CUSTOMER TRAINING
PT6T-3/6 TRAINING MANUAL MARCH 2001 R
Pratt & Whitney Canada
PT6T-3/6 Series TRAINING MANUAL February 2001
Pratt & Whitney Canada Corp. © 2001 Pratt & Whitney Canada, Corp. Printed in Canada
Student: Instructor:
INTRODUCTION
PT6T-3/6
TRAINING USE ONLY
INTRODUCTION
II
PRATT & WHITNEY CANADA This manual is issued by the Pratt and Whitney Canada (P&WC) Customer Training Department, Longueuil, Quebec, Canada and should be used for TRAINING PURPOSES ONLY. The data contained herein does not replace or supersede the information contained in the appropriate airframe or engine maintenance manuals or other official publications. For information concerning P&WC Customer Training, contact : Tel : 1-450-468-7774, Fax : 1-450-468-7834, or Email :
[email protected] For technical queries, contact the P&WC Help Desk (24 Hour Service) : Tel : USA & Canada .............................. 1-800-268-8000 International................................... (IAC*)+8000-268-8000 Other ............................................. 1-450-647-8000 Fax................................................. 1-450-647-2888 * International Access Code
Visit the P&WC web site at: http://www.pwc.ca (From the home page, select Customer Support and then select Customer Training on the left-hand margin.)
PT6T-3/6
TRAINING USE ONLY
INTRODUCTION
III
TABLE OF CONTENTS Introduction :
CHAPTER 3 : Hot Section
Scope of course .................................................. VI Courses Syllabus................................................. VII Abbreviations....................................................... XI PWC publications ................................................ XII Engine covered.................................................... XVI
Combustion chamber liner..................................... 3.4 Small and large ducts ............................................ 3.6 Compressor turbine area ....................................... 3.8 Power turbine area ................................................ 3.18 Turbine cooling and air-bleed system .................... 3.22 Hot section sealing ................................................ 3.26 Compressor turbine wash ...................................... 3.28
CHAPTER 1 : Engine Overview
CHAPTER 4 : Gearbox
Features ................................................................ 1.6 Bearings ................................................................ 1.8 Engine operation ................................................... 1.12 Stations ................................................................. 1.14 Externals................................................................ 1.15
Reduction gearbox................................................. 4.2 Clutch-gear sealing ................................................ 4.6 Accessory gearbox ................................................ 4.10
CHAPTER 2 : Cold Section
CHAPTER 5 : Oil System
Inlet case and compressor .................................... 2.4 Bleed valve ............................................................ 2.6 BOV closing point check........................................ 2.8 Gas generator case ............................................... 2.10 Compressor wash.................................................. 2.12
Power section oil system ....................................... 5.2 Bearing sealing ...................................................... 5.14 Breather system..................................................... 5.16 Reduction gearbox oil system................................ 5.18 CHAPTER 6 : Engine Indicating System Inter Turbine Temperature system (ITT)................6.4 EGT system ...........................................................6.8 Torque system .......................................................6.12 Chip detector ......................................................... 6.20
PT6T-3/6
TRAINING USE ONLY
INTRODUCTION
IV
TABLE OF CONTENTS (cont'd) CHAPTER 7 : Ignition System
CHAPTER 10 : Maintenance Practices
Ignition ................................................................... 7.2
Periodic Inspections.............................................10.2 Borescope Inspection ..........................................10.4 First stage blade inspection .................................10.6 Oil filter cleaning ..................................................10.7 P3 filter cleaning ..................................................10.8 Fuel pump and filter inspection............................10.9 AGB Lip seal replacement ...................................10.10 Carbon seal replacement.....................................10.12 Fuel nozzles Inspection .......................................10.13 Gas Generator case Inspection ...........................10.14 Special tools ........................................................10.15 Activity report .......................................................10.19
CHAPTER 8 : Performance Performance check................................................ 8.2 Engine condition trend monitoring ......................... 8.10 Operating limit ....................................................... 8.14 HSI & TBO interval ................................................ 8.15 Rotor service life.................................................... 8.16 CHAPTER 9 : Fuel System Schematic.............................................................. 9.3 Fuel heater ............................................................ 9.4 Fuel pump ............................................................. 9.6 MFCU .................................................................... 9.8 Flow divider ........................................................... 9.14 Fuel nozzles .......................................................... 9.16 AFCU..................................................................... 9.20 N2 governor........................................................... 9.24 TCU ....................................................................... 9.28 FCU adjustments................................................... 9.32 Troubleshooting chart............................................ 9.36
PT6T-3/6
TRAINING USE ONLY
INTRODUCTION
V
SCOPE This training manual contains information pertaining to the description, operation, maintenance and troubleshooting of the PT6T-3 /-3B /-3BE /-3BF /-3BG /-3D /-3DE /-3DF /-6 and -6B engines. This training manual is intended for classroom use only and includes cross section drawings, schematics and text. A basic understanding of jet engine principles would be an asset. This manual may be used for Line Maintenance, Hot Section Maintenance or Heavy Maintenance training. •
Line Maintenance : Includes engine description, operation and "on-aircraft" maintenance.
•
Hot Section Inspection : Includes removal, inspection, refurbishment of hot section parts as per Maintenance Manual procedures. Due to the commonality between PT6T and PT6B, hot section, the course is common for these two engine models.
•
Heavy Maintenance : Is a combination of the Line Maintenance and the Hot Section Inspection courses.
PT6T-3/6
TRAINING USE ONLY
INTRODUCTION
VI
LINE MAINTENANCE Course Schedule: Courses duration : 5 days (30 hours) class time Breaks : 15 minutes at 10:00 and 14:00 Lunch period : 12:00 to 12:45
Lubrication System: General. Power section oil system. Oil filter and by-pass valve. Oil pressure regulation. Scavenge system. Bearing compartment sealing. Reduction gearbox oil system. Oil system troubleshooting.
Course Objectives: To teach the fundamentals and skills necessary to maintain the engine. At the end of the course, the student should be able to perform all Line Maintenance operations covered during the course.
Indicating System: General. Engine temperature. Trimming. Torque system. Chip detector. Indicating system Troubleshooting.
Course Syllabus
Ignition System: General. Ignition exciter unit. High tension leads. Igniter plugs
Introduction: Registration and orientation. Video presentation Engine Overview: Introduction to the engine. Main features Glossary of terms (abbreviations). Bearing locations. Stations and flanges. External views Engine Construction: Compressor inlet case. Compressor. Compressor bleed valve. Gas generator case. Combustion chamber liner. Compressor turbine vane ring. Turbine support case. Power turbine vane ring. Power turbine. Turbine cooling. Exhaust section. Reduction gearbox. Accessory Gearbox. Accessory Gearbox breather. Cold section troubleshooting. Hot section troubleshooting. Compressor wash.
PT6T-3/6
Engine Performance: HECTM description. Engine operating limits. Cycle life calculation. Fuel System: Description and features. Fuel system general. Fuel pump. Automatic/Manual Fuel control units. Flow divider. Fuel nozzles. Fuel system Troubleshooting. Maintenance Practices: During this phase every trainee will have the opportunity to perform maintenance, inspection and repair included in the engine Maintenance Manual. This portion of the course is done in the training centre shop on a production like engine.
TRAINING USE ONLY
INTRODUCTION
VII
LINE MAINTENANCE (cont’d) The Following is a List of Areas Covered : Oil and fuel filters inspection. Oil pressure adjustment. Chip detector inspection. Lip seals and Carbon seals replacement. Removal and installation of external accessories. Fuel nozzles removal and inspection, Fuel control adjustments. Borescope inspection
Exams: Four comprehensives multiple choice exams are administered during the course and the student must maintain an overall average of 70% on each exam to obtain a Line Maintenance certificate.
HOT SECTION INSPECTION The Following is a List of Areas Covered: Removal and installation of external accessories. Borescope inspection. Power section removal. Hot section inspection. Turbine tip clearance calculation. Sealing of hot section components. Grinding procedure.
Course Schedule: Courses duration : 3 days (18 hours) class time Breaks : 15 minutes at 10:00 and 14:00 Lunch period : 12:00 to 12:45 Course Objectives: To teach the fundamentals and skills necessary to maintain the engine. At the end of the course, the student should be able to perform all Hot Section Inspection and maintenance operations covered during the course.
Exam: One comprehensive multiple choice exam is completed at the end of the course and the student must have at least 70% to obtain a Hot section inspection certificate.
Course Syllabus
This certificate and the line maintenance certificate are equivalent to the previously issued Heavy maintenance certificate.
Practical Training: During this phase every trainee will have the opportunity to perform Hot Section Inspection maintenance and repair included in the engine Maintenance Manuals. This portion of the course is done at different times in the training centre shop on a production like engine.
PT6T-3/6
TRAINING USE ONLY
INTRODUCTION VIII
HEAVY MAINTENANCE Course Schedule: Courses duration : 7 days (42 hours) class time Breaks : 15 minutes at 10:00 and 14:00 Lunch period : 12:00 to 12:45
Lubrication System: General. Power section oil system. Oil filter and by-pass valve. Oil pressure regulation. Scavenge system. Bearing compartment sealing. Reduction gearbox oil system. Oil system troubleshooting.
Course Objectives: To teach the fundamentals and skills necessary to maintain the engine. At the end of the course, the student should be able to perform all heavy Maintenance operations covered during the course.
Indicating System: General. Engine temperature. Trimming. Torque system. Chip detector. Indicating system Troubleshooting.
Course Syllabus
Ignition System: General. Ignition exciter unit. High tension leads. Igniter plugs.
Introduction: Registration and orientation. Video presentation Engine Overview: Introduction to the engine. Main features Glossary of terms (abbreviations). Bearing locations. Stations and flanges. External views Engine Construction: Compressor inlet case. Compressor. Compressor bleed valve. Gas generator case. Combustion chamber liner. Compressor turbine vane ring. Turbine support case. Power turbine vane ring. Power turbine. Turbine cooling. Exhaust section. Reduction gearbox. Accessory Gearbox. Accessory Gearbox breather. Cold section troubleshooting. Hot section troubleshooting. Compressor wash.
PT6T-3/6
Engine Performance: HECTM description. Engine operating limits. Cycle life calculation. Fuel System : Description and features. Fuel system general. Fuel pump. Automatic/Manual Fuel control units. Flow divider. Fuel nozzles. Fuel system Troubleshooting. Maintenance Practices: During this phase every trainee will have the opportunity to perform the maintenance, inspection, repairs, and to perform Hot Section Inspection, included in the engine Maintenance Manuals. This portion of the course is done in the training centre shop on a production like engine.
TRAINING USE ONLY
INTRODUCTION
IX
HEAVY MAINTENANCE (cont’d) The Following is a List of Areas Covered: Oil and fuel filters inspection. Oil pressure adjustment. Chip detector inspection. Lip seals and Carbon seals replacement. Removal and installation of external accessories. Fuel nozzles removal and inspection, Fuel control adjustments. Borescope inspection. Power section removal. Hot section inspection. Turbine tip clearance calculation. Sealing of hot section components. Grinding procedure. Exams: Four comprehensives multiple choice exams (15 questions each) are administered during the course and the student must maintain an overall average of 70% on each exam to obtain a Heavy Maintenance certificate.
PT6T-3/6
TRAINING USE ONLY
INTRODUCTION
X
ABBREVIATIONS AGB AFCU BS CW CCW CSU CT EGT FOD HSI IGE ITT MFCU N1 or Ng N2 or Nf Nr Ns OAT OEI P2.5/2.8 P3 Pa PAV
Pb Pg
Accessory Gearbox Automatic Fuel Control Unit Built Specification Clockwise Counter Clockwise Controlled Service Use Compressor Turbine Exhaust Gas Temperature Foreign Object Damage Hot Section Inspection In Ground Effect Hover InterTurbine Temperature (or T5) Manual Fuel Control Unit Compressor Rotor Speed Power Turbine Speed Main Rotor Speed Output Shaft Speed Outside Air Temperature One Engine Inoperative Compressor Interstage Air Pressure Compressor Discharge Air Pressure Ambient Air Pressure Pressure Ajusting Valve
Pm PPH Pr PRV Ps Psi Psia Psid PT P3/Px Py RGB SB SFC SHP T1 T5 TBO TCU Wa Wf
Fuel Pressure by-pass (returned to pump) Pneumatic Pressure to N2 Governor and Torque Control Unit Fuel Pressure metered (to Fuel Nozzles) Pounds Per Hour Regulated Pneumatic Pressure Pressure Regulating Valve Fuel Pressure supply (Pump outlet) Pounds Per Square Inch Pounds Per Square Inch Absolute Pounds Per Square Inch Differential Power Turbine Pneumatic Pressure (AFCU) Pneumatic Pressure (AFCU) Reduction Gearbox (CGB) Service Bulletin Specific Fuel Consumption Shaft Horse Power Temperature at air inlet Gas temperature at station 5 Time Between Overhaul Torque Control Unit Air Mass Flow Fuel Flow
Note: For Clarification, the following will be used in the manual N1 For gas generator speed N2 For Power turbine speed ITT For Turbine temperature
PT6T-3/6
TRAINING USE ONLY
INTRODUCTION
XI
P&WC PUBLICATIONS : Pratt and Whitney Canada publish various documents and manuals to support all the engines in service. Illustrated Parts Catalogue (IPC) : Contains all part numbers and parts history information along with identifying drawings for an engine series. To be used for ordering parts. Maintenance Manual (MM) : The manual defines all the line and heavy maintenance tasks that can be done on the engine as well as various tests and adjustments. Service Bulletin (SB) : Service bulletins are published to introduce new parts, modify existing parts to improve the product. Spare Parts Bulletins (SPB) : Spare parts bulletins are published to advise for new parts, fully interchangeable with existing parts. Commercial Support Program Notification (CSPN) : Program issued to assist operators in the accomplishment of SB’s. Airworthiness Directive (AD) : Issued by Governmental Aviation Regulatory Agencies. Requires compliance to rectify potential problems affecting the airworthiness of the aircraft. AD’s refer to applicable SB’s for accomplishment instructions.
PT6T-3/6
Special Instruction (SI) : Special instructions are produced by Customer Support to provide specific maintenance information to specific customers. Service Information Letter (SIL) : Service information letters are produced by Customer Support to inform all operators on new techniques, new products and other general information. Training Manual : Training manual are published by the Customer Training Centre to assist the instructors in class. Publication Price List : The publication price list contains the prices of all P&WC publications and training material available to customers. For more information on Pratt & Whitney Canada publications contact : Supervisor, Publications Customer Services (01CA4) 1000 Marie Victorin Longueuil, Quebec Canada J4G 1A1 Telephone : 1-450-647-2705 Fax : 1-450-647-2702 Email :
[email protected]
TRAINING USE ONLY
INTRODUCTION
XII
PUBLICATION STANDARDS General:
Example:
The engine manuals are published following the ATA 100 revision 15
A basic Chapter will be identified as 72 - 00 - 04 Indicates engine chapter Indicates engine general Indicates fuel nozzles
Chapters: In relation with the documentation used on an aircraft the chapter 71 is the POWERPLANT Chapter, and chapter 72 is the ENGINE Chapter. The basic engine chapters are : 71 - 00 POWER PLANT (Ground Operating Limits, Ground Testing Procedures) 72 - 00 ENGINE (General, Tools, Consumable Materials, Periodic Inspections) 72 - 10 REDUCTION GEARBOX 72 - 30 GAS GENERATOR 72 - 50 POWER TURBINE AND EXHAUST 72 - 60 ACCESSORY GEARBOX Component Parts: Component parts number as follows : 72 – 00 - 01 & … 72 – 10 - 01 & … 72 – 30 - 01 & … 72 – 50 - 01 & … 72 – 60 - 01 & …
PT6T-3/6
are treated under engine section ENGINE EXTERNALS RGB COMPONENTS GAS GENERATOR COMPONENTS POWER TURBINE AND EXHAUST COMPONENTS AGB COMPONENTS
Pages: The pages block number inside each chapter is used for breaking the subjects within the manual to small topics for ready reference and ease of use. The standard page blocks are as follows : Description and Operation ......................1 to 99 Fault isolation .........................................101 to 199 Maintenance Practices ...........................201 to 299 Servicing .................................................301 to 399 Removal/Installation ...............................401 to 499 Adjustment/Test......................................501 to 599 Inspection/Check ....................................601 to 699 Cleaning/Painting....................................701 to 799 Approved Repairs ...................................801 to 899 Example: On page 72 - 00 - 04, page 201 you will find the Maintenance practice of the fuel nozzles.
TRAINING USE ONLY
INTRODUCTION XIII
SERVICE BULLETIN COMPLIANCE CODES Category 7 Do this SB when the supply of superseded parts is fully used.
Category 1 Do before the next flight. Category 2 Do the first time the aircraft is at a line station or maintenance base that can do the procedure.
Category 8 Do this SB if the operator thinks the change is necessary because of what he knows of the parts history.
Category 3 Do before xxx hours or xxx cycles. This Category may be expanded as required, to specify a minimum and/or a maximum and/or repetitive interval/inspection.
Category 9 Spare parts information only. Old and new parts are directly interchangeable and operators can mix old and new parts.
Category 4 Do this SB the first time the engine or module is at a maintenance base that can do the procedures, regardless of the scheduled maintenance action or reason for engine removal.
Category CSU: Used to evaluate new parts before final introduction in commercial service. Operators who participate should include this SB at the next maintenance or overhaul of the engine.
Category 5 Do this SB when the engine is disassembled and access is available to the necessary sub-assemblies. Do all spare part assemblies. Category 6 Do this SB when the sub-assembly is disassembled and access is available to necessary part.
PT6T-3/6
TRAINING USE ONLY
INTRODUCTION XIV
NOTES
PT6T-3/6
TRAINING USE ONLY
INTRODUCTION XV
ENGINES COVERED IN THIS MANUAL ENGINE MODEL
CERTIFICATION DATE
TAKE-OFF RATING (SHP)
INSTALLATION BELL 212 AGUSTA BELL AB 212 SIKORSKY S-58T
PT6T-3
1970
1800
PT6T-3B PT6T-3BF
1979 1998
1800
BELL 212 BELL 412 & 412 SP AGUSTA BELL AB 212 & 412
PT6T-3BE PT6T-3BG
1990 1998
1800
BELL 412 HP AGUSTA BELL AB 412 HP
PT6T-3D PT6T-3DE
1993 1995
1800
PT6T-3DF
1996
1800
BELL 412 HP & 412 EP BELL CFUTTH CH-146 “Griffon” AGUSTA BELL AB 412 HP/EP BELL 412 EP
PT6T-6
1974
1875
PT6T-6B
1992
1875
T400-CP-400
1970
1800
T400-CP-401
1972
1800
T400-WV-402
1975
1970
PT6T-3/6
AGUSTA BELL AB 212 & 412 SIKORSKY S-58T AGUSTA BELL AB 412 USN, USAF, CF MILITARY BELL AH-1J, UH-1N, CUH-1N US ARMY MILITARY BELL VH-1N US NAVY MILITARY BELL AH-1J, AH-1T
TRAINING USE ONLY
INTRODUCTION XVI
MAJOR ENGINE MODEL DIFFERENCES The Twin-Pacengines covered in this manual can be divided in three major groups : 123-
PT6T-3 /-3B /-3BE /-3BF /-3BG /-3D /-3DE /-3DF PT6T-6 /-6B T400-CP-400 /CP-401 /WV-402
Group 1: PT6T-3 : PT6T-3B :
Reference model Similar to PT6T-3 with PT6T-6 hot section components for higher output during OEI operation. PT6T-3BE : Similar to PT6T-3B except for a new torque control unit (deletion of torque sharing) and new of Nos. 16 and 17 bearing housing sleeve in RGB. PT6T-3BF : Similar to PT6T-3B with increase in the 30 minute OEI rating. PT6T-3BG : Similar to PT6T-3BE with increase in the 30 minute OEI rating. PT6T-3D/-3DE : Similar to PT6T-3BE with improved hot section hardware, Duplex Fuel Nozzles & upgraded RGB. Continuous OEI rating (-3D) 30 minutes OEI rating (-3DE). PT6T-3DF : Similar to PT6T-3D, New Power Turbine components, 30 minutes OEI rating.
Group 2: The T-6 engines differ from the T-3 engines by the EGT temperature measuring system in lieu of an ITT system. PT6T-6 : Up-rated version of PT6T-3 with hot section improvements to accommodate higher power. PT6T-6B : Similar to PT6T-6 except for a new torque control unit (deletion of torque sharing). Group 3: The T400 engine series listed below is for reference only, military engines not for commercial use. T400-CP-400 : US Navy, US Air Force and Canadian Forces version of the PT6T-3 with reduction and accessory gearboxes made of aluminium Housing. T400-CP-401 : US Army designation for the T400-CP400 with features similar to the PT6T-3. T400-WV-402: US Navy designation for an up-rated T400-CP-400 with hot section hardware improvements and Duplex Fuel Nozzles to accommodate higher power and the addition of a power turbine overspeed protection system.
Refer to SB 5352 for details.
PT6T-3/6
TRAINING USE ONLY
INTRODUCTION XVII
NOTES
PT6T-3/6
TRAINING USE ONLY
INTRODUCTIONXVIII
ENGINE OVERVIEW
PT6T-3/-6
TRAINING USE ONLY
ENGINE OVERVIEW
1.1
TWIN PAC INSTALLATION The Twin-Pac® is installed in the commercial Bell Helicopter / Agusta-Bell 212 and 412 or in the Sikorsky S58 T The engine is secured in the aircraft by 4 engine mounts : • 1 at the bottom of each accessory gearbox. • 2 at the bottom of the reduction gearbox.
PT6T-3/-6
TRAINING USE ONLY
ENGINE OVERVIEW
1.2
TWIN PAC INSTALLATION
PT6T-3/-6
TRAINING USE ONLY
ENGINE OVERVIEW
1.3
LEFT FRONT VIEW
PT6T-3/-6
TRAINING USE ONLY
ENGINE OVERVIEW
1.4
RIGHT FRONT VIEW
PT6T-3/-6
TRAINING USE ONLY
ENGINE OVERVIEW
1.5
PT6T-3 TURBOSHAFT The Twin-Pac engine has 3 modules, 2 power section (PS) modules and 1 reduction gearbox (RGB) module. References: SHP : .................................................1,800 shp Length : ............................................66 inches Width : ..............................................44 inches Height : .............................................33 inches Dry Weight : .....................................690 lbs 100% N1 speed ................................38,100 rpm 100% N2 speed ................................33,000 rpm 100% Output shaft (Ns) ...................6,600 rpm
Reduction Gearbox (RGB) • Two stage reduction gearbox with idler gear. • Built in torque measurement system. • Reduce the power turbine speed to a speed satisfactory for the aircraft main transmission. • Supply the power for two oil cooler blowers. • Supply the power for two power turbine (N2) governors.
Main Components and Features Accessory gearbox (AGB) • Support the engine accessories. • Driven by the compressor rotor. Compressor • 3 axial stages plus 1 centrifugal impeller. • Supply the necessary air pressure and flow, for combustion and cooling of hot section components. Combustion Chamber • Annular, Reverse flow (for shorter and lighter engine). • Area for the combustion of the air-fuel mixture. Compressor Turbine • Single stage turbine, turns clockwise (CW). • Supply the power to drive the compressor.
PT6T-3/-6
Power Turbine • Single stage turbine, turns counterclockwise (CCW). • Independently of compressor turbine (free turbine). • Extract the energy to supply necessary power to the aircraft main transmission.
Fuel and Control System • Separate and identical hydro-pneumatic fuel control systems for each power section. · Two fuel heater · Two fuel pump · Two automatic fuel control unit (AFCU) · Two manual fuel control unit (MFCU) · Two N2 governor · One common torque control unit (TCU) • Two operating modes · Automatic (normal flight) · Manual (Emergency, Troubleshooting) • Governing function • Torque limiting • Torque sharing (except 412HP/EP and Post SB5267)
TRAINING USE ONLY
ENGINE OVERVIEW
1.6
PT6T CROSS SECTION
PT6T-3/-6
TRAINING USE ONLY
ENGINE OVERVIEW
1.7
BEARINGS Function:
Gearbox Bearings
Holds major rotating assemblies.
Bearings Nos. 5 to 17 inclusively are installed in the reduction gearbox.
Ball Bearings Absorb axial and radial loads. Roller Bearings Absorb radial load only Permit thermal expansion Description: The Twin-Pac has a total of 33 main bearings, which does not include accessory gearbox bearings. Power-Section Bearings Bearings Nos. 1 to 4 are installed in each power section: • • • •
No 1 No 2 No 3 No 4
Ball Roller Roller Ball
Front compressor Rear compressor Front power turbine shaft Rear power turbine shaft
• • • • • • •
No 5 No 6 No 7 No 8 No 10 No 10.5 No 11
Ball duplex Roller Roller Ball duplex Ball Roller Ball
•
No 12
Ball
• • • • • •
No 12.5 No 13 No 14 No 15 No 16 No 17
Roller Roller Roller Roller Roller Ball
Front input drive shaft Rear input drive shaft Front idler gear Rear idler gear Torquemeter piston Rear clutch gearshaft / housing Rear clutch gear / 2nd stage gearshaft Front clutch gear / 2nd stage gearshaft Front clutch gearshaft / housing Center 2nd stage gearshaft Front 2nd stage gearshaft Rear output shaft Front output shaft Front output shaft
Bearings 1 to 8 are lubricated by the power-section oil system. Bearings 10 to 17 are lubricated by the reduction gearbox oil system. Maintenance : • No scheduled field maintenance on bearings.
PT6T-3/-6
TRAINING USE ONLY
ENGINE OVERVIEW
1.8
BEARINGS
12
11
12 12 13
15
16
17
10 12
10 14
8
PT6T-3/-6
6
7
5
4
TRAINING USE ONLY
3
2
1
ENGINE OVERVIEW
1.9
MAJOR ASSEMBLIES AND FLANGES
POWER SECTION MODULE POWER TURBINE STATOR HOUSING POWER TURBINE NO. 3 & NO. 4 BEARING SUPPORT HOUSING B
D A C EXHAUST DUCT
REDUCTION GEARBOX MODULE
POWER TURBINE SHAFT HOUSING
A
RGB , POWER TURBINE & EXHAUST SECTION PT6T-3/-6
TRAINING USE ONLY
ENGINE OVERVIEW 1.10
MAJOR ASSEMBLIES AND FLANGES ACCESSORY GEARBOX
G INLET CASE
INLET SCREEN
F
F C E
COMPRESSOR
COMPRESSOR TURBINE SHROUD HOUSING
COMPRESSOR TURBINE VANE RING
GAS GENERATOR CASE
GAS GENERATOR SECTION PT6T-3/-6
TRAINING USE ONLY
ENGINE OVERVIEW 1.11
BASIC TURBOSHAFT OPERATION The PT6T (Twin-Pac) engine series is a lightweight free turbine engine. It drives one output shaft via a two-stage reduction gearbox. The power section consists of two major assemblies : • The Compressor rotor assembly • The Power Turbine rotor assembly. The Compressor Rotor assembly has a compressor and a compressor turbine. The Power Turbine rotor assembly has a power turbine and a power turbine shaft. The two assemblies are not connected together. They turn at different speeds and in opposite directions. This design is referred to as a "Free Turbine Engine". It permits the power turbine and the rotor to turn at a constant speed, while the fuel control system schedules any compressor speed (N1) as necessary. Starter cranking torque is low, since only the compressor rotor rotates on start. Engaging the accessory gearbox mounted starter/generator starts the Power Section. The compressor pulls air in the engine via an annular plenum chamber (inlet case). The pressure increases across 3 axial stages and one centrifugal impeller. The air is directed into the combustion chamber. Air enters the combustion chamber via small holes and at the proper compressor speed, the fuel is sprayed in the combustion chamber by 14 fuel nozzles. Two spark igniters located in the combustion chamber ignite the airfuel mixture.
