P-402.pdf

NAVAL AIR TRAINING COMMAND

NAS CORPUS CHRISTI, TEXAS CNATRA P-402 (Rev. 01-15)

SYSTEMS WORKBOOK,

ENGINEERING, AND TRANSITION

TH-57B/C

HELICOPTER

ADVANCED PHASE

iii

FLIGHT TRAINING INSTRUCTION

FOR

SYSTEMS WORKBOOK TH-57B/C

P-402 iv

LIST OF EFFECTIVE PAGES

Dates of issue for original and changed pages are:

Original...0...15 Sep 99 (this will be the date issued)

Revision1…19 Apr 02

Revision2…28 Feb 07

Change Transmittal…1…30 Sep 08

Revision1…08 Jun 11

Revision2...25 Feb 15

TOTAL NUMBER OF PAGES IN THIS PUBLICATION IS 166 CONSISTING OF THE FOLLOWING:

Page No. Change No. Page No. Change No.

COVER 0 5-24 (blank) 0

LETTER 0 6-1 – 6-10 0

iii – xii 0 6-11 (blank) 0

1-1 – 1-12 0 6-12 0

1-13 (blank) 0 7-1 – 7-10 0

1-14 0 8-1 – 8-8 0

2-1 – 2-26 0 8-9 (blank) 0

2-27 (blank) 0 8-10 0

2-28 – 2-29 0 9-1 – 9-12 0

2-30 (blank) 0 10-1 – 10-10 0

3-1 – 3-10 0 A-1 0

3-11 (blank) 0 A-2 (blank) 0

3-12 0 B-1 – B-2 0

4-1 – 4-16 0

5-1 – 5-17 0

5-18 (blank) 0

5-19 – 5-23 0 v

INTERIM CHANGE SUMMARY

The following Changes have been previously incorporated in this manual:

CHANGE

NUMBER

REMARKS/PURPOSE

The following interim Changes have been incorporated in this Change/Revision:

INTERIM

CHANGE

NUMBER

REMARKS/PURPOSE

ENTERED

BY

DATE

vi

PREFACE

This publication is used for training only and not meant to replace the NATOPS manual. Should a conflict arise, the NATOPS manual will govern. Maintenance personnel should consult current maintenance and overhaul manuals for the latest approved procedures and specifications.

vii

TABLE OF CONTENTS

LIST OF EFFECTIVE PAGES .................................................................................................. iv

INTERIM CHANGE SUMMARY ...............................................................................................v TABLE OF CONTENTS ........................................................................................................... vii TABLE OF FIGURES ...................................................................................................................x

CHAPTER ONE - INTRODUCTION TO THE TH-57 ......................................................... 1-1

100. TERMINAL OBJECTIVE........................................................................................... 1-1

101. ENABLING OBJECTIVES......................................................................................... 1-1

102. TH-57B/C AIRFRAME AND GENERAL CHARACTERISTICS ............................ 1-1

CHAPTER ONE REVIEW QUESTIONS ............................................................................ 1-12 CHAPTER ONE REVIEW ANSWERS ................................................................................ 1-14

CHAPTER TWO - ROLLS-ROYCE 250-C20J TURBOSHAFT ENGINE ........................ 2-1

200. TERMINAL OBJECTIVE........................................................................................... 2-1

201. ENABLING OBJECTIVES......................................................................................... 2-1

202. ROLLS-ROYCE 250-C20J TURBOSHAFT ENGINE, ENGINE OIL SYSTEM,

ENGINE CONTROLS................................................................................................. 2-3

203. COMPRESSOR SECTION ......................................................................................... 2-4

204. COMBUSTION SECTION ......................................................................................... 2-6

205. TURBINE SECTION .................................................................................................. 2-8

206. ACCESSORY GEARBOX ........................................................................................ 2-10

207. ENGINE OIL SYSTEM ............................................................................................ 2-13

208. OIL TANK RESERVOIR.......................................................................................... 2-16

209. ENGINE OIL SYSTEM MONITORS ...................................................................... 2-19

210. ANTI-ICE SYSTEM ................................................................................................. 2-19

211. ENGINE FIRE DETECTOR SYSTEM .................................................................... 2-20

212. ENGINE FAILURE WARNING SYSTEM .............................................................. 2-20

213. ENGINE CONTROLS............................................................................................... 2-21

214. TORQUEMETER ...................................................................................................... 2-23

215. TURBINE OUTLET TEMPERATURE INDICATOR............................................. 2-24

216. GAS PRODUCER TACHOMETER ......................................................................... 2-24

217. DUAL TACHOMETER ............................................................................................ 2-24

218. ENGINE OIL AND PRESSURE GAUGE................................................................ 2-24

CHAPTER TWO REVIEW QUESTIONS ........................................................................... 2-25

CHAPTER TWO REVIEW ANSWERS ............................................................................... 2-28

CHAPTER THREE - FUEL SYSTEM.................................................................................... 3-1

300. TERMINAL OBJECTIVE........................................................................................... 3-1

301. ENABLING OBJECTIVES......................................................................................... 3-1

302. TH-57B/C FUEL SYSTEM ......................................................................................... 3-2

303. AIRFRAME FILTER .................................................................................................. 3-8

