Engine PT6A-60 SERIES. TRAINING MANUAL (2007)

DISCLOSURE

WARNING - PROPRIETARY RIGHTS NOTICE

This document is the property of Pratt & Whitney Canada Corp. “(P&WC)”. You may not possess,

use copy or disclose this document or any information in it, for any purpose, including without

limitation to design, manufacture or repair parts, or obtain FAA or any other government approval

to do so, without P&WC’s express written permission. Neither receipt or possession of this docu-

ment alone, from any source constitutes such permission. Possession, use, copying or disclo-

sure by anyone without P&WC’s express written permission is not authorized and may result in

criminal or civil liability

NOTICE - DISCLOSURE OF INFORMATION

This document contains trade secrets or other confidential information, the further disclosure of

which may be harmful to Pratt & Whitney Canada Corp. if the head of a government agency or

department intends to disclose any of this information, written notice should be given to: the Vice

President - Legal Services, Pratt & Whitney Canada Corp., 1000 Marie Victorin (01BE5), Longueuil,

Quebec J4G 1A1

PRATT & WHITNEY CANADA

The Customer Training Centre, Pratt and Whitney Canada, Longueuil, Quebec, Canada issued this document. This

document is to be used for Training Use 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 this manual, contact the P&WC Customer Training Department, by :

Tel: 1-450-468-7774, Fax: 1-450-468-7824, or Email: customer.training@pwc.ca

P&WC Customer Training course schedule and registration on Internet: http://www.pwccustomertraining.ca

For technical queries, contact the P&WC technical support Customer First Centre (CFC) (24 HOUR SERVICE):

Telephone : (USA & Canada)1-800-268-8000

International Direct Access :1-8000-268-8000

General :1-450-647-8000

Fax :1-450-647-2888

Pratt & Whitney Canada on the Internet : http://www.pwc.ca

TABLE OF CONTENT

PREFACE

COMPRESSOR INLET CASE

2.6-2.7

DISCLOSURE

COMPRESSOR

2.8-2.9

PRATT & WHITNEY CANADA

III-IV

COMPRESSOR WASH

2.10-2.11

TABLE OF CONTENT

V-VIII

COMPRESSOR BLEED VALVE

2.12-2.15

PRE-SWIRL SYSTEM

2.16-2.19

INTRODUCTION

BLEED VALVE CLOSING POINT

2.20-2.23

SCOPE

GAS GENERATOR CASE

2.24

ABBREVIATIONS

GAS GENERATOR CASE / DIFFUSER

2.25

ENGINES COVERED IN THIS MANUAL

XII

COLD SECTION TROUBLESHOOTING

2.26

PT6 GENERAL NOTES

XIII

MAJOR ENGINE DIFFERENCES

XIV-XV

CHAPTER 3 - COMBUSTION & TURBINE

3.1

P&WC PUBLICATIONS

XVI

HOT SECTION

3.2

PUBLICATION STANDARDS

XVII-XVIII

HOT SECTION AREA

3.3

SERVICE BULLETIN COMPLIANCE CODES

XIX

COMBUSTION CHAMBER LINER

& SMALL EXIT DUCT

3.4-3.5

CHAPTER 1 - ENGINE OVERVIEW

1.1

COMPRESSOR TURBINE VANE RING

3.6-3.9

PT6A-61 RIGHT FRONT VIEW

1.2

COMPRESSOR TURBINE

3.10-3.11

PT6A-64 LEFT FRONT VIEW

1.3

COMPRESSOR TURBINE TRIM BALANCING... 3.12

PT6A-60 RIGHT FRONT VIEW

1.4

COMPRESSOR TURBINE

3.13

PT6A-67 LEFT VIEW

1.5

ALTERNATE TRIM WEIGHTS (64/66/67)

3.14

MAJOR ASSEMBLIES AND FLANGES

1.6-1.7

ALTERNATE TRIM WEIGHTS

3.15

FEATURES

1.8

POWER TURBINE VANE RINGS

3.16-3.17

GENERAL TURBOPROP OPERATION

1.10

POWER TURBINES

3.18-3.19

TURBOPROP ENGINE

1.11

TURBINE WASH

3.20-3.21

MAIN ENGINE BEARINGS

1.12

EXHAUST DUCT & PT SHAFT HOUSING

3.22-3.23

BEARINGS

1.13

HOT SECTION SEALING

3.24-3.27

STATIONS

1.14-1.15

HOT SECTION TROUBLESHOOTING

3.28

ENGINE EXTERNAL COMPONENTS

1.16-1.19

CHAPTER 2 - COMPRESSOR SECTION

2.1

COMPRESSOR SECTION

2.2-2.3

INERTIAL SEPARATOR (AIRFRAME)

2.4

INERTIAL SEPARATOR (TYPICAL)

2.5

PT6A-60 SERIES

TRAINING USE ONLY

TABLE OF CONTENT V

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

TABLE OF CONTENT (CONT’D)

CHAPTER 4 - GEARBOXES

4.1

CHAPTER 8 - IGNITION SYSTEM

8.1

REDUCTION GEARBOX

4.2-4.3

IGNITION SYSTEM

8.2-8.3

STANDARD ROTATION REDUCTION GEARBOX4.4

PT6A-66 REVERSE ROTATION GEARBOX

4.5

CHAPTER 9 - PERFORMANCE

9.1-9.2

ACCESSORY GEARBOX

4.6-4.7

ENGINE PERFORMANCE CHECK (TYPICAL)9.3

PIN LOCK ARRANGEMENT

4.8

PERFORMANCE CHECK (SHORTS INSTALL)9.4-9.6

ACCESSORY GEARBOX

4.9

WebECTM

9.7-9.8

ECTM SAMPLE PLOT

9.9

CHAPTER 5 - OIL SYSTEM

5.1-5.7

TBO & HSI INTERVAL

9.10

OIL PRESSURE REGULATION & FILTRATION..

5.8-5.9

OPERATING LIMITS*

9.11-9.18

THERMOSTATIC BYPASS

ROTOR COMPONENTS - SERVICE LIFE

9.19

& CHECK VALVE

5.10-5.11

OVERTORQUE CHART (TYPICAL)

9.20

OIL SYSTEM TROUBLESHOOTING

5.12-5.13

OVERTEMPERATURE CHART (TYPICAL)

9.21

ENGINE TROUBLESHOOTING

9.22

CHAPTER 6 - SECONDARY AIR SYSTEM

6.1-6.3

PERFORMANCE TROUBLESHOOTING

9.23-9.27

ACCESSORY GEARBOX BREATHER

6.4-6.5

OIL TANK PRESSURIZING VALVE

6.6-6.7

CHAPTER 10 - FUEL SYSTEM

10.1

TURBINE COOLING

POWER MANAGEMENT

10.2-10.3

AND AIRBLEED SYSTEM

6.8-6.9

FUEL SYSTEM

10.4-10.6

BEARING COMPARTMENT SEALING

6.10-6.11

FUEL SYSTEM SCHEMATIC

10.7

FUEL HEATER

10.8-10.9

CHAPTER 7 - ENGINE INDICATING SYSTEM ..

7.1-7.3

FUEL PUMP

10.10-10.11

INTER-TURBINE TEMPERATURE (T5)

7.4

FUEL CONTROL UNIT (MAIN FLOW)

10.12-10.13

TEMPERATURE INDICATING SYSTEM (T5)

7.5

FUEL METERING SECTION

10.14-10.15

TEMPERATURE INDICATING SYSTEM (ITT)

7.6

METERING SECTION (3D CAM)

10.16

T5 SYSTEM SCHEMATIC

7.7

FUEL CONTROL SYSTEM

10.17

TORQUE SYSTEM

7.8-7.9

COMPRESSOR DELIVERY AIR LINES

10.18

CHIP DETECTOR

7.10-7.11

P3 AIR FILTER ELEMENT

10.19

FLOW DIVIDER WITH DUMP VALVE

10.20-10.21

FLOW DIVIDER WITH PURGE VALVE

10.22-10.23

FLOW DIVIDER WITH DUMP VALVE

10.20-10.21

PT6A-60 SERIES

TRAINING USE ONLY

TABLE OF CONTENT VI

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

TABLE OF CONTENT (CONT’D)

FLOW DIVIDER WITH PURGE VALVE

10.22-10.23

HOT SECTION TOOLS

12.8-12.9

SIMPLEX FUEL NOZZLES

10.24-10.25

CT TIP CLEARANCE MEASUREMENT

12.10

DUPLEX FUEL NOZZLES

10.26-10.27

HOT SECTION INSPECTION (CONT’D)

12.12

FUEL CONTROL UNIT MANUAL OVERRIDE .10.28

CT BLADE SULPHIDATION

12.13

FCU MANUAL OVERRIDE

10.29

HOT SECTION INSPECTION (CONT’D)

12.14-12.19

POWER RECOVERY SYSTEM

10.30-10.31

OVERTORQUE LIMITER

10.32-10.33

CHAPTER 13 - RIGGING

13.1

FUEL CONTROL UNIT ADJUSTMENT

10.34-10.35

BASIC ENGINE RIGGING

13.2

FUEL SYSTEM

REAR LINKAGE RIGGING

13.3

TROUBLESHOOTING SUMMARY

10.36

WOODWARD FUEL CONTROL RIGGING

13.4

REAR LINKAGE (WOODWARD)

13.5

CHAPTER 11- PROPELLER SYSTEM

11.1-11.3

FRONT LINKAGE RIGGING

13.6

PITCH CHANGE MECHANISM

11.4-11.5

FRONT LINKAGE

13.7

PROPELLER GOVERNOR

FUEL CONDITION LEVER

13.8

GOVERNING MODE

11.6-11.7

FUEL & PROPELLER LEVER RIGGING

13.9

PROPELLER GOVERNOR

11.8

POST RUN UP ADJUSTMENTS

13.10-13.11

BETA MODE (FORWARD OPERATION)

11.9

TWIN ENGINE RIGGING

PROPELLER GOVERNOR

11.10-11.12

TROUBLESHOOTING

13.12

BETA MODE (REVERSE OPERATION)

11.13

POST RUN-UP ADJUSTMENTS

PROPELLER FEATHERING

11.14-11.15

(TWIN ENGINE)

13.13

NF GOVERNOR

11.16-11.17

PROPELLER OVERSPEED GOVERNOR

11.18-11.19

PROPELLER GOVERNOR

ADJUSTMENTS

11.21-11.23

PRIMARY BLADE ANGLE (PBA) CHECK

11.24

PRIMARY BLADE ANGLE CHART

11.25

PROPELLER SYSTEM TROUBLESHOOTING11.26

CHAPTER 12 - MAINTENANCE PRACTICES.12.1

PERIODIC INSPECTION

12.2-12.3

HOT SECTION INSPECTION

12.4

BORESCOPE INSPECTION

12.6

GUIDE TUBE ORIENTATION

12.7

PT6A-60 SERIES

TRAINING USE ONLY

TABLE OF CONTENT VII

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

SCOPE

This training guide contains information pertaining to the

description, operation, maintenance and troubleshooting of

the PT6A-52 /60A / 60AG / 61 / 64 / 65AG / 65AR / 65B /

65R / 66 / 66A / 66B / 66D / 67 / 67A / 67AF / 67AG / 67AF

/ 67AR / 67B / 67D / 67F / 67P /67R engines. This training

guide is intended for training use only and includes cross

section drawings, schematics and text.