PT6T-3/-6
The generated hot gases are then directed to the turbine area. At this point, ignition is turned off since a continuous flame exists in the combustion chamber. The hot expanding gases accelerate through the compressor turbine vane ring and cause the compressor turbine to rotate. The gases leaving the compressor turbine are accelerated again as they flow through the power turbine vane ring. The power turbine provides rotational energy to drive the main rotor via the reduction geartrain. Gases leaving the power turbine are expelled into the atmosphere by the exhaust duct. The reduction gearbox reduces the power turbine speed to a suitable speed for the aircraft geartrain (6,600 rpm). The engine oil supply is contained in three integral oil tanks, which provide oil to lubricate and cool all bearings and gears. A hydro-pneumatic fuel control system installed on the Accessory Gearbox regulates fuel flow to the fuel nozzles in response to power requirements and flight conditions. The fuel system controls the main rotor speed by varying the engine's output power as a function of the load demand set by the pilot. Engine shutdown is accomplished by cutting the fuel going to the fuel nozzles.
TRAINING USE ONLY
ENGINE OVERVIEW 1.12
TURBOSHAFT ENGINE
PT6T-3/-6
TRAINING USE ONLY
ENGINE OVERVIEW 1.13
STATIONS (GRAPH) C 1200
PSIA 120
900
90
600
60
T
300 0
30 P T
P
STATIONS
7
6
5
4 3 2.8
2.5
2
0
1
TEMPERATURE PRESSURE NOTE: AT TAKE-OFF POWER, STANDARD DAY, SEA LEVEL PT6T-3/-6
TRAINING USE ONLY
ENGINE OVERVIEW 1.14
LEFT FRONT VIEW TACHOMETER GENERATOR PAD (N1)
FUEL FILTER
FUEL SYSTEM INLET PORT
REDUCTION GEARBOX OUTPUT SHAFT T5 SYSTEM TERMINAL BLOCK
OIL FILLER CAP FUEL ACCUMULATOR POWER SECTION OIL LEVEL SIGHT GLASS
NO.2 BEARING OIL SCAVENGE PUMP ACCESSORY GEARBOX POWER SECTION OIL CHIP DETECTOR TEMPERATURE PORT POWER SECTION OIL TANK DRAIN PT6T-3/-6
TRAINING USE ONLY
POWER SECTION OIL PRESSURE PORT
ENGINE OVERVIEW 1.15
RIGHT FRONT VIEW REDUCTION GEARBOX OIL PRESSURE PORT
OIL TO FUEL HEATER
Py ACCUMULATOR
FUEL CONTROL UNIT (AFCU + MFCU)
STARTER GENERATOR PAD
FUEL PUMP
P.S. OIL PRESSURE SENSING LINE
Pg LINE OIL PRESSURE LINE
P.S. OIL PRESSURE REGULATING VALVE
No. 3 TO 8 BEARING P.S. OIL LEVEL SIGHT GLASS SCAVENGE LINE NO. 2 BEARING SCAVENGE LINE PT6T-3/-6
TRAINING USE ONLY
ENGINE OVERVIEW 1.16
RIGHT REAR VIEW P.S.OIL PRESSURE ADJUSTMENT VALVE
COMPRESSOR WASH RING FITTING
AGB OIL BREATHER CARBON SEAL
P3 AIR CABIN BLEED
CHECK VALVE
AIR INLET SCREEN FUEL NOZZLES N2 GOVERNOR
SPARK IGNITER P.S. OIL INLET (FROM AIRFRAME OIL COOLER)
PT6T-3/-6
T5 TRIM COMPENSATOR
TRAINING USE ONLY
P.S. OIL OUTLET (TO AIRFRAME OIL COOLER)
ENGINE OVERVIEW 1.17
BACK VIEW
RGB STATIC AIR PRESSURE PORT RGB BREATHER PORT (TO TORQUE TRANSDUCER) TORQUE CONTROL UNIT
TORQUEMETER OIL PRESSURE OUTLET (TO TRANSDUCER)
BLOWER DRIVE COVER
NO.1 P.S. OIL FILTER NO.1P.S. CHIP COVER DETECTOR PT6T-3/-6
RGB OIL FILTER
RGB CHIP DETECTOR
RGB OIL LEVEL SIGHT GLASS
TRAINING USE ONLY
TACHOMETER NO.2 P.S. OIL FILTER GENERATOR PAD (N2) BYPASS VALVE
ENGINE OVERVIEW 1.18
LEFT SIDE VIEW
METERING TEE ORIFICE
Pg ACCUMULATOR
P3 LINE TO R.G.B. CARBON SEAL P3 LINE TO AFCU
P3 AIR FILTER
COMPRESSOR BLEED VALVE
PT6T-3/-6
DRAIN VALVE
OIL PRESSURE LINE
FLOW DIVIDER VALVE
TRAINING USE ONLY
ENGINE OVERVIEW 1.19
NOTES
PT6T-3/-6
TRAINING USE ONLY
ENGINE OVERVIEW 1.20
COLD SECTION
PT6T-3/-6
TRAINING USE ONLY
COLD SECTION
2.1
COLD SECTION Function:
Operation:
Supply the necessary mass of air at the right pressure to the combustion chamber and all the supporting systems.
The compressor draws air into the engine and compresses it, before delivery to the combustion chamber area.
Transmit the rotational energy from the compressor turbine to drive the accessories mounted on the accessory gearbox. Topics Covered in this Chapter: • • • • •
Inlet case Compressor assembly Bleed valve Gas generator case Cold section cleaning
PT6T-3/-6
Compressed Air: • Sustains combustion in order to produce the energy necessary to drive the compressor and the power turbines. • Provides cooling air for hot section components. • Provides air to seal bearing cavities. • Assists in the operation of the fuel control unit. • Controls bleed valve operation. • Provides heating for cabin use.
TRAINING USE ONLY
COLD SECTION
2.2
COLD SECTION
INLET CASE
COMPRESSOR GAS GENERATOR
BLEED VALVE
PT6T-3/-6
TRAINING USE ONLY
COLD SECTION
2.3
COMPRESSOR AND INLET CASE Function:
Compressor
Inlet Case • Directs air into the compressor • Supports No. 1 bearing
• Three stages of axial rotors consisting of bladed disks, separated by stator vanes (1st stage Titanium blades, 2nd and 3rd stages, stainless-steel blades). • One stage centrifugal consisting of a centrifugal impeller (Titanium). • All the rotating components are held in place with tie rods that extend through the four stages. • The No 1 bearing flexible housing absorbs compressor rotor vibrations. • The compressor discs and the impeller are limited in cycles (refer to chapter Performance).
Compressor • Provides the combustion chamber with the correct airflow at the required pressure. References: Compression ratio : ....................... 7.3 : 1 Maximum airflow (Wa) :................. 6.60 lbs/sec Maximum N1 speed : (PT6T-3) : ...................................... 100% (38,100 rpm) (PT6T-3B’s/-6’s) : .......................... 103.4% (39,400 rpm) (PT6T-3D’s) : ................................. 109.2% (41,600 rpm) Construction: Inlet case • One piece aluminum casting protected against corrosion. • Anti-ice protection by heat from oil tank. • Inlet screen (1/4 inch mesh) prevents objects from entering the compressor.
PT6T-3/-6
Maintenance: Scheduled • Check compressor inlet area for corrosion, dirt deposits and erosion and check first-stage blades and vanes every 300 hours or 1 year and whenever condition of inlet screen warrants its removal. • Inspect inlet screen cleanliness and condition of mesh and rubber sealing rims for damage every 150 hours. • Wash / rinse compressor at regular intervals.
TRAINING USE ONLY
COLD SECTION
2.4
COMPRESSOR AND INLET SECTION AIR INLET SCREEN INTERSTAGE AIR (P2.5) INTERSTAGE AIR (P2.8) COMPRESSOR AIR INLET CASE
IMPELLER HOUSING
NO.1 BEARING
IMPELLER TIE ROD
FLEXIBLE HOUSING
COMPRESSOR STUB SHAFT
BLEED VALVE
PT6T-3/-6
TRAINING USE ONLY
COLD SECTION
2.5
A larger secondary orifice requires more N1 speed (more P3 pressure) to make the valve close.
COMPRESSOR BLEED VALVE Function: Prevent compressor stalls and surge below 91% N1, due to different efficiencies between the axial compressor and the centrifugal compressor. Description: A piston sliding on a guide pin inside the housing controls the amount of interstage pressure (P2.5/P2.8) bled off from the compressor. A rolling diaphragm mounted on the valve piston prevents leakage between P2.5/P2.8 and the piston chamber. Operation: Two forces act on the bleed valve piston : • Modified P3 air pressure, inside the bleed valve, pushes to close the bleed valve. • P2.5/P2.8 pressure, from the interstage compressor area, pushes to open it. P3 air flows through the valve and across 2 orifices (primary and secondary). The valve closing point is achieved during engine acceleration when the pressure acting on the piston (modified P3) is sufficient to overcome the compressor interstage pressure (P2.5/P2.8).
Maintenance: Unscheduled • Perform Bleed valve closing point check. • Check for evidence of air losses at sealing faces and mating surface. • Replace diaphragm if leaking. • Clean orifices. • Check for bleed valve sticking or seat/piston damage. Note: • Refer to SB 5394 for bleed valve assembly / desassembly. • P2.8 bleed for PT6T-3D’s and post SB 5351 Power Sections Compressor Efficiencies Wa
Centrifugal Axial
Bleed Valve opened
As the compressor speed increases, modified P3 increases higher than P2.5/P2.8, thus increasing the pressure acting on the piston and gradually closes it. The N1 speed at which the valve closes is a function of the primary and secondary orifice sizes.
Bleed Valve closed
N1 % 91
PT6T-3/-6
TRAINING USE ONLY
COLD SECTION
2.6
COMPRESSOR BLEED VALVE
PISTON
OPEN POSITION
GAS GENERATOR CASE
CLOSED POSITION P2.5/P2.8
P2.5/P2.8
GUIDE PIN P3
P3 GUIDE TUBE DISCHARGE TO ATMOSPHERE
DISCHARGE TO ATMOSPHERE
ROLLING DIAPHRAGM
PRIMARY ORIFICE
COVER PT6T-3/-6
Pa
Pa
SLEEVE SECONDARY ORIFICE
TRAINING USE ONLY
COLD SECTION
2.7
BLEED VALVE CLOSING POINT Adjustment: (Post SB 5380)
Purpose: Verify that the bleed valve closes within an acceptable N1 range. Operation: • • • • • • •
Install the bracket assembly as per maintenance manual instructions Start engine and accelerate slowly while watching air bubbles forming in the water container. As N1 speed increases more bubbles will appear. Keep accelerating until the bubbles stop. Record N1 speed where bubbles stop. Repeat the procedure to confirm closing point. Plot closing point of bleed valve on graph. Closing point must be within the gas generator speed band for the indicated outside air temperature (OAT).
The compressor bleed valve contains different sized orifices, which control the closing point on individual engines. If the closing point is not within the specified limits, replacement of the secondary orifice is permitted. If closing point speed is above the limit, install an orifice of a smaller size (smaller dash number). If closing point speed is below the limit, install an orifice of a bigger size (higher dash number). A one size change will shift the valve closing point by approximately 1% N1. Orifices P/N : ST 3268-xxx (range from –067 to –090) Baseline orifice : ST 3268-073 Note: The bleed valve closing point limits apply to all bleed valve configurations.
PT6T-3/-6
TRAINING USE ONLY
COLD SECTION
2.8
BLEED VALVE CLOSING POINT CHECK N1 % 98
PERFORMANCE LOSSES
96 AREA " B " REJECT
94 92
E BL A PT
90 88
" ND A B
86
A
A
E CC A "
84
BLEED VALVE
AREA " B " REJECT
82 80
BRACKET ASSEMBLY
COMPRESSOR STALL -40
0
+40 C
OUTSIDE AIR TEMPERATURE (OAT)
DETAIL "A" PT6T-3/-6
TRAINING USE ONLY
COLD SECTION
2.9
GAS GENERATOR CASE Purpose:
Maintenance:
Houses and supports various engine components. The diffuser pipes change the high velocity pressure into static pressure and cause the compressor air to turn 90°.
Scheduled • Verify drain valve for security and leaks at each engine periodic inspection. • Inspect gas generator case for cracks (around fuel nozzles, ports and spot welds), distortion, corrosion and evidence of overheating every 150 hours or 6 months. • For Pre-SB 5239 only (PT6T-3/3B), Longitudinal seam welds inspection every 600 hours (no inspection if post SB and all helical weld configuration).
Construction: • •
Welded assembly of steel alloy machine parts and sheet metal with an aluminide corrosion resistant coating. 21 brazed diffuser pipes.
The case provides : • Support for the compressor stator parts • Support for the No. 2 bearing • 14 bosses for fuel nozzles • 2 bosses for igniter plugs • 2 bosses for drain valves • 1 boss for P3 air (to Automatic Fuel Control Unit) • 1 boss for P3 air (to clutch gear carbon seals) • 1 boss for P3 air (airframe bleed) • 1 boss for the ITT harness
Unscheduled • Cleaning and touch-up of protective coating. • Repair of fuel nozzle pad threads using "Keensert" inserts. • During HSI, visually inspect case and diffuser pipes for wear and cracks. • Replacement of shanknuts.
Two drain valves are provided on the gas generator case to drain fuel from the combustion chamber in the event of a false start or following power section shutdown.
PT6T-3/-6
TRAINING USE ONLY
COLD SECTION 2.10
GAS GENERATOR CASE IGNITER PORT P3 PRESSURE TO RGB CLUTCH GEAR CARBON SEALS P3 PRESSURE TUBE TO AUTOMATIC FUEL CONTROL UNIT
P3 BLEED PORT TO CABIN HEATER
FLANGE "F"
FLANGE "C" DRAIN VALVE
P3 PRESSURE TO BLEED VALVE
NO.2 BEARING SCAVENGE OIL TUBE NO.2 BEARING PRESSURE OIL TUBE DRAIN VALVE PORT PT6T-3/-6
STRAIGHTENING VANE IGNITER PORT DIFFUSER PIPE TRAINING USE ONLY
COMPRESSOR BLEED VALVE PORT
NO.2 BEARING PRESSURE OIL TUBE
COLD SECTION 2.11
COMPRESSOR WASH Function: Restore the compressor efficiency by removing salt and dirt deposits from the compressor gas path. Type of Washes: • Desalination wash • Performance recovery wash Desalination Wash (Rinse): This method of washing consists of motoring the engine with the starter while injecting water into the compressor via the wash ring to remove salt deposits. The wash is done with normal drinking water. Performance Recovery Wash: This method of washing consists of motoring the engine with the starter while injecting a cleaning solution into the compressor via the wash ring. Approved cleaning agents are used to remove dirt deposits, which cannot be removed using water only. A 15-30 minute period is allowed for the cleaning agent to soak in, followed by one or two rinse cycles (water). A drying run should follow the compressor wash.
PT6T-3/-6
Wash Frequency: It is recommended that compressor washes be carried out depending on the operating environment. • Desalination wash should be performed daily if operating frequently in salt laden environment or weekly if operating occasionally in salt laden environment. • Performance recovery wash should be performed every 50 hours, weekly or as required depending on the operating environment. When the temperature is below 2°C (36°F), methanol must be added to the water to prevent freezing. Note: Prior to washing, make sure that : • Engine had a minimum of 40 minutes cooling period. • Aircraft bleed air system is “OFF”. • Flow divider/dump valve line is disconnected. • Ignition is turned “OFF” (circuit braker). • P3 filter is removed on PRE SB 5309 engines. • RGB P3 filter is removed (post SB 5174/5320), P3 line disconnected at elbow fitting or cap removed on Tee fitting (post SB 5423). • Fuel Boost Pump and Fuel valve "ON". Refer to the maintenance manual 72-00-00 page block 700 for compressor wash procedure. Caution: Do not motor engine for more than 30 seconds. Observe starter-cooling period (ref. Aircraft Maintenance Manual)
TRAINING USE ONLY
COLD SECTION 2.12
COMPRESSOR WASH
PRESSURE GAUGE
TURBINE WASH
CLEANING SOLUTION SHUTOFF VALVE
REGULATED AIR PRESSURE
SPRAY RING
WATER
PT6T-3/-6
TRAINING USE ONLY
COLD SECTION 2.13
COLD SECTION TROUBLESHOOTING
PROBABLE CAUSE Restricted inlet screen Dirty compressor Damaged compressor blades P3 leaks Excessive loading of starter generator or other AGB mounted accessories. Bleed valve stuck open
SYMPTOMS AT CONSTANT POWER N1 ITT ⇑ ⇑ ⇑ ⇑ ⇑ ⇑ ⇒ ⇑
⇑
⇓
⇑
⇑
⇑
Bleed valve stuck closed
Loss of power (Closing too late) or compressor stalls (Closing too early) Compressor stalls
Hooting/Rumbling noise Humming sound
Bleed valve flutters Compressor rotor out of balance
Bleed valve closing point out of limit
ACTION REQUIRED Clean and/or remove obstruction Perform compressor wash /revise schedule Return to an authorized overhaul facility if damage is beyond limit Check for external leaks on gas generator. At HSI verify sealing surfaces. Replace faulty accessories. Ensure P3 is not leaking between bleed valve and gas generator case. Inspect, repair, replace bleed valve. Remove and clean valve orifices or change orifice to get proper closing point. Remove and clean valve orifices or change orifice to get proper closing point. Check/replace bleed valve If humming disappears above 60% N1, no further action. If present above 60% N1 borescope inspection of compressor and compressor turbine for damage.
Note: Generally, cold section problems cause N1 and ITT to increase. However, the above list includes some that will make the engine react differently.
PT6T-3/-6
TRAINING USE ONLY
COLD SECTION 2.14
HOT SECTION
PT6T-3/-6
TRAINING USE ONLY
HOT SECTION
3.1
HOT SECTION Purpose:
Operation:
Extract energy from the hot expanding gases to :
The hot section of the engine comprises of components down stream of the gas generator. Hot expanding gases leaving the combustion chamber are directed towards the compressor turbine vane ring and hit the compressor turbine blades. The energy extracted by the compressor turbine will drive the compressor and the Accessory Gearbox.
• Drive the compressor turbine • Drive the power turbine and the reduction gearbox Topics Covered in this Chapter: • • • • • • • •
Combustion chamber Compressor turbine vane ring Compressor turbine Power turbine vane ring Power turbine Exhaust duct Sealing of the hot section Compressor turbine wash
PT6T-3/-6
Thereafter, gases travel across the power turbine vane ring and hit the power turbine blades. The power turbine rotation is transmitted to the output shaft via the power turbine shaft and the reduction gearbox. Gases leaving the power turbine are expelled to the atmosphere through the exhaust duct.
TRAINING USE ONLY
HOT SECTION
3.2
HOT SECTION COMPONENTS PT6T-3/3B's/6's
PT6T-3/-6
TRAINING USE ONLY
HOT SECTION
3.3
COMBUSTION CHAMBER LINER Purpose: Provide an area for combustion of the fuel/air mixture. The reverse flow feature provides for a shorter and lighter engine.
The combustion chamber combined with the large and small exit ducts form an envelope that turns the gas 180° (reverse flow). This configuration permits location of the turbines closer to the compressor and within the combustion chamber area, thus making the engine shorter and lighter.
Construction: • Annular, reverse flow type combustion chamber made of nickel alloy sheet metal • 14 fuel nozzle adapter bosses • 2 spark igniter bosses • Cooling rings maintain a layer of cooling air to protect the combustion chamber walls from the flame • On PT6T-3D’s power section, the small exit duct is an integral part of the liner and it is covered with ceramic coating as thermal barrier. Operation: P3 air enters the combustion chamber through holes in the inner and outer liner walls. The shape, size and location of these holes provide the correct fuel/air ratio for all operating conditions.
PT6T-3/-6
Cooling rings direct P3 air into the combustion chamber, close to the walls, to form a flame barrier. Maintenance: Unscheduled • Borescope inspection through fuel nozzle bosses. During Hot Section Inspection: • Inspect Liner for evidence of burning, cracking, buckling, etc. • Regap cooling rings if they are distorted. • Some damage is acceptable. Note: Local damage to the combustion chamber is most likely related to fuel nozzle spray pattern problem.
TRAINING USE ONLY
HOT SECTION
3.4
COMBUSTION CHAMBER LINER
PT6T-3/3B's/6's
PT6T-3/3B's/6's IGNITER BOSS FUEL NOZZLE PORT WITH SUPPORT BRACKET
IGNITER BOSS FUEL NOZZLE PORT WITH SUPPORT BRACKET PT6T-3D's
PT6T-3D's
PT6T-3/-6
TRAINING USE ONLY
HOT SECTION
3.5
SMALL AND LARGE EXIT DUCTS Purpose:
Maintenance:
Change direction of the airflow 180° (reverse flow).
During Hot Section Inspection: • Inspect the small and large exit ducts for evidence of burning, cracking or coating loss. • On the small exit duct only stop drill cracks up to 1 inch long (1/16” drill size).
Construction: The small exit duct (except PT6T-3D’s) and large exit duct are made of two layer of heat resistant nickel alloy, air cooled by P3 air, and coated with aluminide coating. On PT6T-3D’s the large exit duct is partially coated with a ceramic compound to act as thermal barrier. Operation: Hot expanding gases are re-directed towards the compressor turbine vane ring. P3 air for cooling flows between the double skin configuration and cools the two ducts. Via the small exit duct P3 air is routed to the compressor turbine vane ring for internal cooling of each vane.
PT6T-3/-6
TRAINING USE ONLY
HOT SECTION
3.6
SMALL AND LARGE EXIT DUCT
LARGE EXIT DUCT CERAMIC COATING (PT6T-3D's ONLY)
SMALL EXIT DUCT (EXCEPT PT6T-3D's)
COMBUSTION CHAMBER LINER
PT6T-3/-6
TRAINING USE ONLY
HOT SECTION
3.7
COMPRESSOR TURBINE VANE RING (AND ASSOCIATED PARTS) Vane Ring:
Shroud Segments:
• Direct the gases toward the compressor turbine at optimum angle and speed • Convergent vanes change the static pressure into velocity • Cobalt or nickel alloy casting, coated using a diffused aluminide process. Air-cooled core passages allow P3 air to flow through each vane. • Exit area is classed.
• Make close tolerance compressor turbine blades tip clearance, to reduce hot gases leakage. • Machined from nickel alloy steel, thickness is classed to fit different compressor turbine wheel diameters. Baffle (All Except PT6T-3): • Create an area to insulate the turbine vane ring and No.2 Bearing area.
Shroud Housing: • Support the shroud segments and interstage sealing ring. • Slots in the shroud housing match with corresponding lugs on the vane ring prevent any side play. Small Exit Duct: • Pinched the compressor turbine vane ring on the shroud housing. • Machined face contact shroud housing and turbine vane ring to prevent P3 air leakage. Interstage Sealing Ring(s):
No. 2 Bearing Cover (PT6T-3) or Cover Flange (All other): • Locate the compressor turbine vane ring, shroud housing and small exit duct assemblies with the center line of the power section. • The inner lugs of the vane ring match with the slots on the cover (T-3) or cover flange (all others). Lock Plate: • Secure compressor turbine vane ring and No.2 bearing cover or cover flange to the gas generator case.
• Encloses P3 air, prevents leakage to station 5.
PT6T-3/-6
TRAINING USE ONLY
HOT SECTION
3.8
COMPRESSOR TURBINE VANE RING (T-3) INTERSTAGE SEALING RING
PRESSURE SIDE
SHROUD SEGMENT
RETAINING RING
SMALL EXIT DUCT P3
COMPRESSOR TURBINE SHROUD HOUSING
LARGE EXIT DUCT
TIP CLEARANCE
P3 COOLING PASSAGE P3
COMPRESSOR TURBINE VANE RING
COMPRESSOR TURBINE NO. 2 BEARING COVER
PT6T-3/-6
TRAINING USE ONLY
LOCK PLATE
HOT SECTION
3.9
COMPRESSOR TURBINE VANE RING (cont'd) Operation: The compressor turbine vane ring receives hot gases from the combustion chamber. The converging vane airfoils direct the air towards the turbine blades, accelerating and changing its direction simultaneously. The vane ring is pinched between the small exit duct and the shroud housing. Lugs on the vane ring fit into slots on the shroud housing to prevent rotational movement. The vane ring class determines the total area of all the openings between the vanes trailing edges. A smaller vane ring class (smaller area) accelerates the air more and therefore increases the compressor turbine speed (N1). A higher N1 speed provides more air to the engine, more cooling and a lower ITT. The compressor turbine vane ring is subject to extreme temperatures within the engine. Cooling of the vane ring will thus determine its life expectancy. P3 air traveling inside the vane airfoils keeps them at a temperature lower than the gases flowing on the outside. After cooling, air is ejected in the gas path.
PT6T-3/-6
Segments come in different classes (thickness) to fit different compressor turbine diameters and maintain the necessary clearance between the compressor turbine blades and the segments. Effect of Vane Ring Class Change: Increase area : Decrease area :
N1 ⇓ N1 ⇑
ITT ⇑ ITT ⇓
Note: Replacement vane ring must have a class number identical to the original vane ring (tolerance ±0.03). Maintenance: During Hot Section Inspection • Inspect vane ring for : evidence of burning, cracking and coating loss. • Insure proper sliding fit (lugs to slots) with mating parts. • Check flatness of all mating flanges to reduce P3 air leakage to the minimum
TRAINING USE ONLY
HOT SECTION 3.10
COMPRESSOR TURBINE VANE RING (T-3B’S/6’S) INTERSTAGE SEALING RING
PRESSURE SIDE
SMALL EXIT DUCT
SHROUD RETAINING SEGMENT RING P3
COMPRESSOR TURBINE SHROUD HOUSING
LARGE EXIT DUCT
TIP CLEARANCE
P3 COOLING PASSAGE
COMPRESSOR TURBINE VANE RING
P3
COMPRESSOR TURBINE
NO. 2 BEARING COVER PT6T-3/-6
TRAINING USE ONLY
LOCK PLATE
NO. 2 BEARING COVER FLANGE
HOT SECTION 3.11
COMPRESSOR TURBINE VANE RING PT6T-3D’S (AND ASSOCIATED PARTS) Vane Ring: Similar to the PT6T-3B configuration except : • Nickel alloy casting. • Air-cooled core passages allow P3 air to flow through each vanes and exit at the trailing edge of the vanes for increased efficiency. • Lugs on outer diameter used to maintain segments in place. Baffle: • Close tolerance baffle to create an area to insulate the turbine vane ring and No.2 Bearing area.
