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TECHNICAL MANUAL

OPERATOR’S MANUALARMY MODEL OH-58A/C

HELICOPTER

MASTER COPY

This copy is a reprint which includescurrent pages from Changes 1-6.

This manual supersedes TM 655-1620-228-10 and TM 566-1520-235-10, 7 April 1978, including all changes.

HEADQUARTERS, DEPARTMENT OF THE ARMY17 JANUARY 1989

Lunsford Air Consulting, Inc. 1

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C 9

CHANGE

NO. 9

HEADQUARTERS

DEPARTMENT OF THE ARMY

WASHINGTON, D.C., 18 July 1997

Operator"s Manual

ARMY MODEL OH-58A/C HELICOPTER

DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited

TM 55-1520-228-10, 17 January 1989, is changed as follows:

1. Remove and insert pages as indicated below. New or changed text material is indicated byvertical bar in the margin. An illustration change is indicated by a miniature pointing hand.

Remove pages Insert pages

2-33 and 2-343-23 and 3-24

3-31 and 3-32

8-5 and 8-6

2-33 and 2-343-23 and 3-243-24.1/(3-24.2 blank)3-31 and 3-323-32.1 and 3-32.28-5 and 8-6

2. Retain this sheet in front of manual for reference purposes.

By Order of the Secretary of the Army:

Administrative Assistant to the

Secretary of the Arm y 03872

DENNIS J. REIMERGeneral, United States Army

Chief of Staff

DISTRIBUTION:To be distributed in accordance with DA Form 12-31-E, block no. 0230, requirements for

TM 55-1520-228-10.


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CHANGE HEADQUARTERSDEPARTMENT OF THE ARMY

NO. 8 WASHINGTON, D.C., 22 JUNE 1996

Operator’s Manual


DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited


1. Remove and insert pages as indicated below. New or changed text material is indicated by a vertical bar in themargin. An illustration change is indicated by a miniature pointing hand.


i and ii i and ii2-29 and 2-30 2-29 and 2-305-7 and 5-8 5-7 and 5-88-5 and 8-6 8-5 and 8-69-15/(9-16 blank) 9-15/(9-16 blank)


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NO. 5 WASHINGTON, D.C., 22 July 1991

Operator’s Manual


TM 55-1520-228-10, 17 January 1989, is changed as follows:1. Remove and insert pages as indicated below. New or changed text material is indicated by a vertical bar in themargin. An illustration change is indicated by a miniature pointing hand.


3-27 and 3-28 3-27 and 3-285-11 and 5-12 5-11 and 5-128-17/8-18 8-17/8-18


By Order of the Secretary of the Army:GORDON R. SULLIVAN

General, United States Army Official: Chief of Staff

PATRICIA P. HICKERSONColonel, United States Army

The Adjutant General

DISTRIBUTION:To be distributed in accordance with DA Form 12-31-E, block no. 0230, -10 and CL maintenance requirements for TM

55-1520-228-10.

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NO. 4 WASHINGTON, D.C., 31 July 1990

Operator’s Manual





2-21 and 2-22 2-21 and 2-222-45 and 2-46 2-45 and 2-462-46.1 and 2-46.23-23 and 3-24 3-23 and 3-243-25 and 3-26 3-25 and 3-26


By Order of the Secretary of the Army:CARL E. VUONO


WILLIAM J. MEEHAN IIBrigadier General, United States Army


DISTRIBUTION:To be distributed in accordance with DA Form 12-31, -10 and CL Maintenance requirements for OH-58A and OH-58C

Helicopter, Observation.

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NO. 3 WASHINGTON, D.C., 6 March 1990

Operator’s Manual





6-7 and 6-8 6-7 and 6-8



General, United Stages Army Official: Chief of Staff



DISTRIBUTION:

To be distributed in accordance with DA Form 12-31, -10 and CL Maintenance requirements for OH-58A and OH-58CHelicopter, Observation.