A basic understanding of jet engine principle would be an

asset.

This guide may be used for Line Maintenance or Heavy

Maintenance training.

PT6A-60 SERIES

TRAINING USE ONLY

INTRODUCTION X

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

ABBREVIATIONS

Agricultural

Palt

Pressure Altitude

AGB

Accessory Gearbox

Pamb

Ambient Air Pressure

AMM

Airframe Maintenance Manual

PBA

Primary Blade Angle

BOV

Bleed Off Valve

PLA

Power Lever Angle

CCW

Counterclockwise

PPH

Pounds Per Hour

Clockwise

PSI

Pounds Per Square Inch

CSU

Constant Speed Unit (Prop Governor)

PSIA

Pounds Per Square Inch Absolute

Compressor Turbine

PSID

Pounds Per Square Inch Differential

ECTM

Engine Condition Trend Monitoring

PSIG

Pounds Per Square Inch Gage

ESHP

Equivalent Shaft Horsepower

Power Turbine

FCU

Fuel Control Unit

Modified P3, After A Restrictor

Flight Idle (High Idle)

Modified Px, After A Restrictor

FOD

Foreign Object Damage

RGB

Reduction Gearbox

Ground Idle (Low Idle)

S/N

Serial Number

HSI

Hot Section Inspection

Service Bulletin

IAS

Indicated Air Speed

SIL

Service Information Letter

IBR

Integrally Bladed Rotor

SFC

Specific Fuel Consumption

ISA

International Standard Atmosphere

SHP

Shaft Horsepower

ITT

Interturbine Temperature (T5)

T/O

Take-Off

Maintenance Manual

Temperature At Station 5 (ITT)

MOP

Main Oil Pressure

TBO

Time Between Overhaul

MOT

Main Oil Temperature

Torque

Free Turbine Speed

Air Mass Flow

Gas Generator Speed (N1)

Fuel Flow

Propeller Speed (N2)

OAT

Outside Air Temperature

Bold highlights indicate engine parameters

OSG

Overspeed Governor

Bypass Fuel Pressure

Fuel Pump Delivery Pressure

Metered Fuel Pressure

P2.5

Compressor (axial stage) discharge pressure

(station 2.5)

Compressor Discharge Pressure (Station 3)

PT6A-60 SERIES

TRAINING USE ONLY

INTRODUCTION XI

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

ENGINES COVERED IN THIS MANUAL

Weight

Certification

Engine Model

SHP

Aircraft

(Lbs)

Date

PT6A-52

850

430

April 2007

Blackhawk B200GT

PT6A-60A

1050

475

May 1983

Beech KA 300/350

PT6A-60AG

1050

500

May 1995

Air Tractor AT-602, Ayres

PT6A-61

850

429

March 1983

Piper Cheyenne IIIA

PT6A-64

700

472

April 1990

Socata TBM 700

PT6A-65B

1100

495

December 1992

Beech 1900 C

PT6A-65R

1376

496

August 1982

Shorts 360

PT6A-65AG

1300

501

March 1985

Air Tractor AT-602, Ayers Turbo Thrush

PT6A-65AR

1424

501

January 1984

Shorts 360

PT6A-66

850

469 & 483

July 1986

Piaggio Avanti

PT6A-66A

850

456

December 2003

AeroVodochody Ae 270HP

PT6A-66B

850

460

March 2006

Piaggio Avanti II

PT6A-66D

850

458

November 2005

TBM 850

PT6A-67

1200

520

November 1986

Beech Starship

PT6A-67A

1200

520

January 1988

Beech Starship

PT6A-67AG

1350

525

July 1998

Air Tractor AT-802AF

PT6A-67AF

1424

552

November 1987

Conair IMP S-2

PT6A-67B

1200

538

October 1990

Pilatus PC-12

PT6A-67D

1279

534

December 1991

Beech 1900 D

PT6A-67F

1600

550

June 2007

Air Tractor AT-1002

PT6A-67P

1200

550

September 2007

Pilatus PC12 Next Generation

PT6A-67R, A-67AR

1424

534

December 1991

Shorts 360, DC-3 (Conversion)

PT6A-67T

1400

535

November 2000

DHC-4A (Conversion)

PT6A-60 SERIES

TRAINING USE ONLY

INTRODUCTION XII

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

PT6 GENERAL NOTES

Initial Design

1958

First Production Engine (PT6A-6, 550 SHP)... 1963

Engines Delivered

42338*

Hours Accumulated

316 000 000*

Certified Aircraft Applications

128

Different Operators

6724

Different Countries

171

* Numbers Current as of December 2006

The Birth Of Pratt & Whitney Canada:

In June 1927 a Wright-powered Vedette flying boat crashed

in a northern Quebec lake . The RCAF purchased the sea-

plane from the estate of the deceased pilot and installed the

engine on a Douglas seaplane . The performance of the

engine led to an order for additional powerplants , with the

proviso that a Canadian facility be established to service

the U.S. produced engines .

PT6A-60 SERIES

TRAINING USE ONLY

INTRODUCTION XIII

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

MAJOR ENGINE DIFFERENCES

The PT6A Engines Covered In This Manual Are Divided

equipped and connected)

In 4 Groups:

Group 3: PT6A-67, A-67A, A-67R, A-67AF, A-64, and

- PT6A-52, 60A, 60AG, 61

A-66/A/B/D

- PT6A-65B, A-65R, A-65AR, A-65AG

The A-67 engines differ from the A-65 in the following

- PT6A-67, A-67A, A-67AF, A-64, A-66/A/B/D

manner:

- PT6A-67AG, A-67B, A-67D, A-67F and A-67P

- Large compressor diameter for increased mass flow

- Improved compressor turbine blades design

Group 1: PT6A-52, A-60A, A-60AG, and A-61

- Modified compressor turbine vane ring and shroud

PT6A-52: Similar to A-61 with higher ITT at take-off

segments

PT6-A60A: Reference model. Derived from PT6A-42

- Redesigned power turbines

with A-45 type RGB (long RGB).

- Light weight magnesium inlet case instead of

PT6A-60AG: Agricultural version of A-60A. Manual

aluminum

override system on the fuel control unit.

- Light weight magnesium reduction gearbox case

(long RGB).

instead of aluminum for A-67 and A-67A

PT6A-61:

Mechanically similar to A-60 with A-41

- Reinforced reduction gearbox and bearing for A-67R

type RGB (short RGB).

and A-67AF)

- Six engine mount pads instead of four

Group 2: PT6A-65B, A-65R, A-65AR and A-65AG

- Improved fuel control unit design

PT6A-65R: Reference model. Similar to the PT6A-45R

- Larger diameter propeller shaft flange

except for increased compressor airflow

- Electronic oil level indicator

and pressure ratio (additional compressor

- Oil tank with oil level sight glass

stage). Automatic power recovery system

on the fuel control unit.

PT6A-67: Reference model. Derivative of A-65B with

PT6A-65B: Similar to A-65R, no automatic power

10% increased flow and redesigned turbine.

recovery system on the fuel control unit.

PT6A-67A:Mechanically identical to the A-67 but 5%

PT6A-65AR: Similar to A-65R, new fuel control unit,

increase in increase cruise rating. Pusher

longer compressor turbine blades for 4%

application.

increase in thermodynamic power.

PT6A-67R:Mechanically similar to A-67A. Automatic

PT6A-65AG: Hardware derivative of A-65B. Engine

power recovery system on the fuel control

ratings similar to A-65AR. No automatic

unit. Exhaust duct rotated 30º (Shorts only).

power recovery system but a manual

PT6A-67AF:Derivative of A-67R with the automatic

override system on the fuel control unit (if

power recovery system blanked off.

PT6A-60 SERIES

TRAINING USE ONLY

INTRODUCTION XIV

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

MAJOR ENGINE DIFFERENCES (CONTINUED)

Group 3: (continued)

Group 4: PT6A-67AG, A-67B, A-67D, A-67F and A-67P.

The engines from this group include the following design

PT6A-66/B: Mechanically similar to A-67 with reduction

modifications for increase power ratings:

gearbox capable of standard or reverse

rotation (A-61 derivative, 2000 rpm). Flat

- Airflow increased through fine-tuning of the

rated at 850 SHP. Pusher application.

compressor blade airfoil.

PT6A-66D:Silimar to A-66. Single engine application.

- Redesigned compressor turbines blades

Flat rated to 850 shp. Manual override.

- Improved cooling of the compressor turbine vane ring

PT6A-64: Mechanically similar to A-66 with A-61

- Compressible seals in the hot section ("W" and "C"

reduction gearbox (2000 rpm). Manual

seals)

override on the fuel control unit and a torque

- Redesigned no. 1 bearing area

limiter on the reduction gearbox. Flat rated to

- Redesigned reduction gearbox to withstand higher

700 SHP. Single engine application.

torque

PT6A-66A: Mechanically similar to A-64 with A-64

- P3 air seal on flange "C"

reduction gearbox, A-66 propeller governor

- Exhaust case structurally strengthened

unit and A-67AG fuel control unit (manual

override). Flat rated at 850 SHP. Single

PT6A-67AG: Agricultural version of the A-67R. Manual

engine application.

override on the fuel control unit.

PT6A-67B: Mechanically similar to A-67A with

increased capacity reduction gearbox.

Single engine application. Manual

override on fuel control unit, fixed speed

propeller governor. Manual propeller

overspeed governor reset/test function.

Improved durability hot section.

PT6A-67D: Mechanically similar to A-67B with A-67R

reduction gearbox (lighter) and A-67 fuel

control unit.

PT6A-67F: Similar to A-67AG with higher take-off

power and cruise rating.

PT6A-67P: Similar to A-67B with faster climb and

higher cruise speed, A-67A compressor

and AGB backup generator pad.

PT6A-60 SERIES

TRAINING USE ONLY

INTRODUCTION XV

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

P&WC PUBLICATIONS

Pratt and Whitney Canada publish various documents and

Training Manuals

manuals to support all the engines in service. This is a brief

description of the documents:

Training guides are published by the Customer Training

Centre to assist the instructors in class.

Illustrated Parts Catalog (IPC)

Publication Price List

Contain all part numbers and parts history information

along with identifying drawings for an engine series. To be

The publication price list contains the prices of all P&WC

used for ordering parts.

publications and training material available to customers.

For more information on Pratt & Whitney Canada

Maintenance Manual (MM)

publications contact:

The manual defines all the line and heavy maintenance

Supervisor, Publications Distribution

tasks that can be done on the engine as well as various

1000 Marie Victorin

tests and adjustments.

Longueuil, Quebec

Canada J4G 1A1

Service Bulletin (SB)

Telephone: 1-450-647-2705

Fax: 1-450-647-2702

Service bulletins are published to introduce new parts and

E-mail: Publications@pwc.ca

modify existing parts to improve the product.

13XXX series is used for the PT6A-52 / 60A / -61

/ -65.

-14XXX series is used for the PT6A-64 / -66 / -67.

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. They are usually

valid for a 1 year period.