PT6T-3/-6
TRAINING USE ONLY
HOT SECTION 3.12
COMPRESSOR TURBINE VANE RING (T-3D) COMBUSTION CHAMBER LINER
LARGE EXIT DUCT CERAMIC COATING COMPRESSOR TURBINE VANE RING
SEALING RING
PRESSURE SIDE P3
EXIT DUCT SUPPORT FLANGE
SHROUD HOUSING SHROUD SEGMENT TIP CLEARANCE COMPRESSOR TURBINE BLADE AIR BAFFLE
P3 CLEARANCE
NO.2 BEARING COVER LOCK PLATE PT6T-3/-6
TRAINING USE ONLY
HOT SECTION 3.13
COMPRESSOR TURBINE Purpose:
Operation:
Extract energy (66%) from the hot gases to drive the compressor rotor unit.
Expanding gases, accelerated through the vane ring hit the turbine blades. The energy available in the gases is converted into rotational movement to drive the compressor and the engine accessories. Nearly two thirds of all the energy available from the products of combustion is needed to drive the compressor. The one third remaining is used to drive the power turbine.
Construction: The compressor turbine is a two-plane balanced disk assembly, the disk is made of nickel alloy steel with firtree serrations that provide a firm attachment as well as allowing for thermal expansion differences between the blades and the disk. Rivets are used to axially retain the 58 blades on the disk. A master spline ensures reinstallation of the compressor turbine in its initial position on the compressor stub shaft during maintenance.
The turbine is individually balanced on two planes with weights and rivets. This feature allows for turbine replacement in the field. The turbine disc is limited in cycles (refer to chapter Performance).
References:
Maintenance:
Maximum N1 speed : (PT6T-3) : ..................................100% (38,100 rpm) (PT6T-3B’s/-6’s) : ......................103.4% (39,400 rpm) (PT6T-3D’s) : .............................109.2% (41,600 rpm) Rotation ........................... CW viewed looking forward
During Hot Section Inspection: • Inspect turbine disk for cracks, overheating, and scratches.
PT6T-3/-6
TRAINING USE ONLY
HOT SECTION 3.14
COMPRESSOR TURBINE
PIN
BLADE DISK RIVET
DETAIL COMPRESSOR TURBINE
BALANCING WEIGHT & RIVETS MASTER SPLINE
CUP WASHER
RETAINING BOLT
PT6T-3/-6
TRAINING USE ONLY
HOT SECTION 3.15
COMPRESSOR TURBINE BLADES Stage 4 Deep penetration with metal separation. Blade fracture imminent. Unbalance of rotor assembly. Operation is unsafe.
Purpose: Extract energy from the hot gases Construction: The compressor turbine blades are made from a nickel alloy, using a Directionally Solidified casting process known as D.S. blades or Single Crystal on PT6T-3D’s. DS Blades features include triple taper design construction, firtree retention, growth check pad (PT6T3B’s) and diffused corrosion resistant protective coating Single Crystal blades have firtree retention, new airfoil design, no growth check pads. The blades are serialized for life tracking purpose. The sulphidation attack can described in four levels : Stage 1 Mild sulphidation : Evident slight roughness of surface and breakdown of the coating layer. Condition acceptable in the field. Stage 2 Medium sulphidation : Heavy roughness of the surface, Base material is attacked, Blade integrity still not affected. Condition acceptable in the field. Stage 3 Severe sulphidation : Heavy roughness of the surface, Built-up of blister, Base material is attacked, Blade integrity is affected. Condition NOT acceptable in the field.
PT6T-3/-6
If sulphidation of the C.T blades is experienced a boroscope inspection should be scheduled to monitor the sulphidation stage. A regular Turbine wash should be established to reduce sulphidation progress. Special sulphidation resistance coatings are available as customer option. Maintenance: Unscheduled • Wash turbine blades based on past sulphidation experience. • Borescope inspection through fuel nozzle bosses. During Hot Section Inspection: • Inspect turbine blades for sulphidation, cracks, erosion, tip rub, burning, coating loss, impact damage and blade shift. C.T Blades Retirement Life: PT6T-3 : .............................................one TBO period PT6T-3B’s/-6’s : .................................“On Condition” PT6T-3D’s : ........................................8000 hours
TRAINING USE ONLY
HOT SECTION 3.16
CT BLADES SULPHIDATION
EQUIAXED ALLOYS
STAGE 1
STAGE 2
SC ALLOYS
DS ALLOYS
STAGE 3
CT BLADES PT6T-3/-6
STAGE 4
CT BLADE SULPHIDATION TRAINING USE ONLY
HOT SECTION 3.17
POWER TURBINE VANE RING Purpose:
Effect of Vane Ring Class Change:
Direct gases to the power turbine and change static pressure into velocity.
Increase area : Decrease area :
Construction:
Note: Replacement vane ring must have a class number identical to the original vane ring (tolerance ±0.1).
• Nickel alloy casting with a riveted sheet metal center baffle. • The exit area (throat) of the vane ring is classified. • Supported by the power turbine housing. • A lug to slot arrangements centers and prevents movements of the vane ring. Operation: Gases leaving the compressor turbine are accelerated through the power turbine vane ring and cause the power turbine to rotate.
N1 ⇑ N1 ⇓
ITT ⇓ ITT ⇑
Maintenance: During Hot Section Inspection: • Inspect vane ring for evidence of burning, cracking and coating loss. • Insure proper fit (lugs to slots) with mating parts. • Lap sealing face to obtain 100% contact.
The vane ring is held in place by lugs fitted in the power turbine housing. The riveted inner baffle directs air close to the power and compressor turbine disks for cooling. During engine assembly, selection of the correct vane ring class (area) will allow for optimization (matching) of the N1 and ITT parameters and engine performance.
PT6T-3/-6
TRAINING USE ONLY
HOT SECTION 3.18
POWER TURBINE VANE RING
POWER TURBINE VANE
PT6T-3/-6
TRAINING USE ONLY
HOT SECTION 3.19
POWER TURBINE Purpose:
References:
Extract energy (33%) from the gases to drive the aircraft main rotor through the reduction gearbox.
N2 at 100% ................ 33,000 rpm Rotation ..................... CCW viewed looking forward NR at 100% ............... 324 rpm
Construction: The power turbine is a single-plane balanced disk assembly, the disk is made of nickel alloy steel and is splined to the power turbine shaft. A master spline insures that the turbine can only fit in one position on the turbine shaft. The 41 blades are retained in the firtree serrations with rivets. There is no mechanical links between the power and compressor turbines thus the power turbine is "Free" to turn independent of the compressor turbine operation. Removal of the power turbine is permissible at field level if an operator wants to inspect the area beneath the turbine (ie : No. 3 bearing cover pre SB 5222).
The turbine disc is limited in cycles (refer to chapter Performance). Maintenance: Unscheduled During Hot Section Inspection : • Inspect the turbine disk for cracks, overheating, scratches. • Inspect the turbine blades for : cracks, burning, coating loss, corrosion, impact damage and blade shift.
Balancing of the power turbine must be done with the power turbine shaft and the No. 3 and 4 bearings altogether and for that reason the power turbine is not field replaceable.
PT6T-3/-6
TRAINING USE ONLY
HOT SECTION 3.20
POWER TURBINE
POWER TURBINE
MASTER SPLINE
PT6T-3/-6
TRAINING USE ONLY
HOT SECTION 3.21
SECONDARY AIR SYSTEM General:
Hot Section Cooling
The secondary air system consists of all the pressure air that is not used directly to produce power.
General:
Three Sources of Air Are Used in the Secondary Air System: • P2.5 interstage air pressure • P2.8 interstage (shroud bleed) air pressure • P3 compressor delivery pressure
A port (at 12 o’clock position) on the gas generator case delivers P3 air pressure for airframe use (heater etc. ). Operation:
Of all the air entering the power section :
P3 air is taken from the gas generator section and guided with various baffles to provide cooling and prolong hot section components life. Once the air has been used for cooling, it is evacuated in the gas path.
Primary Air System (85%) (Power Production): - 25% is used in the combustion process. - 60% is used to cool the combustion gasses. Secondary Air System (15%): - 8% is used for : • Turbine disks cooling and CT vane. • Sealing of bearing compartments. - 2% is used for : • Operation of bleed valve. • Operation of Automatic Fuel Control Unit. • Sealing of Reduction Gearbox carbon seals. - 5% is used for : • Cabin bleed (heating).
PT6T-3/-6
Internal passages in the engine guide P3 air for cooling of various hot section components like, combustion chamber, vane ring and turbine disks.
Air flowing into bearing compartments is evacuated via the oil scavenge system (described in oil system chapter). Maintenance: Unscheduled • Ensure no leak exists on airframe air bleed system. • Ensure that cooling rings in the combustion chamber are in satisfactory condition.
TRAINING USE ONLY
HOT SECTION 3.22
SECONDARY AIR SYSTEM
CUSTOMER PORT P3 BLEED
COMPRESSOR BLEED VALVE
PT6T-3/-6
TRAINING USE ONLY
HOT SECTION 3.23
POWER TURBINE & EXHAUST SECTION Exhaust Case: • Single port case, direct the exhaust gases to ambient atmosphere. • Welded assembly of nickel-steel alloy sheet metal. • Ski jump helps to evacuate the exhaust gas.
Maintenance:
Power Turbine Stator Housing: • Support: the power turbine vane ring, the integral ITT harness and thermocouple. • Interface with the gas generator section via a seal ring.
•
Insulation Blanket: • Reduce heat transmission between the exhaust case and other internal components.
•
Power Turbine Shaft Housing: • Support the power turbine shaft. • Form a cavity for No. 3 and 4 bearings.
Note: No welding is permitted on an installed exhaust case.
Scheduled: •
Pre SB 5222 only (PT6T-3/3B/6): No. 3 bearing cover inspection. Visually inspect exhaust duct for cracks and/or distortion every 50 hours or 6 months.
Unscheduled: Stop drill cracks on the exhaust flange (mating flange with the airframe) if crack does not extend into the seam weld.
Power Turbine Shaft: • Supported by No. 3 and 4 bearings. • Transmit power turbine speed and torque to the reduction gearbox via the RGB input shaft coupling.
PT6T-3/-6
TRAINING USE ONLY
HOT SECTION 3.24
EXHAUST DUCT
VIEW A
NO.3 & 4 BEARING HOUSING
A
SEAL (PT6T-3D's AND POST-SB 5364)
SEAL LOCATION EXHAUST CASE INSULATION BLANKET
THERMOCOUPLE POWER TURBINE POST SB 5222 PRE SB 5222
COUPLING SHAFT
PT VANE RING
COUPLING
NO.3 & 4 BEARING HOUSING SUPPORT
PT6T-3/-6
NO.3 BEARING NO.4 BEARING
PT STATOR HOUSING
POWER TURBINE SHAFT
TRAINING USE ONLY
HOT SECTION 3.25
SEALING OF THE HOT SECTION Purpose: Gas sealing in the hot section area is a very important factor affecting hot section life, and engine performance. This section describes the major sealing surfaces in the hot section and their purposes. SEALING FACE A B C
D
PT6T-3/-6
DESCRIPTION Lock plate to vane ring. Vane ring to small exit duct (exit duct support housing for PT6T-3D’s) and shroud housing. Power turbine housing to compressor turbine shroud housing. Power turbine vane ring to power turbine shroud.
TRAINING USE ONLY
FUNCTION Prevent P3 leaks from combustion chamber area to other side of vane ring. Prevent P3 air around the combustion chamber to leak and bypass the vane ring. Prevent P3 leaks into P5
Prevent leaks around the second stage vane ring.
HOT SECTION 3.26
HOT SECTION SEALING
D
PT6T-3/-6
C
TRAINING USE ONLY
B
A
HOT SECTION 3.27
TURBINE WASH Purpose:
When the temperature is below 2°C (36°F), methanol must be added to the water to prevent freezing.
Remove salt deposits from the turbine section of the engine to minimize blade sulphidation attack. Type of Wash: Desalination wash (rinse) Operation/Description: As the engine is motored, water is injected in front of the Compressor turbine, using a turbine wash nozzle through one igniter port. Ensure that the arrow sign on the tool tang is pointing towards the reduction gearbox. Drinkable water is used for turbine wash. The procedure to perform the turbine wash is identical to the rinse cycle for the compressor. Wash Frequency:
Note: Prior to washing, make sure that : • Engine had a minimum of 40 minutes cooling period. • Aircraft bleed air system is “OFF”. • Flow divider/dump valve line is disconnected. • Ignition is turned “OFF” (Circuit braker). • P3 filter is removed on PRE SB 5309 engines. • RGB P3 filter is removed (post SB 5174/5320), P3 line disconnected at elbow fitting or cap removed on Tee fitting (post SB 5423). • Fuel Boost Pump and Fuel valve "ON". Refer to the maintenance manual 72-00-00 page block 700 for compressor turbine wash procedure. Caution: Do not motor engine for more than 30 seconds. Observe starter-cooling period (ref. Aircraft Maintenance Manual)
It is recommended that compressor turbine washes be carried out depending on the operating environment. The turbine wash should be performed based on operator experience with sulphidation. It is recommended to perform the turbine wash in conjunction with compressor wash.
PT6T-3/-6
TRAINING USE ONLY
HOT SECTION 3.28
TURBINES WASH
A RGB
PRESSURE GAUGE
B RG
REGULATED AIR/NITROGEN PRESSURE
VIEW A
WATER
SHUTOFF VALVE
PT6T-3/-6
TRAINING USE ONLY
HOT SECTION 3.29
HOT SECTION TROUBLESHOOTING
PROBABLE CAUSE Gas leakage at junction between Compressor Turbine vane and lock plate A Gas leakage at junction between Small Exit Duct and Compressor Turbine vane ring B Interstage seal ring leak C Gas leakage at junction between Power Turbine vane and Power Turbine shroud housing D Burnt Compressor Turbine vane ring (larger throat area) High Compressor Turbine tip clearance Eroded compressor turbine blades
SYMPTOMS AT CONSTANT POWER N1 ITT ⇓ ⇓
ACTION REQUIRED
⇑
Lap sealing faces. Replace parts if distorted
⇑
Lap sealing faces. Replace parts if distorted
⇒⇓
⇑
⇓
⇑
Reposition or replace seal ring. Verify shroud housing and replace if necessary Lap sealing faces. Replace parts if distorted
⇓
⇑
Replace vane ring
⇓
⇑
⇓
⇑
Replace shroud segments to restore clearance. Send assembly to an authorized facility for blade replacement
Note: Hot section problems are all characterized by high ITT. N1 usually goes down or remains constant. If a flowmeter is installed the fuel flow will directly follow the ITT.
PT6T-3/-6
TRAINING USE ONLY
HOT SECTION 3.30
GEARBOXES
PT6T-3/-6
TRAINING USE ONLY
GEARBOXES
4.1
REDUCTION GEARBOX (RGB) Purpose: Reduce the power turbine speed to a speed suitable for helicopter operation. Construction: • • • • • • • • • •
Two stages gear reduction system with idler gear. Five magnesium-alloy casings. 25 main bearings (5 through 17). Externally splined output shaft. Provide a drive for the power turbine governors’ (N2). Provide a drive for the N2 tachometer generators. Provide a drive for the aircraft oil cooler blowers. Built in torque measurement system. Support 2 engine mounts. 3 out of 5 chip detectors installed on reduction gearbox.
Gears and Drive Pads Input shaft Idler gear Clutch gear Output shaft N2 Governor Drive Tacho-generator Drive Oil Cooler Blower Drive
PT6T-3/-6
Speed at 100% N2 (rpm) 33,000 22,338 16,499 6,600 4,219 4,219 9,269
References: Reduction ratio:................................. 5.0:1 Output shaft speed (Ns) at 100% : ... 6,600 rpm Rotation: ........................................... clockwise Nr (rotor) at 100% ............................. 324 rpm Aircraft transmission reduction ratio...... 20.4:1 Maintenance: Scheduled • Refer to Oil System and Indicating System Chapters. • Check Output shaft seal for oil leaks every 150 Hours or 1 year • Inspect clutch assemblies (Ref. Overhaul Manual) every 2500 Hours for PT6T-3BE/D/DE/DF/6B
Unscheduled • Replace the output shaft carbon seal and seal runner if found leaking or damaged. Maximum oil leakage is 0.2 cc/minute. • Replace rubber lip seals if found leaking. Maximum oil leakage is 3 cc/hour. • Replace torquemeter system seals when problem is suspected (Refer to indicating system). Direction of rotation (view from rear) CCW CW CCW CW CW Dry splines CCW Dry splines CW Wet splines, oil mist
TRAINING USE ONLY
GEARBOXES
4.2
REDUCTION GEARBOX CLUTCH GEAR OUTPUT SHAFT CLUTCH
2ND STAGE HELICAL GEAR
CLUTCH GEAR
TORQUEMETER VALVE
IDLER GEAR
2ND STAGE HELICAL GEAR
IDLER GEAR
BLOWER DRIVE IDLER GEAR N2 GOVERNOR DRIVE N2 TACH GENERATOR
BLOWER DRIVE
INPUT SHAFT
INPUT SHAFT
PT6T-3/-6
TRAINING USE ONLY
GEARBOXES
4.3
RGB CLUTCH ARRANGEMENT Purpose: To allow the power sections to drive the aircraft main transmission and prevent the main rotor from driving the engine. Without the clutch arrangement, the main rotor any time an auto-rotation is attempted would drive the engine. In addition, any seizure of the engine would prevent the possibility of auto-rotation. Description: The clutch arrangement used in the Twin-Pac® gearbox is the sprag clutch type. This clutch allows movement in only one direction.
A spring loaded cage assembly, towards the engaged position holds them in position. This engaged position places the sprags against both races at a slight angle. Rotation from the power section(s) on the clutch gear(s) jams the sprags between the outer and inner races and this interference fit drives the helical gearshaft attached to the output shaft. If the output shaft attempts to drive the engine, the sprags will be relieved and the output shaft will rotate without the engine. The same would happen in the event of malfunction of one power section. Only a difference in speed will cause the clutch to disengage. Maintenance:
Operation: No maintenance permitted at field level. The sprag assembly is made up of a number of sprags resembling the rollers in a roller bearing. The sprags, unlike the circular bearings, have a figure 8 shape. The vertical height of each of these sprags is slightly greater than the gap between the Inner diameter of the outer race (clutch gear) and the Outer diameter of the inner race (helical gearshaft).
PT6T-3/-6
TRAINING USE ONLY
GEARBOXES
4.4
REDUCTION GEARBOX CLUTCHES
FREEWHEEL GEARSHAFT
SPRAG CLUTCH ASSEMBLY
A FREEWHEEL GEARSHAFT (DRIVING)
FREEWHEEL GEARSHAFT (FREE)
SPRAGS
OUTPUT SHAFT (DRIVEN) SPRING
PT6T-3/-6
VIEW A CLUTCH ENGAGED TRAINING USE ONLY
OUTPUT SHAFT (OVERRUNNING)
CLUTCH DISENGAGED GEARBOXES
4.5
CLUTCH GEAR SEALING Purpose: Prevent oil transfer from reduction gearbox to power section oil system. Description: Compressor discharge P3 air for pressurization of clutch carbon seals is taken from a boss at the 7 o'clock position on the gas generator case. From there, P3 air is directed to the check valve, the P3 tee metering orifice and finally routed inside the reduction gearbox to the internal carbon seals. Check Valve (SB 5100): Used to prevent the flow of P3 air into the inoperative power section during single power section operation.
P3 Filter (Optional) (SB 5174/SB 5320): Operators flying in sand and dirty environment, based on their experience, may elect to install the optional P3 filter on the RGB. The filter protects the clutch gear/carbon seal from contamination. Maintenance: Scheduled • RGB P3 filter is removed (post SB 5174/5320), P3 line disconnected at elbow fitting or cap removed on Tee fitting (post SB 5423) for compressor wash to reduce possible corrosion at clutch gear location. • Clean RGB Tee metering orifice every 300 hrs. Unscheduled • In case of oil transfer, increase Tee fitting orifice size, on affected side to 0.043“ (drill No 57) (refer to Maintenance Manual, Troubleshooting section). Note: The use of "555" oils can cause Power Section/RGB oil transfer on pre SB 5414 engines.
Tee Fitting (Metering Orifice): The tee fittings have a calibrated orifice in order to restrict P3 air and send the proper airflow to the carbon seals. SYMPTOM PROBABLE CAUSE FIX Oil transfer from either Leak on P3 lines, Optional RGB filter blocked Check lines, check P3 filter if installed RGB or power section Partially blocked P3 line going to carbon Clean metering "T" orifices or increase orifice size seals to 0.043" using no. 57 drill on affected side only
Oil transfer from power section to RGB
PT6T-3/-6
Damaged carbon seals Torquemeter cover “V” seal
TRAINING USE ONLY
Send RGB to an Overhaul Facility Replace defective seals ("V" seals, Teflon seal and O-rings)
GEARBOXES
4.6
CLUTCH GEAR SEALING
CARBON SEALS CHECK VALVE
TEE FITTING N0. 2
P3 FILTER OPTIONAL
P3 POWER SECTION N0.2 P3 POWER SECTION N0.1
TEE FITTING N0. 1 TORQUE METER PISTON P.S. STATIC PRESSURE R.G.B. STATIC PRESSURE P3 PT6T-3/-6
CLUTCH GEAR
TRAINING USE ONLY
P3 FILTER OPTIONAL
CHECK VALVE
GEARBOXES
4.7
SEAL MAINTENANCE A
B
REMOVAL TOOL PWC 300646
RETAINING RING
REMOVAL TOOL PWC 30046-57
CARRIER
SEAL
PACKING
SEAL
PACKING
POSITION A
POSITION B PT6T-3/-6
CARRIER
TRAINING USE ONLY
GEARBOXES
4.8
RGB SEAL MAINTENANCE
PWC 50054 PWC 50055
PWC 30810
OUTPUT SHAFT CARBON SEAL
PT6T-3/-6
TRAINING USE ONLY
GEARBOXES
4.9
ACCESSORY GEARBOX
Maintenance:
Purpose:
Scheduled • Check Fuel Pump driveshaft coupling to accessory gearbox for wears every 600 hrs maximum interval. • Inspect chip detector (refer to Indicating) every 150 Hours.
Provide drive pads for the fuel pump/fuel control unit, starter generator, oil pressure and scavenge pumps and N1 tachometer generator. Drive the centrifugal breather impeller that separates air from oil in the accessory gearbox. Construction: • Two magnesium casings support the drive gears. • The casings are bolted to the inlet case. • The front casing (cover) separates and seals the accessory gearbox from the oil tank. • Provide support for the oil filler neck, oil level indicator oil pressure regulating valve assemblies, oil to fuel heater and chip detector.
Drive Pad Starter Generator Drive Fuel Pump Tacho-generator Drive
PT6T-3/-6
Lubrication Wet splines type by oil mist Wet splines type by oil mist Dry splines
Unscheduled • Inspect the chip detector for contamination. • Replace rubber lip seals (Starter, Fuel Pump and N1 Tacho-Generator) if found leaking. Maximum oil leakage is 3 cc/hour. • Breather carbon seal replacement. Maximum oil leakage is 5 cc/hour. • On Pre SB 5241 Engines Replacement of No.1 Bearing strainer, as per SB instructions. Note: A double lip seal is available for starter-generator drive (post SB 5264).
Speed at 100% N1 (rpm) 12,586
Direction of rotation (viewed from front of engine) CW
6,611
CCW
12,342
CW
TRAINING USE ONLY
GEARBOXES 4.10
ACCESSORY GEARBOX CENTRIFUGAL BREATHER
FUEL PUMP AND AFCU GEAR
CARBON SEAL
STARTER GENERATOR GEAR
N1 TACHO-GENERATOR GEAR IDLER GEAR STARTER GENERATOR DRIVE IDLER GEAR
IDLER GEAR
IDLER GEAR
PRESSURE PUMP
COUPLING SHAFT
SCAVENGE PUMPS
COUPLING SHAFT LUBRICATING OIL PUMPS
PT6T-3/-6
TRAINING USE ONLY
GEARBOXES 4.11
ACCESSORY GEARBOX LIP SEALS
PT6T-3/-6
TRAINING USE ONLY
GEARBOXES 4.12
ACCESSORY GEARBOX CARBON SEAL
PWC32810
PWC31062
CARBON SEAL CARRIER
PT6T-3/-6
TRAINING USE ONLY
GEARBOXES 4.13
NOTES
PT6T-3/-6
TRAINING USE ONLY
GEARBOXES 4.14
OIL SYSTEM
PT6T-3/-6
TRAINING USE ONLY
OIL SYSTEM
5.1
POWER SECTION OIL SYSTEM Purpose: Supply a flow of filtered oil to the power section in order to cool, lubricate and clean various components. Description: The power-section system lubricates bearings Nos. 1 to 8 and the accessory gearbox. The power section oil system consists of a pressure system, a scavenge system and a breather system. These provide a constant supply of clean oil to the engine bearings, reduction and accessory drives gears. The oil tank is an integral part of the accessory gearbox and incorporates a drain plug to facilitate oil drainage. The oil lubricates and cools the bearings and carries any extraneous matter to the oil filter where it is precluded from further circulation. Two chip detectors, one located in the accessory gearbox and the other in the reduction gearbox, detect ferrous metal particles and warn operators of metal contamination. References: Oil tank capacity: ...............................1.60 U.S. gal Normal oil pressure: ..........................80-115 Psi Minimum pressure: ............................40 Psi Oil Temperature Limits (Typical) Starting : ............................................- 54°C min. Take off : ...........................................0°C - 115°C Normal : .............................................74°C - 80°C
PT6T-3/-6
Servicing: • Use approved synthetic oil listed in SB 5001 • Check oil level within 30 minutes after shut down • Motor engine prior to oil level verification if engine has been shut down for more than 30 minutes • Replenish as required to bring oil level to a half quart below max. cold • Aircraft attitude may affect oil level sight glass readings. Avoid overfilling oil tank. • The basic recommended time between oil changes is 400 ± 50 hours or 12 months, whichever comes first. Caution: • Do not mix different brands or types of oil because their different chemical structures can make them incompatible. • When changing from an existing oil to a “third Generation” oil, P&WC strongly recommends that such a change should only be made on a new or freshly overhauled engine. Max Oil Consumption: 0.4 lb/hr per engine measured over a 10 hour period (4 lbs [2.0 U.S quart/liter approx]/10 hrs ), per engine (2 Power Sections and the RGB) Note: The use of "555" oils can cause Power Section/RGB oil transfer on pre SB 5414 engines.