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NOTICE: THIS CHANGE HAS BEEN PRINTED AND DISTRIBUTED OUT OF SEQUENCE. IT SHOULD BE INSERTEDIN THE MANUAL AND USED. UPON RECEIPT OF THE EARLIER SEQUENCED CHANGE INSURE A MORECURRENT CHANGE PAGE IS NOT REPLACED WITH A LESS CURRENT PAGE.

TM 55-1520-228-10C 2


NO. 2 WASHINGTON, D.C., 11 October 1989

Operator’s Manual





5-11 and 5-12 5-11 and 5-128-13 and 8-14 8-13 and 8-14






DISTRIBUTION:To be distributed in accordance with DA Form 12-31, -10 and CL Maintenance requirements for OH-58A and OH-58C

Helicopter, Observation.

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NO. 1 WASHINGTON, D.C., 1 February 1990

OPERATOR’S MANUAL

ARMY MODEL OH-58A/CHELICOPTER




a through c/d a through c/di through iv i through iv1-1 and 1-2 1-1 and 1-22-1 through 2-4 2-1 through 2-4

2-7 through 2-14 2-7 through 2-142-21 and 2-22 2-21 and 2-222-25 and 2-26 2-25 and 2-262-29 and 2-30 2-29 and 2-302-41 and 2-42 2-41 and 2-422-51 and 2-52 2-51 and 2-522-57 and 2-58 2-57 and 2-583-3 through 3-8 3-3 through 3-84-1 and 4-2 4-1 and 4-24-5 through 4-20 4-5 through 4-205-7 and 5-8 5-7 and 5-86-1 and 6-2 6-1 and 6-26-7 and 6-8 6-7 and 6-86-8.1/6-8.28-1 through 8-8 8-1 through 8-89-1 and 9-2 9-1 and 9-29-9 through 9-15/9-16 9-9 through 9-15/9-16A-1/A-2 A-1/A-2Index 1 through Index 9/10 Index 1 through Index 9/10

2. Retain this page in front of manual for reference purposes.By Order of the Secretary of the Army:

CARLE. VUONOGeneral, United States Army

Official: Chief of Staff


The Adjutant General DISTRIBUTION:

To be distributed in accordance with DA Form 12-31, -10 and CL Maintenance requirements for OH-58A and OH-58CHelicopter, Observation.


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WARNING

Personnel performing operations, procedures and practices which are included or implied in this technical manual shallobserve the following warnings. Disregard of these warnings or precautionary information can cause serious injury or lossof life.

STARTING ENGINE

Coordinate all cockpit actions with ground observer. Ensure that rotors and blast areas are clear and fire guard is posted,if available.

FIRE EXTINGUISHER

Exposure to high concentrations of monobromotribluoromethane (CF Br) extinguishing agent or toxic fumes produced bythe agent should be avoided. The liquid should not be allowed to come into contact with the skin, as it may cause frostbiteor low temperature burns.

GROUND OPERATION

Engines will be started and operated only by authorized personnel. Reference AR 95-1.

ELECTROLYTE

Battery electrolyte is harmful to the skin and clothing. Neutralize any spilled electrolyte by flushing contacted areasthoroughly with water.

CARBON MONOXIDE

When smoke, suspected carbon monoxide fumes, or symptoms of anoxia exist, the crew should immediately ventilate

cabin and shut off heater.

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HANDLING FUEL AND OILS

Turbine fuels and lubricating oil contain additives which are poisonous and readily absorbed through the skin. Do not allowthem to remain on skin longer than necessary.

HANDLING HYDRAULIC FLUID (MIL-H-83282)

Prolonged contact with liquid or mist can irritate eyes and skin. After prolonged contact with skin, immediately washcontacted area with soap and water. If liquid contacts eyes, flush immediately with clear water. If liquid is swallowed, donot induce vomiting; get immediate medical attention. Wear rubber gloves when handling liquid. If prolonged contact withmist is likely, wear an appropriate respirator. When fluid is decomposed by heating, toxic gasses are released.