PT6A-60 SERIES

TRAINING USE ONLY

INTRODUCTION XVI

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

PUBLICATION STANDARDS

General:

The engine manuals are published following the ATA 100

revision 15

The engine Maintenance Manual basic chapters and

The engine illustrated parts catalogue (IPC) basic

sections are:

chapters and sections are:

FRONT MATTER (TEMPORARY REVISION, SERVICE

61 - 20

PROPELLER GOVERNING

BULLETIN LIST)

72 - 00

ENGINE (SHIPPING)

INTRODUCTION (TOOLS, CONSUMABLES)

72 - 10

REDUCTION GEARBOX

AIRWORTHINESS LIMITATIONS (LIFE LIMITED PARTS)

72 - 20

AIR INLET

61 - 20

PROPELLER GOVERNING

72 - 30

COMPRESSOR SECTION

70 - 00

STANDARD PRACTICES

72 - 40

COMBUSTION SECTION

71 - 00

POWER PLANT

72 - 50

TURBINE SECTION

72 - 00

ENGINE (GENERAL)

72 - 60

ACCESSORY GEARBOX

72 - 10

REDUCTION GEARBOX

73 - 10

ENGINE FUEL and CONTROL

72 - 20

AIR INLET SECTION

73 - 20

FUEL CONTROLLING

72 - 30

COMPRESSOR SECTION

74 - 10

IGNITION

72 - 40

COMBUSTION SECTION

74 - 20

IGNITION SYSTEM

72 - 50

TURBINE SECTION

75 - 30

AIR

72 - 60

ACCESSORY GEARBOX

76 - 10

ENGINE CONTROLS

73 - 00

ENGINE FUEL AND CONTROL

77 - 20

ENGINE INDICATING SYSTEM

74 - 00

IGNITION SYSTEM

79 - 20

OIL SYSTEM

75 - 00

AIR SYSTEM

76 - 00

ENGINE CONTROLS

77 - 00

ENGINE INDICATING SYSTEM

79 - 00

OIL SYSTEM

Example:

A basic chapter identified as: 72-40-01

Indicates the engine chapter

Indicates the combustion section

Indicates the combustion chamber liner

PT6A-60 SERIES

TRAINING USE ONLY

INTRODUCTION XVII

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

PUBLICATION STANDARDS (CON’T)

Page blocks:

The page block numbers of each chapter are used to separate the subjects within the manual for ease of reference.

The standard page blocks are as follows:

CHAPTER APPLICABILITY

Pages

61-20

70-00

71-00

72-00

All others

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:

In chapter 73-10-05, page 201, you will find the maintenance practices for the fuel manifold and nozzles.

PT6A-60 SERIES

TRAINING USE ONLY

INTRODUCTION XVIII

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

SERVICE BULLETIN COMPLIANCE CODES

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 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 4

Do this SB the first time the engine or module is at a maintenance base that can do the procedures, regard-

less of the scheduled maintenance action or reason for engine removal.

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.

Category 7

Do this SB when the supply of superseded parts is fully used.

Category 8

Do this SB if the operator thinks the change is necessary because of what he knows of the parts history.

Category 9

Spare parts information only. Old and new parts are directly interchangeable and operators can mix old and

new parts.

Category 10 For information purposes only.

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.

PT6A-60 SERIES

TRAINING USE ONLY

INTRODUCTION XIX

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

FEATURES

Modules:

Reduction Gearbox:

- Gas Generator

- 2 stage planetary reduction

- Power Section

- Built-in hydro-mechanical torque measurement sys-

tem.

Main Components:

- Reduce the power turbine speed to a speed suitable

for propeller operation.

Accessory Gearbox:

- Driven by the compressor

Engine Control System:

- Provide drives for engine and aircraft accessories

- Variable speed propeller

- Reverse thrust capability

Compressor:

- Hydro-pneumatic fuel control unit

- 3 or 4 axial stages plus 1 centrifugal impeller.

- Fuel control with manual override *

- Provides the necessary air mass flow at the required

- Reserve power capability *

pressure to sustain combustion and cool hot section

- Two or Three lever power management *

components.

- Torque limiting device *

Combustion Chamber:

* Applicable to certain models only.

- Annular type

- Reverse flow (shortens engine)

References:

- Provides an area for combustion of the air-fuel mixture

Rated power

700 to 1650 SHP

Max. air mass flow

10.22 to 11.21 lbs./sec

Compressor Turbine:

Max. compressor P/R

9:1 to 12:1

- Single stage (CCW rotation)

Specific fuel consumption

509 to .680 LB/ESHP/hr

- Recuperate power to drive the compressor

Power Turbines:

- 2 stage turbine (CW rotation)

- Independent from the compressor turbine (free tur-

bine)

- Extract energy to turn the propeller

PT6A-60 SERIES

TRAINING USE ONLY

ENGINE OVERVIEW 1.8

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

GENERAL TURBOPROP OPERATION

The PT6 is a lightweight turbine engine driving a propeller

The hot expanding gases accelerate through the compres-

via a two-stage reduction gearbox. Two major rotating

sor turbine vane ring and cause the compressor turbine to

assemblies compose the heart of the engine. The first is

rotate (which rotates the compressor (approx. 39,000 rpm)).

the compressor and the compressor turbine (compressor

The expanding gases travel across the 1st and 2nd stage

section) and secondly, the two power turbines and the

power turbines which provides rotational energy to drive the

power turbine shaft (power section). The two rotors are not

propeller shaft. The reduction gearbox reduces the power

connected and rotate at different speeds and in opposite

turbine speed (30,000 rpm approx.) to one suitable for pro-

directions. This design is referred to as a "Free Turbine

peller operation (1700/2000 rpm).

Engine” and has certain advantages:

Gases leaving the power turbines are expelled to the atmo-

- Np independent of Ng.

sphere by the exhaust duct.

- Lower Starter cranking torque

- Modular design concept

Engine shutdown is accomplished by shutting off fuel going

- On-wing maintenance (Hot Section Inspection.)

to the combustion chamber.

The compressor draws air into the engine via an annular

An integral oil tank located in the rear section of the inlet

plenum chamber (inlet case), air pressure increases across

case and the accessory gearbox provides oil to bearings

3 or 4 axial stages and one centrifugal stage and is then

and other various systems, such as propeller and torque

directed to the combustion chamber.

systems.

Air enters the combustion chamber via small holes. At the

A Woodward Governor Co. fuel control unit mounted on the

correct compressor speed, fuel is introduced into the com-

accessory gearbox regulates fuel flow to the fuel nozzles in

bustion chamber via 14 fuel nozzles. Two spark igniters

response to power requirements and flight conditions.

located in the combustion chamber ignite the mixture. The

hot gases generated by the combustion are then directed to

The propeller governor mounted on the reduction gearbox,

the turbine area.

controls the speed of the propeller by varying blade angle,

depending on power requirements, pilot speed selection

At this point, ignition is turned off since a continuous flame

and flight conditions.

now exists in the combustion chamber.

PT6A-60 SERIES

TRAINING USE ONLY

ENGINE OVERVIEW 1.10

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

MAIN ENGINE BEARINGS

Function:

Operation:

- The ball bearings withstand the following thrusts:

To support major rotating assemblies and minimize friction.

- No. 1 bearing: Compressor thrust (rearward)

- No. 4 bearing: Power turbine thrust (forward)

Ball Bearings:

- No. 6 bearing: Propeller thrust (forward)

- Bearing nos. 2, 3, 5 and 7 are roller bearings

Support axial and radial loads.

- They support radial loading and permit axial rotor

movement caused by thermal expansion

Roller Bearings:

- Bearings are pressure lubricated and cavities are

drained by scavenge pumps

Support radial load only and allows for thermal expansion.

- No. 1 bearing is gravity drained

Rotating Assemblies And Their Supporting Bearings:

Maintenance:

- None at field level

- Inspect oil filter, chip detector

- Keep oil pressure within tolerances

Propeller Shaft

Power Turbine

Compressor

No 5: roller

No 3: roller

No 1: ball

No 6: ball

No 4: ball

No 2: roller

No 7: roller

Note:

Smaller Reduction Gearboxes (PT6A-52/-60/-61/-64 and

-66) do not require a No. 7 bearing.

PT6A-60 SERIES

TRAINING USE ONLY

ENGINE OVERVIEW 1.12

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

ENGINE EXTERNAL COMPONENTS

Reversing Cable

T5 Harness

T1 Trim Resistor (Trim Stick)

Decal Patents Designation

Cam Box (Reversing)

Oil Return From Airframe Cooler

Overboard Breather Discharge

Oil Dipstick - (Electrical A-67B)

Starter/Generator Pad

10.

Fuel Control Unit

11.

Oil To Airframe Cooler

12.

Fuel Pump

13.

Oil To Fuel Heater

14.

Oil Pressure Tapping

15.

P3 Air Filter

16.

Oil Filter Cover

17.

P3 Air Delivery Tube To Fuel Control Unit

18.

Bleed Valve

19.

Main Oil Pressure Line

20.

Propeller Tach-Generator Pad

21.

Data Plate Gas-Generator (Engine)

22.

Plate Instructions, Gas Generator

PT6A-60 SERIES

TRAINING USE ONLY

ENGINE OVERVIEW 1.16

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

ENGINE EXTERNAL COMPONENTS

Inlet Screen

P2.5 Cabin Bleed

Fireseal - Front

Fuel Nozzle Adapter

Py Air Line

Data Plate - Power Section

Propeller Governor (CSU)

Propeller Shaft

Propeller Overspeed Governor Pad

10.

Torque Oil Pressure Port

11.

Chip Detector

12.

Igniter Plug

13.

Engine Mount Pad

14.

P3 Cabin Bleed Port

15.

Oil Scavenge Tubes

16.

Ignition Cables

17.

Exciter Box

18.

Wash Spray Ring

19.

Oil Level Sightglass

20.

Rear Fireseal

21.

Oil From Airframe Cooler

PT6A-60 SERIES

TRAINING USE ONLY

ENGINE OVERVIEW 1.18

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

COMPRESSOR SECTION

Function:

Compressor Air Is Used For The Following:

- Supplies the required mass of air at the right pressure

- Sustain combustion in order to produce the energy

to the combustion chamber and all the supporting sys-

required to drive the compressor and the power sec-

tems

tion (propeller)

- Transmits the rotational energy from the compressor

- Provide cooling air for hot section components

turbine to drive the accessories mounted on the acces-

- Provide air to seal bearing cavities

sory gearbox

- Assist in the operation of the fuel control unit

- Controls bleed valve operation

- Provides heating and pressurization for cabin use

Subjects Covered:

- De-ice various airframe components

- Inertial separator (airframe)

- Inlet case

- Compressor assembly

- Bleed valve

- Pre-swirl system (jet flap piccolo inlet)

- Gas generator case

- Cold section cleaning

Operation:

The compressor draws air into the engine and compresses

it before delivery to the combustion chamber area.

PT6A-60 SERIES

TRAINING USE ONLY

COMPRESSOR SECTION 2.2

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

INERTIAL SEPARATOR (AIRFRAME)

Function:

Protects the engine from ingesting foreign objects such as

When carrying-out a performance check, always assure

stones, ice, sand, snow, rain, etc.

that the inertial separator doors are in the CLOSED posi-

tion. Inertial separator doors left in the open position will

cause an increase in Ng, ITT and Wf which could be

Operation:

interpreted as a deteriorated compressor.

Deployment of the inertial separator to the bypass (icing)

position forces air in the nacelle to execute a sharp turn

before entering the engine. Water droplets, ice crystals or

snow, because of their inertia, tend to maintain their original

high velocity path and are discharged overboard through

the separator bypass duct.