CHAPTER THREE REVIEW QUESTIONS ......................................................................... 3-9 CHAPTER THREE REVIEW ANSWERS........................................................................... 3-12 viii

CHAPTER FOUR - TH-57B/C POWER TRAIN................................................................... 4-1

400. TERMINAL OBJECTIVE........................................................................................... 4-1

401. ENABLING OBJECTIVES......................................................................................... 4-1

402. TH-57B/C POWER TRAIN ........................................................................................ 4-2

CHAPTER FOUR REVIEW QUESTIONS .......................................................................... 4-15 CHAPTER FOUR REVIEW ANSWERS ............................................................................. 4-16

CHAPTER FIVE - MAIN ROTOR, TAIL ROTOR, AND FLIGHT

CONTROL SYSTEM ................................................................................................................ 5-1

500. TERMINAL OBJECTIVE........................................................................................... 5-1

501. ENABLING OBJECTIVES......................................................................................... 5-1

502. TH-57 MAIN ROTOR, TAIL ROTOR, AND FLIGHT CONTROL SYSTEMS ...... 5-3

503. THE TH-57 FLIGHT CONTROL SYSTEM ............................................................ 5-11

CHAPTER FIVE REVIEW QUESTIONS. .......................................................................... 5-19 CHAPTER FIVE REVIEW ANSWERS ............................................................................... 5-22

CHAPTER SIX - HYDRAULIC SYSTEM ............................................................................. 6-1

600. TERMINAL OBJECTIVE........................................................................................... 6-1

601. ENABLING OBJECTIVES......................................................................................... 6-1

602. TH-57B/C HYDRAULIC SYSTEM ........................................................................... 6-2

603. FORCE TRIM SYSTEM ............................................................................................. 6-7

CHAPTER SIX REVIEW QUESTIONS ................................................................................ 6-9 CHAPTER SIX REVIEW ANSWERS .................................................................................. 6-12

CHAPTER SEVEN - ENVIRONMENTAL CONTROL SYSTEM ..................................... 7-1

700. TERMINAL OBJECTIVE........................................................................................... 7-1

701. ENABLING OBJECTIVES......................................................................................... 7-1

702. ENVIRONMENTAL CONTROL SYSTEM .............................................................. 7-2

CHAPTER SEVEN REVIEW QUESTIONS .......................................................................... 7-9 CHAPTER SEVEN REVIEW ANSWERS ........................................................................... 7-10

CHAPTER EIGHT - TH-57B ELECTRICAL SYSTEM ...................................................... 8-1

800. TERMINAL OBJECTIVE........................................................................................... 8-1

801. ENABLING OBJECTIVES......................................................................................... 8-1

802. TH-57B ELECTRICAL SYSTEM .............................................................................. 8-2

CHAPTER EIGHT REVIEW QUESTIONS .......................................................................... 8-8

CHAPTER EIGHT REVIEW ANSWERS ........................................................................... 8-10

CHAPTER NINE - TH-57C ELECTRICAL SYSTEM ......................................................... 9-1

900. TERMINAL OBJECTIVE........................................................................................... 9-1

901. ENABLING OBJECTIVES......................................................................................... 9-1

902. TH-57C ELECTRICAL SYSTEM .............................................................................. 9-2

CHAPTER NINE REVIEW QUESTIONS ........................................................................... 9-11 CHAPTER NINE REVIEW ANSWERS............................................................................... 9-12 ix

CHAPTER TEN - THE MINISTAB SYSTEM .................................................................... 10-1 1000. TERMINAL OBJECTIVE..................................................................................... 10-1 1001. ENABLING OBJECTIVES................................................................................... 10-1 1002. THE MINISTAB SYSTEM ................................................................................... 10-2

CHAPTER TEN REVIEW QUESTIONS ............................................................................. 10-9 CHAPTER TEN REVIEW ANSWERS .............................................................................. 10-10

APPENDIX A - GLOSSARY ................................................................................................... A-1 A100. NOT APPLICABLE ............................................................................................... A-1

APPENDIX B - TRAINING SYNOPSIS .................................................................................B-1 B100. ADVANCED PHASE SYNOPSIS .........................................................................B-1 B101. TERMINAL OBJECTIVE.......................................................................................B-1 x

TABLE OF FIGURES

Figure 1-1 Components of the TH-57 ................................................................................. 1-2

Figure 1-2 TH-57 Dimensions .............................................................................................. 1-3 Figure 1-3 Forward Section ................................................................................................. 1-4 Figure 1-4 Landing Gear ..................................................................................................... 1-5 Figure 1-5 Cowling Section .................................................................................................. 1-6 Figure 1-6 Tail Boom Section .............................................................................................. 1-7

Figure 1-7 Cargo Hook Assembly ....................................................................................... 1-8 Figure 1-8 Exterior Lighting ............................................................................................... 1-9

Figure 2-1 Turboshaft Engine ............................................................................................. 2-3 Figure 2-2 Compressor Section ........................................................................................... 2-4

Figure 2-3 Typical Axial Compressor ................................................................................. 2-5

Figure 2-4 Bleed Air Control Valve .................................................................................... 2-5 Figure 2-5 Combustion Section ........................................................................................... 2-6