TRAINING USE ONLY
OIL SYSTEM
5.2
OIL SYSTEM (OVERVIEW) SCAVENGE FROM NO.3 THROUGH 8 BEARINGS
PRESSURE SENSE LINE PRESSURE LINE TO PRESSURE OIL FOR PRV OIL-TO-FUEL HEATER FROM COOLER OPERATION CASTING PASSAGE TAKING OIL TO AGB BEARINGS
OIL PRESSURE ADJUSTMENT
CHIP DETECTOR
PRESSURE LINE TO NO.1 BEARING & AGB BEARINGS
SCAVENGE FROM NO.2 BEARING
UNDER SIDE VIEW
PRESSURE OIL TO COOLER
NO.1 P.S. OIL FILTER NO.2 P.S. OIL FILTER
PRESURE LINE TO OIL-TO-FUEL HEATER
PRESSURE OIL SCAVENGE FROM NO.3 THROUGH 8 BEARINGS
PRESSURE SENSE LINE FOR PRV OPERATION
FRONT VIEW PT6T-3/-6
SCAVENGE OIL FROM NO.2 BEARING
FILLER CAP
NO.1 P.S. OIL FROM COOLER NO.1 P.S. OIL TO COOLER
TRAINING USE ONLY
CHIP DETECTORS
REAR VIEW
NO.2 P.S. OIL TO COOLER
OIL SYSTEM
5.3
OIL SYSTEM Pressure System: The power section oil pump, located inside the accessory gearbox, takes the oil at the bottom of the integral oil tank. Oil from the pump holds open the check valve to allow oil flow through two external pressure lines. The oil is directed to the oil/fuel heater and to the airframe mounted oil cooler. The check valve cavity is opened to the pressure-regulating valve. The oil going to the oil/fuel heater is returned to the oil tank via the pressure-adjusting valve.
To provide a more accessible pressure adjustment, a valve is mounted at the top of the accessory gearbox. The valve consists of a variable orifice, which bleeds pressure oil from the fuel heater line into the oil tank. Scavenge System: The scavenge system consists of three gear type pumps and one ejector pump. Two pumps are located inside the accessory gearbox, one is mounted externally at the front of the accessory gearbox. The ejector pump is located inside the Nos. 3 and 4 support housing.
The oil returning from the cooler is sent to the oil filter then to various locations inside the engine.
Oil from the power turbine cavity (Nos. 3 and 4 bearings) is scavenged into the input section of the reduction gearbox by the ejector pump.
A check valve set at 40 Psi prevent oil to flow to the Nos. 3 and 4 bearing cavity during start and shut-down to prevent flooding of the bearing cavity.
Oil from the input section of the reduction gearbox is then scavenged through a screen mesh by a gear-type pump and returned to the oil tank.
A pressure-regulating valve (PRV) housed in the combined check and regulating valve assembly mounted on the bottom of the accessory gearbox, controls the oil pressure. When the sensing line pressure from oil system exceeds a pre-set value, the regulating valve is moved against spring pressure to open a port and allow excess pressure oil to flow back to the main oil tank. Oil flow to the engine is, therefore, limited to actual demand rather than full pressure pump capacity.
A gear-type pump into the accessory gearbox scavenges oil from No. 2 bearing cavity. Above 50% N1 rpm, the air pressure in No. 2 bearing cavity is sufficient to pressure scavenge the oil through the ball-type bypass valve.
PT6T-3/-6
No.1 bearing cavity is gravity drained into the accessory gearbox. Oil in the accessory gearbox is finally scavenged through a screen by a gear-type pump and returned to the oil tank.
TRAINING USE ONLY
OIL SYSTEM
5.4
POWER SECTION OIL SYSTEM PRESSURE PUMP SCAVENGE PUMPS
TORQUE SYSTEM COOLER
FINE OIL PRESSURE ADJUSTING VALVE
FUEL HEATER
BREATHER STRAINER NO.8
NO.7 NO.5
OIL FILTER
CHECK VALVE NO.4
NO.3
NO.1 NO.2
NO.6
EJECTOR PUMP
MAIN CHECK VALVE
OIL PRESS.
AIR PRESSURE OIL PRESSURE SCAVENGE OIL PT6T-3/-6
PRESSURE REGULATING VALVE
TRAINING USE ONLY
CHIP OIL T.
OIL P.
OIL SYSTEM
5.5
PRESSURE-ADJUSTING VALVE (POST SB 5077)
Maintenance:
Purpose: Provides accessible external fine oil pressure adjustment from the top of the accessory gearbox. Description:
• Oil pressure check is done at 90-91% N1. When oil temperature rise between 66 and 71°C, the observed pressure should be between 90-95 Psi. • It is recommended to check the accuracy of the indicating system prior to adjust the oil adjusting valve.
The valve located at the top of the accessory gearbox consists of a variable orifice, which bleeds oil from the oil-to-fuel heater line into the oil tank.
Notes: - Each spacer transferred from one side of the valve collar to the other side will change the oil pressure by 2 to 3 Psi.
The transfer of spacers (washers) on a valve to achieve required increase or decrease in oil pressure performs fine oil pressure adjustment.
- All four spacers must be kept in the valve at all times.
Operation: Maximum oil pressure is obtained with all four washers above the valve collar. Each washer transferred below the valve collar will reduce oil pressure by 2 to 3 Psi. If the proper oil pressure cannot be obtained, it will be necessary to adjust the pressure-regulating valve. It is then recommended to reposition the spacers in place (two at the top, two at the bottom) in order to keep further adjustment authority.
PT6T-3/-6
TRAINING USE ONLY
OIL SYSTEM
5.6
PRESSURE ADJUSTING VALVE COVER SPACERS VALVE SPACERS PACKING HOUSING ACCESSORY GEARBOX PACKINGS
PT6T-3/-6
TRAINING USE ONLY
OIL SYSTEM
5.7
PRESSURE REGULATING VALVE AND CHECK VALVE
Operation:
Check Valve Purpose: Prevent static oil flow from airframe oil cooler back to power section oil tank. Description: The Main check valve preset at 15 Psi is a spring loaded valve housed in the combined check valve and regulating valve assembly, mounted at the bottom right hand side of the accessory gearbox
Maintenance: Unscheduled • If necessary, after fine oil pressure adjustment : Install required number of spacers to change oil pressure.
Pressure Regulating Valve Purpose: Maintain oil pressure within specified limits (80 - 115 Psi) Description: The pressure-regulating valve is a spring-loaded valve housed in the combined check valve and regulating valve assembly, mounted at the bottom right hand side of the accessory gearbox.
PT6T-3/-6
Pressure oil from the pump holds open the check valve to allow oil flow through two external pressure lines, one via the cooler and the other to the oil/fuel heater. The check valve is also opened to the pressure-regulating valve. When the sensing line pressure from oil system reaches a pre-set value, the regulating valve is moved against spring tension to open a port and allow excess pressure oil to flow back to the oil tank. Oil flow to the system is, therefore, limited to actual demand rather than full pump capacity.
Notes: - One spacer change oil pressure by 3 to 4 Psi (add to rise, remove to lower the pressure). - Maximum number of spacers is : 12, but total thickness of all spacers must not exceed 0.400 inch.
TRAINING USE ONLY
OIL SYSTEM
5.8
PRESSURE REGULATING VALVE HOUSING
CHECK VALVE
TO TANK
SPRING VALVE HOUSING PACKINGS
SENSING LINE
REGULATING VALVE
PRESSURE REGULATING VALVE
SPACERS SPRING COVER
MAIN CHECK VALVE
FROM PUMP
PRV
TO ENGINE PT6T-3/-6
TRAINING USE ONLY
OIL SYSTEM
5.9
OIL FILTER AND BYPASS VALVE Purpose: Provide oil filtration for the power sections and the reduction gearbox.
Maintenance:
Oil filter:
Scheduled • Clean and inspect oil filter at 150 hours intervals (electrosonic cleaning) • Send filter to overhaul facility every 900 hours or 2 years, whichever occurs first (ultrasonic cleaning)
• 10 micron (µ) mesh size • Cleanable cartridge type filter element
Unscheduled • Inspect filter in case of chip detector indication.
Bypass Valve:
Notes: • If dents and/or broken wires are found, element must be replaced • If more than five percent of visible passages are found to be clogged, filter element must be sent to an authorized overhaul facility for ultrasonic cleaning and bubble point testing
Description:
The bypass valve opens in the event of oil filter partial restriction or blockage. The bypass valve is normally in the closed position (as shown) and is opened by a pressure drop across the filter of approx. 50 Psid. Controlled Leakage Orifice: A small-screened orifice on the inlet side of the filter allows venting of oil vapor into reduction gearbox or power section internal cavities.
PT6T-3/-6
Caution: To prevent internal contamination of the oil filter during cleaning, ensure filter outlet opening is plugged before submerging filter in the cleaning solution.
TRAINING USE ONLY
OIL SYSTEM 5.10
OIL FILTRATION AND BYPASS VALVE
OIL FROM COOLER TO BEARINGS
CONTROLLED LEAKAGE ORIFICE
FILTER HOUSING
FILTER ELEMENT
VALVE BYPASS TEFLON RING (POST SB 5350)
PT6T-3/-6
TRAINING USE ONLY
OIL SYSTEM 5.11
OIL FILTERS PACKING RETAINING RING
TEFLON RING PACKING
COVER OIL FILTER
PLUG ELECTROSONIC CLEANER TANK
PT6T-3/-6
TRAINING USE ONLY
OIL SYSTEM 5.12
OIL FILTER BYPASS VALVES
BYPASS VALVE SPRING PACKING PLUG
PT6T-3/-6
TRAINING USE ONLY
OIL SYSTEM 5.13
BEARING COMPARTMENT SEALING Purpose:
Symptoms of Labyrinth Seal Problems
Prevent oil from leaking outside the bearing cavities.
Oil consumption is a common symptom to all labyrinth seal problems
Description: Seal location −
Air pressure is used to prevent oil from leaking into areas where it is not required or where it would be detrimental to the engine operation. The air seal consists of two separate parts, one stationary and one rotating with the bearing; one of the two parts has machined grooves. A small clearance is maintained between the two parts and pressure air is allowed to flow between them to create the required sealing.
No. 1 bearing −
No. 2 bearing rear
−
No. 3 bearing − −
Maintenance:
PT6T-3/-6
−
−
The air used for the sealing is routed to the accessory gearbox by the oil scavenge system.
Labyrinth seals are maintenance free items. Premature wear would be an indication of severe unbalance or bearing distress, which would be evident to the crew. A malfunction of the oil system even though improbable, may cause flooding of certain bearing cavities and possible smoke at the exhaust or oil smell in the cabin.
No. 2 bearing front
Symptoms Oily inlet, compressor and Bleed valve. Oil smell and/or smoke in the cabin. Oil smell and/or smoke in the cabin. At HSI, coke oil around compressor turbine. Smoke through exhaust on start and shutdown. Oily exhaust. Coke oil around power turbine.
Contact a P&WC representative if you suspect any labyrinth seal problems.
TRAINING USE ONLY
OIL SYSTEM 5.14
BEARING COMPARTMENT SEALING
P3
NO.3 BEARING
P3 P2.5 NO.1 BEARING NO.2 BEARING PT6T-3/-6
TRAINING USE ONLY
OIL SYSTEM 5.15
OIL BREATHER Purpose: Separate oil particles from the air in the oil system before discharging overboard.
The relatively oil free breather air flows through the center of the impeller and out to the atmosphere via a cored passage in the accessory gearbox housing. The line is routed to the power section exhaust on the aircraft side.
AGB Breather Maintenance: Description: • Centrifugal impeller mounted on the starter generator gearshaft. • Starter/generator gearshaft rear end is sealed with a carbon face seal. Operation: Oil and air scavenged from the bearing cavities are directed to the accessory gearbox. The continuous flow of scavenged air and oil causes the accessory gearbox to pressurize. Prior to venting the air to the atmosphere, the air must be separated from the oil.
Unscheduled • Replacement of breather impeller carbon seal. RGB Breather Consist of a screen mesh located in a small housing at the upper part of the RGB rear housing. The breather is connected to the No 1 Power section exhaust
The pressure in the accessory gearbox forces the air/oil mixture inside the breather impeller. The centrifugal force imparted by the impeller causes the heavier oil particles to be ejected back into the accessory gearbox.
PT6T-3/-6
TRAINING USE ONLY
OIL SYSTEM 5.16
ACCESSORY GEARBOX BREATHER BREATHER OUTLET TO EXHAUST
FRONT
CARRIER
CARBON SEAL CENTRIFUGAL BREATHER
STARTER GENERATOR GEAR SHAFT
AIR AIR / OIL MIX OIL PT6T-3/-6
TRAINING USE ONLY
OIL SYSTEM 5.17
REDUCTION GEARBOX OIL SYSTEM Purpose: Supply a flow of filtered oil to the reduction gearbox in order to cool, lubricate and clean various components. Description: The reduction gearbox oil system consists of a pressure system and a breather system. These provide a constant supply of clean oil to the bearings. The oil tank is an integral part of the reduction gearbox. The oil lubricates and cools gears and bearings (Nos. 10 to 17) and carries any extraneous matter to the oil filter where it is precluded from further circulation. A chip detector is located in the reduction gearbox oil tank to detect metal particles and warn operators of metal contamination. References: Oil tank capacity: ................................. 1.25 U.S. gal Normal oil pressure: ............................ 60-80 Psi Minimum pressure: .............................. 40 Psi Oil temperature limits (typical) Starting : .............................................. - 54°C min. Take off : ............................................. 0°C - 115°C Normal : ............................................... 74°C - 80°C
Servicing: • Use approved synthetic oil listed in SB 5001. • Check oil level within 30 minutes after shut down. • Motor engine prior to oil level verification if engine has been shut down for more than 30 minutes. • Replenish as required to bring oil level to middle of the green band. • Aircraft attitude may affect oil level sight glass readings. Avoid overfilling oil tank. • The basic recommended time between oil changes is 400 ± 50 hours or 12 months, whichever comes first. Caution: • Do not mix different brands or types of oil because their different chemical structures can make them incompatible. • When changing from an existing oil to a “third Generation” oil, P&WC strongly recommends that such a change should only be made on a new or freshly overhauled engine. Max Oil Consumption: 0.4 lb/hr per engine measured over a 10 hour period (4 lbs [2.0 U.S quart/liter approx]/10 hrs), per engine (2 Power Sections and the RGB). Note: The use of "555" oils can cause Power Section/RGB oil transfer on pre SB 5414 engines.
PT6T-3/-6
TRAINING USE ONLY
OIL SYSTEM 5.18
RGB OIL SYSTEM (OVERVIEW) OIL PRESSURE TRANSDUCER PORT
FILLER CAP RGB OIL SYSTEM CAVITY
R.G.B. OIL FROM COOLER
PT6T-3/-6
R.G.B. OIL FILTER OIL TEMPERATURE PROBE PORT TRAINING USE ONLY
R.G.B. OIL TO COOLER R.G.B. OIL SYSTEM DRAIN (CHIP DETECTOR LOCATION)
OIL SYSTEM 5.19
RGB OIL SYSTEM Pressure Pump:
Impending Bypass Indication:
Gear type pump, driven by the RGB and protected by a screen at the inlet. Pressure Regulating Valve:
A impending bypass indicator (red button, airframe part) is installed on the left side of the reduction gearbox. The red button pop out if the pressure drop across the filter reaches 30 Psid
Maintain oil pressure within specified limits (60 - 80 Psi)
Maintenance:
Oil filter and Bypass Valve:
Scheduled • Refer to filter inspection and chip detector.
Refer to Power section (page 5.8) for details Operation: Pressure oil from the pump flow through the airframe cooler and then to the oil filter.
Unscheduled • Inspect filter in case of filter by-pass indication. • If there is by-pass indication at low operating temperature check by-pass indicator (aircraft part).
A pressure-regulating valve housed in the combined oil pump and regulating valve assembly mounted in the center of the reduction gearbox, controls the oil pressure. The pressure-regulating valve controls the main oil pressure by returning excess oil pressure back to the tank. After filtration and regulation, the oil lubricates Nos. 10 to 17 bearings using several nozzle jets.
PT6T-3/-6
TRAINING USE ONLY
OIL SYSTEM 5.20
RGB OIL SYSTEM OIL T
10
15
T
5 0
-5
OIL C
10
PSI
X10
8
P2
6 4
OIL PRESSURE PUMP
OIL P.
OIL PUMP HOUSING
0
OVERBOARD BREATHER
PRESSURE REGULATING VALVE
STRAINER SPACER CHIP DETECTOR CHIP
BYPASS VALVE
SPRING
OIL FILTER
IMPENDING BYPASS INDICATOR
HOUSING
SPACERS
C BOX OIL P. A/F COOLER
PT6T-3/-6
PACKING
VALVE
RETAINING RING
TRAINING USE ONLY
OIL SYSTEM 5.21
PRESSURE REGULATING VALVE Purpose:
Maintenance:
Maintain oil pressure within specified limits (60 - 80 Psi)
• Oil pressure check is done at 97-100% N2 when oil temperature rise between 66°C and 71°C the observed pressure should be between 65-75 Psi. • Install required number of spacers to change oil pressure adjustment • It is recommended to check the accuracy of the indicating system prior to adjust the oil pressureadjusting valve.
Description: The pressure-regulating valve is a spring-loaded valve housed inside the oil manifold, inside the RGB housing. Operation: Oil under pressure from the filter reaches a pre-set value, the regulating valve is moved against spring tension to open a port and allow excess pressure oil to flow back to the casing. Oil flow to the system is, then limited to actual demand rather than full pump capacity.
Notes: • One spacer change oil pressure by 2 to 3 Psi (add to rise, remove to lower the pressure). • •
Maximum number of spacers is : 4. Minimum number of spacer is : 1.
Caution: • Care must be exercised during disassembly of valve to prevent components from falling into RGB. • The removal of spacers to rectify an increase in oil pressure is not recommended, an increase in oil pressure of an in service RGB may be due to restriction in oil passages. If oil pressure remains high after fault isolation the RGB must be removed and sent to an overhaul facility for repair.
PT6T-3/-6
TRAINING USE ONLY
OIL SYSTEM 5.22
RGB PRESSURE REGULATING VALVE
SPACER VALVE SPRING SPACERS PACKING HOUSING REMOVAL TOOL PWC 30871
PT6T-3/-6
TRAINING USE ONLY
RETAINING RING
OIL SYSTEM 5.23
OIL SYSTEM TROUBLESHOOTING SYMPTOMS RGB Oil pressure is high
Power Section Oil pressure is high
Oil pressure is low on Power section or RGB
Oil pressure fluctuation on Power section or RGB High oil level
High oil temperature
High oil consumption On Power section or RGB
PROBABLE CAUSE Indicating system ---------------------------- > Pressure Regulating Valve ---------------- > Restriction of internal oil passages------ >
Indicating system ---------------------------- > Pressure Regulating/Adjusting Valve --- > Oil level too low ------------------------------ > Indicating system ---------------------------- > Oil filter restriction --------------------------- > Oil leaks---------------------------------------- > Pressure Regulating/Adjusting Valve --- > Oil level ---------------------------------------- > Indicating system ---------------------------- > Oil filter ----------------------------------------- > Pressure regulating valve------------------ > Fuel Heater ----------------------------------- > Oil level too low ------------------------------ > Indicating system ---------------------------- > Airframe oil cooler --------------------------- > Oil level ---------------------------------------- > Fuel heater (P.S only) ---------------------- > Breather Carbon seal (P.S only) --------- > Labyrinth seals (P.S only) ----------------- >
Silver flakes in oil filter
Bearing cage or bearing race plating
Oil leaks Oil Transfer problems
AGB Breather tube Refer to Gearbox Chapter
PT6T-3/-6
TRAINING USE ONLY
FIX Check indicating system. Valve installed backwards. The removal of spacers to rectify an increase in oil pressure of an in service Power Section is not recommended. Return RGB for repair. Check indicating system. Adjusting Spacers not seated (PRV) Check operation of PRV Check level Check indicating system Clean or replace filter Examine engine for leaks Adjust or replace after inspection. Insufficient or excess quantity of oil Check indicating system Clean & inspect - replace as required Clean & check operation Fuel Heater internal leak when Power Section not running and fuel boost pressure is “ON”. Check level Check indicating system Verify/replace Possible over-servicing. Check for internal leaks (P.S only). Fuel Heater internal leak when Power Section is running If excessive amount of oil is discharged, seal may be damaged. Replace carbon seal. Examine exhaust stacks & compressor for traces of oil, if found, contact P&WC representative Flush oil system. Inspect oil filter after 5, 10, 25 and 50 flight hours. Contact P&WC if silver particles are still evident after 50 flight hours. Check for blocked/restricted AGB Breather tube
OIL SYSTEM 5.24
ENGINE INDICATING SYSTEM
PT6T-3/-6
TRAINING USE ONLY
ENGINE INDICATING SYSTEM
6.1
ENGINE INDICATING SYSTEM Purpose:
Opposite page shows typical airframe indicating systems:
Provide the pilot with indications concerning the engine parameters during flight.
• • • • •
Provide the required data for engine performance check and for condition trend monitoring. Description: Different systems are designed into the engine to transmit signals such as : • • • • • •
Torque Interturbine temperature (ITT) Compressor rotor speed (N1) Power turbine speed (N2) Oil pressure and temperature Metal particles (Chip) detection
Compressor rotor speed (N1) Oil pressure and temperature ITT Power turbine speed (N2) Torque
The following are the built in indicating system provided with the engine : • • • •
Inter turbine temperature system (ITT) Exhaust gas temperature system (EGT) (T6 only) Torque indication system Chip detector
All these signals are sent electrically to the instrument panel in the cockpit.
PT6T-3/-6
TRAINING USE ONLY
ENGINE INDICATING SYSTEM
6.2
ENGINE INDICATING SYSTEM
3 4
8
7
6
PT6T-3/-6
5
10
15
T
5 0
-5
OIL C
10
PSI
X10
8
P2
0
6 4
ITT 3
8 C X 100
7
4 5 6
120 110 100
0 10
ROTOR
20 30
90 80
PERCENT RPM
70 60
TRAINING USE ONLY
40 50
8
9
7 6 5
10
11
10
TORQUE MAST
4
3
9
1
CAUTION PANEL 8 7 6 5 4
ENG
% X 10
2
CAUTION PANEL
1
10 9
2
ENG
9 10
TORQUE
M
6 5 4
0
1 2 X 10 3 %RPM
N2
R
9 0 1
ITT
OE I
8 7
OIL TEMPERATURE & PRESSURE
2
N1
1
2
3
ENGINE INDICATING SYSTEM
6.3
INTERTURBINE TEMPERATURE SYSTEM (ITT) Purpose : Provide the pilot with an indication of the temperature of the engine gases between the compressor turbine and the power turbine (station 5). Components : • • • •
Integral ITT harness (8 thermocouple probes) Trim compensator Detachable terminal block Electrical wiring harness
Operation : As temperature increases, an increasing voltage is generated at the chromel/alumel junction of each thermocouple. The signal is sent to the trim compensator where it is corrected and then transmitted to the cockpit gauge. Notes Always clean connectors carefully to ensure the system's resistance is not disturbed. It is possible to repair the terminal block if the ceramic insulation is cracked.
PT6T-3/-6
Troubleshooting : The ITT system can be tested and calibrated with the Barfield tester (TT1000 or TT1200) or using any similar equipment. Loop resistance : • Disconnect all leads from the detachable terminal block on the generator case or at the terminal block. • Measure loop resistance of the harness between alumel and chromel terminals. • Refer to Engine Maintenance Manual for resistance limits 1.8 to 2.6 Ω (Ohms). Insulation resistance : • Connect test set to alumel or chromel terminal and ground (exhaust case etc.) • Measure insulation resistance • 5,000 Ω (Ohms) minimum acceptable resistance required. Heat response (if there is access to the probes) : • Connect test set to alumel and chromel posts on terminal block. • Apply heat to each thermocouple tip and verify for a positive temperature indication. Note A heat source such as a heat gun, a soldering iron, capable of heating individual probes to 94°C (200°F) but not exceeding 540°C (1,000°F) may be used.
TRAINING USE ONLY
ENGINE INDICATING SYSTEM
6.4
TEMPERATURE INDICATING SYSTEM (ITT) DETACHABLE TERMINAL BLOCK (POST SB 5235) TERMINAL BLOCK
PROBE RETAINING NUT
PROBE ASSEMBLY
CHROMEL
INTEGRAL HARNESS
ALUMEL PT6T-3/-6
JUNCTION BOX TRAINING USE ONLY
ENGINE INDICATING SYSTEM
6.5
TEMPERATURE SYSTEM CALIBRATION (ITT TRIM)
To verify and adjust the indication in order to get a true representation of the engine temperature (Correct for sampling error).
The amount of trimming provided by the trim compensator, is a function of the trim compensator internal resistance. The resistance is set at engine test to generate the calculated temperature trim. The trim value (in °C) is indicated on the power section trim data-plate.
Operation:
Adjustment:
Uneven heat distribution within the gas path causes individual thermocouple to see different temperatures and generate different voltages.
The ITT trim compensator can be adjusted using a Barfield tester (TT1000, TT1200 or similar), to simulate operating conditions (adjust tester to obtain reading of 600°C/750°C on cockpit gage). Adjustment with the engine running is possible but it will be less accurate and should be limited for a functional check.
Purpose:
To obtain an average reading, the thermocouples are connected in parallel. The Indicated ITT is the average temperature of 8 specific locations (thermocouple tips) within the gas path and therefore does not represents the exact average temperature at station 5. The actual temperature is calculated at engine test and is used to determine engine acceptance. The adjustable trim compensator, installed on the reduction gearbox, reflects how much correction is applied to the (untrimmed) indication in order to send a valid engine temperature to the cockpit. 0 70 600 -70 670 °C 32
158
PT6T-3/-6
1112
-126
1238
°F
The ITT indication should go up by the value indicated on the power section trim data-plate as the power supply is removed from the trim compensator box. Maintenance: Scheduled • Functional check every 1200 hours. Unscheduled • If the trim compensator is found defective, replace the unit and adjust the new compensator to the trim value indicated on the power section trim data-plate.