Note:

The inertial separator is an airframe-supplied item. Not

using the inertial separator in icing conditions could result in

costly damage to the compressor blades. Ensure separator

operates freely. Erratic movement of the separator vane

may cause engine parameter fluctuation. For specific main-

tenance action, refer to the Airframe Maintenance Manual.

PT6A-60 SERIES

TRAINING USE ONLY

COMPRESSOR SECTION 2.4

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

COMPRESSOR INLET CASE

Function:

Maintenance:

- Directs air into the compressor

- Inspect inlet screen for damage and cleanliness. Wire

- Support no. 1 bearing

mesh damage is not acceptable

- Forms the oil tank

- Inspect inlet screen rubber sealing rims for damage

- Piccolo holes in hollow struts generate pre-swirl

- Inspect inlet case for cracks in the strut area

- Sight glass on left side of case allows for quick oil level

- Cracks are not acceptable on Inlet Case

check (not on A-60/61/65)

- Inlet screen (1/4 inch mesh) prevents objects from

entering the compressor

Construction:

- One piece magnesium casting

- External surfaces painted with epoxy paint

Operation:

The annular configuration of the PT6 inlet case facilitates

the protection against Foreign Object Damage (FOD).

Because the compressor rotor intake is not in line with the

flight path, the incoming air makes a sharp turn before

entering the inlet case. This configuration is combined with

the inertial separator for maximum protection against FOD.

Piccolo holes in the inlet case strut change the direction of

incoming air at the face of the compressor rotor. Inlet case

strut anti-icing is provided by heat conduction from the oil

contained in the tank.

PT6A-60 SERIES

TRAINING USE ONLY

COMPRESSOR SECTION 2.6

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

COMPRESSOR

Function:

Compression Ratios:

- Provides the combustion chamber with the correct air-

flow at the required pressure

52, 60A,61

9.0

- The number 1 bearing supports the rear end of the

compressor

64, 65, 66, 67

12.1

- The flexible housing transforms compressor vibrations

Operation:

Construction:

Axial stage accelerates the air, which is then decelerated

A-52/60/61:

through divergent stator vanes, thus increasing the air pres-

- Three axial rotors and a centrifugal impeller

sure. The same process is repeated throughout all the com-

- Early engines used assembly of disks and blades for

pressor stages.

all 3 axial stages

The dynamic pressure (air velocity) generated by the cen-

- SB 13093, introduces integral bladed rotor (IBR) on

trifugal impeller speed is transformed into static pressure by

1st. stage only

the diffuser pipes divergent shape which reduces the air

speed and increases the compressor discharge pressure

A-65’s:

(P3).

- Four axial (blade & hub) rotors and a centrifugal impel-

Nos. 1 and 2 bearings support the compressor rotor. The

ler.

IBR root forms the inner gas path profile; the stator vanes

- SB 13017 Introduces 1^st stage IBR.

form the outer gas path wall.

- SB 13140 Introduces 4 stages of IBR’s.

The no. 1 bearing is supported by the compressor inlet

case via a flexible housing. Compressor unbalance caused

A-64. 66 & 67:

by normal engine wear produces vibrations that are trans-

- Four IBR type axial rotors and a centrifugal impeller

formed by the number 1 bearing flexible housing, reducing

vibrations transmitted to the engine mounts and aircraft.

Stator vanes are mounted after each axial rotor. Rotating

components are made of titanium and are held in place with

Maintenance:

tie rods that extend through the compressor stages.

- Check first stage blades for FOD every time the inlet

Maximum compressor speed 39,000 rpm (104%).

screen is removed

- Blending is recommended to prevent cracks from

developing on the leading edge of the blades

- Refer to the Engine Maintenance Manual for accept-

able blade damage and blending limits

- Do compressor Wash at regular intervals

PT6A-60 SERIES

TRAINING USE ONLY

COMPRESSOR SECTION 2.8

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

COMPRESSOR WASH

Function:

- Remove salt and dirt deposits from the compressor

After Wash Procedure:

gas path

- Reconnect P3 line to the FCU

- Promote parts life and reduce potential overhaul costs

Special Procedure:

- If isopropyl alcohol or kerosene was used in the

Type Of Washes:

cleaning solution perform a dry motoring run before

- Desalination wash

starting the engine to avoid a hot start.

- Performance recovery wash

- Ref. M/M 71-00-00

Desalination Wash:

- Recommended when operating in a salt laden atmo-

sphere

Method:

- Use drinking water with low mineral content

- Motoring wash

- De-mineralized water is recommended

- Refer to the Engine Maintenance Manual for washing

mixtures preparation and procedures

Performance Recovery Wash:

- Recommended every 100 - 200 hr based on the flying

environment

Prior To Washing, Make Sure That:

- Water based detergents are used to remove stubborn

- 40 minutes minimum cooling period

dirt deposits which cannot be removed using water

- P3 line going to the FCU is removed*

only

- Cabin bleed is off

- Solution is injected into the compressor using the

- No power extraction

wash ring mounted over the inlet screen

- Follow starter limitations

- At OAT below 2 °C (36 °F), isopropyl alcohol must be

- Ensure removal of exhaust duct drain plug if installed

added to the water to prevent freezing

* Not applicable if post SB 13175/14054 (P3 filter bowl drain valve)

- Allow 15-20 minute soaking period

- Perform two rinse cycles (water)

PT6A-60 SERIES

TRAINING USE ONLY

COMPRESSOR SECTION 2.10

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

COMPRESSOR BLEED VALVE (64/65/66/67)

Function:

Px pressure depends on the restriction at the outlet of the

cavity where it is drawn. This restriction is controlled by the

Prevents compressor stall at low Ng.

inside diameter of the compressor turbine stator air seal

(baffle). SB14117 introduces a classified stator air seal on

Construction:

certain engine models to improve control of Px pressure.

- Non-flowing type

Some late A-65 models also incorporate a classified stator

- A piston slides on a guide pin inside a housing

air seal. ( SB 13108 & SB 13311 )

- Seal rings on the piston minimize Px leak

- A classified seat controls the closing point (Ng) of the

The surface area on which P2.5 pushes depends on the

bleed valve

inside diameter of the bleed valve classified seat. Different

classes of seats are available for bleed valve closing point

Operation:

adjustment.

Two forces act on the bleed valve piston. Px air pressure

pushes to close the bleed valve and P2.5 air pressure, from

Maintenance:

the inter-stage compressor area, pushes to open it. Px is

- Check for evidence of air losses at sealing faces and

derived from P3 air. P3 passes through a restriction when it

mating surface

flows between the no. 2 bearing housing and the no. 2 bear-

- Check valve seat/piston for damage

ing cover. At low power setting, Px is lower than P2.5 keep-

- Check free movement of piston

ing the bleed valve open. In this position, P2.5 air is directed

- Bleed valve closing point

into the plenum chamber and into the inlet case struts.

- Retain classified seat when replacing bleed valve

When the compressor speed increases, Px rises faster than

P2.5, thus increasing the pressure acting on top of the pis-

The piston can fall out of the BOV assembly

ton to gradually close it. The speed (Ng) at which the valve

when the classified seat is removed

closes is a function of 2 variables. One is the Px pressure

and the second is the surface area on which P2.5 air pres-

sure is pushing on the piston.

PT6A-60 SERIES

TRAINING USE ONLY

COMPRESSOR SECTION 2.12

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

COMPRESSOR BLEED VALVE (52/60/61)

Function:

As Ng increases, P3 rises faster than P2.5, thus increasing

the pressure acting on the piston to gradually close it. The

Prevents compressor stall at low Ng

speed (Ng) at which the valve closes is a function of the Pri-

mary and Convergent Divergent orifice sizes. A larger Pri-

Description:

mary orifice requires less Ng speed (less P3 pressure) to

close the valve.

Pressure operated piston sliding on a guide pin. Piston dis-

charges P2.5 to atmosphere at low Ng. speed. A rolling

Maintenance:

diaphragm mounted on the valve piston prevents leakage

- Check for air losses at sealing faces and mating sur-

between P2.5 and the Px chamber.

faces

- Check that piston moves freely

Construction:

- Check seat or piston for damage

- Flowing type

- Pressure check

- A piston slides on a guide pin inside a housing

- Clean orifices

- A flexible diaphragm seals the piston

- Calibrated orifices control the valve closing point (Ng)

Pressure Check:

Operation:

To verify the integrity of the Bleed Valve diaphragm

Two forces act on the bleed valve piston. Modified P3 air

Description:

(Px) pressure pushes to close the valve and P2.5 air pres-

- Remove Bleed valve spring pin

sure, from the inter-stage compressor area, pushes to open

- Seal valve seat on a rubber sheet and secure in posi-

it.

tion

- Remove two plugs on Bleed valves and install appro-

P3 air flows through a primary metering orifice and is

priate equipment as per M/M

directed to the top of the piston and to atmosphere via a

- Apply required pressure to valve and check that leak-

convergent divergent orifice. The bleed valve closing point

age is within limits

occurs, during engine acceleration, when the pressure act-

ing on the valve diaphragm (Px) is sufficient to overcome

the compressor inter-stage pressure (P2.5).

PT6A-60 SERIES

TRAINING USE ONLY

COMPRESSOR SECTION 2.14

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

PRE-SWIRL SYSTEM

Function:

Operation:

- Change the relative angle of attack of the air entering

the compressor

When the bleed valve opens, P2.5 air flows to the plenum

- Improve surge margin at low compressor speed

chamber and to the inlet case hollow struts. The piccolo

holes located on the inlet case struts produce P2.5 air jets

Description:

that cause swirling of the incoming air before it enters the

Hollow inlet case struts with holes

compressor. The swirl is turning in the same direction of

Piccolo holes on most A-64/67

the compressor, which makes it easier to draw in air thus

Slotted holes combined with swing check valve and

increase compressor performance at low Ng.

orifice A-52/60/61, A65AG,AR

Bleed valve

Swing Check Valve:

Bleed valve plenum chamber

Pre-SB13016 A-65 engines use an orifice and a swing

check valve to relieve excess P2.5 air pressure when the

compressor bleed valve opens. The swing check valve is on

the left-hand side of the gas generator on A-65's, or on top

of the bleed valve for A-52/60/61's. The swing check valve

prevents air from entering the plenum chamber at high

power after the bleed valve has closed. Inlet case with Pic-

colo holes can handle all the airflow without a swing check

valve.

Maintenance:

- Check for proper operation of the bleed valve

- Proper installation/sealing of the bleed valve

PT6A-60 SERIES

TRAINING USE ONLY

COMPRESSOR SECTION 2.16

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

BLEED VALVE CLOSING POINT (65/67)

Function:

Note:

If closing point does not fall within the tolerance band, the

To verify at what Ng speed the bleed valve closes.

following adjustments can be made.

- Install higher class seat to raise Ng closing point

Description:

- Install lower class seat to lower Ng closing point

- Replace bleed valve if piston does not move freely

Use the pressure pick-up port located on the P2.5 cabin

bleed adapter.

Bleed Valve Closing Point (64/66):

Operation:

There is no closing point test for these models.