Figure 2-6 Air Flow Schematic ............................................................................................ 2-7 Figure 2-7 Gas Producer Gear Train ................................................................................. 2-8 Figure 2-8 Power Turbine Gear Train ............................................................................... 2-9

Figure 2-9 Thermocouple Location..................................................................................... 2-9 Figure 2-10 Accessory Gearbox Mounting Pad Locations ............................................... 2-11

Figure 2-11 Accessories Location ........................................................................................ 2-12 Figure 2-12 Engine Oil System ............................................................................................ 2-14 Figure 2-13 Typical Lubrication System Schematic ......................................................... 2-15

Figure 2-14 Engine Oil Reservoir Location ....................................................................... 2-16

Figure 2-15 Oil Filter, Filter Housing, and Pressure Regulating Valve .......................... 2-17

Figure 2-16 Engine Oil System ............................................................................................ 2-18 Figure 2-17 Oil Cooler Fan .................................................................................................. 2-19

Figure 2-18 Anti-Ice System ................................................................................................ 2-20 Figure 2-19 Fuel Control ...................................................................................................... 2-21 Figure 2-20 Pilot’s Collective ............................................................................................... 2-22

Figure 2-21 Droop Compensating and Engine Fuel Controls .......................................... 2-23

Figure 3-1 Fuel System Schematic ...................................................................................... 3-2 Figure 3-2 Fuel Cell .............................................................................................................. 3-3 Figure 3-3 Closed Circuit Fuel Receiver ............................................................................ 3-3

Figure 3-4 Fuel Boost Pumps ............................................................................................... 3-4 Figure 3-5 Boost Pump Schematic ...................................................................................... 3-5

Figure 3-6 Upper and Lower Quantity Indicator Units .................................................... 3-6 Figure 3-7 Fuel Low Level Switch....................................................................................... 3-6

Figure 3-8 Fuel Shutoff Valve.............................................................................................. 3-7 Figure 3-9 Airframe Fuel Filter .......................................................................................... 3-8

Figure 4-1 Power Train System ........................................................................................... 4-2 Figure 4-2 Main Transmission Mounting .......................................................................... 4-3 Figure 4-3 Transmission Assembly ..................................................................................... 4-4 xi

Figure 4-4 Transmission Oil Schematic.............................................................................. 4-5

Figure 4-5 Hydraulic Pump and Nr Tach Generator Mounting ...................................... 4-6 Figure 4-6 Transmission Oil Filter Assembly .................................................................... 4-7

Figure 4-7 Transmission Oil Cooler.................................................................................... 4-8 Figure 4-8 Transmission Chip Detectors and Oil Level Sight Gauge .............................. 4-9 Figure 4-9 Freewheeling Unit ............................................................................................ 4-10 Figure 4-10 Freewheeling Unit ............................................................................................ 4-11 Figure 4-11 Sprags ................................................................................................................ 4-12

Figure 4-12 Engine to Transmission Drive Shaft Assembly ............................................. 4-13 Figure 4-13 Main and Tail Rotor Drive.............................................................................. 4-14

Figure 5-1 Main Rotor ......................................................................................................... 5-3 Figure 5-2 Yoke and Trunnion Assembly .......................................................................... 5-4

Figure 5-3 Yoke ..................................................................................................................... 5-5 Figure 5-4 Blade Grip Assembly ......................................................................................... 5-5

Figure 5-5 Main Rotor Blade ............................................................................................... 5-6

Figure 5-6 Flap Restraint Assembly ................................................................................... 5-6 Figure 5-7 Rotor Brake ........................................................................................................ 5-7 Figure 5-8 Tail Rotor and Gearbox Assembly ................................................................... 5-8

Figure 5-9 Tail Rotor Assembly .......................................................................................... 5-9 Figure 5-10 Yoke Assembly ................................................................................................. 5-10

Figure 5-11 Flight Control System ...................................................................................... 5-11 Figure 5-12 Cyclic Control................................................................................................... 5-12 Figure 5-13 Swashplate Assembly ....................................................................................... 5-13

Figure 5-14 Uni-ball Assembly ............................................................................................ 5-14 Figure 5-15 Swashplate Motion ........................................................................................... 5-14

Figure 5-16 Collective Control ............................................................................................ 5-15 Figure 5-17 Swashplate Assembly ....................................................................................... 5-16

Figure 5-18 Tail Rotor Controls .......................................................................................... 5-17

Figure 6-1 Hydraulic System ............................................................................................... 6-2

Figure 6-2 Power Pack ......................................................................................................... 6-3 Figure 6-3 Hydraulic Filter Assembly ................................................................................ 6-3

Figure 6-4 Hydraulic Pressure Switch ................................................................................ 6-4 Figure 6-5 Hydraulic ON/OFF Control Switch ................................................................. 6-4 Figure 6-6 Hydraulic System Schematic ............................................................................ 6-5

Figure 6-7 Servo Actuator Diagram ................................................................................... 6-6 Figure 6-8 Force Trim .......................................................................................................... 6-7

Figure 6-9 Cyclic Grip .......................................................................................................... 6-8