TRAINING USE ONLY
ENGINE INDICATING SYSTEM
6.6
ITT SYSTEM CALIBRATION POWER TURBINE STATOR HOUSING
TRIM COMPENSATOR
9 10 OEI
ITT 3
8
POWER SUPPLY LEAD
C X 100
7
4 5 6
4 5 6 7 8 3 2 0 0 0 0 9 01 1 0 10 00 0 0 1 0 0
ADJUSTER 9 10 OEI
ITT 3
8 C X 100
7
4 5 6
DETACHABLE TERMINAL BLOCK
TRIM COMPENSATOR
TERMINAL BLOCK
PROTECTIVE CAP
28V INPUT LEAD
TRIM DATA PLATE PERFORMANCE REFERENCE DATA
NG
THERMOCOUPLES ITT TRIM PT6T-3/-6
TRAINING USE ONLY
126
SHP
AT F
70
C
ENGINE INDICATING SYSTEM
6.7
EXHAUST GAS TEMPERATURE SYSTEM (PT6T-6/6B ONLY) Purpose: Provide the pilot with an indication of the temperature of the engine gases in the exhaust (station 7). Components: • • • •
T7 harness 4 thermocouple T1 resistance sensor Trim compensator Electrical wiring harness
Operation: As exhaust gas temperature increases, an increasing voltage (T7 signal) is generated at the chromel/alumel junction of each thermocouple. The T7 signal is sent to the trim compensator where it is corrected by the T1 sensor as a function of the inlet temperature. The signal is then transmitted to the cockpit gauge through the wiring harness. Note: Always clean connectors carefully to ensure the system's resistance is not disturbed
PT6T-3/-6
Troubleshooting: The ITT system can be tested and calibrated with the Barfield tester (TT1000 or TT1200) or using any similar equipment. Loop Resistance: • Disconnect all leads from the probes. • Measure loop resistance of the probes between alumel and chromel terminals. • Refer to Engine Maintenance Manual for complete details and resistance limits Insulation Resistance: • Connect test set to alumel or chromel terminal and ground (exhaust case etc.) • Measure insulation resistance • 5,000 Ω (Ohms) minimum acceptable resistance required. Heat Response: • Connect test set to alumel and chromel posts on the probe. • Apply heat to the thermocouple tip and verify for a positive temperature indication. • Repeat for all probes Note: A heat source such as a heat gun, a soldering iron, capable of heating individual probes to 94°C (200°F) but not exceeding 540°C (1,000°F) may be used.
TRAINING USE ONLY
ENGINE INDICATING SYSTEM
6.8
EGT SYSTEM THERMOCOUPLE PROBE
POWER INPUT
EXHAUST GAS TEMPERATURE COMPENSATOR
PT6T-3/-6
TEMPERATURE OUTPUT TO INDICATOR
T1 SENSOR
T7 INPUT T1 INPUT
TRAINING USE ONLY
AIR INTAKE T1 SENSOR
ENGINE INDICATING SYSTEM
6.9
EXHAUST GAS TEMPERATURE SYSTEM CALIBRATION Purpose: To verify and adjust the indication in order to get a true representation of the engine temperature. (Correct for sampling error)
The amount of trimming provided by the trim compensator, is a function of the trim compensator internal resistance. The resistance is set at engine test to generate the required temperature trim. The trim value in °C is indicated on the power section trim data-plate.
Operation:
Adjustment:
Uneven heat distribution within the gas path causes individual thermocouple to see different temperatures and generate different voltages.
The EGT trim compensator can be adjusted using a Barfield tester (TT1000 or similar), to simulate operating conditions. Adjustment with the engine running will be possible but it will be less accurate and should be limited for a functional check.
To obtain an average reading (T7), the thermocouples are connected in parallel. T7 is the average temperature of 4 specific locations (thermocouple tips) within the gas path and therefore does not represents the exact average temperature at station 7. The actual temperature is calculated at engine test and is used to determine engine acceptance. The adjustable trim compensator mounted on the reduction gearbox reflects how much correction is applied to the (untrimmed) indication in order to send a valid engine temperature to the cockpit.
Use the EGT compensator chart and the value on the trim data plate to find how much the delta EGT should be as a function of OAT. Check that the EGT indication raise by the amount found per the chart when the power supply is removed from the EGT compensator box. Maintenance: Scheduled • Functional check. Unscheduled • If the trim compensator is found defective, replace the unit and adjust the new compensator to the trim value indicated on the power section trim data-plate
PT6T-3/-6
TRAINING USE ONLY
ENGINE INDICATING SYSTEM 6.10
EGT SYSTEM CALIBRATION
o
110
120
100
110
90
100
80
90
70
80
60
70
50
60
40
50 C 40
B
30 20
30 20
o
DAY TRIM FROM POWER SECTION LOG BOOK - C
REQUIRED TRIM SETTING AT EXISTING AMBIENT del EGT - C
130
A ENTER GRAPH AT ENGINE SCREEN INLET TEMPERATURE * B FROM POWER SECTION LOG BOOK OBTAIN STANDARD DAY TRIM VALUE AND SELECT APPROPRIATE CURVE C FROM INTERSECTION OF T1 TEMPERATURE ORDINATE AND CURVE SELECTED AT B READ TO LEFT OF GRAPH TO DETERMINE del EGT REQUIRED AT PREVAILING CONDITIONS
EGT ADJUSTMENT SCREW
10 0
-40 -30 -20 -10
0 A 10
20
30
40
50
o
C
ENGINE SCREEN INLET TEMPERATURE T1 - C o
PT6T-3/-6
TRAINING USE ONLY
TRIM COMPUTER BOX ENGINE INDICATING SYSTEM 6.11
TORQUE SYSTEM Purpose: Provide an indication of the torque applied to the output shaft.
The axial movement of the gearshaft stops when metered oil pressure in the torquemeter chamber exactly balances the axial force of the helical gear.
Description: The torque system comprising :
The oil pressure and the mechanical force of the gearshaft will remain equals and opposite in all conditions, and will be directly related to the torque produced by the power section.
• • • •
is
an
hydro-mechanical
unit
Helical gearshaft Piston Cylinder Torquemeter oil control valve and sleeve
A constant bleed of the torquemeter chamber will prevent hydraulic lock in the cavity.
Operation: Torque applied to the reduction gearbox output shaft induces a axial movement of the 2nd stage helical gearshaft. This movement is due to the angular force applied from the output shaft (helical gear) to the 2nd stage helical gear. The axial force of the 2nd stage gearshaft will be proportional to the torque delivered by the power section. The piston and the control valve located at the opposite end of the gearshaft are moving by the same amount of travel, as torque increase. Moving the control valve into the sleeve opens the orifice and allows more oil pressure in the chamber, to push on the piston, opposite to the gearshaft axial force.
PT6T-3/-6
The pressure of the torquemeter chamber is directed to the torque transducer and to the torque control unit (TCU) by external lines. Static air pressure inside the RGB acts on the opposite side of the torquemeter piston and would cause erroneous (higher) torque reading. For this reason, static pressure is applied to the transducer to compensate for internal RGB pressure. Maintenance: Unscheduled • Replacement of torquemeter piston seals • Replacement of torquemeter valve sleeve packing • Calibrate transducer as per Airframe Maintenance Manual instructions.
TRAINING USE ONLY
ENGINE INDICATING SYSTEM 6.12
TORQUE SYSTEM TO T.C.U.
NO.2 TRANSDUCER
LOW POWER 8
9
7 6 5
10
11
10
TORQUE
7
% X 10
2
1
6 5 4
ENG 2
3
8
1
M
MAST
4
9
1
2
P.S. 2 OIL PRESSURE
3
RGB STATIC PRESSURE NO.1 TRANSDUCER TO T.C.U.
P.S. OIL PRESSURE NO.1 TORQUE PRESSURE NO.2 TORQUE PRESSURE RGB STATIC PRESSURE P.S. 1 OIL P.S. STATIC PRESSURE PRESSURE
PT6T-3/-6
HIGH POWER
TRAINING USE ONLY
ENGINE INDICATING SYSTEM 6.13
TORQUE TRANSDUCER CALIBRATION Purpose:
Calibration:
Provide a means that allows correction of the torquemeter signal sent by the airframe mounted torque transducers to the aircraft indicators.
Both torquemeters (Left-hand side and Right-hand side) in the reduction gearbox are individually calibrated at engine test. Correction factors, (Span, Zero, index numbers, Valves positions and alpha angle) are established for each side and the values are stamped on the RGB trim data-plate. When the RGB or the engine is installed on an aircraft, the airframe supplied torque pressure transducer must be adjusted, using the appropriate torquemeter correction factors.
Operation: At the power section maximum output torque of 738 ft.lb, the equivalent nominal torquemeter chamber oil pressure is 53.5 Psi. Due to manufacturing tolerances, a particular torquemeter will usually vary from this nominal pressure, either more or less. If this discrepancy is not compensated for, then there will be some error in the indicated torque. The torquemeter index represents a correction on either side of this nominal value such that, for any Twin-Pac installation, at the same given power, the engine torque will be exactly the same on the cockpit instrument. The correction factors (Index, Span, Zero, Valve positions alpha angle) are required to perform the correction of the various transducer models found on the PT6T’s.
PT6T-3/-6
This procedure is described in the aircraft maintenance manual. This ensures that the airframe cockpit indicator reading is always representative of actual engine power. Any error in the torque transducer calibration will affect the engine and / or the aircraft performance. Both N1 and ITT margins will be affected and will react in the same direction. Guidelines: Torque indicated 1% too high 1% too low
TRAINING USE ONLY
N1 change - 0.3% ⇓ + 0.3% ⇑
ITT change - 6°C ⇓ + 6°C ⇑
ENGINE INDICATING SYSTEM 6.14
TORQUEMETER INDEXING
PRATT & WHITNEY CANADA R LONGUEUIL, QUEBEC, CANADA
Twin-Pac
R
ASSY NO. MODEL SERIAL NO. TAKE-OFF SHP DOT TYPE APPROVAL FAA TYPE CERTIFICATE
L.H. TM INDEX 4.5 L.H. ZERO NEG 5.1 L.H. SPAN POS 9.2
GEARBOX 3024780 PT6T 3/3B/6 CP-GB 2597 1875 SHP E 10 E22 E A R.H. TM INDEX 6.4 R.H. ZERO NEG 4.0 R.H. SPAN POS 4.9
SPAN FACTOR CORRECTION
TORQUE
738 Lb. Ft
SPECIFICATIONS
R REGISTERED TRADEMARKS
ACTUAL VALUES
TORQUE TRANSDUCER SETTINGS B.H.T. PN 412-075-205 L.H. VALVES L.H. C
PT6T-3/-6
ABD 87.7
R.H. VALVES R.H. C
D 84.1
- 0 + ZERO FACTOR CORRECTION
TRAINING USE ONLY
50 51 52 53 54 55 56 0 2 4 6 8
PSI
INDEX
ENGINE INDICATING SYSTEM 6.15
TORQUE TRANSMITTER (OLD) INDEX NUMBER
INDEX NUMBER 3
3
ELECTRICAL CONNECTOR
6 5 4
D
A
C
B
5
1
7
ELECTRICAL CONNECTOR
9
VENT
0 1 2
7
9 7
D
A
C
B
RGB STATIC AIR PRESSURE
TRANSMITTER, PRESSURE,TORQUE 26V 400HZ TSO C47
OLD BELL 212
RGB STATIC AIR PRESSURE
ZERO ADJ SCREW
ELECTRICAL CONNECTOR
PRATT & WHITNEY CANADA R LONGUEUIL, QUEBEC, CANADA
Twin-Pac
R
ASSY NO. MODEL SERIAL NO. TAKE-OFF SHP DOT TYPE APPROVAL FAA TYPE CERTIFICATE
L.H. TM INDEX 4.5 L.H. ZERO NEG 5.1 L.H. SPAN POS 9.2
GEARBOX
RGB STATIC AIR PRESSURE
3024780 PT6T 3/3B/6 CP-GB 2597 1875 SHP E 10 E22 E A R.H. TM INDEX 6.4 R.H. ZERO NEG 4.0 R.H. SPAN POS 4.9
VALVE IDENTIFICATION PLACARD
R REGISTERED TRADEMARKS
L.H. C
PT6T-3/-6
ABD 87.7
R.H. VALVES R.H. C
INPUT/OUTPUT ADJ VALVE A
TORQUE TRANSDUCER SETTINGS B.H.T. PN 412-075-205 L.H. VALVES
D
VALVES WITH COVER REMOVED
84.1
TRAINING USE ONLY
ON
OFF
B
C
D
VALVES AB AND D ARE ON. VALVE C IS OFF.
ENGINE INDICATING SYSTEM 6.16
TORQUE TRANSDUCER (412HP, 412EP) PRATT & WHITNEY CANADA
ELECTRICAL CONNECTOR
R LONGUEUIL, QUEBEC, CANADA
Twin-Pac
R
ASSY NO. MODEL SERIAL NO. TAKE-OFF SHP DOT TYPE APPROVAL FAA TYPE CERTIFICATE
L.H. TM INDEX 4.5 L.H. ZERO NEG 5.1 L.H. SPAN POS 9.2
GEARBOX 3024780 PT6T 3/3B/6 CP-GB 2597 1875 SHP E 10 E22 E A R.H. TM INDEX 6.4 R.H. ZERO NEG 4.0 R.H. SPAN POS 4.9
ZERO ADJUSTMENT
SLOPE ADJUSTMENT
R REGISTERED TRADEMARKS
NIL A B AB D AD BD ABD BCD ALL
7 8 9
84.1
TRANSDUCER SLOPE SWITCH SETTING 1 2 3 4 5 6 7 8 9 10
3
GEARBOX DATA PLATE SLOPE
R.H. C
1
10
D
6
87.7
R.H. VALVES
5
L.H. C
ABD
2
L.H. VALVES
4
TORQUE TRANSDUCER SETTINGS B.H.T. PN 412-075-205
RGB STATIC AIR PRESSURE
TRANSDUCER SETTING CHART PT6T-3/-6
TRAINING USE ONLY
ENGINE INDICATING SYSTEM 6.17
Calibration:
TORQUEMETER CALIBRATION (OPTIONAL KIT) Customers willing to replace the current configuration may install the optional kit. The Torque Transmitting kit consist of : • • • •
One transducer per side One Torque signal converter per side One Interface cable per side Installation hardware
aircraft
The Torque system needs to be calibrated using a specific procedure for good accuracy of the torque indicating. The adjustment of the system is done at the converter instead of on the transducer, using a dead weight tester to pressurise the transducer. The slope adjustment is made first (in reference with the valve position from the reduction gearbox trim setting values) similar to the regular transducer procedure. The zero adjustment is completed using the alpha angle from the data plate and a conversion factor (this factor is function of the indicator/helicopter model). The dead weight is pressurise at 35.4 Psi, and the zero adjustment screw is used to match the indication in the torque gauge with the target value from the Bell Maintenance manual chart or calculated as follows : Note: 212 Indicator 212-070-160....................... Alpha / 1.842 412 Indicator 412-075-008-101 ............... Alpha / 1.928 412 Indicator 412-075-008-111/113 ........ Alpha / 2.003 Same as stated in the Bell Maintenance Manual Example for Bell 212 LH Alpha : 87.7 / 1.842 = 47.6 % should be indicated on the No1 engine torque indicator.
PT6T-3/-6
TRAINING USE ONLY
ENGINE INDICATING SYSTEM 6.18
NOTES
PT6T-3/-6
TRAINING USE ONLY
ENGINE INDICATING SYSTEM 6.19
CHIP DETECTOR Purpose: Indicate the presence of metal particles in the oil system Construction: • 5 chip detectors (AGB and RGB). • Normally open circuit. • 2 strainers (reduction gearbox input section). • Wired to lights in the cockpit. • Built in self-closing valve allows removal without having to drain oil. Operation: If enough ferrous material is collected to bridge the gap between the magnets of the chip detector, an electrical ground is provided and a relay will be activated. •
•
If either the front or rear PS chip detector is shorted by particles the related (No 1 or No 2) PS Caution light (Amber : ENGINE CHIP) will illuminate in the cockpit. If the RGB chip detector is shorted by particles the RGB Warning light (Red : C’BOX CHIP) will illuminate in the cockpit.
Maintenance: Scheduled • Check chip detector for continuity and weight lift (6 oz or 170 grams) every 150 hours • Pre SB 5097 Check paint strip at connector junction with chip detector body, every 150 hours Unscheduled • Check for metal pickup. • Whenever a chip detector light illuminates, the appropriate oil filters must also be checked. • At each oil change; if ferrous metallic pick-up is found on either one of the two reduction gearbox input section chip detectors, the strainer(s) must also be removed and cleaned accordingly. Note: All PT6T-3D’s and all other PT6T post SB 5354 do have bayonet type (quick disconnect) chip detectors with a built-in test feature (30KΩ resistor).
There is no Fuzz burning function, but a optional kit is available.
PT6T-3/-6
TRAINING USE ONLY
ENGINE INDICATING SYSTEM 6.20
CHIP DETECTOR
SPRING OIL
VALVE MAGNETIC POLES PREFORMED PACKING INSULATION VALVE HOUSING
ELECTRICAL CONNECTOR POST SB 5322
30 KΩ PAINT STRIP (PRE SB 5097) WIRING PT6T-3D's AND POST SB 5354 PT6T-3/-6
PRE SB 5097 TRAINING USE ONLY
ENGINE INDICATING SYSTEM 6.21
INDICATING SYSTEM TROUBLESHOOTING SYMPTOMS Torque indication dropping (with no drop of other engine parameters) Torque indication high at idle power (N1 and ITT at idle values)
Fluctuating torque indication (with no fluctuation of other engine parameters)
PROBABLE CAUSE Indicating system ------------------------ > Piston seals worn out------------------- > Indicating system ----------------------- > Torque Meter Chamber blocked bleed orifice (Pre SB5125, PT6T-3) -------- > Damage O-rings on Torque Meter control valve sleeve--------------------- > Air in torque oil pressure line --------- > Torque pressure transducer ---------- >
FIX Check system Replace Teflon and "V" seals on piston Check system Check/clean Replace seals Bleed air Check transducer calibration or replace Check appropriate filter and run power section or RGB for ten minutes. If no significant pick-up is found power section or RGB is acceptable. Check appropriate filter. Change oil, run power section or RGB for ten minutes. If no significant pick-up is found power section or RGB is acceptable.
Chip detector light "ON" power section or RGB
Fuzz or fine slivers ---------------------- >
Chip detector light "ON" during the ten minute run or within next 10 operating hours
Fuzz or fine slivers ---------------------- >
If significant or excessive metallic pickup is found on :
RGB centre system --------------------- >
Replace RGB
AGB on power section ----------------- >
Replace power section and RGB
RGB on input section side ------------ >
Replace RGB, flush and check power section No. 3 and 4 bearing area for smooth running Note: When torque meter "V" seals start to leak, the first sign you see on the engine is an oil transfer from the Power section to the RGB. Note: In case of oil contamination it is recommended to replace the oil cooler, flush the oil circuit at the same time the module is replaced.
PT6T-3/-6
TRAINING USE ONLY
ENGINE INDICATING SYSTEM 6.22
INDICATING SYSTEM TROUBLESHOOTING SYMPTOMS High ITT or EGT
Low ITT or EGT
Erratic ITT or EGT indication
Unusual torque split
PT6T-3/-6
PROBABLE CAUSE Trim box malfunction ------------------- >
FIX Test and replace as required
No electric power to trim box --------- >
Check for power at connector
Gauge lead, ITT or EGT lead ------- >
Check for corrosion on connection
Several thermocouples burned ----- >
Replace thermocouple and/or harness
Trim box setting-------------------------- >
Verify trim box setting
Loose terminals -------------------------- >
Tighten
Chaffed harness ------------------------- >
Fix or replace harness
Grounded lead --------------------------- >
Check ceramic insulator
Fuel heater
Check fuel filter bowl for comfortable temperature at shutdown. If filter bowl is hot check fuel heater.
TRAINING USE ONLY
ENGINE INDICATING SYSTEM 6.23
NOTES
PT6T-3/-6
TRAINING USE ONLY
ENGINE INDICATING SYSTEM 6.24
IGNITION SYSTEM
PT6T-3/-6
FOR TRAINING USE
IGNITION SYSTEM
7.1
IGNITION SYSTEM Ignition Cables Two cables carry the electrical energy from the exciter box to the igniters. Each cable consists of an insulated electrical lead contained in a flexible metal braiding.
Purpose: Provide the spark to ignite the fuel/air mixture. Description: The spark ignition system consists of an airframe mounted ignition exciter, two high-tension cables and two spark igniters. The system is energized only during engine start up and operates between 9-30 VDC range. Exciter Box The airframe mounted sealed unit, which transfers a low DC voltage input into a high output voltage. When the unit is energized, a capacitor is progressively charged until the energy stored is sufficient to ionize a spark gap, then the capacitor discharges through the igniter plugs. References: Input voltage : ............................................ 9-30 VDC Input current : ............................................... 3.5 Amp Spark rate 10 VDC : ................................ 1 spark/sec 30 VDC : ................................. 4 spark/sec Output voltage : ....................................... 8,000 Volts Stored energy : .......................................... 4.7 Joules
PT6T-3/-6
Spark Igniters Located at 4 and 11 o'clock positions on the gas generator case, the spark igniters are in the form of threaded plugs with a central electrode enclosed in an annular semi-conducting material. At high voltage level, the air between the central electrode and the plug outer shell ionizes and allow a high-energy spark to discharge from the center electrode. Caution: • Should an igniter plug be dropped, internal damage not detectable by test can occur. Recommendation is to replace the spark igniter plug. • Under no circumstance lubricant containing grease, silicone or such as petrolatum, can be used on any ignition component. • Do not allow any lubricant to come in contact with central conductors of cables, or exciter connectors. Contact with conductors may result in high resistance path, which could generate heat and oxidation.
FOR TRAINING USE
IGNITION SYSTEM
7.2
IGNITION SYSTEM
SPARK IGNITER
POWER TURBINE STATOR HOUSING
COMBUSTION CHAMBER SPARK IGNITER
GAS GENERATOR CASE SPARK IGNITER
INPUT POWER RECEPTACLE IGNITION EXCITER
IGNITION LEADS PT6T-3/-6
FOR TRAINING USE
IGNITION SYSTEM
7.3
IGNITION SYSTEM Maintenance: Scheduled • Inspect Spark Igniters for wear and erosion every 300 hours. • Carry out functional test by disconnecting one ignition cable at the exciter box, switch ignition “ON” and listen for the sparking noise every 300 hours. • Inspect cables for chaffing and connectors for corrosion every 150 hours or 6 months.
Warning: Residual voltage in ignition exciter may be dangerously high. Ensure ignition is switched OFF and system has been inoperative for at least 6 minutes before removing any ignition components. Always disconnect cable-coupling nuts at ignition exciter end first. Always use insulated tools to remove cable-coupling nuts. Do not touch output connectors or coupling nuts with bare hands.
Unscheduled • Inspect cooling holes of spark igniters for blockage. • Inspect igniter shell and electrode for erosion. • Proceed by elimination to find faulty components. Refer to Engine Maintenance Manual for limits. Note: • Ignition systems components may be considered "On Condition" with removal based on operator's experience. • The firing end of the igniters should never be cleaned. Do not remove the carbon from the electrodes or annular gap areas. Carbon deposits in the gap area are an aid to the igniter operation.
PT6T-3/-6
FOR TRAINING USE
IGNITION SYSTEM
7.4
SPARK IGNITER 0.300 IN. MAX.
A
A
A WORN OUT SECTION A-A
NEW IGNITER SECTION A-A
PT6T-3/-6
FOR TRAINING USE
IGNITION SYSTEM
7.5
NOTES
PT6T-3/-6
FOR TRAINING USE
IGNITION SYSTEM
7.6
PERFORMANCE
PT6T-3/-6
TRAINING USE ONLY
PERFORMANCE
8.1
POWER ASSURANCE CHECKS (BELL INSTALLATIONS) Purpose:
Procedure (Hover or Light on Skids):
Power Assurance Check charts are provided to determine if the engines can produce installed specification power.
1- Cabin bleed and generator “OFF” 2- Throttles: power section on test : full open, friction “ON”. Opposite power section at ground idle
Description: 3- Beep down N2 rpm to 97% The hover check is performed prior to takeoff. An in-flight check is provided for periodic in-flight monitoring of engine performance. Hover check is the preferred method. If either power section does not meet the requirements of hover or in-flight power assurance check, the published performance may not be achievable. The cause of engine power loss (excessive ITT or N1 rpm), should be determined as soon as practical. It is recommended to perform the Power assurance check in similar conditions in order to prevent misleading information. Example: P Alt 2,000 ft - OAT 10°C - Torque applied 60 % Recorded (indicated) ITT : 760°C - N1 : 97.5 % Maximum from chart : ITT : 780°C - N1 : 99.0 % Margins ITT : 20°C - N1 : 1.5 %
PT6T-3/-6
4- Increase collective until light on skids or hovering. Do not exceed 810°C ITT, 100.8% N1 (103.2%, -3D series). 5- Stabilize power one minute, then record OAT, P Alt. (Altimeter set at 29.92 In hg or 1013 Hpa), Power section Torque, ITT and N1 rpm. 6- Enter chart at indicated engine torque, move up to intersect pressure altitude, proceed to the right to intersect outside air temperature, then move up to read values for maximum allowable ITT and N1 rpm 7- If indicated ITT or N1 rpm exceeds max. allowable value, repeat check stabilizing power four minutes 8- Repeat check using opposite power section
TRAINING USE ONLY
PERFORMANCE
8.2
ENGINE PERFORMANCE CHECK (TYPICAL)
MAXIMUM ALLOWABLE ITT - C BLEED VALVE 500 OPENS
550
600
90
99 % 100
95
105
40 50 40
30
85
T0 OA C
-20
2 OA 1 0 T 0 -10 0 C
780 800
30 20 10
-30
750
-10 -20 -30
-40
700
-40 -50
FE EUD L) TIT E AL LEV RE EA SU (S 2000 0 ES 0 0 40 00 PR 60 00 80 0 ,00
10
-50
650
MAXIMUM ALLOWABLE NI RPM - PERCENT
ET 40 50 60 70 80 ENGINE TORQUE - PERCENT (INDICATED)
MAXIMUM FOR TAKEOFF
MAXIMUM CONTINUOUS
HOVER CHECK, BELL 212, 412, 412SP
PT6T-3/-6
TRAINING USE ONLY
PERFORMANCE
8.3
NOTES
PT6T-3/-6
TRAINING USE ONLY
PERFORMANCE
8.4
POWER CHECK PT6T-3D’S
MAXIMUM ALLOWABLE ITT - C BLEED VALVE 500 OPENS
550
600
FE EUD L) TIT E AL LEV RE EA SU (S 2000 0 ES 0 0 40 00 PR 60 00 80 0 ,00
10
-50
650
-40
-30
700
-20
750
2 OA 1 0 T0 0 -10 C
780 800
30
40
ET 40 50 60 70 80 ENGINE TORQUE - PERCENT (INDICATED)
MAXIMUM FOR TAKEOFF
HOVER CHECK, BELL 412 HP,412 EP
PT6T-3/-6
TRAINING USE ONLY
PERFORMANCE
8.5
BELL 212 POWER ASSURANCE (PT6T-3 ONLY) Purpose:
Procedure:
Power Assurance Check charts are provided to determine if the engines can produce installed specification power.
1- Obtain P.Alt. (Altimeter set at 29.92 In hg or 1013 Hpa), and Torque target from chart A. 2- Start both power sections.
Description: 3- Turn heater and generator “OFF”. The check is recommended to be performed daily, prior to takeoff. The aircraft is on the ground and should not become airborne. If either power section does not meet the requirements of the power assurance check, published performance may not be achievable. The cause of engine power loss, excessive ITT or N1 rpm, should be determined as soon as practical.