- The pick-up tube connects to a flexible hose in a con-

tainer filled with water

- Bubbles form when the bleed valve opens

- Stabilize engine at ground idle

- Increase Ng until bubbles stop forming

- Record Ng speed (closing point)

- Ensure closing point falls within tolerance band on MM

graph

PT6A-60 SERIES

TRAINING USE ONLY

COMPRESSOR SECTION 2.20

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

BLEED VALVE CLOSING POINT (52/60A/61)

Description:

Closing Point Too HIGH (Ng) ->Install Larger Orifice:

A different closing point test is required for these BOV’s

because these engines are ‘flat rated’ so they can make

If plotted point is above acceptable range with

more power at higher altitudes and temperatures. For this

existing class of metering plug, and falls

reason the BOV is open under most circumstances at low

below acceptable range with next higher class

altitude and temperature (on the ground).

from existing plug, the Final Orifice

(convergent/divergent) must be enlarged.

The closing point is extrapolated in reference to a running

Refer to M/M section 71-00-00 Adjustment/

condition taken as follows:

Test

Remove P2.5 transfer tube from bleed air case and

install adapter using suitable flexible tube. Connect to

a digital pressure gauge.

Record Tam in degree °C, and Pam in In. Hg.

Start engine, let Ng stabilize at ground idle.

Slowly increase power until plenum pressure (PP)

peaks, then starts falling.

Continue to accelerate engine to max. allowable power

Ref. M/M. 71-00-00.

Let engine stabilize for 2 minutes, record Ng and PP

Shut down engine.

Calculate normalized Gas Generator speed and nor-

malized plenum pressure as per M/M. 71-00-00

(Adjustment/Test) to determine the closing point as

per the chart in the MM.

If closing point is above or below acceptable range

replace the primary metering plug with next higher or

lower class as required.

PT6A-60 SERIES

TRAINING USE ONLY

COMPRESSOR SECTION 2.22

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

GAS GENERATOR CASE

Function:

Operation:

Houses and supports various engine components such as

The gas generator case houses the components necessary

#2 brg, compressor assembly, engine mounts, diffuser

for the compression of air and combustion of the fuel/air

pipes.

mixture. The gas generator case contains P3 air pressure.

The diffuser pipes change the high velocity (2000ft/sec) low

Tubes for oil pressure and scavenge to the number 2 bear-

pressure into low velocity (200ft/sec) and high pressure.

ing as well as tapping for P3 air for the operation of the

They also turn the air flow 90° to direct the air to the Com-

bleed valve and fuel control unit are provided inside the gas

bustion Chamber.

generator case.

Description:

Two P3 operated drain valves located at the six o'clock posi-

- Welded assembly of steel alloy machined parts and

tion ensures fuel does not remain in the case after engine

sheet metal

shutdown.

- Diffused aluminized coating

- 21 brazed diffuser pipes

Maintenance:

- Support for the compressor stator parts

- Inspect for cracks and signs of P3 leaks.

- Support for the no. 2 bearing

- Inspect engine mount threaded holes.

- 14 bosses for fuel nozzles

- Inspect diffuser pipes for cracks etc.

- 2 bosses for igniter plugs

- 2 bosses for drain valves

Note:

- 1 boss for P3 air (to FCU)

The A67B & D models have studs instead of bolts to secure

- 1 P2.5 bleed port

the nozzles

- 2 P3 bleed port (A-60/61/65 one)

- Provision for 6 engine mounts (A-60/61/65 four)

PT6A-60 SERIES

TRAINING USE ONLY

COMPRESSOR SECTION 2.24

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

COLD SECTION TROUBLESHOOTING

Problem

Symptoms At Constant Power

Action Required

Restricted inlet screen

Clean and/or remove obstruction

Dirty compressor

Perform compressor wash /revise

schedule

Damaged compressor blades

Blend blades as per Engine

Maintenance Manual. Return to

an approved overhaul facility if

damage is beyond limit.

Bleed valve stuck open or clos-

Ensure P3 is not leaking between

ing at too high Ng

bleed valve and gas generator

case. Replace bleed valve.

P3 leaks

same

Check for external leaks on gas

generator. Verify sealing surfaces

in Hot section at next HSI. Check

engine bleed system.

Excessive loading of starter gen-

down

Replace faulty starter

erator or other AGB mounted

accessories.

Bleed valve closes too soon

Compressor stalls during acceleration at altitude

Replace faulty BOV. Re-check

closing point.

Bleed valve stuck closed

Compressor stalls

Replace bleed valve

Note:

Generally, compressor section problems cause Ng, T5 and Wf to increase. However, the above list of possible problems

includes some that will make the engine react differently.

PT6A-60 SERIES

TRAINING USE ONLY

COMPRESSOR SECTION 2.26

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

HOT SECTION

Description:

Produce and extract energy from the hot expanding gases

to drive the compressor turbine, compressor and AGB

accessories. At the same time, drive the power turbines /

propeller to provide thrust for the aircraft.

Components:

- Combustion chamber

- Compressor turbine vane ring

- Compressor turbine

- Power turbine housing

- Power turbine vane rings

- Power turbines

- Exhaust duct

Operation:

The hot section of the engine is comprised of components

down stream of the compressor. Hot expanding gases

leaving the combustion chamber are directed towards the

compressor turbine blades by the compressor turbine vane

ring and drive the compressor. Gases then travel across

the 1^st stage power turbine vane ring and drive the 1^st stage

power turbine (and again across the 2^nd stages).

Turbine rotation is transmitted to the propeller via the power

turbine shaft and the reduction gearbox. Gases leaving the

power turbine are expelled to the atmosphere through the

exhaust duct. The exhaust gases add some ‘jet thrust’ as a

result of the airframe exhaust stubs.

PT6A-60 SERIES

TRAINING USE ONLY

COMBUSTION & TURBINE 3.2

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

COMBUSTION CHAMBER LINER & SMALL EXIT DUCT

Function:

The combustion chamber forms an envelope that turns the

gas 180°. This configuration permits location of the tur-

Provide an area for the combustion of fuel/air mixture and

bines closer to the compressor and within the combustion

form an envelope that changes the direction of the gas flow

chamber area, thus making the engine shorter and lighter.

180°.

Cooling rings direct P3 air into the combustion chamber,

close to the walls, to form a flame barrier.

Construction:

Maintenance:

- Annular, reverse flow type combustion chamber

- Replace the liners as a set.

- Made of nickel alloy (Inconel) sheet metal

- Check the cooling ring gaps as per MM.

- Ceramic coating on inner walls create a thermal bar-

- Inspect for cracks, burning, buckling repair as per MM.

rier

- 14 fuel nozzle bosses

- 2 spark igniter bosses

Troubleshooting:

- Cooling rings protect the combustion chamber walls

from the flame

Intermittent puffs of black smoke indicate carbon build-up in

the C.C. The fix is to incorporate a liner with more cooling

holes (SB13177/14055) or replace the existing liners with a

Operation:

TDF* liner (SB 14048).

P3 air enters the combustion chamber through holes in the

* Thermal Distribution Factor

inner and outer liners. The shape, size and location of

these holes provide the correct fuel/air ratio for all operating

conditions.

PT6A-60 SERIES

TRAINING USE ONLY

COMBUSTION & TURBINE 3.4

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

COMPRESSOR TURBINE VANE RING

Vane Ring:

Operation:

- Directs and accelerates gases to the compressor tur-

bine at the optimum angle and speed.

The compressor turbine vane ring receives hot gases from

- Convergent vanes change static pressure into velocity

the combustion chamber. The vane airfoil arrangement

- The lug to slot fit determines the radial location of the

converges the air towards the exit, accelerating and chang-

shroud housing and is important for tip clearance con-

ing its direction simultaneously.

trol

Vane ring classes determine the sum of the area in square

Effect Of Vane Area (Class) On T5 And Ng At Constant

inches, of all the openings between the vane trailing edges.

Power:

At assembly, the proper class of vane is selected to ensure

that NG and T5 will be within specified limits. A lower vane

ring class (smaller area) accelerates the air therefore

increases the speed of the compressor turbine and com-

Increase Area

Ng ↓

T5 ↑

pressor (Ng). A higher Ng speed provides more air to the

Decrease Area

Ng ↑

T5 ↓

engine, increasing cooling and lowering T5.

Shroud Housing:

The compressor turbine vane ring is subject to very high

- Supports shroud segments and inter-stage sealing

temperatures. Vane airfoils are cooled with P3 air. After

ring

cooling, air is ejected in the gas path at the vane trailing

- Slots in the shroud housing match with corresponding

edge.

lugs on the vane ring to prevent shroud housing rota-

tion

Shroud segments come in different classes (thickness) to fit

different compressor turbine diameters this maintains the

Shroud Segments:

gap between the compressor turbine blades and the seg-

- Correct class selection and grinding of shroud seg-

ments (tip clearance) within specified limits.

ments provide adequate blade tip clearance and mini-

mize gas leakage. (10 or 20 segments)

Replacement:

- Thickness is classified to fit different compressor tur-

bine outside diameter

Replace with same area as original or within ±0.03 sq.in.

of the original class from the last test. (Ref. SIL PT6A-032)

PT6A-60 SERIES

TRAINING USE ONLY

COMBUSTION & TURBINE 3.6

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

COMPRESSOR TURBINE

Function:

At maximum speed, the compressor rotor turns at approxi-

mately 39,000 rpm (104%), with each blade pulling on the

Extract energy from the hot gases to turn the compressor

disk with a force of approximately one ton (2000 lbs.).

rotor unit.

The turbine is individually balanced on two planes with

detail weights. This feature allows for turbine replacement in

Description:

the field. The PT6A-64/66/67 has detail weights plus trim

- Turbine disk is machined from a nickel alloy.

weights to match the disk to the compressor rotor.

- Blades are cast of a nickel-based alloy and coated with

a sacrificial coating for protection against sulphidation.

- Fir-tree serration’s support turbine blades and allow for

thermal expansion differences between the blades

Engine Type

# Of Blades

and the disk

- Rivets lock the blades onto the disk

A52/60/61/65

- A master spline on the disk ensures reinstallation of

A64 pre SB14118

the compressor turbine in its initial position

A66/67R,A,AF pre SB14061

- PT6A-64/67 blade tip is hollow (pocketed), to reduce

weight and centrifugal pull

A64 post SB14118

A66/67R,A,AF post SB 14061

A66B/D, A67B, D, F, P

Operation:

Expanding gases, accelerated through the vane ring hit the

turbine blades. The energy available in the gases is con-

verted 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 and the accessories. The remain-

ing one third is used to drive the power turbines.

PT6A-60 SERIES

TRAINING USE ONLY

COMBUSTION & TURBINE 3.10

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

COMPRESSOR TURBINE TRIM BALANCING

(64, 66, 67)

Function:

Example:

A residual unbalance remains once the CT is mated with

1st weight -- B 05 L --

the compressor assembly. Adding TRIM weights minimizes

vibration and maintains original compressor rotor balance

B Denotes trim weight class (A,B, C, D, E and G)

during field replacement of the compressor turbine.

Number from 01 to 40 denotes position of first rivet

retaining trim weight from number 1 in direction of J

arrow.

Description:

Denotes weight offset in relation to first hole occu-

- Detail Balancing (PWC approved facilities only)

pied by weight retaining rivet from number 1 in direc-

- Initial balancing of the compressor turbine using detail

tion of arrow.

weights on the two balancing planes

- Trim Balancing

- H Heavy offset

- After initial detail balancing, the compressor turbine is

- L Light offset

re-balanced with the compressor assembly using

- N No offset (weight symmetrical)

trim weights on the same two balancing planes.

