Ref MM 49-61-12/401 *(3) See Fig. 107 See Fig. 108 See Fig. 109 See Fig. 110 See Fig. 111 See Fig. 112 See Fig. 113 See Fig. 114 See Fig. 115 See Fig. 116 See Fig. 117 See Fig. 117 A

OVSP PWRF SFVL SPD1 SPD2 SPVL SRVB

OVERSPEED FAULT

STRT

FAULT

See Fig. 125

MAINT*(2) MAINT*(2)

See Fig. 126 See Fig. 127

FAULT

See Fig. 128

TC1 TC2 UNSP

MAINT*(1) MAINT*(1)

*(2) IF BOTH TC1 AND TC2 ARE SET, THE FAULT LIGHT WILL SHOW. MCDU DISPLAY: BOTH TC FAIL.

LOP FADEC Bite Code Indication.

See Fig. 118 See Fig. 119 See Fig. 120 See Fig. 121 See Fig. 122 See Fig. 123 See Fig. 124

*(3) IF ECU SHOWS AFTER REPLACEMENT OF THE FADEC, DO THESE PROCEDURE ”SPD 1”( FIG 121) AND ”SPD 2” ( FIG 122 ).


INSTRUMENTS INDICATING (MCDU)

31-10 MCDU, APU DATA PAGES. APU DATA Pages. are monitored and stored by the FADEC . This data are displayed by the MCDU.  These are the DATA pages: - APU DATA - ACTUAL APU BITE - APU BITE HISTORY All DATA can be displayed and print. APU DATA Page  for indication push the following keys: - MENU - LINE SELECT KEY 3: ACMS - LINE SELECT KEY 1: APU DATA  With the APU Master Control Switch in ON, the display shows actual APU Data. These are the data: - EGT  C - INLET  C - INLET PRESS. PSIA - SPEED % - GEN LOAD. KVA.


B737-300/400/500

A Current Transformer measures the Gen. Load. The wires are routed via a solid state circuit (installed in the Misc. Switching Unit) to the MCDU. ACTUAL APU BITE  7 aktuell APU BITE Codes can be displayed. With the APU Master Switch in ON and a given AUTO SHUTDOWN the MCDU shows the reason.  When you move the APU Master Switch to OFF the “FAULT“ changes to the „APU BITE HISTORY“  < shows a HELP Page for additional information.

APU BITE HISTORY  12 APU BITE HISTORY Codes can be displayed.

LINE SELECT KEYS LEFT

DATA SCREEN

1L 2L 3L 4L 5L 6L

1R 2R 3R 4R 5R 6R BRT

INIT REF KEY

D S P Y

NEXT PAGE KEY F A I L A

INIT REF

RTE

CLB

CRZ

DES

MENU

LEGS

DEP ARR

HOLD

PROG

N1 LIMIT

FIX

PREV PAGE

NEXT PAGE

EXEC

A

B

C

D

E

F

G

H

I

J

M S G W

1

2

3

K

L

M

N

O

4

5

6

P

Q

R

S

T

7

8

9

U

V

W

X

Y

.

0

+/-

Z

DEL

/

CLR

W

Multi purpose Control Display Unit ( MCDU )

LINE SELECT KEYS RIGHT


INSTRUMENTS INDICATING (MCDU)

B737-300/400/500 31-10

MENU

LINE SELECT KEYS LEFT

1L

< FMC

2L

< ACARS

3L

1/5

APU DATA

MENU < ACT >

1R 2R

< ACMS

3R

4L

4R

EGT

1L

INLET TEMP 020 DEG C

321 DEG C

INLET PRES

N1- APU

2L

FUEL FLOW

GEN LOAD 0.37 KVA

4L

156 KG/H

ACTUAL APU BITE

5L

5R

5L

6L

6R

6L

2R

13 PSIA

100 %

3L

1R

3R 4R

HELP

5R

< LOW OIL PRESSURE ------------------------< RETURN

PRINT >

6R

NEXT PAGE

APU DATA

ACMS


2/5

APU BITE HISTORY

1L

< APU DATA

1R

1L

2L

< ACMS MENU

2R

2L

3L

< FREE REPORT

3R

3L

4R

4L

4L 5L

5R

6L

6R

Figure 47

FAIL TO ACCELERATE DATE FLIGHTMODE 03JUN96 01

2R

A / C FAULT DATE FLIGHTMODE 01 01JUN96

UTC 094656

3R 4R

LOW OIL QUANTITY

5L 6L

1R

UTC 120429

DATE FLIGHTMODE 01 01JUN96

------------------------< RETURN

MCDU APU DATA Display

UTC 164546

5R PRINT >

6R


AIRBORNE AUXILIARY POWER TROUBLE SHOOTING

49-00 TROUBLE SHOOTING.  A This section gives the troubleshooting tips and the procedures to correct problems of the APU.