Figure 7-1 Ram Air Ventilation .......................................................................................... 7-2 Figure 7-2 Louvered Grills .................................................................................................. 7-3 Figure 7-3 ECS Layout......................................................................................................... 7-4 Figure 7-4 Air Conditioner Switch Panel ........................................................................... 7-5 Figure 7-5 Location of Compressor and Condenser Assembly ........................................ 7-5 Figure 7-6 Location of Evaporator and Evaporator Blower ............................................ 7-6 xii

Figure 7-7 Location of Bleed Air Heater ............................................................................ 7-7

Figure 7-8 Major Components of Heater System .............................................................. 7-8

Figure 8-1 Electrical System Schematic ............................................................................. 8-2 Figure 8-2 Battery Installation ............................................................................................ 8-3 Figure 8-3 Battery and External Power Circuit ................................................................ 8-4 Figure 8-4 Generator Installation ....................................................................................... 8-5 Figure 8-5 Electrical Equipment Shelf ............................................................................... 8-6

Figure 9-1 DC System........................................................................................................... 9-2 Figure 9-2 Electrical Control Panel .................................................................................... 9-3 Figure 9-3 Standby Battery ................................................................................................. 9-4 Figure 9-4 Battery Compartment ....................................................................................... 9-5

Figure 9-5 Starter/Generator .............................................................................................. 9-6 Figure 9-6 Pilot’s Collective ................................................................................................. 9-7

Figure 9-7 Equipment Shelf ................................................................................................. 9-8

Figure 9-8 Standby Generator............................................................................................. 9-9

Figure 10-1 Ministab Controller ......................................................................................... 10-2

Figure 10-2 Force Trim and Stab Control Buttons ........................................................... 10-3 Figure 10-3 Electromechanical Actuator ........................................................................... 10-4

Figure 10-4 Ministab and Flight Control System Components ....................................... 10-6

INTRODUCTION TO THE TH-57 1-1

CHAPTER ONE

INTRODUCTION TO THE TH-57

100. TERMINAL OBJECTIVE

Upon completion of this chapter, the student will understand the basic characteristics of the

TH-57 and be able to identify the sections of the airframe, including their associated functions and characteristics.

101. ENABLING OBJECTIVES

1. Describe the basic design characteristics and capabilities of the TH-57 helicopter.

2. Recognize the five major sections of the airframe.

a. Recognize the items associated with the forward section.

b. Identify the components of the landing gear.

c. State the main purpose of the cowling section.

d. State the purpose of the tail boom and identify its associated parts and their functions.

e. Describe the purpose of the vertical fin and state how it provides directional stability and reduces tail rotor loads.

3. Identify the components of the cargo hook assembly with its associated capabilities and limitations.

4. Describe the aircraft lighting system and identify the associated lights, switches, and circuit protection.

5. Identify the seat restraints, doors, and caution panels within its associated capabilities and limitations.

102. TH-57B/C AIRFRAME AND GENERAL CHARACTERISTICS

1. GENERAL

The TH-57 is the Navy’s designation for the Bell 206B Jet Ranger. The TH-57 (Figure 1-1) is a land-based, skid-configured utility type helicopter designed to land and take off from reasonably level terrain. A Rolls-Royce 250-C20J turboshaft engine powers the main rotor, which is used for lift and thrust, and the tail rotor, which is used to counteract torque and provide yaw control. The maximum takeoff gross weight is 3200 pounds. The maximum

CHAPTER ONE SYSTEMS WORKBOOK, ENGINEERING, AND TRANSITION

1-2 INTRODUCTION TO THE TH-57

forward airspeed at sea level on a standard day is 130 kts, maximum sideward airspeed is 25 kts, and maximum rearward airspeed is 15 kts.

Figure 1-1 Components of the TH-57

SYSTEMS WORKBOOK, ENGINEERING, AND TRANSITION CHAPTER ONE

INTRODUCTION TO THE TH-57 1-3

2. DIMENSIONS

Figure 1-2 depicts the principal dimensions of the TH-57. Note the following dimensions:

a. Main rotor diameter

b. Main rotor to ground clearance

c. Main rotor to tail boom clearance

Figure 1-2 TH-57 Dimensions

1-4 INTRODUCTION TO THE TH-57

This concludes our discussion of TH-57 general characteristics.

3. AIRFRAME

The airframe is divided into the following sections:

a. Forward/cabin

b. Landing gear

c. Cowling

d. Tail boom

e. Vertical fin

Forward/Cabin. The forward/cabin section (Figure 1-3) is primarily constructed of aluminum honeycomb covered with either fiberglass or aluminum skin. This type construction provides an excellent weight-to-strength ratio and also helps soundproof the cabin area.

Figure 1-3 Forward Section

INTRODUCTION TO THE TH-57 1-5

Landing gear. The skid type landing gear (Figure 1-4) consists of two aluminum alloy curved cross tubes, two aluminum skid tubes, and a formed steel tail skid. The two curved cross tubes are mounted to the bottom of the forward section by four strap assemblies. The skid tubes have a forward portion curved upward for sliding landings, tow rings for ground towing, and replaceable skid shoes to absorb the wear caused by normal ground contact. Provisions are made for mounting ground handling wheels on the skid tube just forward of the aft cross tube.