Note:

- The data plate indicate the location of the trim weights

- Trim weights are always installed in pairs facing one

another on the two balancing planes.

- Detail weights are installed by approved facilities only

- Trim weights can be installed by the operator

- An Overhaul Shop or Service Center can install the

trim weights when requested by the operator

PT6A-60 SERIES

TRAINING USE ONLY

COMBUSTION & TURBINE 3.12

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

COMPRESSOR TURBINE

TRIM BALANCE WEIGHTS

#1 ALIGNED WITH

C/T DISK REAR FACE

PLANE B

PLANE A

MASTER SPLINE

REAR

FRONT

FACE

C/T DISK FRONT FACE

MANUFACTURED HEADS

LIGHT

ON INSIDE OF RIM, BOTH FACES

OFFSET

HEAVY

OFFSET

DATA PLATE

PERFORMANCE REFERENCE DATA

SHP

NUMBER FROM 01 TO 40 DENOTES POSITION OF

35050

1137

√θ

FIRST RIVET RETAINING TRIM WEIGHT FROM

ITT TRIM

90.2

OHMS

THIRD

NUMBER 1 IN DIRECTION OF ARROW.

COMPRESSOR TURBINE TRIM WEIGHTS

WEIGHT

B 05 L

B 08 H

G 10 N

N/R

G 10 N

ENG. BUILD SPEC.

T.C.

DENOTES WEIGHT OFFSET

H. HEAVY OFFSET

IN RELATION TO FIRST

L. LIGHT OFFSET

DENOTES TRIM WEIGHT CLASS

HOLE OCCUPIED BY WEIGHT

N. NO OFFSET

A CLASS 1 C CLASS 3 E CLASS 5

RETAINING RIVET FROM

(WEIGHT SYMMETRICAL)

B CLASS 2 D CLASS 4 G NO WEIGHT, RIVET ONLY

NUMBER 1 IN DIRECTION OF ARROW

CL1

CL2

CL3

CL4

CL5

PT6A-60 SERIES

TRAINING USE ONLY

COMBUSTION & TURBINE 3.13

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

ALTERNATE TRIM WEIGHTS (64/66/67)

Function:

Starting from hole no. 4 counter clockwise and from hole

no. 7 clockwise (the weights are installed at holes no. 39

Allows the trim balancing to perform even when the trim

and 40 on one side and holes no. 11 and 12 in the other).

weights location as per the data plate is occupied by detail

Alternatively, 2 class # 1 weights can be installed 6 holes

balancing weights.

away or 2 class # 4 weights can be installed 8 holes away.

For cases where class 2 or class 4 weights must be

Description:

installed as alternate trim weights; try to maintain symmetry

by installing one weight with a light offset and the other with

A table in the maintenance manual provides a choice of

a heavy offset.

alternative location to install the trim weights away from the

position marked on the reference data plate when this posi-

tion is occupied by detail balancing weights. The trim

weight is replaced by a pair of weights that are installed on

each side and equidistant from original trim weight location

(ref. data plate)

Example:

On the turbine illustrated below there is a detail weight at

the positions 5 and 6 so the trim weight B 05 L marked on

the data plate cannot be installed (interference at hole no.

5). According to the table, we can replace a “B” type weight

(class 2) by installing two class # 1 (‘A’) weights, 5 holes

away on each side of the detail weight.

PT6A-60 SERIES

TRAINING USE ONLY

COMBUSTION & TURBINE 3.14

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

ALTERNATE TRIM WEIGHTS

NOTE: WHEN A NEW DETAIL WEIGHT OCCUPIES A TRIM WEIGHT ORIGINAL LOCATION

TRIM WEIGHT TABLE

(REF. DATA PLATE), ALTERNATIVE TRIM WEIGHTS MUST BE USED IN PAIRS

ONE EACH SIDE OF AND EQUIDISTANT FROM ORIGINAL TRIM WEIGHT LOCATION

TRIM WEIGHT CLASS

CLASS

SINGLE

(REF. DATA PLATE).

FROM DATA PLATE

RIVET

CL1

ORIGINAL POSITION OF TRIM

WEIGHT (REF. DATA PLATE),

CL1

NOW OCCUPIED BY NEW

DETAIL WEIGHT.

CL1

NUMBER OF HOLES

C/T DISK ASSEMBLY

EACH SIDE OF

CL1

CL2

BALANCING

ORIGINAL TRIM

RIM

WEIGHT LOCATION

CL1

CL2

HOLES

CL1

CL2

CL3

SINGLE

CL1

CL3

CL4

CL5

RIVET

CL3

CL4

HOLES

ALTERNATIVE TRIM WEIGHT LOCATION

DETERMINED USING TRIM WEIGHT TABLE

DATA PLATE

PERFORMANCE REFERENCE DATA

SHP

CT DISK ASSEMBLY TRIM WEIGHTS

35050

1137

√θ

ITT TRIM

90.2

OHMS

COMPRESSOR TURBINE TRIM WEIGHTS

B 05 L

B 08 H

G 10 N

N/R

ENG. BUILD SPEC.

T.C.

PT6A-60 SERIES

TRAINING USE ONLY

COMBUSTION & TURBINE 3.15

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

POWER TURBINE VANE RINGS

Function:

Operation:

- Direct gases to the first and second stage power tur-

bines at the optimum speed and angle

Gases leaving the compressor turbine are accelerated

- Change static pressure into velocity

through the first and second stage vane rings while causing

their respective power turbines to rotate.

First Stage:

- Riveted centre baffle directs air for cooling onto the

The first and second stage vane rings are held in place by

Compressor turbine disk and the power turbines.

lugs fitted in the power turbine housing. The riveted inner

- Exit area of the vane ring is classified.

baffle directs air close to the power and compressor turbine

- Keep with the Gas Generator as a matched set.

disks for cooling. The selection of different vane areas

allows for optimization of Ng vs. T5 during engine test.

Second Stage:

- Inner section supports an abradable seal.

The second stage vane ring supports an abradable seal

- Both vane rings are supported by the Power Turbine

that diverts cooling air to the two adjacent faces of the

Housing.

power turbines.

- A lug to slot arrangement centralizes and prevents

rotation of the two vane rings.

- Not classified

Replacement:

Replace within ±0.1 sq.in. of the original area from the last

Effect Of Vane Ring Class Change At Constant Power:

test. (Ref. SIL PT6A-032)

Increase area

Ng ↑

T5 ↓

Decrease area

Ng ↓

T5 ↑

PT6A-60 SERIES

TRAINING USE ONLY

COMBUSTION & TURBINE 3.16

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

POWER TURBINES

Function:

Operation:

Extract energy from the gases to drive the propeller through

The two power turbines extract the energy necessary to

the reduction gearbox.

drive the propeller.

The rotational energy extracted by the power turbine is

Description:

transmitted to the power turbine shaft through splines on

- Turbine disks are machined from nickel alloy

the second stage turbine hub.

- Coupled together by a lug to slot arrangement

- Fir-tree serration’s in the disks support the blades and

Removal of the power turbines is permissible at field level to

allow for thermal expansion differences between the

replace the second stage vane ring. Balancing of the power

disk and the blades

turbines is done with the power turbine shaft and the num-

- Rivets lock the blades in place

ber 3 and 4 bearings, this is the reason why power turbines

- 2nd stage turbine attaches to the power turbine shaft

are not field replaceable.

via splines

- Power turbine blades are shrouded at the tip to form a

solid rim around blade tips and reduce blade vibration

Maintenance:

To allow for thinner, more efficient airfoil that offsets

- Inspect the 2^nd stage PT blades for cracks. SB 14172

the weight penalty of the shrouded blade tips

Pre SB every 1500 hrs.

To reduce gas leakage at the tip of the blade

Post SB every 4000 hrs.

- No shroud segments, a double knife edge provides

sealing at the blade tip

References:

Max Nf A-52/60/61

30400 rpm

Max Nf A-64

30144 rpm

Max Nf A-66

30400 rpm

Max Nf A-65/67

29930 rpm

PT6A-60 SERIES

TRAINING USE ONLY

COMBUSTION & TURBINE 3.18

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

TURBINE WASH

Function:

Sulphidation:

Remove salt deposits from the turbine section of the engine

Sulphidation is a common name for a type of hot corrosion

to minimize sulphidation of the turbine blades.

which can affect turbine area components.

Sulphidation occurs at engine operating temperatures when

Method:

sodium and sulphur are present. All turbine fuels contain

sulphur in sufficient amounts for this chemical reaction to

Motoring wash with turbine wash nozzle inserted in igniter

occur. Common sources of sodium are seawater, atmo-

port. PT6A-67B/D/F/P’s have a dedicated wash port.

spheric pollutants and volcanic discharge.

Sulphidation attacks the CT blades, but it is not uncommon

Description:

for the CT stator and other non-rotating components to be

affected. It can not be detected by performance run data

The washing medium used is drinkable water. It is recom-

analysis.

mended that this procedure be carried out when operating

in a salt laden atmosphere. It is also recommended to per-

Stage 1: Initial coating deterioration. Slight roughen-

form the turbine wash in conjunction with compressor wash.

ing of the surface caused by some growth and break-

It is essential that the compressor section be washed first

down of the oxide layer. Mechanical integrity is not

(refer to compressor section in this manual).

affected.

Water is injected into the turbine section using a turbine

Stage 2: Initial corrosion. Surface roughness is more

wash nozzle through one igniter port. Ensure that the arrow

marked as oxide layer breakdown continues. Mechani-

sign on the tool tang is pointing towards the reduction gear-

cal integrity is not affected.

box.

Stage 3: Advanced corrosion. Oxidation of the base

material has penetrated to significant depth, with obvi-

The procedure to perform the turbine wash is identical to

ous build-up scale. Mechanical integrity seriously

the compressor desalination wash. Refer to the Engine

affected. Progression to Stage 4 will accelerate.

Maintenance Manual chapter 71 for more details.

Stage 4: Severe corrosion. Deep penetration, large

blisters are apparent. Failure is likely due to loss of

structural material.

PT6A-60 SERIES

TRAINING USE ONLY

COMBUSTION & TURBINE 3.20

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

EXHAUST DUCT & PT SHAFT HOUSING

Exhaust Duct:

- Direct the exhaust gases to ambient atmosphere with

minimum flow restriction

- Welded assembly of heat resistant Nickel alloy sheet

metal

- On the A-67R/A-65AR, the exhaust duct is rotated 30°

to suit the airframe installation (Shorts)

Power Turbine Stator Housing:

- Support the power turbine vane rings, the T5 harness

and thermocouples

- Interfaces with the gas generator section via a seal

ring

Insulation Blanket:

- Minimizes heat transfer between the hot gases and the

reduction gearbox and the power turbine shaft housing

Power Turbine Shaft Housing:

- Support the power turbine shaft

- Forms a cavity for bearing no. 3 and 4

Power Turbine Shaft:

- Supported by bearing no. 3 and 4

- Transmits power turbine speed and torque to the

reduction gearbox via the power turbine shaft coupling

and the reduction gearbox first stage sun gear

PT6A-60 SERIES

TRAINING USE ONLY

COMBUSTION & TURBINE 3.22

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

SEALING OF THE HOT SECTION AREA

(52/60/61/64/65/66/67, A, AF, R)

Function:

Gas sealing in the hot section area is a very important factor affecting hot section life. This section describes the major

sealing surfaces in the hot section and their purposes.