4- Set one power section at flight Idle, opposite power section to ground idle, Beep down N2 speed to 97%. 5- Stabilize power section on test for 4 minutes at torque target. Record ITT, N1 rpm and OAT (outside air temperature in °C). 6- Recorded ITT & N1 must be less than value in chart B. 7- Repeat check using opposite power section. 8- If observed ITT and or N1 are greater than values from chart B, for observed OAT, steps should be taken to determine the cause of the power loss. 9- Hover in ground effect (IGE) and check No. 1 & No. 2 torque needle split. No greater than 4% torque split allowed.
PT6T-3/-6
TRAINING USE ONLY
PERFORMANCE
8.6
GROUND CHECK BELL 212 ONLY CHART A PRESS ALT % TORQUE
-500 50.5
-1000 51.5
-1500 52.5
PRESS ALT % TORQUE
0 49.5
500 48.5
1000 48.0
1500 47.0
2000 46.0
2500 45.0
3000 44.0
3500 43.5
4000 42.5
4500 42.0
5000 41.0
5500 40.5
PRESS ALT % TORQUE
6000 39.5
6500 38.5
7000 38.0
7500 37.5
8000 36.5
8500 36.0
9000 35.0
9500 34.5
10000 34.0
10500 33.0
11000 32.5
-
25 97.0 750
20 96.3 735
15 95.6 720
10 94.8 705
5 94.1 690
0 93.4 675
-35 88.5 575
-40 87.8 560
-45 87.1 545
-50 86.4 530
-54 85.8 520
-
PT6T-3 POWER ASSURANCE CHECK CHART OAT - °C N1 - % ITT - °C
52 100 810
50 100 810
45 99.8 805
40 99.1 795
35 98.4 780
OAT - °C N1 - % ITT - °C
-5 92.7 660
-10 92.0 645
-15 91.3 630
-20 90.6 615
-25 89.9 605
CHART B 30 97.7 765 -30 89.2 590
Example : 1500 feet, Torque target : 47.0%, OAT : 20°C, Recorded ITT : 710°C, Recorded N1 : 95.2% From Chart B, Maximum ITT :735°C, Maximum N1 : 96.3% Calculated Margin : ITT: 735 - 710 = 25°C, N1 : 96.3 - 95.2 = 1.1%
PT6T-3/-6
TRAINING USE ONLY
PERFORMANCE
8.7
SIKORSKY S58 T POWER ASSURANCE CHECK Purpose: Power Assurance tables are provided, in the aircraft flight manual, to determine if the engines can produce installed specification power.
6- Compare values with table at indicated engine torque, recorded values should not exceed maximum allowable ITT and N1 rpm. 7- Repeat check using opposite power section Example:
Description: The power assurance check is performed in hover prior to takeoff.
90 % torque, P.Alt : 1500 ft, OAT 15°C, N1 93.1% ITT 705°C Sample of table From flight manual for PT6T-3
If either power section does not meet the requirements of hover power assurance check, the published performance may not be achievable. The cause of engine power loss (excessive ITT or N1 rpm), should be determined as soon as practical.
OAT ∼°C .............. -10 -5 0 5 10 15 20 ...........
Procedure (Hover): 1- Cabin bleed and generator “OFF” 2- Throttles: power section on test : full open, friction “ON”. Opposite power section at ground idle 3- Beep N2 rpm to 89% 4- Increase collective until appropriate torque is obtained (for example 90 %) for the aircraft to be light on wheels or hovering. Do not exceed red line ITT, or N1. 5- Stabilize power one minute, then record OAT, P.Alt. (Altimeter set at 29.92 In hg), Power section ITT and N1 rpm.
PT6T-3/-6
Pressure Altitude + 1500 Feet limiting limiting N1/Ng ∼ % ITT/T5 ∼ °C ............ ............ 90.8 651 91.6 666 92.3 681 93.0 695 93.6 711 94.3 725 95.0 740 ............. .................
N1 Margin : 1.2%, ITT margin : 20 °C
TRAINING USE ONLY
PERFORMANCE
8.8
NOTES
PT6T-3/-6
TRAINING USE ONLY
PERFORMANCE
8.9
HELICOPTER ENGINE CONDITION TREND MONITORING (HECTM) Purpose:
Data Acquisition:
HECTM is a maintenance tool, which allows the user to monitor the engine performance and will : • Permit early detection of engine deterioration • Help determine trouble area • Increase dispatch reliability • Perform repairs at the most economical time
The accuracy of the HECTM process depends on the quality of the data entered in computer system. There is only one condition where engine reaction can be predictable, the power assurance check.
Description:
• Once per day, or every 6 hours if flown more often • Allow the engine to stabilize not less than one minute without ANY collective pitch movements. • Record data within a reasonable time frame.
HECTM is a process of periodically recording engine and aircraft instrument parameters and comparing them to a reference model. Under specific ambient conditions, engine parameters such as compressor speed (N1), interturbine temperature (ITT) are predictable. The difference between the actual engine parameters and the model values will be plotted, using a graphical chart method as illustrated below.
The data will be valid if you apply the following restrictions:
Data Entry and Calculation: HECTM data can be processed using a computer with PWC supplied HECTM system version 1.10 Plotting and Trend Analysis:
Once a trend is established by the plotting of these values, any deviation would indicate some engine deterioration. Analysis of the trend reveals extent of deviation and possible need for corrective action.
PT6T-3/-6
Once the margins are calculated, the computer does the plotting and displays the result on the screen or sends it to a printer. Analysis of the trend reveals extent of deviation and possible need for corrective action.
TRAINING USE ONLY
PERFORMANCE 8.10
SAMPLE PLOT
NI MARGIN ( 1.8 ) 0.0 1.0 2.0 3.0 4.0 ITT MARGIN ( 32 ) 0 15 30 45 60 HRS 1
PT6T-3/-6
9
17
TRAINING USE ONLY
25
33
41
PERFORMANCE 8.11
ENGINE PERFORMANCE TROUBLESHOOTING ENGINE PARAMETERS ITT N1
⇑
⇓
⇓
PT6T-3/-6
⇑
⇓
PROBABLE CAUSE
ACTION REQUIRED
Restricted inlet screen Compressor dirty Compressor Foreign Object Damage or rubs Compressor bleed valve stuck open Torque indicating system
Do an inspection or a repair Do a compressor wash Do a borescope inspection
Aircraft OAT or P alt indicating system Oxidation of Power Turbine blade tip or damage caused by rubs Torque indicating system
Do an inspection or a repair
Aircraft OAT or P alt indicating system ITT indicating system
Do an inspection or a repair
Check/repair/replace compressor bleed valve. Do an inspection or a repair
Do an inspection or a repair
Do an inspection or a repair
REMARKS
Remove the power section if FOD limits are exceeded
If only one power section affected If both power sections affected Damage not typical
If only one power section affected If both power sections affected
Do an inspection or a repair
TRAINING USE ONLY
PERFORMANCE 8.12
ENGINE PERFORMANCE TROUBLESHOOTING ENGINE PARAMETERS ITT N1 ⇑or⇓
⇑
⇓
⇑
⇓
⇑
PROBABLE CAUSE N1 indicating system Compressor Turbine vane ring burned or flow area increased Oxidation of Compressor Turbine blades tip or damage caused by rubs Deterioration of hot section Power Turbine vane ring burned or flow area increased Air leaks from airframe or engine systems ITT indicating system Gas generator case leaks at : fuel nozzles, flanges, bosses Air leaks at gas generator case drain valves Defective fuel nozzles or bad spray pattern Cold and Hot sections deterioration
ACTION REQUIRED
REMARKS
Do an inspection or a repair Do a borescope inspection of the Compressor Turbine vane ring and the Compressor Turbine blades
Do Hot Section Inspection if limits are exceeded
Do a Hot Section Inspection if ITT limits are exceeded Do a borescope inspection of the Power Damage not typical Turbine vane ring and Power Turbine blades
Do an inspection or a repair
Deterioration of both sections could make N1 seem unchanged NOTE : An increase in ITT, without changes to other parameters can be the result of a defective fuel nozzle. This can cause a change in the combustion pattern and modify the distribution of the temperature.
PT6T-3/-6
Do a borescope inspection of Hot and Cold sections.
TRAINING USE ONLY
PERFORMANCE 8.13
OPERATING LIMITS PT6T-3 2.5 minute Rating (OEI)
SHP Rated at (°C) Max. ITT (°C) Max. N1 (%) Ns (%) 30 Minute SHP Rating or Rated at (°C) Continuous Max. ITT (°C) (OEI) Max. N1 (%) Ns (%) Take-off SHP 5 minutes Rated at (°C) Twin Engine Max. ITT (°C) Max. N1 (%) Maximum SHP Continuous Rated at (°C) Twin Eng. Max. ITT (°C) Max. N1 (%) No Load Max. ITT (°C) N1 (%) Max Ns (%) Starting (*) Max. ITT (°C) Min. Oil T. Transient Max. ITT (°C) Max. N1 (%) Max Ns (%)
N/A
900 15 810 100 100 1800 15 810 100 1600 15 765 100 600 64.3 105 1090 -54 850 101.0 110
PT6T-3B/3BE PT6T-3BF/3BG PT6T-6/6B 1025 15 850 103.4 100 970 15 822 100.8 100 1800 15 810 100.8 1600 15 765 100.8 600 64.3 105 1090 -54 850 104.7 110
1025 15 850 103.4 100 1025 15 850 103.4 100 1800 15 810 100.8 1600 15 765 100.8 600 64.3 105 1090 -54 850 104.7 110
1025 15 645 102.4 100 970 15 624 100.8 100 1875 21.5 624 100.8 1675 18 593 100.8 545 64.3 105 760 -54 645 103.7 110
PT6T-3D
PT6T-3DE
PT6T-3DF
1100 25 925 109.2 100 970 15 820 103.7 100 1800 22 810 103.2 1600 35 810 103.2 600 64.3 105 1090 -54 950 110.5 110
1133
1133
109.2 100 1025 15 855 100 1800 22 810 103.2 1600 35 810 103.2 600 64.3 105 1090 -54 950 110.5 110
940 109.2 100 1060 15 885 106.8 100 1800 22 810 103.2 1600 35 810 103.2 600 64.3 105 1090 -54 950 110.5 110
(*) ITT, 2 seconds limit for starting, oil 3 Centistoke only.
PT6T-3/-6
TRAINING USE ONLY
PERFORMANCE 8.14
TIME BETWEEN OVERHAUL(TBO) AND HOT SECTION INSPECTION (HSI) General:
TBO Escalation Program
Time Between Overhaul and Hot Section Inspections are defined under the Service Bulletin 5003.
Operators desiring to increase their engine TBO’s should submit a formal request in writing, together with details of sample engine log book to : Manager, Technical Support, turboshaft engines.
Modular Concept: The Twin-Pac is comprised of three modules, the reduction gearbox and two power sections. These three modules may be maintained at their own intervals at the operators’ discretion.
The extension will be for 500 hours. Note: Accessories, except ignition components, have a TBO of 500 hours above the module TBO.
Time Between Overhaul (TBO): Hot Section Inspection (HSI): Initial TBO for the Power Section modules is set at 4,000 hours. For the Reduction Gearbox refer to the Bell Helicopter maintenance manual. Recommendations for time between-overhaul take into consideration the average effect of the many variables affecting overhaul life such as average flight duration, percentage of time at any given power level, climatic conditions and environment, maintenance practices, utilization and engine modification standard. Under extreme conditions of very low utilization coupled with continuous operation in salt water atmosphere or heavy sand environment, periodic inspections in accordance with the applicable maintenance instructions may indicate maintenance action prior to the recommended overhaul life.
PT6T-3/-6
Hot Section Inspections are "On Condition" performed based on engine performance.
and
There is a requirement for hot section inspection on PT6T-3D(BS 802/928), PT6T-3DE(BS 893) and PT6T3DF(BS 946) models (refer to SB 5003).
TRAINING USE ONLY
PERFORMANCE 8.15
ROTOR COMPONENTS SERVICE LIFE Description: Certain engine rotating parts are subject to low cycle fatigue due to cyclic operation of the engine. Other factors such as high-frequency fatigue and metallurgical changes related to time rather than flight cycles, have to be considered. As a result, these parts must be replaced when either the cycle count or the hourly limit is reached.
Start: For the purpose of accumulated total cycle calculation, a start is defined as an engine start followed by one or more flights. Flight: Each time the aircraft performs the following mission: ground, air, ground, it is logged as one flight.
The cycle limits are published in Service Bulletin 5002 Life Limited Components Consist of: Rotary-wing aircraft operation often includes abbreviated engine cycles. The definition of abbreviated cycle is: *** idle - takeoff - flight - landing - idle *** Whereas a normal of full cycle includes the foregoing, plus an engine start and a shutdown. When applicable, each use of the 2.5 minutes rating (OEI rating, single engine condition), results in the additional accumulation of an extended cycle defined as : *** Idle - 2.5 minutes rating - Idle ***
• • • • •
Compressor hub Compressor disks (No. 2 & No. 3) Centrifugal impeller Compressor turbine disk Power turbine disk
Note: No extensions are permitted on cycle limits
To simplify record keeping, it is mandatory that the operator log engine hours, engine starts, aircraft flights, and each use of the 2.5 minute rating, when applicable. The definitions of starts and flights are as follows:
PT6T-3/-6
TRAINING USE ONLY
PERFORMANCE 8.16
ROTOR COMPONENTS - SERVICE LIFE At repair and overhaul, component life is calculated in accordance with the following formula : Accumulated No. Ext ' d Flight No.of 2.5 No.of Flights − No.of Starts Total = of + + Min.rating X cycle X Count Abbreviated cycleFactor Starts Cycles Excursions Factor Factor
Example for a turbine disk : P.N. 3024211
from SB 5002 Abbreviated Cycle Factor Extended Cycle Factor Flight Count Factor Life Limit in Cycles
Accumulate d Total Cycles
4 1 1 10,000
from engine log book Number of Starts Number of Flights Number 2 ½ min. Rating Excursions
850 1910 5
1910 − 850 = 850 + + 5 X 1 X 1 = 1120Cycles 4 [850 + 265 + 5 ] X 1 = 1120
Reference: SB 5002
PT6T-3/-6
TRAINING USE ONLY
PERFORMANCE 8.17
NOTES
PT6T-3/-6
TRAINING USE ONLY
PERFORMANCE 8.18
FUEL SYSTEM
PT6T-3/-6
TRAINING USE ONLY
FUEL SYSTEM
9.1
FUEL SYSTEM Purpose: Provide the engine with clean fuel at the required pressure and flow to permit control of engine power. Components: • Fuel heater • Fuel pump and filter • Manual Fuel Control unit (MFCU) • Automatic Fuel Control Unit (AFCU) • Fuel accumulator • Flow divider • Fuel nozzles • Power turbine governor (N2) • Torque control unit Inputs Requirement: • Power lever position (twist grips) • N1 speed • N2 speed • P3 air • Torque • Collective position to N2 Governor
PT6T-3/-6
Operation: Fuel from the aircraft tanks is sent to the fuel heater via the airframe boost pump. From the fuel heater, the fuel is directed to the fuel pump. The fuel pump sends the fuel to the manual fuel control unit which depending on the operation mode, direct it to the automatic fuel control units (automatic mode) or meter the fuel (manual mode). The correct amount of fuel metered by either unit then flows to the flow divider and to the fuel nozzles. The fuel control system function on a helicopter installation is to maintain constant power turbine speed, and therefore the aircraft rotor speed. As collective pitch is changed, the load on the power turbine changes tending to change its speed. The gas generator (N1) must then be corrected by changing its own speed accordingly, in order to supply the power required to maintain a constant output shaft speed. Fuel, Additives and Limitations: • Refer to Service Bulletin 5144 for complete listing of approved fuel and additives. • Use of Aviation Gasoline (AVGAS) is limited to 150 hours per engine between overhaul periods (TBO).
TRAINING USE ONLY
FUEL SYSTEM
9.2
FUEL SYSTEM FUEL HEATER OIL IN OUT
FUEL PUMP FILTER
JET PUMP
PUMP
MANUAL FUEL CONTROL UNIT
AUTOMATIC FUEL CONTROL UNIT
TRANSFER VALVE
METERING UNIT (N1 GOV.)
METERING CUT-OFF VALVE
CUT OFF FUEL FILTER
Py
BOOST PUMP (AIRFRAME)
P3
FUEL TANK PRIMARY
PT6T-3/-6
SECONDARY FUEL NOZZLE
TRAINING USE ONLY
Pg FLOW DIVIDER
Pg
FUEL SURGE ACCUMULATOR
TCU N2 GOVERNOR
FUEL SYSTEM
ACCUMULATOR
INLET PRESSURE Ps SUPPLY PRESSURE Pm METERED FUEL Pb BYPASS FUEL P3 PRESSURE Pg PRESSURE Py PRESSURE
ACCUMULATOR
POST SB5409
9.3
FUEL HEATER Purpose:
Specifications:
Heat the fuel to prevent ice crystal formation in the fuel filter.
Normal fuel temp: ......................................... 20-32°C Normal oil temp (A/F cooler): ........................ 70-90°C
Description:
Maintenance:
The fuel heater is a heat exchanger using hot oil to heat fuel. A thermal element reacts to fuel temperature and moves a sliding valve to control the amount of oil flowing into the heat exchanger.
Scheduled • Every 300 hours, perform touch test. Immediately after shutdown, the Fuel Pump Filter housing should be comfortable to touch. If too hot to touch, replace Fuel Heater (max temperature 60°C or 140°).
Operation: Cold fuel from the aircraft boost pump enters the fuel heater and surrounds the thermal element. The cold thermal element is contracted and allows pressure oil from main oil pump to travel across the heat exchanger. Heat from the oil transfers to the fuel and fuel temperature starts to rise. Around 20°C the thermal element begins to expand and push on the spring loaded sliding valve. In this position, the oil progressively bypasses the fuel heater and fuel temperature begins to stabilize. A spring located at the back of the sliding valve pushes it back to the left (heating position) when fuel temperature drops. During operation, the thermal element constantly reacts to adjust fuel outlet temperature.
PT6T-3/-6
Notes: • •
Internal leaks of fuel heater will cause high oil consumption when engine is running. Internal leaks of fuel heater will cause high oil level when engine is not running and fuel boost pumps are “ON”.
Hot fuel in one power section control system will induce abnormal torque splits. And power section losing power during electrical emergency ground check. Flickering fuel filter impending bypass light or unable to reach maximum power (same as N1 limit) or power drop may be caused by restrictions in fuel heater core due to contamination.
TRAINING USE ONLY
FUEL SYSTEM
9.4
FUEL HEATER
FUEL HEATER
FUEL INLET
PUSH ROD VALVE
BYPASS
OPEN THERMAL ELEMENT
FUEL OUTLET PT6T-3/-6
OIL
HEATING
FUEL
OIL
OIL
OIL
BYPASS TRAINING USE ONLY
FUEL SYSTEM
9.5
FUEL PUMP Purpose: Provide clean fuel under pressure to the fuel control unit. Description: • Supports the fuel filter • Dual stage pump : - Positive displacement gear type pump - Ejector type • Pump gears are sealed with bronze bushings and carbon seals Pump Capacity (Typical): N1 Fuel flow 12 % 155 pph 100 % 1,200 pph
Pressure 75 Psig 900 Psig
Filter : 10 micron (µ) non-metallic disposable type filter. Impending Bypass Indication: Airframe provision switch, activated at 1.4 to 1.8 Psid. The pressure is taken between the inlet of the engine and the outlet of the fuel filter. This configuration will take in account a possible restriction in the fuel heater. Filter Bypass Valve: Piston type bypass valve set to open at 2.7 to 3.0 Psid if filter gets restricted.
PT6T-3/-6
Operation: Fuel enters the pump through the filter element. In the event of filter blockage, a spring-loaded piston-type bypass valve provides an alternative route for unfiltered fuel. The gear type pump pressurizes the fuel. Excess fuel (bypass) from the fuel controls is returned to the pump inlet through an ejector type pump. Two carbon face type seals prevent fuel from leaking out of the pump. Maintenance: Scheduled • Inspect filter for contamination every 300 hours if not equipped with a fuel filter impending bypass switch. • Check for security and leaks every 300 hours • Inspect/replace filter every 600 hours • Check pump driveshaft coupling to accessory gearbox for wears (corrosion) every 600 hours maximum interval. Unscheduled • Return pump to overhaul if operated more than 10 hours without A/C boost pump pressure. Caution: Do not remove AGB coupling from the pump All trace of grease must be removed from the pump coupling splines and AGB gearshaft. Only engine oil is to be used as a lubricant. Make sure the oil mist lubrication hole in the AGB gearshaft is open Note: • Cross-feed is not considered as a “no” boost pump operation • Maximum fuel leakage is 0.5 cc/minute.
TRAINING USE ONLY
FUEL SYSTEM
9.6
FUEL PUMP
HIGH PRESSURE FUEL DELIVERY
MFCU BYPASS RETURN AFCU BYPASS RETURN
FUEL FILTER IMPENDING BYPASS PORT FILTER BYPASS VALVE
FUEL EJECTOR PUMP 10 MICRON FILTER
FUEL INLET FROM FUEL HEATER
INLET PRESSURE Ps SUPPLY PRESSURE Pb BYPASS FUEL
PT6T-3/-6
TRAINING USE ONLY
FUEL SYSTEM
9.7
MANUAL FUEL CONTROL UNIT (MFCU) Purpose: In automatic mode, directs the fuel from the pump to the AFCU and then from the AFCU to the fuel nozzles. In manual mode, calibrate and directs the fuel from the pump directly to the fuel nozzles.
Pressure Regulating Valve: The pressure-regulating valve prevents the MFCU to transfer inadvertently into manual mode in case of leakage from the solenoid valve. It maintains internal MFCU pressure 100 Psi above bypass pressure (Pb).
Description:
Check Valves (2): Depending on which mode is being used, prevent to pressurize the inoperative side of the control. The set of check valves closes the system not in use.
High Pressure Relief Valve: Prevents build up of excess Ps and Pm pressure in the fuel system. This valve is normally closed unless Ps pressure reaches 1,050 Psi and allows Ps fuel to dump into Pb. Transfer Valve: Depending on its position, direct the fuel to the AFCU in automatic mode (down position) or to the metering side of the MFCU in manual mode (up position). The solenoid valve controls the position of the transfer valve. Solenoid Valve: Control the transfer valve position by dumping fuel from the top of the transfer valve into the bypass line. The resultant pressure drop causes the transfer valve to move up. The solenoid valve is closed when no electrical power is applied (NC).
PT6T-3/-6
Metering and Cut-Off Valve: This valve is manually controlled by the twist grip. One end (bottom) of the valve meters the fuel in manual mode, where the other end (top) closes the main fuel passage in cut-off position. Pressurizing Valve: It ensures that no fuel flows to the manifold until a pre-set minimum pressure of 75 Psi is attained. At shutdown, provide a positive shut-off of the fuel to the fuel nozzles. Bypass Valve: The diaphragm-type bypass valve controls bypass fuel flow to maintain a constant 15-18 Psid between the pump delivery pressure Ps and the metered fuel pressure Pm.
TRAINING USE ONLY
FUEL SYSTEM
9.8
MANUAL FUEL CONTROL UNIT (MFCU) AUTO
TO FLOW DIVIDER & NOZZLES PRESSURIZING VALVE
CUT-OFF VALVE CHECK VALVE FROM A.F.C.U.
SOLENOID VALVE (N.C.) TWIST GRIP INPUT
TRANSFER VALVE Ps SUPPLY PRESSURE Pm METERED FUEL Pb BY-PASS FUEL
PT6T-3/-6
H.P. RELIEF VALVE
FROM PUMP TO A.F.C.U.
TRAINING USE ONLY
PRESSURE REG.VALVE BYPASS FUEL
FUEL SYSTEM
9.9
MANUAL FUEL CONTROL UNIT (MFCU) Operation Automatic Mode (Normal) During the initial starting phase, fuel enters the MFCU from the pump. Pressure (Ps) built-up inside the MFCU (solenoid closed and PRV not opened). The transfer valve remains in position as pressure is equalized on all sides of the valve and the spring maintains the valve in position. When internal pressure rise above 100 Psi the fuel flows towards the AFCU. Until 12% N1, before the pilot moves the twist grip, the fuel cut-off valve prevent any fuel to flow towards the engine. When the pilot moves the twist grip to the Ground-Idle position the fuel starts to flow towards the engine. A minimum of 75 Psi is required before the pressurizing valve opens. Internal check valves prevent fuel to flow backwards in the MFCU. In normal operation (twist grip positioned in fly, 90 or 95° on the quadrant) the MFCU metering valve is in the maximum flow position but no fuel is flowing by. Manual Mode (Emergency or Trouble Shooting) Manual start is similar to above, when the pressure buildup inside the MFCU the solenoid dump the fuel coming from the backside of the transfer valve to the bypass. The fuel pressure applied to the transfer valve now override the spring and the valve is pushed all the way.
PT6T-3/-6
This allows the fuel to flow towards the MFCU metering valve and across the minimum flow orifice. In the same time prevent the fuel to go to the AFCU. Pressure keep building up, the by-pass valve will maintain the 15 to 18 delta pressure inside the MFCU. Around 12% N1, when the pilot moves the twist grip, he opens the cut-off, and the fuel can flow towards the engine. The pilot will have to supervise the start for temperature and speed. The engine should stabilize somewhere around 52-58% N1. The pilot now will have to adjust the fuel flow to match the power demand by rotating the twist grip. The minimum fuel flow fixed orifice will prevent inadvertent engine shutdown during manual operation. In normal or emergency conditions, engine running, when the pilot want to select Manual operation, the twist grip should be retarded to the ground-Idle stop, before activating the solenoid. This will prevent to introduce large amount of fuel in the engine. When the solenoid is activated the pressure on the back of the transfer valve is reduced to by-pass pressure and the transfer valve moves rapidly to the manual position. The fuel is directed to the engine by the MFCU. A surge damper will assist the engine in absorbing the transitory fuel pressure drop. Maintenance: Scheduled • With fuel system pressurized, inspect MFCU shaft for fuel leaks every 300 Hours or 1 year.
TRAINING USE ONLY
FUEL SYSTEM 9.10
MFCU MANUAL TO FLOW DIVIDER & NOZZLES PRESSURIZING VALVE
CUT-OFF VALVE
BYPASS VALVE SOLENOID VALVE (N.C.)
TWIST GRIP INPUT MIN. FLOW ORIFICE
28 VDC
METERING VALVE TRANSFER VALVE
H.P. RELIEF VALVE
Ps SUPPLY PRESSURE Pm METERED FUEL Pb BY-PASS FUEL PT6T-3/-6
FROM PUMP
TRAINING USE ONLY
BYPASS FUEL
FUEL SYSTEM 9.11
POWER LEVER ADJUSTMENTS Purpose:
Ground Idle Adjustment:
Ensure that the input from the twist-grip is correctly transmitted to the fuel control system.