Also considered part of the landing gear is the formed steel tail skid. This skid is mounted to the base of the vertical fin and protects the tail rotor from ground contact due to a tail low landing. Furthermore, the tail skid is curved upward to prevent it from embedding in the ground during rearward flight. The tail skid is stressed for loads of 200 pounds downward or

400 pounds upward.

Figure 1-4 Landing Gear

1-6 INTRODUCTION TO THE TH-57

Cowling section. The cowling section (Figure 1-5) streamlines airflow and consists of the forward, induction, engine, and aft fairings. The forward fairing is made of aluminum honeycomb with a fiberglass skin. This fairing reduces sound and vibrations, but primarily streamlines the airflow around the flight controls and transmission. The induction fairing is made of fiberglass to provide weight savings and allow formed compound curves to channel air to the engine. The engine cowling is made of heavy alloyed aluminum and permits access to the engine and engine parts. Finally, we have the aft fairing, which is made of aluminum honeycomb with a fiberglass skin. The aft fairing streamlines the airflow around the engine oil tank and cooler.

Figure 1-5 Cowling Section

INTRODUCTION TO THE TH-57 1-7

Tail boom. The tail boom (Figure 1-6) is mounted to the rear of the forward section, via a mounting pad and four bolts.

Figure 1-6 Tail Boom Section

With the exception of the first ten inches, the tail boom is a very strong and lightweight full monocoque structure of aluminum alloy. The main purpose of the tail boom is to provide an extended support to mount the tail rotor. Other functions include supporting the horizontal stabilizer, vertical fin section, tail rotor drive shaft, and tail rotor gearbox. The horizontal stabilizer is mounted approximately at the midpoint of the tail boom and it is made with a negative camber. This negative camber creates a download on the tail boom, which enables the aircraft to fly at near level attitude during cruise flight.

Vertical Fin. The vertical fin is a semimonocoque construction made of aluminum honeycomb and aluminum skin that provides directional stability and reduced tail rotor loads at cruise airspeed. This is accomplished by mounting the fin with a 5.5º offset from the longitudinal axis. This offset creates a horizontal lift component that assists in countering torque. (The greater the airspeed, the greater the lift.)

1-8 INTRODUCTION TO THE TH-57

4. CARGO HOOK

The cargo hook (Figure 1-7) consists of a frame and hook assembly with electrical and manual release. The cargo hook assembly has a structural weight capacity of 1500 pounds and can be mounted on the new B and C models only.

Figure 1-7 Cargo Hook Assembly

The frame attaches to three mounting points under the aircraft. These mounting points are firmly attached to the main structural frame of the aircraft. The entire assembly is mounted so that weight lifted by the cargo hook is lifted in line with the main rotor mast. This minimizes changes in the aircraft center of gravity caused by picking up an external load.

The cargo hook has three release mechanisms (one electrical and two manual). Once the hook is closed, it remains locked until one of these release mechanisms is activated and a down force is applied on the hook itself. During normal operations, the electrical release switch on either cyclic is used to release the external load. This switch activates a solenoid on the hook assembly that unlocks the hook. The weight of the load then pulls the hook open, and the load is released.

Also in the cockpit is a manual release. This release consists of a “T” handle connected to a cable assembly attached to the hook. Pulling the handle mechanically unlocks the cargo hook and releases the load. The manual release is also called the emergency release because it is used to release a load when the electrical release fails. There is one more mechanical release, and it is located on the hook itself. This release may be used by a ground handler to release a

INTRODUCTION TO THE TH-57 1-9

load; if, the other two releases have failed and cargo must be released to allow the aircraft to land. The two manual releases for the cargo hook are independent systems and will operate at all times, but the electrical release is subject to electrical failure. Power is supplied through a circuit breaker located on the overhead panel. Recall that we said the cargo hook is structurally limited to 1500 pounds; but, that is not necessarily the maximum weight you can lift, it may be much less. Extreme caution and planning must be exercised anytime an external cargo lift is planned, due to aircraft limitations.

5. LIGHTING SYSTEMS

All aircraft light systems (Figure 1-8) are DIRECT CURRENT (DC) powered. Protection is given to the light circuits by circuit breakers and circuit breaker type switches. Aircraft interior lighting is provided for consoles, overhead placard, and instrument panel. These lights are controlled by the instrument light rheostat, located on the overhead console. The instrument light rheostat controls the level of brightness, with an OFF position. The cockpit map lights are located on both sides of the control column. Each light is mounted to the side of the control column and is connected to a power source by an extension cord. Lamp brightness is controlled by a rheostat switch, located on the end of the light. The lens casing may be rotated to focus the beam. A two-position switch (dim-bright) controls brightness of the caution lights. Two high visibility anti-collision lights are mounted on the exterior of the aircraft.

Figure 1-8 Exterior Lighting

One anti-collision light is mounted to the top of the vertical fin and the other is mounted to the bottom of the fuselage, aft of the baggage compartment. Circuit protection and control is provided by the anti-collision light circuit breaker type switch, located on the overhead console.

Position lights consist of a red light on the port end of the horizontal stabilizer, a green light on the starboard end of the stabilizer, and on the extreme end of the tail boom is a white position light. Control of the position light system is accomplished by three switches:

a STEADY/FLASH switch, an ON/OFF position light switch, and the BRIGHT/DIM switch.