Sealing

Description

Function

Face

Vane ring to small exit duct and shroud housing

Prevent P3 air around the combustion chamber to

leak and bypass the vane ring

Lock plate to vane ring

Prevent P3 leaks from combustion chamber area to

other side of vane ring

Power turbine housing to shroud housing seal

Prevent P3 leaks into P5

First stage PT vane to second stage PT vane

Prevent leaks around the second stage vane ring

PT6A-60 SERIES

TRAINING USE ONLY

COMBUSTION & TURBINE 3.24

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

SEALING OF THE HOT SECTION AREA

(67AG, 67B, D, F, P, T, 66B, 66D)

Function:

Gas sealing in the hot section area is a very important factor affecting hot section life. This section highlight sealing sur-

faces in the hot section and their functions.

Sealing

Description

Function

Face

Lock plate to vane ring

Prevent P3 leaks between combustion chamber

and no. 2 bearing cover area.

Small exit duct to shroud housing

Prevent P3 leaks between combustion chamber

and vane ring top section.

C&D

Vane ring to shroud housing

Forms a chamber for vane ring cooling air.

Power turbine housing to shroud housing seal

Prevent P3 leaks into P5

ring

First stage Power turbine vane to second stage

Prevent leaks around the second stage vane ring.

PT vane

PT6A-60 SERIES

TRAINING USE ONLY

COMBUSTION & TURBINE 3.26

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

HOT SECTION TROUBLESHOOTING

Problem

Symptoms At Constant Power

Action Required

Seal ring leak

Same

Reposition or replace seal ring. Verify

seal ring groove and replace shroud

housing if damaged.

Gas leakage at junction between

Same

Lap sealing faces. Send parts to an

small exit duct and vane ring

approved shop if required to restore

the sealing faces. Replace compress-

ible seals (certain models only)

Burnt CT vane ring (larger throat area)

Down

Replace vane ring

High compressor turbine tip clearance

Down

Replace shroud segments to restore

clearance. Send turbine to overhaul

facility for reblading if necessary.

Eroded compressor turbine blades

Down

Send assembly to an approved facility

for blade replacement.

NOTE:

Hot section problems are all characterized by high T5 and Wf.

Ng usually goes down or remains constant.

PT6A-60 SERIES

TRAINING USE ONLY

COMBUSTION & TURBINE 3.28

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

REDUCTION GEARBOX

Function:

The second stage reduction system is similar to the first

stage but uses five planet gears instead of three. The sec-

Reduce the power turbine speed to a speed suitable for pro-

ond stage gear carrier drives the propeller shaft via splines.

peller operation.

Reverse rotation on the A-66 is achieved by securing the

second stage carrier to the front reduction gear case and

Construction:

allowing the second stage ring gear to rotate.

- Two stage planetary reduction system

- Magnesium front and rear housing

A bevel gear on the propeller shaft provides drive for 3 RGB

mounted accessories:

Reduction Ratios:

1. Propeller Governor (CSU)

2. Propeller Overspeed Governor (A/F)

3. Np Tacho Generator

60A/65/67

A-52/A61/64/66

5.78:1

5.33:1

Maintenance:

1^StStage

- Verify chip detector for metal contamination.

3.04:1

2.83:1

2^nd Stage

- Verify reduction gearbox scavenge strainer for metal

contamination.

Overall ratio

17.58:1

15.10:1

- Replace propeller shaft oil seal if leak is evident.

Max. Np (rpm)

1700

2000

- Replace Np Tach-Gen lip seal on RGB accessory

drives

- Touch-up scratches on prop shaft.

- CSU & OSG gaskets

Operation:

Field repairs are not allowed inside the reduction gear-

box.

The PT6 engines use a planetary type reduction gearbox

system with two stages of reduction. The first stage con-

sists of a sun gear meshing with three planet gears

mounted in a carrier. The three planet gears mesh on the

outside with a ring gear splined into the reduction gearbox

casing. The first stage gear carrier drives the second stage

sun gear through a flexible coupling arrangement. Provi-

sion to measure torque is provided by the first stage reduc-

tion system.

PT6A-60 SERIES

TRAINING USE ONLY

REDUCTION GEARBOX 4.2

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

ACCESSORY GEARBOX

Function:

Construction:

- Two light alloy casings (diaphragm and rear hsg.) sup-

Provides drive pads for engine and airframe accessories

port the drive gears.

such as:

- The casings are bolted together and then to the inlet

- Fuel pump and fuel control unit

case.

- Starter-generator

- The front casing (diaphragm) separates and seals the

- Oil pressure and scavenge pumps

accessory gearbox from the oil tank

- Ng tacho-generator

- Optional aircraft accessories

- Centrifugal breather impeller to separate air from oil in

Maintenance:

the accessory gearbox

- On condition

- Replace accessory drive seals

- Replace air/oil separator carbon seal

Forms a housing and supports the following:

- Replace starter drive gear

- Oil filler neck

- Inspect AGB scavenge pump inlet screen

- Electric/standard dipstick

- Oil filter and housing assembly

- Oil pressure pump

- Oil pressure regulating valve

- Cold oil pressure relief valve

PT6A-60 SERIES

TRAINING USE ONLY

REDUCTION GEARBOX 4.6

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

OIL SYSTEM

Function:

Oil System Flushing:

- Supplies filtered oil to the engine in order to cool, lubri-

- Flush oil system if new type of oil is to be used

cate and clean various components

- Refer to Engine Maintenance Manual for flushing pro-

- Provides oil to the propeller governor to allow propeller

cedure

pitch and speed control.

- Changing from Type II to Type II Third Generation oil

- Provides oil to the torque measurement system

can only be done with new or newly overhauled

engines

Description:

The engine oil system consists of a pressure system, a

Oil Temperature Limits (Typical):

scavenge system and a breather system. The PT6 lubrica-

tion system provides a constant supply of clean oil to the

Starting:

- 40° C min

engine bearings, reduction gears, accessory drives,

Take off:

0° C - 110° C

torquemeter and propeller governor. The oil tank is inte-

Recommend oil temp:

74° C - 80° C

grated in the engine air inlet casing. The oil lubricates and

cools bearings and carries any extraneous matter to the oil

Note:

filter where it is precluded from further circulation. A chip

Refer to engine Maintenance Manual for specific limits.

detector is located on the reduction gearbox to detect metal

particles and warn operators of metal contamination.

Max Oil Consumption:

- 0.3 lb/hr oil consumption

Servicing:

- measured over a 10 hour period

- Use approved synthetic oil listed in SB 13001 and

- (3 lb/10 hr.) (2 lb/10 hr. for A-52/60/61/66)

14001.

- Check oil level within 15-20 minutes after shut down.

- If more than 30 minutes have elapsed before checking

References:

oil level, and dipstick shows oil is needed, run engine

prior to adding oil.

3 lbs

1.5 U.S. qt

- Oil changes required as specified by the Airframe

Oil tank capacity

2.5 U.S. gal

maintenance manual.

Oil tank expansion space

0.7 U.S. gal

- Ensure that oil pressure is within limits (approx. 90-135

Oil tank usable quantity

1.5 U.S. gal

PSIG). Check with NG above 72%.

PT6A-60 SERIES

TRAINING USE ONLY

OIL SYSTEM 5.2

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

OIL SYSTEM

Pressure System:

The accessory gearbox receives oil from the No. 1, 2, 3 and

4 bearings scavenge systems. From there, the oil is routed

Oil is drawn from the oil tank through a gear type pump and

to the fuel heater by the AGB scavenge pump.

is delivered to the oil filter and Pressure Regulating Valve.

At the filter outlet, pressure oil separates into several paths.

From the outlet of the fuel heater, the oil is directed to the

thermostatic bypass valve. Depending on the oil tempera-

The no. 1 bearing and accessory input drive shaft are lubri-

ture, the thermostatic bypass valve directs the oil to either

cated with oil directed through cored passages and transfer

the oil tank or the airframe oil cooler.

tubes. The oil pressure transmitter and the oil temperature

bulb are mounted on ports located on this internal passage.

The oil coming back from the airframe oil cooler gets back

to the tank through an anti-splashing adapter at the top of

A single tube located at the bottom right hand side of the

the tank.

engine, delivers oil to lubricate the no. 2, 3 and 4 bearings,

the reduction gearbox, front accessories and then to the

propeller and torque measurement systems.

Scavenge System:

The scavenge system consist of four gear type pumps

assembled in two double elements. Two pumps are located

inside the accessory gearbox while the other two are

mounted externally at the rear of the accessory gearbox.

No. 1 bearing scavenges into the accessory gearbox by

gravity. No. 2 bearing scavenge through a tube mounted

underneath the engine. At high power a relief valve

mounted on the line near the scavenge pumps allows air/oil

from the bearing cavity to bleed into the accessory gearbox,

preventing flooding of the number 2 bearing cavity.

PT6A-60 SERIES

TRAINING USE ONLY

OIL SYSTEM 5.4

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

OIL SYSTEM (CONT’D)

No. 3 and 4 bearing area scavenge into the accessory

gearbox via a scavenge tube mounted on the left-hand side

of the engine. Oil is scavenged by one of the externally

mounted pumps located at the rear of the accessory

gearbox.

The reduction gearbox and the propeller oil system are

scavenged through an external tube located beside the No.

3 and 4 bearing scavenge tube. The oil is pumped by the

second externally mounted scavenge pump and goes

directly to the airframe oil cooler.

Note:

The PT6A- 64/66/67/67A/AF/AG/B/D/F/P/R scavenge

system differs from the other engines. The No. 2 bearing

scavenge pump sends oil directly to the fuel heater and

diverter valve instead of sending it to the accessory

gearbox. (post SB 14108)

PT6A-60 SERIES

TRAINING USE ONLY

OIL SYSTEM 5.6

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

OIL PRESSURE REGULATION & FILTRATION

Oil Pump:

Filter:

- Gear type

- 15 micron filter with 40 micron internal screen.

- Inlet screen protects the pump

- Clean electro-sonically only (post SB 13412 and

14392 are not cleanable).

- Inspect every 100 hours.

Pressure Regulating Valve:

- Discard at 1000 hours

- Maintains engine oil pressure within specified limits

(90 - 135 PSI) (100 - 135 PSI for PT6A-52/60/61/64

/66).

Filter Bypass Valve:

- When oil pressure increases above the spring tension,

- Bypasses oil if the oil filter becomes restricted

the valve moves up, opening a passage to the inlet of

- Valve opens when pressure inside the oil filter is 24 psi

the pump, thereby limiting the oil pressure

lower than the pump pressure

- Allows oil to flow through the secondary filter and to

engine lubrication system

Cold Oil Pressure Relief Valve:

- At this point, indicated oil pressure is lower than nor-

- Controls excessive pressure build up during cold

mal (24 psid)

weather starting

- When the pressure regulating valve is fully open and

oil pressure keeps increasing, the cold oil valve opens

Maintenance:

to dump more oil back to the pump

- Service oil tank

- The relief valve opens at 160 psid

- Check chip detector for presence of metal

- Maintain oil pressure within limits

- Inspect and clean oil filter

Filter Check Valve:

- Replace oil filter at 1000 hr

- Opens at a 15 psid to allow oil flow to the filter.

- Replace oil if operated above max oil temperature

- Prevents static oil transfer from the oil tank to the pres-

- Min oil pressure @IDLE : 60 psi

sure system and AGB.