3) Fault Isolation

 B. The troubleshooting tips give the data that can help to identify and to isolate a problem. The troubleshooting tips also has the cautions and the warnings that must be obeyed during the troubleshooting procedures.

 C. The fault index gives the APU operation problems and the corrective action for the problems.

(1) The fault index has six groups of APU problems: (a) APU indication problems before the start


B737-300/400/500

(b) APU start problems (c) APU automatic shutdown (d) APU indication problems during APU operation (e) APU bleed air problems (f) Other APU problems. (2) The fault index can refer you to a figure or a table in this section to correct the problem. ( a) The FADEC BITE codes are on Table 101. Table 101 gives the corrective action or the figure number for each FADEC BITE code. ( b) Each figure has a troubleshooting procedure. The troubleshooting procedure has three sections: 1) Description. a) The description has the data about the problem. For the FADEC BITE codes, the description tells what makes the code show. 2) Possible Causes. a) The list of possible causes can be used if there is not much time. The possible causes are given in a sequence with the most possible and easiest causes at the top. The least possible and most difficult causes are at the bottom.

a) The fault isolation is a diagram which gives the procedure to find the problem.



B737-300/400/500 49-00 PREREQUISITES

”LOP” FADEC BITE CODE SHOWN

MAKE SURE THIS SYSTEM WILL OPERATE: APU (AMM 49-11-00/201)

___________ DESCRIPTION: THE CIRCUIT FOR THE LOW OIL PRESSURE WAS OPEN (THE SWITCH FOR THE LOW OIL PRESSURE OPENED) WHEN THE APU SPEED WAS MORE THAN 98% FOR 10 SECONDS. THIS USUALLY OCCURS WHEN THE OIL PRESSURE DECREASES TO LESS THAN 20-22 PSIG. _______________ POSSIBLE CAUSES: 1. 2. 3. 4. 5. 6.

LOW OIL QUANTITY (AMM 12-13-31/301) CLOGGED OIL PRESSURE RELIEF VALVE (AMM 49-91-21/401) OIL PRESSURE SWITCH PROBLEM (AMM 49-94-22/401) OIL FILTER AND PUMP ASSEMBLY PROBLEM (AMM 49-91-11/401) DE-PRIME VALVE PROBLEM (AMM 49-91-91/401) FADEC, M3056, PROBLEM (AMM 49-61-12/401).

_______________ FAULT ISOLATION:

1 EXAMINE THE MAGNETIC DRAIN PLUG (AMM 49-91-81/601). ARE METAL PARTICLES FOUND THAT ARE NOT PERMITTED?

YES

51 REPLACE THE APU (AMM 49-11-00/401).

YES

52 SERVICE THE APU OIL TANK (AMM 12-13-31/301).

YES

53 REPLACE THE OIL PRESSURE RELIEF VALVE (AMM 49-91-21/401).

NO


2 LOOK AT THE OIL SIGHT GLASS ON THE LOWER, FRONT SIDE OF THE GEARBOX HOUSING. IS THE OIL LEVEL BELOW THE ”ADD” MARK? NO 3 EXAMINE THE OIL PRESSURE RELIEF VALVE. IS IT CLOGGED OR STUCK IN THE OPEN POSITION? NO SEE SHEET 2 (BLOCK 4)

Figure 113 (Sheet 1)

Figure 48

LOP FADEC BITE Code Shown



B737-300/400/500 49-00

FROM SHEET 1 (BLOCK 3) NO NO 4 REMOVE THE OIL PRESSURE SWITCH (AMM 49-94-22/401). DISCONNECT THE CONNECTOR P5 FROM THE DE-PRIME VALVE. INSTALL A T-FITTING IN THE GEARBOX PORT FOR THE OIL PRESSURE SWITCH. INSTALL THE OIL PRESSURE SWITCH AND A 0-50 PSI (0-300 KPA) PRESSURE GAGE ON THE T-FITTING. CONNECT AN OHMMETER TO PINS 1 AND 2 OF THE OIL PRESSURE SWITCH. START THE APU (AMM 49-11-00/201). LOOK FOR THE OIL PRESSURE SWITCH TO CLOSE WITH AN INCREASE IN OIL PRESSURE. DID THE OIL PRESSURE INCREASE TO ABOVE 26 PSI (179 KPA)?

21 REPLACE THE DE-PRIME VALVE (AMM 49-91-91/401). START THE APU (AMM 49-11-00/201). DOES THE PROBLEM CONTINUE?

YES

54 REPLACE THE OIL FILTER AND PUMP ASSEMBLY (AMM 49-91-11/ 401).

NO 55

THE SYSTEM IS OK.