1-10 INTRODUCTION TO THE TH-57

A vertical landing light is mounted under the fuselage, aft of the forward cross tube, for illumination of the area beneath the helicopter for hovering operations. The light is controlled by a LDG LT switch, located on the overhead console. The light is fixed in position and is not adjustable from the cockpit. Excessive use of the landing light (ten minutes or more during periods of prolonged hovering or taxiing) may cause overheating with a resultant fire hazard.

An adjustable searchlight is mounted under the fuselage, just aft of the nose, for illumination of the approach area. The light is controlled by two switches on the pilot’s collective head

(Figure 2-20). Circuitry is protected by two circuit breakers, labeled SEARCHLIGHT POWER and SEARCHLIGHT CONT; located on the overhead console. The SEARCH LT switch has

ON, OFF, and STOW positions. The searchlight control switch controls the direction of the searchlight. The light moves left, right, up, or down corresponding to the direction in which the switch is pushed. The light retains the position it is in when the switch is released. When no longer required, the light may be automatically retracted by placing the SEARCH LT switch to

STOW. Once the automatic stow cycle is completed, the switch should be placed in the OFF position.

6. PITOT SYSTEM

The TH-57 Pitot System consists of:

a. Pitot tube Supplies impact air to the airspeed indicator

b. Heater Electric pitot heater installed on pitot tube and serves to prevent ice from obstructing the pitot tube.

c. Static ports Static air pressure for instrument operation is obtained from two static vents located on each side of the fuselage forward of cabin doors.

d. Tubing Pitot static system utilizes steel tubing to connect the pitot tube and static ports

e. Altimeter Senses static pressure from the static ports.

f. VSI Actuated by the rate of the atmospheric pressure change in the instrument and is vented to the static air system.

g. Airspeed indicator Measures the differences between impact air pressure from the pitot tube and static pressure from the static vents.

INTRODUCTION TO THE TH-57 1-11

7. SEAT RESTRAINTS, DOORS, AND CAUTION PANEL

Seat Restraints. Pilot and copilot seats are equipped with a lap safety belt and inertia reel shoulder harness with a manual lock-unlock handle located on the left side of both seats. In the unlocked position, the reel cable will extend to allow the pilot to lean forward; however, the reel will automatically lock when the helo encounters a longitudinal impact and a deceleration force of 2 to 3 Gs.

Doors. Both cockpits are accessed via forward hinged doors that are jettisonable in the event of an emergency landing or are removable during the execution of external lifts.

Caution Panel. The caution panel is located on the instrument panel. Illumination of any of the lights on the caution panel alerts the pilot to a system fault or condition. The caution panel is powered by the common BUS (TH-57B) or ESS #2 BUS (TH-57C) and protected by the

CAUTION LT circuit breaker.

1-12 INTRODUCTION TO THE TH-57

CHAPTER ONE REVIEW QUESTIONS

1. The maximum gross takeoff weight is

a. 2300 pounds. c. 3350 pounds.

b. 3200 pounds. d. 4000 pounds.

2. The main rotor diameter is approximately

a. 22 feet c. 54 feet.

b. 33 feet. d. 60 feet.

3. The vertical fin is offset 5.5 to

a. prevent side slip. c. maintain balanced flight.

b. provide a yaw axis. d. assist in countering torque.

4. Match the items in column one with their associated airframe sections in column two.

a. _____Aft fairing 1. Forward/cabin section

b. _____Skid shoes 2. Landing gear section

c. _____Cross tubes 3. Cowling section

d. _____Induction fairing 4. Tail boom section

e. _____Aft electrical compartment 5. Vertical fin section

f. _____90º gearbox

g. _____Upper cabin deck

h. _____Battery compartment

i. _____5.5º offset

j. _____Horizontal stabilizer

k. _____Tail skid

5. The _____ is made with a _____ camber and creates a download to help maintain a level attitude.

6. The cargo hook has a weight capacity of ___ pounds.

a. 1100 c. 1500

b. 1300 d. 1700

7. All interior lights are controlled by the instrument light rheostat.

a. True b. False

INTRODUCTION TO THE TH-57 1-13

THIS PAGE INTENTIONALLY LEFT BLANK

1-14 INTRODUCTION TO THE TH-57

CHAPTER ONE REVIEW ANSWERS

1. b

2. b

3. d

4. a. 3.

b. 2.

c. 2.

d. 3.

e. 1.

f. 4.

g. 1.

h. 1.

i. 5.

j. 4.

k. 2.

5. Horizontal stabilizer…negative

6. c

7. False

ROLLS-ROYCE 250-C20J TURBOSHAFT ENGINE 2-1

CHAPTER TWO

ROLLS-ROYCE 250-C20J TURBOSHAFT ENGINE

200. TERMINAL OBJECTIVE

Upon completion of this chapter, the student will have a basic understanding of the design features of the Rolls-Royce 250-C20J turboshaft engine, engine oil system, engine controls, and the nomenclature associated with each.

201. ENABLING OBJECTIVES

1. Identify the type of gas turbine engine used in the TH-57.

- State the power output of the 250-C20J engine.