- Inspection of the oil filter without draining the oil tank

PT6A-60 SERIES

TRAINING USE ONLY

OIL SYSTEM 5.8

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THERMOSTATIC BYPASS & CHECK VALVE

Function:

The check valve opens when the oil pressure coming from

the fuel heater is higher than the pressure of the scavenge

Bring oil to normal operating temperature faster during first

oil from the reduction gearbox by 5 psi. This allows the oil

few minutes of engine operation.

from the fuel heater to mix with the reduction gearbox scav-

enge oil and go to the airframe before it returns to the tank.

Description:

If the bypass valve fails to open at low oil temperatures then

- Mounted on the inlet case

oil pressure will build up and force the check valve to open.

- Consists of a housing, a thermostatic valve and a

check valve

If the check valve can not open, the relief spring of the ther-

mostatic bypass valve bypasses oil from the fuel heater to

the tank, even if the expansive material is fully expanded, to

Operation:

prevent over pressurization and over loading of the acces-

sory gearbox scavenge pump. A pressure of 40 to 55 PSID

Oil coming out from the fuel heater is directed to the ther-

is necessary to overcome the relief spring.

mostatic bypass and check valve. The thermostatic ele-

ment contracts when the oil is cold. This allows the oil to

return to the tank instead of going to the airframe oil cooler.

Maintenance:

Thermal element can be replaced in the field if defective.

The check valve prevents back flow of the scavenge oil from

Check valve may be lapped in the field.

the reduction gearbox to the tank through the thermostatic

bypass valve. As the oil warms-up, the thermostatic ele-

ment expands to gradually close the bypass valve. It begins

Troubleshooting:

to close when the oil temperature reaches approximately

- Oil taking too long to reach normal operating tempera-

60° C and is fully closed around 72° C. As the bypass valve

ture may be caused by faulty thermostatic element

closes, the oil is forced towards the check valve.

- Oil temperature higher than normal may be caused by

faulty thermostatic valve and/or check valve stuck

closed.

PT6A-60 SERIES

TRAINING USE ONLY

OIL SYSTEM 5.10

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

THERMOSTATIC BYPASS & CHECK VALVE

RETURN FROM COOLER

EXPANSIVE

AGB

THERMOSTATIC

MATERIAL

ELEMENT

OIL OUT

OIL

TO TANK

TANK

RETURN

BYPASS

SPRING

VALVE

OIL

FROM

AGB

FCU

SCAVENGE

RELIEF

FUEL

SPRING

OUT

CHECK

OIL OUT TO

THERMOSTATIC

FUEL IN

FUEL HEATER

VALVE

AIR FRAME COOLER

BYPASS

SCAVENGE OIL

OUT TO COOLER

AIR & OIL MIST

RGB SCAVENGE

AIRCRAFT BOOST FUEL PRESSURE

PT6A-60 SERIES

TRAINING USE ONLY

OIL SYSTEM 5.11

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

OIL SYSTEM TROUBLESHOOTING

Symptoms

Possible Cause And Fix

High Oil Pressure

Check indicating system

Adjust/verify pressure regulating valve.

Low Oil Pressure

Clean/replace oil filter

Check indicating system

Cracked oil pump housing

Adjust pressure regulating valve

Oil Pressure Fluctuation

Check oil level

Check indicating system

Check oil tank pressurizing valve

Replace/Clean pressure regulating valve

High Oil Temperature

Check oil temperature indicating system

Check airframe oil cooler

Check thermostatic bypass and check valve

Check scavenge pump inlet for blocage

PT6A-60 SERIES

TRAINING USE ONLY

OIL SYSTEM 5.12

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

OIL SYSTEM TROUBLESHOOTING (CONT’D))

Symptoms

Possible Cause And Fix

Excessive Oil Discharged From

Oil level kept too high.

Overboard Breather

Verify oil filter check valve (static transfer, blown out during start).

Check O-rings between oil filter housing and inlet case (static transfer)

Verify/replace centrifugal breather carbon seal in accessory gearbox.

Check pressure pump drive seal (static transfer blown out during start).

Check AGB scavenge pump screen for blockage (flooding of AGB).

Excessive Oil Consumption

All of the above.

Check for oil external leaks.

Ensure oil is not transferring into AGB & leaking out of Inlet/BOV.

Check for traces of oil in the exhaust (#3 brg. lab. seal leaking).

Check oil to fuel heater for internal leakage.

Oil Leak From Intake

Check O-ring and Teflon® ring on oil filter housing.

(Oil Transfer To AGB)

Check oil filter check valve for leakage.

Main oil pump lip seal.

Check for broken O-rings in AGB.

Oil Pressure Follows Power Lever

Check Main Oil Pump Housing for correct assembly torque or cracks.

PT6A-60 SERIES

TRAINING USE ONLY

OIL SYSTEM 5.13

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SECONDARY AIR SYSTEM

General:

The secondary air system consists of all the compressor air

that is not used to sustain combustion or for airframe use.

Of all the air entering the engine the combustion process

uses only 25%, 65% cools the combustion gases, the air-

frame uses 5% and the secondary air system uses the

remaining 5%.

The Secondary Air System Provides Pressure Air For:

- Cooling of hot section parts

- Sealing of bearing compartment

- Operates bleed valve and pre-swirl (jet flap)

- Operates fuel purge valve

- Operates fuel control unit (P3 Filter)

Two sources of air used in the secondary air system:

P2.5 Compressor Inter-stage air pressure

P3 Compressor delivery pressure

This Section Is Divided Into 4 Parts:

1. Accessory gearbox breather

2. Oil tank pressurizing valve

3. Turbine cooling

4. Bearing compartment sealing

PT6A-60 SERIES

TRAINING USE ONLY

ENGINE INDICATING 6.2

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ACCESSORY GEARBOX BREATHER

Function:

The relatively oil free breather air flows through the center

of the impeller and out to the atmosphere via a cored pas-

Separates oil particles from air in the accessory gearbox

sage in the accessory gearbox diaphragm.

before discharging overboard.

Maintenance:

Description:

- On condition

- Centrifugal impeller

- Replace carbon seal

- Mounted on the starter generator gear shaft

- Starter generator gearshaft front end is sealed with a

Blocked Or Restricted Breather Hose May:

carbon face seal

- Cause loss of oil through No. 1, 2 and 3 bearing cavi-

ties

- Cause oil leak at flange "G"

Operation:

- Cause accessory drive seals to leak

- Increase oil consumption

Oil and air scavenged from the bearing cavities are directed

- Cause an oil smell in the cabin

to the accessory gearbox. The air/oil combination in the

accessory gearbox causes foaming of the oil. The continu-

ous flow of scavenged air and oil causes the accessory

gearbox to pressurize. Prior to venting the air to the atmo-

sphere, the oil must be separated from the air.

The pressure builds up in the accessory gearbox forces the

air/oil mixture inside the breather impeller. The centrifugal

force imparted by the impeller causes the heavier oil parti-

cles to be ejected back into the accessory gearbox.

PT6A-60 SERIES

TRAINING USE ONLY

ENGINE INDICATING 6.4

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OIL TANK PRESSURIZING VALVE

Function:

The oil tank pressurizing valve maintains air pressure in the

tank 5 to 7 psi above the accessory gearbox pressure. This

Reduces oil pressure fluctuation and oil consumption at

positive pressure applied on the oil reduces pressure fluctu-

high altitude.

ation and oil consumption at altitude.

When static pressure in the tank reaches the specified limit,

Description:

the piston compresses the spring, allowing oil tank air pres-

- Valve seat and spring loaded piston

sure to flow into the accessory gearbox. From the acces-

- Located in the inlet case (oil tank) at the 11 o'clock

sory gearbox, air flows through the centrifugal impeller and

position

out to the atmosphere.

- Maintains the oil tank pressure 5 to 7 psi above acces-

sory gearbox pressure

Troubleshooting:

Operation:

Oil loss through overboard breather tube or the pressurizing

valve being stuck open may cause oil pressure fluctuation

During normal operation, oil scavenge system collects air

at altitude.

and oil from various bearing cavities. The accessory gear-

box breather removes most of the air contained in the oil but

some air remains trapped in the oil.

Maintenance:

- On condition

When air and oil are carried from the cooler to the tank, it

- Remove and inspect valve

causes oil in the tank to foam. Foaming may cause cavita-

- Ensure freedom of movement

tion of the pressure pump and fluctuation of oil pressure at

- Lap piston and seat

high altitude.

As altitude increases, air pressure in the tank drops and

causes air trapped in the oil to expand (foam) and fill the

tank completely. At this point, the excess foam transfers to

the accessory gearbox thus causing an increase in oil loss

through the centrifugal breather.

PT6A-60 SERIES

TRAINING USE ONLY

ENGINE INDICATING 6.6

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TURBINE COOLING AND AIRBLEED SYSTEM

Description:

Internal passages in the engine distribute P3 air to provide

cooling to the combustion chamber turbine and vane rings.

After cooling, the air is evacuated in the gas path.

Using the same distribution passages, P2.5 and P3 air are

provided to the no. 1, 2 and 3 bearing labyrinth seals. Air

flows into the bearing compartments is evacuated via the oil

scavenge system and discharged overboard through the

centrifugal breather impeller located in the accessory gear-

box.

Tapping on the gas generator case provides P2.5 and/or P3

air for external systems such as cabin environmental con-

trol system, de-icing system, door sealing, etc...

Maintenance And Troubleshooting:

- Keep P3 and P2.5 leaks to a minimum

- (performance losses)

- Ensure cooling rings in the combustion chamber are in

satisfactory condition

- Ensure no leak exists on airframe air bleed system

PT6A-60 SERIES

TRAINING USE ONLY

ENGINE INDICATING 6.8

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BEARING COMPARTMENT SEALING

Function:

Possible Cause For Oil Loss Through Labyrinth Seals:

- Lack of air flow through labyrinth seal (Not probable)

Prevents oil from leaking outside the bearing cavities.

- Wear on the knife's edges due to rotor unbalance or

bearing distress

Description:

- Oil coking in the grooves between the knife's edges

- Labyrinth seals

- Flooding of bearing cavity due to malfunction in the oil

- Consists of a multi-grooved ring running within a

scavenge system (most probable)

straight stator ring

- Air pressure fills the air gap between the two parts

Problem Area

Symptom

Operation:

No. 1 Bearing

Oil smell in cabin

Oily bleed valve and compressor

The air seal consists of two separate parts, one stationary

No. 2 Bearing

Oil smell in cabin

and one rotating. One of the two parts has machined

(Rear)

grooves. A small clearance is maintained between the two

parts and air pressure is blowing between them creating a

No. 2 Bearing

Coking around no. 2

high velocity air flow that draws the oil towards the inside of

(Front)

bearing and compressor turbine

the bearing cavity.

area

Possible smoke on start and shut-

down

Maintenance:

- None

No. 3 Bearing

Possible smoke on start and shut-

- During HSI, ensure holes in the number 2 bearing

down

area of gas Generator are not blocked

Oil in exhaust duct

- Keep accessory gearbox breather outlet free of

obstruction

- Do not over service the oil tank

PT6A-60 SERIES

TRAINING USE ONLY

ENGINE INDICATING 6.10

P&WC Proprietary - Disclosure and use subject to the restrictions on page 2 of preface

Engine PT6A-60 SERIES. TRAINING MANUAL (2007) - page 1