YES NO 5 DID THE OIL PRESSURE SWITCH CLOSE AT APPROXIMATELY 26 PSI (179 KPA)?

56 REPLACE THE OIL PRESSURE SWITCH (AMM 49-94-22/401).

YES

YES 22 EXAMINE THE CIRCUITS FROM THE FADEC, M3056, CONNECTOR D10432A, PINS C10,B11, TO THE OIL PRESSURE SWITCH, S2, CONNECTOR P14, PINS 1,2 (WDM 49-61-11). IS THERE AN OPEN CIRCUIT?


57 REPAIR THE PROBLEMS THAT YOU FIND.

NO 58 REPLACE THE FADEC, M3056 (AMM 49-61-12/401).

Figure 113 (Sheet 2)

Figure 49

LOP FADEC BITE Code Shown



49-10 APU OPERATION LIMITS AND PARAMETERS (1) The APU operation limits and parameters are used when you operate or motor the APU. If the APU does not operate in the specified limits, damage to the APU can occur. (2) The APU operation limits and parameters are shown in the table that follows:

Condition Oil Temperature Maximum EGT Exhaust Gas Temperature (-108 FADEC and Amb. Temp: > -18  C.)


B737-300/400/500

Operation Mode Limit Overtemperature Shutdown 135  C max.

APU Speed -Up to 60% 1100 C max. APU Speed - 60% to 98% 899 C max. APU Speed More than 98% See Fig.201, MM49-11-00/204 Fuel Temperature Any Operation Mode -40 C to 57 C. Oil Consumption: 10.0 cc each hour. Oil Pressure: Maximum at Gearbox 40-45 psig. Low Oil Pressure Shutdown 20-22 psig. Fuel Quantity: APU Start Mode (Minimum) 159 kg. (No. 1 Fuel Tank) Cont. Operation (Minimum) 159 kg./ h. Fuel Pressure Any Operation Mode 10-55 psig Engine Speed: (Cont. Ops.) ECS and MES and Idle 100 #0.25% Maximum Allowable 105 #0.25% (Overspeed Shutdown) Minimum Allowable 97% (Automatic Shutdown)

Condition

Operation Mode

Limit

AC Frequency Meter: with No Load Condition AC Frequency Meter:

Continuous Operation

395-405 Hz

Continuous Operation with Fully Loaded Condition

375-417 Hz

2-4 Hz 0 psig 46#5 psig 30 psig APU Bleed Valve OPEN 21-5 psig See Fig.201, MM49-11-00/204 NOTE: A Fully Loaded Condition for the APU has the two air conditioning packs on HIGH and an electrical load of 100 amps. Battery: APU Start Mode (Without AC Power) 22-28 VDC (With AC Power) 26-28 VDC Starter Motor: APU Start Mode 3 consecutive Duty Cycle starts or tries (Maximum) ( 30 minutes cooldown time ) Bleed Duct Pressure: (No Load Condition) (Minimum) (Fully Loaded Condition)

(Maximum Fluctuation) APU Bleed Valve CLOSED APU Bleed Valve OPEN




B737-300/400/500 49-10

APU OPERATION TEST Procedure (1) Start the APU (AMM 49-11-00/201). (2) Look at the FREQ meter. NOTE: With no load applied to the APU, the FREQ meter should become stable at 400 # 15 CPS. (3) Apply the load to the APU: - a) Put an electrical load of 100 amps on the APU electrical generator. - (b) Set these switches on the P5 forward overhead panel: 1) Set the ISOLATION VALVE switch to the OPEN position. 2) Make sure the engines 1 and /or 2 BLEED switches on the P5 forward overhead panel are in the OFF position. 3) Set the APU BLEED switch to the ON position. 4) Set the switches for the cabin temperature controls to the AUTO position. - (c) Set the L PACK and R PACK switches to AUTO. - (d) Let the EGT become stable in 1 to 2 minutes. - (e) Set the L PACK and R PACK switches to HIGH. - (f) Let the EGT become stable in 1 to 2 minutes. (4) Look at the FREQ meter: NOTE: With the APU fully loaded, the FREQ meter must become stable bet ween 397-417 CPS. (5) Remove the load from the APU: - a) Set the L PACK and R PACK switches to OFF. - (b) Set these switches on the P5 forward overhead panel: 1) Set the switches for the cabin temperature controls to the OFF position. 2) Set the APU BLEED switch to the OFF position. 3) Set the ISOLATION VALVE switch to the CLOSE position. 4) Remove the electrical load from the APU electrical generator. - (c) Let the APU operate in the no load condition for a minimum of 1 minute. (6) Make sure the MAINT light for the APU did not come on. (7) Do the APU usual shutdown (AMM 49-11-00/201).

V2500

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