2. Identify the four subassemblies of the engine.

a. Identify the four subassemblies of the compressor.

- State the three functions served by the front support of the compressor and identify how each function is achieved.

b. Describe the compressor used in the 250-C20J engine by identifying the components, types of compression utilized, the number of stages of compression used, and where the components are mounted.

c. State the main purpose of the compressor bleed air system and identify its location.

d. Trace the path of airflow from the air intake through the engine by identifying the components in the proper sequence with respect to flow.

e. Identify the type of combustor used in the 250-C20J engine.

i. Identify the location of the components in the combustion section and state their purpose.

ii. State the purpose of airflow through the combustor and the amount used for each purpose.

f. State the purpose of the turbine section in the 250-C20J engine.

i. Identify the components of the turbine section and state their function.

ii State what portion of the available energy is used to drive the gas producer and free power turbine sections.

CHAPTER TWO SYSTEMS WORKBOOK, ENGINEERING, AND TRANSITION

2-2 ROLLS-ROYCE 250-C20J TURBOSHAFT ENGINE

iii. Identify the location and name of the components used for measuring turbine outlet temperature (TOT).

g. Identify the functions of the accessory gearbox.

i. Identify the accessories driven by the gas producer.

ii. Identify the units driven by the power turbine gear train.

3. Identify the type of engine oil system utilized in the 250-C20J engine.

a. State the function and location of each component of the engine oil system.

b. Identify how to determine the engine oil level and why it is important to know the exact level.

c. State how engine oil temperature and pressure information is transmitted to the cockpit.

4. State why fuel metering is important for a turboshaft engine by identifying the problems which can occur if fuel is not metered correctly.

a. Identify the type of fuel control used in the 250-C20J engine and state how it controls engine power.

b. Describe the function of the power turbine governor by stating the engine performance parameters sensed and its connection to the fuel control.

c. State what components control the power turbine governor and the gas producer fuel control.

d. State how the twist grip functions.

e. Describe the droop compensation system by identifying the cockpit controls, engine controls, and its effect on power output.

SYSTEMS WORKBOOK, ENGINEERING, AND TRANSITION CHAPTER TWO

ROLLS-ROYCE 250-C20J TURBOSHAFT ENGINE 2-3

202. ROLLS-ROYCE 250-C20J TURBOSHAFT ENGINE, ENGINE OIL SYSTEM,

ENGINE CONTROLS

The TH-57 engine is an internal combustion gas turbine engine featuring a “free” power turbine. The engine consists of a combination axial-centrifugal compressor, a single “can”-type combustor, a turbine assembly which incorporates a two-stage power turbine and exhaust collector, and an accessory gearbox which incorporates a gas producer gear train and a power turbine gear train. Rolls-Royce 250-C20J engine is a 420 SHP engine. 317 SHP is usable if torque limits are maintained (100% TQ) due to power train limitations.

The four subassemblies of the engine (Figure 2-1) are:

1. Compressor section

2. Combustion section

3. Turbine section

4. Accessory gearbox section

Figure 2-1 Turboshaft Engine

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203. COMPRESSOR SECTION

The four subassemblies (Figure 2-2) are:

1. Front support

2. Compressor rotor blades and wheels

3. Case assemblies

4. Diffuser scroll

The front support section is an aerodynamically designed air inlet with seven hollow struts and front bearings for the rotor. The hollow struts serve as part of the anti-ice system, which will be discussed later in this chapter. The struts serve as inlet guide vanes, which ensure ambient air strikes the first stage compressor at the proper angle.

Figure 2-2 Compressor Section

The 250C-20J engine is equipped with a six-stage axial compressor and one-stage centrifugal compressor. A stage of an axial compressor consists of a set of airfoil-shaped blades on a

ROLLS-ROYCE 250-C20J TURBOSHAFT ENGINE 2-5

rotating disc called a rotor, followed by a set of airfoil-shaped stationary blades mounted to the compressor case called stators (Figure 2-3).

Figure 2-3 Typical Axial Compressor

The rotors accelerate the airflow while the stators slow the air (increase static pressure) and direct it to the next stage of rotors. Each stage of the axial compressor acts like a pump, moving the air through the compressor as the cross-sectional area decreases.

After passing through and being compressed by the six stages of the axial compressor, the air enters the centrifugal compressor. The centrifugal compressor compresses air by using a rotary impeller to centrifugally accelerate the air. The accelerated air is slowed (increases static pressure) and collected in the diffuser scroll. By the time the air is collected in the diffuser scroll, it has been compressed to 6.5 times ambient pressure and has risen to a temperature of

500º Fahrenheit.

A bleed air control valve is mounted on the compressor case at the 5 th stage of the compressor.

This valve bleeds air from the 5 th stage of the compressor during starting, acceleration, and at low compressor pressure ratio operation. This system includes a bleed air control valve attached to the compressor case and the necessary plumbing between the diffuser scroll and the bleed air control valve. The bleed air control valve is a modulating pneumatic control which bleeds 5 th stage pressure over a specific range o the ratio of compressor discharge pressure to ambient pressure. This valve bleeds 5 th stage pressure at low pressure ratios to unload the compressor in order to prevent compressor stall and surge. The compressor bleed air system is an entirely automatic system (Figure 2-4).