The ground idle adjustment (61 ± 1% N1) is adjusted on the airframe at the cut-off solenoid, This will represent approximately 35° on the MFCU arm. This adjustment is performed with the engine running.
Description: The Power lever adjustment is done at the MFCU input lever to ensure that there is enough travel from the twistgrip and the pilot could operate the MFCU from cut-off to maximum power. The MFCU arm stops must come in positive contact in both directions (Cut-Off and Maximum) with some extra tension (call cushion) in the linkage to ensure that the lever stays in contact in all flight configurations. Gain Adjustment:
The adjustments related to MFCU/AFCU are described later in this chapter. Afcu/Mfcu Idle Speed Caracteristics N1%
MFCU 61%
AFCU
If a good amount of cushion (4 – 6° as per airframe manual) cannot be obtained, or if it is too important, the gain adjustment is done on the helicopter linkage at the jackshaft adjustment (cargo hook compartment) by moving outboard to increase, or inboard to decrease, the amount of cushion. If the cushion is not equally centered (same amount in Cut-Off and at maximum), it is possible to change its position by adjusting the aft end of the control rod next to the gain adjustment.
PT6T-3/-6
TRAINING USE ONLY
Sea Level
8,000 ft
Altitude
FUEL SYSTEM 9.12
POWER LEVER NO. 2 MFCU
LDG LT
ON
OFF IDLE STOP E E N1 N2 G G REL L
EXT OFF RET SLT
SLT EXT
OFF STOW R
NO. 1 MFCU
START
INCR R P M
NO. 2 GROUND IDLE & CUT-OFF VALVE
RETR
DECR
1 - ENG - 2
NO.1 NO. 2
TWIST-GRIPS
+
-
NO. 2 GAIN ADJUSTMENT NO. 1
PILOT
NO. 1 GROUND IDLE & CUT-OFF VALVE
AJUSTABLE RODS
FROM CO-PILOT PT6T-3/-6
TRAINING USE ONLY
FUEL SYSTEM 9.13
FLOW DIVIDER AND DUMP VALVE Purpose: Divide the fuel flow between primary and secondary fuel manifolds. Dumps fuel from the manifolds when the engine is shutdown. Construction:
When the power section is shutdown, the fuel pressure drops and the two springs push the primary and the secondary valves toward the closed position. This allows fuel to drain (air pressure and gravity). The fuel is dumped outside (old helicopters) or returns to the fuel cells (new helicopters). Maintenance:
Primary valve:
Unscheduled • Replace if defective (refer to troubleshooting) • Maximum leakage at dump is 0.5 cc/minute.
Primary valve opens at fuel pressure of : • 9 - 13 Psi.
Fuel Accumulator
Secondary valve:
•
Secondary valve, located inside the primary valve, opens at fuel pressure of : • 17 - 22 Psi • 33 - 35 Psi for PT6T-3D’s.
•
Operation:
Maintenance:
Fuel enters the flow divider and pushes against the primary and secondary valve. When fuel pressure reaches primary spring tension, the primary valve moves and allows fuel to flow to the primary manifold only.
Scheduled • Deceleration check on pre SB 5398 (Flight to GroundIdle) every 100 Hours • Post SB 5398 only, check pop-out indicator every 150 hours • Inspect for cracks, leaks and distortion • If leak is suspected, pressure check at 100 Psi
As N1 speed increases, the fuel pressure reaches secondary valve spring tension. The secondary valve moves inside the primary valve, to allow the fuel to flow to the secondary manifold.
PT6T-3/-6
TRAINING USE ONLY
A small accumulator is installed in the fuel line to the fuel flow divider to smooth out the fuel pressure pulse during the transition from automatic control to manual control and during rapid power demand changes. It can also prevent power section flameout during rapid deceleration.
FUEL SYSTEM 9.14
FLOW DIVIDER AND DUMP VALVE TO PRIMARY MANIFOLD PRIMARY VALVE
PRIMARY FLOW POSITION TO PRIMARY MANIFOLD SECONDARY VALVE
TO SECONDARY MANIFOLD
FLOW DIVIDER
FUEL SURGE ACCUMULATOR
FUEL INLET
PRIMARY AND SECONDARY FLOW POSITION
ACCUMULATOR WHILE ENGINE IS NOT OPERATING
FUEL INLET END CAP FUEL IS STORED UNDER PRESSURE
SPRING ACCUMULATOR DURING ENGINE OPERATION
DUMP POSITION PT6T-3/-6
TRAINING USE ONLY
FUEL SYSTEM 9.15
FUEL NOZZLES (PT6T3&3B’S&6’S) Purpose:
Maintenance:
Deliver and atomize metered fuel into the combustion chamber.
Scheduled • Inspect, clean and test fuel nozzles as per maintenance manual 1) "In situ" clean every 300 hours, clean and inspect up to next major airframe inspection without exceeding 1200 hours. Or 2) Every 600 hours (removal).
Construction: • 14 fuel nozzle adapters, (7 primary, 6 secondary, 1 Inlet) • 14 nozzle sheaths • 14 nozzle tips • 28 transfer tubes Operation: During start, the 7 primary fuel nozzles receive fuel from the flow divider and deliver it to the combustion chamber. The position of the primary fuel nozzles is such that fuel is sprayed circumferentially towards the spark igniters in order to facilitate ignition. An increase in N1 causes fuel pressure to increase and the secondary fuel nozzles to spray fuel into the combustion chamber. At this point, all the 14 nozzles deliver fuel. The inlet fuel nozzle is connected to the secondary manifold.
PT6T-3/-6
Notes: • In-situ fuel nozzle wash is a method, which permits cleaning of fuel nozzles in place, (without having to remove them). Recommended wash rig and cleaning solution must be used. In-situ cleaning can only start with new/overhauled set of fuel nozzles. • It is acceptable to lockwire the fuel nozzle adapters, using the single strand method (wire 0.032" gauge). • Use approved engine oil to lubricate fuel transfer tube preformed packings ("O" rings). • Ensure transfer tube locking plates are installed properly. Caution: Extreme care must be exercised when handling nozzles since even fingerprints on the nozzle orifice may produce a poor spray pattern. Clean, lint-free cotton gloves or surgical gloves should be worn at all times when handling components.
TRAINING USE ONLY
FUEL SYSTEM 9.16
FUEL NOZZLES SPARK IGNITER S S 14 13 S 12 S 11 10 P 9 P
FUEL NOZZLE SHEATH
FUEL NOZZLE
P P COMBUSTION 1 2 P CHAMBER LINER 3 4 S (REF.) 5 P 6 S 7 8 S P SPARK IGNITER
PRIMARY FUEL MANIFOLD ADAPTER ASSY
GAS GENERATOR CASE (REF.)
FLOW DIVIDER
PRIMARY ADAPTER
PT6T-3/-6
SECONDARY FUEL MANIFOLD ADAPTER ASSY
SECONDARY ADAPTER
TRAINING USE ONLY
FUEL SYSTEM 9.17
DUAL ORIFICE FUEL NOZZLES (PT6T-3D’S)
Maintenance:
Purpose:
Scheduled • Inspect, clean and test fuel nozzles as per maintenance manual 2) "In situ" clean every 300 hours, clean and inspect up to next major airframe inspection without exceeding 1200 hours. Or 3) Every 600 hours (removal). • PT6T-3D’s : Inspect fuel nozzle sheaths for wear every 600 hours
Deliver and atomize metered fuel into the combustion chamber. Construction: • 14 nozzle adapters (dual orifice or duplex) (13 nozzles, 1 inlet) • 14 nozzle sheaths • 14 nozzle tips • 28 transfer tubes Operation: During operation, the 14 fuel nozzles receive fuel from the flow divider and deliver it to the combustion chamber. On start, the flow divider sends fuel to the primary manifold. The 14 fuel nozzles will deliver fuel to the combustion chamber through their primary orifices. An increase in N1 causes fuel pressure to increase and the secondary fuel nozzles to spray fuel into the combustion chamber. At this point, the 14 nozzles deliver fuel through their primary and secondary orifices.
PT6T-3/-6
Notes: • In-situ fuel nozzle wash is a method, which permits cleaning of fuel nozzles in place, (without having to remove them). Recommended wash rig and cleaning solution must be used. In-situ cleaning can only start with new/overhauled set of fuel nozzles. • It is acceptable to lockwire the fuel nozzle adapters, using the single strand method (wire 0.032" gauge). • Use approved engine oil to lubricate fuel transfer tube preformed packings ("O" rings). • Ensure transfer tube locking plates are installed properly. Caution: Extreme care must be exercised when handling nozzles since even fingerprints on the nozzle orifice may produce a poor spray pattern. Clean, lint-free cotton gloves or surgical gloves should be worn at all times when handling components.
TRAINING USE ONLY
FUEL SYSTEM 9.18
DUAL ORIFICE NOZZLES (PT6T-3D) FUEL NOZZLE SHEATH
FUEL NOZZLE
GAS GENERATOR CASE
COMBUSTION CHAMBER LINER GAS GENERATOR CASE INLET ADAPTER FLOW DIVIDER
PRIMARY MANIFOLD
VIEW LOOKING FORWARD
FUEL MANIFOLD ADAPTER
SECONDARY MANIFOLD PRIMARY FLOW
FUEL MANIFOLD ADAPTER SECONDARY FLOW PT6T-3/-6
TRAINING USE ONLY
STRAINER
FUEL SYSTEM 9.19
AUTOMATIC FUEL CONTROL UNIT Purpose:
Bypass Valve:
The AFCU establishes the proper fuel schedule according with P3 air, twist grip and N2 governor inputs.
The bypass valve ensures a constant differential fuel pressure across the metering valve. The diaphragm-type bypass valve maintains a constant 15-18 Psid between the pump delivery pressure (Ps) and the metered fuel pressure (Pm).
The AFCU basically comprises two sections : • Hydraulic section (Fuel metering) • Pneumatic section (Control section)
Fuel Temperature Compensation:
Hydraulic Section: Metering Valve: The metering valve travels between a maximum and a minimum fuel flow position and determines the amount of fuel going to the engine fuel nozzles. The valve is activated by a torque tube function of the position of pneumatic bellows. Torque Tube: The torque tube transmits the control section inputs to the metering valve. The torque tube is spring loaded towards the minimum flow position when there is no air pressure coming to the AFCU.
PT6T-3/-6
Bi-metallic washers installed on the by-pass valve spring will modify the amount of by-pass fuel depending on fuel temperature. As fuel temperature increases, more fuel is required to maintain the engine acceleration constant. Acceleration Dome: An external adjustment (Dome) permits to adjust the engine acceleration. : Note The dome adjustment should only be performed when all the pneumatic side of the control has been verified.
TRAINING USE ONLY
FUEL SYSTEM 9.20
AUTOMATIC FUEL CONTROL UNIT (HYDRAULIC) Ps SUPPLY PRESSURE Pb BY-PASS FUEL Py AIR PRESSURE P3 / Px AIR PRESSURE Pm METERED FUEL
TO MFCU
ACCELERATION DOME
MINIMUM FUEL FLOW STOP
METERING VALVE BYPASS VALVE
BELLOWS Pb RETURN TO TANK
Pb RETURN TO PUMP
TORQUE TUBE Py
MAXIMUM FUEL FLOW STOP
P3/Px PT6T-3/-6
TRAINING USE ONLY
FROM MFCU
FUEL SYSTEM 9.21
AUTOMATIC FUEL CONTROL UNIT PNEUMATIC SECTION Bellows: The bellows section consists of an evacuated bellows and a governor bellows. The bellows assembly is allowed to move up and down depending on Px and Py pressure and torque tube spring loading. Its function is similar to a diaphragm with Px pushing on one side and Py on the other side. When only atmospheric pressure acts on the bellows, (engine stopped or starting), the torque tube springs load the valve towards the closing position (up on the diagram, min. flow position). • To increase fuel flow to the engine, Py is increased. • To reduce fuel flow, Py is decreased. N1 Governor: The function of the N1 governor is to maintain or limit engine compressor speed (N1) in specific conditions : • Maintain constant speed at Idle (N1 Governing) • Limit N1 speed in fly condition (N1 limiter). A set of flyweights, driven by the accessory gearbox via the fuel pump, senses N1 speed. The flyweights oppose a force to a spring tension set by the twist grip position. When the flyweights are accelerated and the spring tension overcome, the governor lever will moved, opening the Py orifice, reducing or limiting fuel flow, and N1 speed.
PT6T-3/-6
Air Regulator and Reset Rod: The air regulator determines Pg pressure used to move the reset rod, which maintains rotor speed constant by varying the governor lever, which control Py pressure. Operation: The AFCU receives P3 pressure and modifies it to Px and Py. Px is directly proportional to P3 and act directly on the bellows. The AFCU adjust Py pressure to move the bellows towards a specific position, based on N2 governor input or internal speed governor action. The twist grip is linked to the N1 governor cam located inside the AFCU. Movement of the twist grip from "OFF", to "Idle", or to "maximum" positions increases the tension on the spring and forces the governor lever to prevent Py from venting into the AFCU body. This operation signals the AFCU to increase fuel flow. • At Idle position the spring tension will be adjusted to stabilize the N1 rpm at a specific value (Ground Idle speed of 61 ± 1 %, Twist-grip linkage adjustment) • In the fly position the spring tension will be adjusted for the maximum N1 speed (i.e. 2.5 minutes rating). However, the reset rod can override it, and push on the governor lever to maintain N2 speed constant. Maintenance: Scheduled • Inspect/clean P3 Filter every 100 Hours • Inspect/clean Drain Valve (post SB5309) every 100 Hours (every 50 hours in severe environment) • Check AFCU for bearing wash-out indicated by blue dye at AFCU vent hole every 150 Hours.
TRAINING USE ONLY
FUEL SYSTEM 9.22
AUTOMATIC FUEL CONTROL UNIT (PNEUMATIC) P3 AIR REGULATOR
Pa PRESSURE Pr PRESSURE Pg PRESSURE P3 / Px PRESSURE Py PRESSURE
Pg
INTERCONNECT LINK GOVERNOR BELLOWS IDLE SPEED ADJUSTMENT ACCELERATION BELLOWS (EVACUATED)
Pr
COUPLING
RESET ROD
PIVOT POINT Py ACCUMULATOR
Pa P3
P3 FILTER PT6T-3/-6
P3 TO AIR REGULATOR
Py METERING ORIFICE
Pa TRAINING USE ONLY
FUEL SYSTEM 9.23
N2 POWER TURBINE GOVERNOR & CONTROL Purpose: The function of the power turbine governor is to maintain N2 and main rotor speed constant in normal operation. • 100% ±1 N2 in all twin engine conditions. • 4.5% beep range (97-101.5% N2) twin engine conditions • 4% beep range (95-99% N2) single engine conditions • Maximum 4% Torque split in steady state. Description: The power turbine governor, located on the reduction gearbox, contains a set of flyweights that senses N2 speed. A spring opposes a force to the spinning flyweights. When the flyweights are accelerated and the spring tension overcome, the reset orifice will be opened modifying the Pg signal coming form the AFCU. The Pg pressure change result in a movement of the reset rod, which applies a force to the N1 governor lever to change the spring force and increase Py bleed. Droop Compensation: The power turbine governor used on the PT6T engine is called a "droop" governor because its speed setting is effectively changed (decreases or droops) when the power output is increased. This droop characteristic must be compensated in order to maintain the helicopter rotor speed constant. This is achieved by linking the N2 governor speed set lever to the collective droop compensator linkage.
PT6T-3/-6
When the collective pitch is moved, (up or down) the droop compensator linkage rotates a cam inside the N2 governor and increase / decrease the spring tension on the flyweights. With this arrangement, the position of the N2 governor control arm is constantly being changed to enable the N2 governor to always be set to the same speed, regardless of collective pitch setting. Beep Motor: An electrically operated linear actuator or beep motor (airframe supplied), is installed in the linkage. It is controlled by a switch on the collective stick, to change the position of the lever on the two power turbine governors, This will modify the settings of N2 turbine speed between 97% and 101.5% (twin engine operation) or 95% and 99% (single engine operation). On PT6T-3BE/3BG/6B/3D/3DE/3DF and modified helicopters (Bell TB), a second actuator, installed on No. 2 governor linkage only, (shorten or lengthen the control rod) allows to move the input lever up or down and thus modify the governor setting. This will permit Power section parameters matching. The pilot activate the actuator by moving sideways (+2 -2) the beeper switch on the collective lever box (Refer to non-torque sharing TCU in this chapter).
TRAINING USE ONLY
FUEL SYSTEM 9.24
N2 POWER TURBINE GOVERNOR TO COLLECTIVE
Pg PRESSURE P ambient
COUPLING
Pg ACCUMULATOR (T3/3B/3BE/3BF/3BG/6/6B) Pa
Pg AIR TO TCU
PIVOT POINT Pg AIR FROM AFCU PT6T-3/-6
TRAINING USE ONLY
FUEL SYSTEM 9.25
N2 GOVERNOR CONTROLS BELL 212&412
Torque
1
2
Purpose: Ensure that the input from the Collective lever is correctly transmitted to the N2 governor in order to control the power turbine and rotor speed.
Collective
Lengthen the tube to decrease indicated torque Description: The first effect of the N2 governor adjustment will be a change in the torque matching between the two powersections. Before any adjustment to be performed, the beep motor and the ITT trim actuators must be verified for stroke length and positioned properly (as per Aircraft manual). The initial adjustment is made at the N2 governor arm, stops may be adjusted as required to prevent any binding.
2 1
Shorten the tube to increase indicated torque 1
2
Always start rigging procedure with No 2 engine side. Tips: Adjust No1 side control rod length if the indicated torques (No 2 and No 1) engine are linearly following each other (same torque split with the collective increased). Shorten the tube length will increase the indicated torque.
Move towards pivot point to decrease slope 2 1
Adjust No1 side control pivot point if the indicated torques (No 2 and No 1) engine are not following linearly each other (the torque split changes with the collective increased). Moving away from the pivot point will increase the slope of the indicated torque.
PT6T-3/-6
Move away from pivot point to increase slope
TRAINING USE ONLY
FUEL SYSTEM 9.26
N2 GOVERNOR CONTROLS BELL 412SP&HP&EP ON
EXT
OFF
L D G
ARMED
L T
RET
OFF
FIXED
ENG 2
ENG 1
ENG 2
SRCH LT
INCR R
212 - 412
ADJUSTABLE LINK
ON
EXT
+2 P
-2
N2 GOVERNORS
ITT ACTUATOR (412 HP/EP) (212 POST SB)
START
IDLE STOP ENG 1
F L O A T S
M
L
R
DROOP COMPENSATOR
STOW
DECR RET
GAIN ADJUSTMENT BEEP MOTOR
GO A
D R
O U
N
COLLECTIVE CONTROL PANEL
TO ROTOR TELEFLEX CABLE CONFIGURATION
PT6T-3/-6
TRAINING USE ONLY
FUEL SYSTEM 9.27
TORQUE CONTROL UNIT (PT6T3&3B&3BF&6 ONLY) Torque Limiting:
Purpose: The TCU maintains the power level of the power sections equal and also limits the maximum total output torque to a specified value. Operation: Torque Sharing: Torque or power sharing is achieved by sensing the torque pressures from each power section by means of opposed bellows. An unbalance in torque pressures will restrict one of the normally opened pneumatic orifices. The effect of this restriction is to increase the set speed on that governor and thus increase the power on that power section. The power output from the power section producing the lower power is increased to bring it up to the level of the other power section.
The TCU limits the maximum total output torque (twin engine operation) to a specified value. Torque limiting is obtained by sensing the torque pressures from each power section and adding their value so at a specified total output torque, two normally closed pneumatic orifices are simultaneously opened. The result of opening the orifices is to reduce the power output of both power sections. Maintenance: Unscheduled • Adjust limiter side of the TCU using dead weight tester and chart (ref. to BELL maintenance manual for full procedure). • Clean orifices of the TCU • Prime TCU Note: The limiter is adjustable to the appropriate value in relation with the aircraft limitations.
PT6T-3/-6
TRAINING USE ONLY
FUEL SYSTEM 9.28
TORQUE CONTROL UNIT (T3&3B&6) Pg FROM P.S. NO. 2
NO. 1 TORQUE NO. 2 TORQUE NO. 1 Pg NO. 2 Pg P ambient
TORQUEMETER PRESSURE FROM P.S. NO.1 BLEED TO POWER SECTION OIL SYSTEM NO. 1
EQUALIZER BELLOWS
LIMITER BELLOWS
TORQUE LIMITER ADJUSTMENT
LIMITER ADJUSTMENT PT6T-3/-6
BLEED TO POWER SECTION OIL SYSTEM NO. 2 Pg FROM P.S. NO. 1
TRAINING USE ONLY
TORQUEMETER PRESSURE FROM P.S. NO.2
FUEL SYSTEM 9.29
TORQUE CONTROL UNIT (PT6T-3BE/3BG/3D/3DE/3DF/6B) Purpose:
Maintenance:
The TCU limits the maximum total (twin engine operation) output torque to a specified value.
Unscheduled • Adjust limiter every time a TCU is installed on a gearbox. • Prime TCU
Description: This TCU is similar to the basic TCU; with the torque sharing function removed or inhibited (new or modified TCU). There is a permanent bleed of Pg inside the TCU. In non-torque sharing configuration, a linear actuator (ITT actuator) controlled by the pilot is installed on the connecting rod of power section No. 2 only. This enables the pilot to match (up or down) the optimum parameter (ITT or Torque) between the two power section, based on ambient and engine conditions. Operation: Torque limiting is obtained by sensing the torque pressures from each power section and summing their total so that at a specified total torque output, two normally closed pneumatic orifices are simultaneously opened. The result of opening the orifices is to reduce the power output of both power sections
PT6T-3/-6
Note: The limiter is adjustable to the appropriate value, in relation, with the RGB index values, and aircraft limitations. The dome is used for coarse adjustments while the center screw is used for fine adjustment. Any time a TCU is installed on an RGB the limiter must be adjusted using dead weight tester and chart (ref. to the aircraft maintenance manual for full procedure). Dome Position versus Torque pressure (Psig) Position Pressure range 1 ............................56.6 to 68.4 2 ............................68.5 to 80.3 3 ............................80.4 to 92.2 4 ............................92.3 to 104.1 5 ..........................104.2 to 116.0 6 ..........................116.1 to 127.9 7 ..........................128.0 to 140.8 8 ..........................140.9 to 152.7 9 ..........................152.8 to 164.6
TRAINING USE ONLY
FUEL SYSTEM 9.30
TORQUE CONTROL UNIT (T3BE&3D&6B) Pg FROM P.S. NO. 2
NO. 1 TORQUE NO. 2 TORQUE NO. 1 Pg NO. 2 Pg P ambient
TORQUEMETER PRESSURE FROM P.S. NO.1 BLEED TO POWER SECTION OIL SYSTEM NO. 1
LIMITER BELLOWS
COARSE ADJUSTMENT FINE ADJUSTMENT
6 5 4
3
2
PT6T-3/-6
LIMITER ADJUSTMENT
BLEED TO POWER SECTION OIL SYSTEM NO. 2 Pg FROM P.S. NO. 1
TRAINING USE ONLY
TORQUEMETER PRESSURE FROM P.S. NO.2
FUEL SYSTEM 9.31
AUTOMATIC FUEL CONTROL UNIT ADJUSTMENTS Min. Governing (Ground Idle, Test Cell): This adjustment should not be required in the field. Note: • If adjustment is required, turn minimum governing screw CW to increase and CCW to decrease. • Refer to airframe manual for aircraft ground idle (61% N1) adjustment, using ground idle/cut-off solenoid position. Acceleration (Automatic Mode Only): 1- With engine running at ground idle (61% N1) 2- Rotate twist grip rapidly to full open (0.5 second max.) 3- Ensure power section accelerates from 61% to 90% N1 in 4 seconds maximum. On PT6T-3D’s add 1 second for every 5000 feet (1525 meters) above Sea Level and/or 0.5 second for every 30°C above 15°C. Note: • Always perform troubleshooting of pneumatic system first. • If adjustment is required, turn acceleration dome CW for faster acceleration or CCW for slower acceleration. The acceleration dome can only be rotated by 3 clicks, on all models except PT6T-3D’s where it is 6 clicks, (CW or CCW) from the datum line • 0.5 second max. acceleration difference between power sections • 0.2-0.3 second/click
PT6T-3/-6
Interconnect (Auto/Manual): The Interconnect link adjustment permits proper positioning of the AFCU and MFCU arms, and insure that the AFCU arm is in contact with the maximum stop. 1- Bring AFCU arm against the maximum N1 stop. 2- With AFCU arm still against the maximum N1 stop, ensure that a gap of 0.015" to 0.020" or 0.025" to 0.035" (PT6T-3 PRE SB 5165) exist between the MFCU maximum stop and the stop screw. Note: This adjustment must be checked in case of maximum N1 stop adjustment. Maximum N1 Stop (Part Power Trim): 1- Load the aircraft to maximum acceptable weight. 2- Deploy part power trim stop 3- Run one power section in automatic, increase collective, check for N2 speed droop, and note N1 speed. 4- Ensure that N1 speed is within limits (refer to Maintenance Manual, Rigging section). 5- Adjust as required : CCW to increase and CW to decrease. 6- Stow part power trim stop after check. 7- Perform Twist-grip linkage rigging (interconnect, Cushion, Ground Idle) after any maximum N1 stop adjustment. Note: ½ turn on adjustment ≅.0.5% N1
TRAINING USE ONLY
FUEL SYSTEM 9.32
FUEL CONTROL UNIT ADJUSTMENTS STOP
MAXIMUM STOP
MIN. GOV. SPEED ADJ.
A CLEARANCE
VIEW C MAX. STOP ADJ. (AUTO. FUEL CONT. ARM)
VIEW A
ACCELERATION ADJ. CONNECTED TO TWIST-GRIP
DATUM LINE (TYPICAL)
"STOWED" PART POWER TRIM STOP
MAN. -AUTO INTERCONNECT LINKAGE ADJ.
"IN USE" PART POWER TRIM STOP ON AUTO. FUEL CONTROL UNIT PT6T-3/-6
C TRAINING USE ONLY
FUEL SYSTEM 9.33
N1 TOPPING CHECK INFORMATION What is N1 Topping: Note: In-flight topping check is not the recommended method to verify max. N1, and cannot be performed on PT6T3D’s, since the maximum N1 is 109.2%, torque or ITT limits are always reached first. N1 topping is a maintenance check that is performed in flight. A qualified pilot will run the engine to ensure that the maximum gas generator speed (N1) is obtainable on each power section without exceeding any ITT or torque limits.
PT6T-3/-6
TRAINING USE ONLY
FUEL SYSTEM 9.34
TYPICAL TABLE FOR TORQUEMETER PRESSURE (PSI) AT TRANSMISSION TORQUE LIMIT Zero Incr.
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
Span Ratio 22 49.36
49.00
48.65
48.29
47.93
47.57
47.21
46.85
46.49
46.13
45.77
45.41
45.05
44.69
49.62
49.26
48.89
48.53
48.17
47.81
47.45
47.09
46.73
46.37
46.01
45.65
45.28
44.92
49.87
49.51
49.15
48.78
48.42
48.06
47.69
47.33
46.97
46.61
46.24
45.88
45.52
45.15
50.13
49.76
49.40
49.03
48.67
48.31
47.94
47.58
47.21
46.85
46.48
46.12
45.75
45.39
50.39
50.02
49.66
49.29
48.92
48.56
48.19
47.82
47.46
47.09
46.72
46.36
45.99
45.62
50.65
50.28
49.92
49.55
49.18
48.81
48.44
48.07
47.70
47.34
46.97
46.60
46.23
45.86
50.92
50.55
50.18
49.81
49.44
49.07
48.70
48.33
47.95
47.58
47.21
46.84
46.47
46.10
51.19
50.81
50.44
50.07
49.70
49.33
48.95
48.58
48.21
47.84
47.46
47.09
46.72
46.35
51.46
51.08
50.71
50.34
49.96
49.59
49.21
48.84
48.46
48.09
47.71
47.34
46.97
46.59
51.73
51.36
50.98
50.60
50.23
49.85
49.47
49.10
48.72
48.35
47.97
47.59
47.22
46.84
52.01
51.63
51.25
50.88
50.50
50.12
49.74
49.36
48.98
48.60
48.23
47.85
47.47
47.09
52.29
51.91
51.53
51.15
50.77
50.39
50.01
49.63
49.25
48.87
48.49
48.11
47.73
47.34
52.57
52.19
51.81
51.43
51.04
50.66
50.28
49.90
49.51
49.13
48.75
48.37
47.98
47.60
52.86
52.48
52.09
51.71
51.32
50.94
50.55
50.17
49.78
49.40
49.01
48.63
48.25
47.86
53.15
52.76
52.38
51.99
51.60
51.22
50.83
50.44
50.06
49.67
49.28
48.90
48.51
48.12
53.44
53.05
52.67
52.28
51.89
51.50
51.11
50.72
50.33
49.94
49.55
49.17
48.78
48.39
53.74
53.35
52.96
52.57
52.18
51.78
51.39
51.00
50.61
50.22
49.83
49.44
49.05
48.66
54.04
53.65
53.25
52.86
52.47
52.07
51.68
51.29
50.89
50.50
50.11
49.71
49.32
48.93
54.34
53.95
53.55
53.16
52.76
52.36
51.97
51.57
51.18
50.78
50.39
49.99
49.60
49.20
54.65
54.25
53.85
53.45
53.06
52.66
52.26
51.86
51.47
51.07
50.67
50.27
49.88
49.48
54.96
54.56
54.16
53.76
53.36
52.96
52.56
52.16
51.76
51.36
50.96
50.56
50.16
49.76
55.27
54.87
54.47
54.06
53.66
53.26
52.86
52.46
52.05
51.65
51.25
50.85
50.44
50.04
55.59
55.18
54.78
54.37
53.97
53.56
53.16
52.76
52.35
51.95
51.54
51.14
50.73
50.33
55.91
55.50
55.09
54.69
54.28
53.87
53.47
53.06
52.65
52.25
51.84
51.43
51.03
50.62
56.23
55.82
55.41
55.00
54.60
54.19
53.78
53.37
52.96
52.55
52.14
51.73
51.32
50.91
56.56
56.15
55.74
55.33
54.91
54.50
54.09
53.68
53.27
52.86
52.44
52.03
51.62
51.21
21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 -1 -2 -3 -4
PT6T-3/-6
TRAINING USE ONLY
FUEL SYSTEM 9.35
FUEL SYSTEM COMPLETE T3
FUEL NOZZLE T.C.U. FUEL SURGE DAMPER FLOW DIVIDER
COLLECTIVE INPUT
TWIST-GRIP INPUT. N2 FUEL INLET
M.F.C.U.
N2 GOVERNOR
INTERCONNECT LINK
FUEL HEATER N1
A.F.C.U. P3
PT6T-3/-6
N1 GOVERNOR
TRAINING USE ONLY
FUEL PUMP
FUEL SYSTEM 9.36
FUEL SYSTEM COMPLETE T3D
FUEL NOZZLE T.C.U. FUEL SURGE DAMPER FLOW DIVIDER
COLLECTIVE INPUT
TWIST-GRIP INPUT. N2 FUEL INLET
M.F.C.U.
N2 GOVERNOR
INTERCONNECT LINK
FUEL HEATER N1
A.F.C.U. P3
PT6T-3/-6
N1 GOVERNOR
TRAINING USE ONLY
FUEL PUMP
FUEL SYSTEM 9.37
FUEL SYSTEM TROUBLESHOOTING SYMPTOMS PROBABLE CAUSE One power section fails to No fuel supply to power section light up
Insufficient N1 at start
PT6T-3/-6
FIX Ensure positive fuel flow from airframe fuel tank.
Air in fuel system
Carry out motoring run. Check airframe purge system. Disconnect line "Return to A/C Tank"
Check linkage to MFCU
Adjust linkage to ensure idle position is attainable and control is in fact out of CUTOFF.
Ignition system
Check operation of spark igniters.
Flow divider
Check flow divider for blockage.
MFCU
Disconnect MFCU outlet tube and check for fuel flow while motoring engine with starter.
Engine-driven fuel pump
Disconnect tube between AFCU and MFCU and check for evidence of flow while motoring. Check if voltage to starter generator is sufficient.
Starter-generator
Indicating system
Ensure N1 indicating system function correctly.
Compressor blade rub
Listen for scraping noise while engine is rotating. If detected, carry out borescope inspection.
TRAINING USE ONLY
FUEL SYSTEM 9.38
FUEL SYSTEM TROUBLESHOOTING SYMPTOMS Power section delayed to light-up (time to light is long)
Switch to manual mode and check if problem persists: If yes, check:-------------->
If no, check:---------------> Torching on start (flames extending past the end of the exhaust stacks)
PT6T-3/-6
PROBABLE CAUSE Location of nozzles (after maintenance) (Not PT6T-3D’s)
FIX Ensure primary and secondary nozzles are correctly positioned.
Ignition system
Check igniters for proper operation.
Flow divider malfunction
Replace flow divider.
Fuel nozzle restrictions
Perform functional check on nozzles.
MFCU
Replace.
Fuel pump shaft seal leakage or damaged O-ring
Verify whether cause is O-ring at mating face between AFCU & pump or fuel pump shaft seal. If O-ring, replace it only. If shaft seal, replace pump and AFCU if blue grease wash out.
AFCU Faulty ignition system
Replace unit. Replace defective components.
Insufficient starter assistance
Check for low battery, deteriorating starter or early starter drop out
Malfunction of drain valve
Check gas generator drain valves for blockage
Flow divider malfunction
Replace flow divider.
Location of nozzles (after maintenance) (Not on PT6T-3D’s)
Ensure primary and secondary nozzles are properly located.
TRAINING USE ONLY
FUEL SYSTEM 9.39
FUEL SYSTEM TROUBLESHOOTING SYMPTOMS Power section fails to start (hung) or is slow to accelerate to idle Switch to manual mode and check if problem persists: If yes, check:------------->
If no, check:-------------->
Hot start
Switch to manual mode and check if problem persists: If yes, check:------------->
If no, check:-------------->
PT6T-3/-6
PROBABLE CAUSE Air in system (from newly installed units).
FIX Try to restart or purge fuel system by removing line to flow divider and motoring (wet) engine.
Flow divider malfunction
Replace flow divider
MFCU
Disconnect MFCU outlet tube to flow divider and check for fuel flow while motoring.
Fuel nozzle restrictions
Perform functional check on nozzles
Leak or restriction in P3 line or blocked P3 filter Leak in Py or Pg. Lines/accumulators Insufficient starter assist
Check P3 filter, filter valve and tubes for restrictions and tube nuts for tightness. Perform pressure test of pneumatic lines Do not select fuel "ON" unless N1 reaches a minimum of 12% Insure that starter-generator provides sufficient cranking speed. Check Battery / Starter-generator.
Location of nozzles (after maintenance) (Not on PT6T-3D’s)
Ensure primary and secondary nozzles are correctly positioned.
Flow divider secondary valve stuck open
Replace flow divider
Fuel nozzle restrictions
Perform functional check on the nozzles.
MFCU AFCU
Replace Replace
TRAINING USE ONLY
FUEL SYSTEM 9.40
FUEL SYSTEM TROUBLESHOOTING SYMPTOMS Surge during acceleration
PROBABLE CAUSE Compressor bleed valve
FIX Check closing point (secondary orifice).
AFCU
Verify acceleration time and adjust dome if required.
Compressor FOD
Examine compressor blades for condition
Dirty compressor Perform compressor wash Uncontrolled acceleration Sheared or missing coupling between pump and Install or replace coupling AFCU
Power section is slow to accelerate in Automatic Mode only
AFCU Leaks in P3, Py or Pg. Lines/accumulators
Replace AFCU Perform pressure test of pneumatic lines
P3 filter restricted
Inspect filter for restriction. Clean or change as required.
P3 filter check valve (Post SB 5309) leaking
Inspect P3 filter check valve, perform acceleration check Ensure MFCU is at idle setting: approx. 35° on quadrant. Adjust A/C linkage as required.
Idle speeds incorrect Too high
Incorrect control linkage rigging.
Too low (N1 45-48%)
P3 restriction or leaks
Check all tubes and P3 filter for restrictions and tube connections for tightness. Check P3 elbow gasket for leakage. Check P3 line for cracks (at P3 filter attachment)
Leaks in P3, Py or Pg. Lines/accumulators
Perform pressure test of pneumatic lines
AFCU
Replace AFCU
PT6T-3/-6
TRAINING USE ONLY
FUEL SYSTEM 9.41
FUEL SYSTEM TROUBLESHOOTING SYMPTOMS N1 overspeed
Leakage out of fuel pump drain Inability to switch from automatic to manual mode Excessive "popping" sound during transfer from automatic to manual mode
PROBABLE CAUSE
FIX
AFCU drive coupling
Check for sheared or missing drive coupling.
AFCU Fuel pump to AFCU interface or Fuel pump carbon seals A/F power supply or solenoid valve
Replace AFCU If leak has a blue tint replace AFCU & pump if no tint change pump only Check airframe 28v supply at solenoid valve.
Improper transfer procedure
Ensure to roll back to ground-idle before switching over. Adjust as necessary
Improper rigging between AFCU and MFCU Repair or replace unit Rumbling noise
Flame-out on rapid deceleration from Flight-Idle to Ground Idle Torque split
PT6T-3/-6
Seized or damaged surge accumulator Compressor bleed valve
Check/replace bleed valve
Fuel surge accumulator Fuel surge accumulator
Inspect-replace is found defective Inspect-replace is found defective
Indication system
Check indicating system, torque transducers
P3,Py or Pg leaks
Perform pressure test of pneumatic lines
N2 governors
Check rigging/replace N2 governor
TCU
Check/replace TCU if necessary
Fuel Heater
Perform touch test. After shutdown, the Fuel Pump Filter housing should be comfortable to touch. If too hot to touch, replace Fuel Heater (max temperature 60°C or 140°).
RGB (torque meter on low side)
Replace torque meter seals
TRAINING USE ONLY
FUEL SYSTEM 9.42
FUEL SYSTEM TROUBLESHOOTING SYMPTOMS Fluctuations of Torque, N1and ITT. In flight, Switch to manual mode and check: Which engine oscillate and at what N1 speed
No oscillation on either engine in manual mode
At Power Assurance check, Low N1and High ITT
PT6T-3/-6
PROBABLE CAUSE Fuel pump leakage
FIX Verify whether cause is O-ring at mating face between AFCU & pump or fuel pump shaft seal. If O-ring, replace it only. If shaft seal, replace pump and AFCU if blue grease is washed out.
Airframe resonance affecting twist grip
Find problem and correct.
Leaks in P3, Py or Pg. Lines/accumulators
Perform pressure test of pneumatic lines
Fuel pump to AFCU coupling
Inspect/replace coupling
AFCU internal problem
Replace AFCU
Faulty TCU or air in bellows (not on PT6T3BE/3BG/3D’s/6B)
Prime TCU, if problem still persists, replace TCU.
N2 governor
Replace it by new one and check if problem persists.
Compressor bleed valve closing point is around 88-91% : is fluctuation around bleed valve closing point ?
Check bleed valve configuration (lip on piston)
Bleed valve excitation inducing automatic control oscillation Hot section distress
Adjust bleed valve closing point
TRAINING USE ONLY
Carry out borescope inspection. Perform hot section inspection, check for interstage sealing ring leaks, high CT disk tip clearance, bad sealing faces etc.
FUEL SYSTEM 9.43
FUEL SYSTEM TROUBLESHOOTING SYMPTOMS At Power Assurance check, High N1and ITT
Can't get maximum torque (with or without Rotor speed droop) Switch to manual mode and check if problem persists: If no, check:------------->
If yes, check:------------>
PT6T-3/-6
PROBABLE CAUSE Torque system calibration
Calibrate transducer
Compressor dirty
Perform compressor wash.
Compressor bleed valve stuck open
Check compressor bleed valve operation, and closing point
Compressor damage P3 air leaks at flanges and in hot section Torque indication system (airframe)
Check if damage is within limit. If not return engine to O/H shop. Check flanges and fittings for leaks Calibrate transducer and check gauge.
Incorrect control linkage rigging.
Adjust N2 linkages
P3/Pg/Py. line restriction or leaks
Change/clean P3 filter /check valve. Check all P3/Pg/Py lines /accumulators for leaks or blockage
Maximum N1 set too low
Check/adjust as required (max. N1)
AFCU
Replace AFCU
TCU
Check/adjust torque limiter side
MFCU/Fuel pump/Filter/Fuel heater/Fuel nozzles. Compressor bleed valve
Check, replace as necessary
TRAINING USE ONLY
FIX
Check closing point and examine for leaks
FUEL SYSTEM 9.44
MAINTENANCE PRACTICES
PT6T-3/-6
TRAINING USE ONLY
MAINTENANCE PRACTICES 10.1
PERIODIC INSPECTION Frequency 25 Hours 50 Hours or 6 Months*
100 Hours
150 Hours or 6 Months*
150 Hours or 1 Year*
150 Hours
Component Oil Content Exhaust Duct P3 Air Filter P3 Air Filter Drain Valve (post SB 5309) Fuel surge accumulator (pre S.B 5398) Wiring
Tubing (Oil/Fuel/P3/Pg/Py)
Gas Generator Case Output Shaft Seals Inlet Screen Fuel surge accumulator (Post S.B 5398) Fireseals Oil Filter Element AGB/RGB Chip Detectors AFCU
PT6T-3/-6
Nature of inspection Check oil level within 30 minutes of shut down Cracks or distortion Inspect and clean filter element. Inspect and clean drain valve. Perform deceleration check, Inspect visually for distortion Replace if distortions found Check for security of all accessible connections, clamps and brackets and for evidence of wear, chafing, cracks and corrosion. Check resistance of heating element of Pg air tube between pins A & B Resistance must be 20± 1.4 Ohms or 10 ± 0.7 Ohms (post SB 5409) Examine insulation on pneumatic tubes for cuts in outer rubber sheaths. Check all tubing, for security of all accessible connections, clamps and brackets, evidence of wear, chafing, cracks, corrosion and evidence of fuel or oil leaks. Cracks, distortion, corrosion and evidence of overheating. Check for oil leaks. Cleanliness and condition of mesh and rubber seals. Inspect visually. Replace if indicator popped-out Cracks and security of brackets Inspect and clean filter element (electrosonic method). Check for metallic pick-up and clean using lint-free cloth. Check for continuity of electrical circuit when the two poles are shorted together. Check weight lift of magnets. Reject component if no continuity, loose pins or broken potting compound. Check AFCU for bearing wash-out indicated by blue dye (grease and fuel mixed) at AFCU vent hole.
TRAINING USE ONLY
MAINTENANCE PRACTICES 10.2
PERIODIC INSPECTIONS Frequency
Component MFCU Ignition leads
300 Hours or 1 Year* Compressor Inlet Area 300 Hours or 600 Hours
300 Hours
Fuel Nozzles RGB P3 air metering tee fittings Spark Igniters Ignition Exciters Fuel Pump Fuel Filter Fuel Heater
600 Hours
900 Hours or 1 year* 900 Hours or 2 years* 900 Hours
Fuel Pump Fuel Filter Gas Generator Case Fuel nozzle sheaths PT6T3D’s only Flanges and joint faces Oil filter P3 Filter
T5 System Fuel nozzles RGB PT6T-3BE/D’s/6B 2500 Hours * Use whichever comes first. 1200 Hours
PT6T-3/-6
Nature of inspection With fuel system pressurised Inspect MFCU shaft for leaks. Security chafing and wear At the required frequency and whenever condition of inlet screen warrants its removal, check compressor inlet area for corrosion, dirt deposits and erosion and check first-stage blades and vanes. 300 hour in-situ cleaning then 1200 hours removal for inspection. Or 600 hours removal for functional check, inspection and cleaning. Clean and inspect. Cleanliness and condition. Functional check. Security Check for security and fuel leaks. Inspect filter for contamination and damage. Not necessary on helicopters equipped with fuel filter impending bypass indication. Perform touch test. Immediately after shutdown, the Fuel Pump Filter housing should be comfortable to touch. If too hot to touch, replace Fuel Heater (max. temperature 60 °C or 140°F). Inspect pump coupling for fretting corrosion. Replace filter Pre SB 5239 only Dye penetrant check (refer to specific inspections) Inspect fuel nozzle sheaths for wear. Apply silicone grease on all external joint faces, flanges, bolts and studs. Send filter for overhaul Send filter for overhaul Carry out functional check. Detail inspection and spray pattern. (if in-situ cleaning every 300 hours) Inspect clutch assemblies (Ref. Overhaul Manual)
TRAINING USE ONLY
MAINTENANCE PRACTICES 10.3
BORESCOPE INSPECTION General:
Notes:
The borescope is an optical device that enables an operator to perform visual inspection of internal components, such as blades, hot section areas, while an engine remains installed in the airframe.
1. Before using the borescope, study the instruction manual, the borescope assembly and its accessories.
Description: – A pattern-controlled rigid guide tube, a bundle of elongated, 5 mm flexible optical fibres (called fibrescope), a light source and other accessories comprise the required equipment for borescope inspection. – With the use of the borescope, an operator can perform periodic inspection of the following without removal of the engine power section:
2. The borescope is a delicate device; it is considered vulnerable to severe shocks, twisting and pinching. Care and attention must therefore be exercised when handling it to prolong service life. Caution: Heat can severely damage the fiberscope: insertion into the guide tube must be accomplish only after the turbine area of the engine has cooled to 65°C (normal cool down period is a minimum of 40 minutes from shutdown).
1) 2) 3) 4)
1st stage Compressor blades and vanes 3rd stage vanes (through bleed valve port) Compressor turbine blades and shroud segments. Leading and trailing edges of compressor turbine vane ring. 5) Combustion chamber walls. 6) Cooling rings and dome section of the combustion chamber liner.
PT6T-3/-6
TRAINING USE ONLY
MAINTENANCE PRACTICES 10.4
GUIDE TUBE ORIENTATION FUEL MANIFOLD ADAPTER PORT
RIGID GUIDE TUBE
POINT OF ENTRY (REF.)
125
DISTAL TIP
VIEW LOOKING FORWARD
FIBERSCOPE TIP
RELATION BETWEEN POINT OF ENTRY AND DISTAL POINT PT6T-3/-6
TRAINING USE ONLY
MAINTENANCE PRACTICES 10.5
FIRST STAGE BLADE EROSION
FOREIGN OBJECT DAMAGE LEADING EDGE TIP CURL NICK (MATERIAL LOSS) DENT (MATERIAL DISPLACED)
EROSION 0.250 MAXIMUM ACCEPTABLE MATERIAL LOSS FROM EROSION WITHOUT REPAIR LEADING EDGE
0.050 INCH NO FOREIGN OBJECT DAMAGE ALLOWABLE IN ROOT FILLET RADIUS
PT6T-3/-6
TRAINING USE ONLY
MAINTENANCE PRACTICES 10.6
OIL FILTERS PACKING RETAINING RING
TEFLON RING PACKING
COVER OIL FILTER
PLUG ELECTROSONIC CLEANER TANK
PT6T-3/-6
TRAINING USE ONLY
MAINTENANCE PRACTICES 10.7
P3 FILTER CLEANING
P3 AIR FILTER ELEMENT
THROUGH HOLE DO NOT PLUG
PRE SB 5309 PT6T-3/-6
CLEANING SOLVENT
LOW FREQUENCY CLEANER
POST SB 5309 TRAINING USE ONLY
MAINTENANCE PRACTICES 10.8
FUEL PUMP AND FILTER
AREA TO BE OBSERVED INSPECT AT THIS PORT PT6T-3/-6
TRAINING USE ONLY
MAINTENANCE PRACTICES 10.9
LIP SEAL REPLACEMENT
PWC 30046-54
PWC 30046-57
A STARTER GENERATOR DRIVE PAD PWC 30046-52
PWC 30075
SEAL
PWC 300646
PT6T-3/-6
DETAIL "A"
SEAL CARRIER TRAINING USE ONLY
MAINTENANCE PRACTICES10.10
AGB DOUBLE LIP SEAL SEAL
MANDREL
1
ASSEMBLY RAMP
ASSEMBLY RAMP
BLACK LIP
3
APPLY ENGINE OIL ON SEAL OUTER DIAMETER
STOPPER
2
BEIGE LIP
BLACK LIP FACING UP
4
PRESS SEAL INTO CARRIER PUSH SEAL ON SHAFT
VIEW OF SEAL AND ASSEMBLY MANDREL PT6T-3/-6
ALIGN MANDREL
TRAINING USE ONLY
MAINTENANCE PRACTICES10.11
CARBON SEAL REPLACEMENT
PWC30046-52
PWC30675
PWC32 810
STARTER
PT6T-3/-6
PWC30810
PWC50054
PWC50055
OUTPUT SHAFT
TRAINING USE ONLY
MAINTENANCE PRACTICES10.12
FUEL NOZZLE INSPECTION
PT6T-3D's
PT6T-3B's/6's
ACCEPTABLE
NOT ACCEPTABLE
GOOD UNIFORM LIGHT STREAKS ONE OR MORE ONE OR MORE SPRAY QUALITY HEAVY STREAKS VOIDS (20%) MAX
PT6T-3/-6
TRAINING USE ONLY
SKEWNESS
DROOLING
SPITTING
MAINTENANCE PRACTICES10.13
GAS GENERATOR CASE
INSPECT LONGITUDINAL SEAM WELDS
PRE SB 5239
PT6T-3/-6
LOCATION OF STIFFENING PLATES
POST SB 5239
TRAINING USE ONLY
HELICAL SEAM WELDS
POST SB 5249
MAINTENANCE PRACTICES10.14
ENGINE TOOLS SLING
PWC30804 P.T. SLING
PWC30801
PT6T-3/-6
TWIN-PAC STAND
BASE
ADAPTER
PWC30721
PWC34300
PWC30712
P.S.SUPPORT
WRENCH
P.T. SUPPORT
PWC30269
TRAINING USE ONLY
PWC30713
PWC30114-10
MAINTENANCE PRACTICES10.15
HOT SECTION INSPECTION Before carrying a Hot Section Inspection, it is recommended to inspect the first stage compressor blades for FOD, inspect oil filter and chip detectors and carry out a power assurance check. Objectives: After completing this project, using technical publications and required tools, each student will be able to: 1. 2. 3. 4.
Disassemble an engine for a hot section inspection. Perform a hot section inspection Repair or replace any components as required. Grind down compressor turbine shroud segments as required. 5. Reassemble an engine after a hot section inspection. General: The criteria for a hot section inspection are detailed in the maintenance manual and it will be used to perform the hot section inspection; however, the following information is offered as a general guide to improve engine performance. • •
Maintain compressor turbine blade tip clearances close to nominal limit. Improve compressor turbine blade tip clearance by maintaining lug and slot geometry and minimising side clearance of lugs.
PT6T-3/-6
•
Maintain same compressor turbine and power turbine vane ring classes as installed in engine initial build or at last overhaul. • Ensure the following conditions apply: − Interstage sealing ring is in satisfactory condition. − Compressor bleed valve is functioning correctly. − No air leaks in the gas generator case area. − Cracks in the compressor turbine vane ring are within limits. • The following requirements should be maintained by rework of affected components. Rework should be accomplished by hand stoning and lapping on locally manufactured lapping plates. − A sliding fit must exist between the combustion chamber liner and small exit duct. Rework by hand. − Flatness and sealing must exist on flat sealing land between small exit duct and leading edge of compressor turbine vane ring outer ring. Lap using lapping plates to obtain good sliding fit. − Flatness and sealing must exist on flat sealing land between compressor turbine vane ring and lock plate. Lap as required. − A free sliding fit must exist between lugs of compressor turbine vane ring and grooves in no. 2 bearing cover flange. Stone lugs if necessary. − Ensure compressor vane ring does not hang-up in small exit duct. Stone lugs and/or grooves, as necessary
TRAINING USE ONLY
MAINTENANCE PRACTICES10.16
HOT SECTION TOOLS
C.T. HOLDER
DE-CRIMPER
SLEEVE
C.T. HOLDER
CRIMPER
PWC30331
PWC30335
PWC30336
PWC430403
PWC30458
PULLER
PULLER
BASE
GRINDER
GAUGE
PWC32822
PWC32823
PWC32209
PWC37918
PWC32380
PT6T-3/-6
TRAINING USE ONLY
MAINTENANCE PRACTICES10.17
SHROUD SEGMENT TIP CLEARANCE TABLE DATE
NAME AIRCRAFT
ENGINE MODEL
SERIAL NO.
1 9 2 8
3 7
4 6 5
PT6T-3/-6
TRAINING USE ONLY
MAINTENANCE PRACTICES10.18
OPERATIONAL REPORT TABLE UNITED TECHNOLOGIES PRATT & WHITNEY CANADA
Twin-Pac Operational Statistics Engine Monitoring Report P&WC 8046 (09-95)
PRATT & WHITNEY CANADA INC. 1000, Marie-Victorin Longueuil, Quebec Canada, J4G 1A1 Attn: Help Desk 01TC4 Fax: 450-647-2888
Operator :
Address : Aircraft Serial
Date :
Gearbox T.T.
Model
Power Section T.S.N.
Serial Number
Serial
Reg
Total Start
T.S.O.
Remarks
No Flight 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2
C.G.B. O/H Agency :
Total Time
T.B.O. P.S.
1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2
1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2
1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2 1 2
Spare
Status
Maintenance Problems: Contact Name :
PT6T-3/-6
Fax Number :
TRAINING USE ONLY
Submitted By:
MAINTENANCE PRACTICES10.19
NOTES
PT6T-3/-6
TRAINING USE ONLY
MAINTENANCE PRACTICES10.20