Figure 2-4 Bleed Air Control Valve

2-6 ROLLS-ROYCE 250-C20J TURBOSHAFT ENGINE

The diffuser scroll has ports from which air may be bled for anti-icing and cabin heat, and a port through which compressor discharge air pressure is sensed by the fuel control system. Air not bled for these purposes is carried to the combustion sections by two air transfer tubes.

204. COMBUSTION SECTION

The combustion section is where the compressed air is mixed with fuel and ignition takes place.

The 250-C20J engine is equipped with a single “can” type combustion chamber. The combustion section consists of the outer case and an inner liner (Figure 2-5). Mounted at the aft end is the fuel nozzle and igniter plug. A burner drain valve is located at the lowest point in the combustion chamber. During normal operation, combustion chamber pressure keeps the valve closed. Pressurized air leaves the air transfer tubes and enters the outer combustion case.

Approximately 75% of the air passes between the inner liner and combustion case, which is used for cooling the combustion chamber. The other 25% enters the combustion liner and is mixed with fuel sprayed from the fuel nozzle. During starting, the fuel-air mixture is ignited by the capacitor-type igniter plug located adjacent to the fuel nozzle. Once the engine is started, combustion is self-sustaining. When the combustion takes place, the gases expand rapidly and are expelled into the turbine section (Figure 2-6).

Figure 2-5 Combustion Section

ROLLS-ROYCE 250-C20J TURBOSHAFT ENGINE 2-7

Figure 2-6 Air Flow Schematic

2-8 ROLLS-ROYCE 250-C20J TURBOSHAFT ENGINE

205. TURBINE SECTION

The turbine section converts heat energy to mechanical energy. It is comprised of a two-stage gas producer (referred to as the Ng or N1) turbine and a two-stage free power (referred to as the

Nf or N2) turbine.

Expanding gases from the combustion section first enter the gas producer turbine where about

2/3 of the energy is used to drive the compressor section and the gas producer drive train

(Figure 2-7). Details of products of this drive train are provided in the next section of this chapter. Most of the remaining energy is used by the free power turbine to power the free power drive train (Figure 2-8). Exact functions are discussed later in this chapter. The remaining gases with very little heat energy left are collected in the exhaust collector. The exhaust gases are discharged from the exhaust collector through the twin stacks into the atmosphere.

Temperature measuring of the engine is accomplished with the use of an equal resistance branch thermocouple harness assembly with four integral probes. These probes sense the temperature of the gases on the outlet side of the gas producer turbine. A DC voltage, which is directly proportional to the gas temperature it senses, is generated by each thermocouple. The thermocouples and thermocouple harness provide an average of the four voltages representative of the TOT for cockpit temperature indication (Figure 2-9). Even though the thermocouples are

“self generating”, 28V DC power is needed to operate the cockpit gauge.

Figure 2-7 Gas Producer Gear Train

ROLLS-ROYCE 250-C20J TURBOSHAFT ENGINE 2-9

Figure 2-8 Power Turbine Gear Train

Figure 2-9 Thermocouple Location

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206. ACCESSORY GEARBOX

The last major section of the 250-C20J engine is the accessory gearbox. The accessory gearbox is the primary structural member for the engine as it provides mounting and support for the compressor and turbine assemblies. The accessory gearbox has four engine mounting pads, but only uses three for mounting. The top pad is used to mount the anti-icing motor.

The accessory gearbox contains most of the lubrication system components and incorporates two separate gear trains (Figures 2-10 and 2-11).

The gear train used with the gas-producer section powers accessories to start and run the engine. The accessories driven by the gas-producer include:

S - Starter-Generator

T - Tachometer-generator (Ng)

O - Oil Pump

F - Fuel Control

F - Fuel Pump

S - Standby Generator (C)

A convenient method to commit these to memory is by the abbreviation STOFF. The TH-57C has one additional unit and that is the standby generator making the abbreviation STOFFS.

The other gear train is driven by the free-power turbine. The free-power for the TH-57 drives four units which can be remembered by the abbreviation GOTT:

G - Governor (Nf)

O - Output Shaft (Power)

T - Tachometer-Generator (Nf)

T - Torquemeter

The torquemeter assembly is located in the accessory gearbox and measures the output torque of the engine. As torque is developed, the helical gear in the free power turbine gear train will provide a proportional oil pressure through an oil line to a transducer. The transducer converts the oil pressure to an electrical voltage for the D.C. powered torque gauge. The power output gear is where the power turbine energy is transmitted to the freewheeling unit to drive the rotor system. The freewheeling unit will allow the rotor system to rotate without driving the engine in the event of a power loss.

ROLLS-ROYCE 250-C20J TURBOSHAFT ENGINE 2-11

Figure 2-10 Accessory Gearbox Mounting Pad Locations

2-12 ROLLS-ROYCE 250-C20J TURBOSHAFT ENGINE

Figure 2-11 Accessories Location

ROLLS-ROYCE 250-C20J TURBOSHAFT ENGINE 2-13

Several ancillary systems support and ensure safe operation of the 250-C20J engine. These include:

1. Oil system

2. Chip warning system

3. Anti-ice…