HAZARDOUS CARGO

Items of cargo possessing dangerous physical properties, such as explosives, acids, flammable, etc., must be handledwith extreme caution and in accordance with established regulations. Refer to TM 38-250.

NOISE

Sound pressure levels in this aircraft during some operating conditions exceed the Surgeon General’s hearingconservation criteria as defined in TB MED 501. Hearing protection devices, such as the aviator helmet or earplugs arerequired to be worn by all personnel in and around the aircraft during its operation.

EXPLOSIVES

The missile round contains explosives. All applicable safety regulations shall be strictly enforced. Explosive componentscontaining electrical wiring must be protected at all times from stray voltages or induced electrical currents.

Handling operations should not be performed during electrical storms.

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TOXIC MATERIALS

The basic stinger missile round and captive flight trainer (CFT) contain mercury thallium. If the IR dome should break, donot touch the basic stinger missile round or CFT in the vicinity of the IR dome. This material is toxic to unprotected skinAvoid all contact with the released material unless protective equipment is being worn, such as a respirator, gloves, andchemical goggles. If the skin or eyes are exposed to the spilled material, immediately flush with large quantities of waterAny person exposed to the released material should be promptly referred to a physician.

Weapons in containers that fall more than 84 inches are considered unsafe and should only be handled by qualifiedpersonnel.

DO NOT load a missile round which has been dropped from two or more feet onto a hard surface.

The coolant reservoir, when fully charged, contains high pressure argon gas (up to 6200 psi). When moving or storing thecoolant reservoir, the protective collar must be installed to protect the male disconnect coupling from being damaged orbroken. When handling the coolant reservoir, extreme care must be taken not to drop, damage, or break any portion othe coolant reservoir. If the coolant reservoir is damaged, high pressure gas could escape causing the coolant reservoir to

become a self-propelled projectile.

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Reproduction for non-military use of the information or illustrations contained in this publication is not permitted. The policyfor military use reproduction is established for the Army in AR 380-5.

LIST OF EFFECTIVE PAGESNote: Text affected by current revision/change indicated by “new” or vertical bar in outer margin.

DATES OF ISSUE FOR ORIGINAL AND CHANGED PAGES ARE:Original ....0... 17 January 1989*Change ....1 ...... 1 February 1990

TOTAL NUMBER OF PAGES IN THIS PUBLICATION IS 290 CONSISTING OF THE FOLLOWING:

Page No Issue Page No Issue Page No IssueCover.............................. 0 *4-7 - 4-20............................. 1a...................................... 0 *5-1 ....................................... 0b-c................................... 1 5-2 - 5-6 ................................ 0d Blank............................ 0 5-7 - 5-8 ................................ 1*A.................................... 1 5-9 - 5-12 .............................. 0B Blank ........................... 0 *6-1 - 6-2............................... 1*i ..................................... 1 6-3 - 6-6 ................................ 0

ii...................................... 0 6-7 - 6-8.1 ............................. 1*iii-v.................................1 *6-8.2 Blank .......................... 01-1 .................................. 0 6-9......................................... 0*1-2................................. 1 6-10 Blank............................. 0*2-1................................. 1 7-1 - 7-15 .............................. 02-2 - 2-3.......................... 0 7-16 Blank............................. 0*2-4................................. 1 7-17 - 7-37 ............................ 02-5 - 2-7.......................... 0 *7-38 - 7-39........................... 0*2-8 - 2-9.........................1 7-40 - 7-81............................ 02-10 ................................0 7-82 Blank............................. 0*2-11 - 2-13..................... 1 7-83 - 7-85............................ 02-14 - 2-21......................0 7-86 Blank............................. 0*2-22...............................1 8-1......................................... 0

2-23 - 2-25......................0 *8-2 - 8-8............................... 1*2-26...............................1 8-9 - 8-17 .............................. 02-27 - 2-29......................0 8-18 Blank............................. 0*2-30...............................1 *9-1 ....................................... 12-31 - 2-40......................0 9-2 - 9-9................................ 0*2-41 - 2-42..................... 1 *9-10 - 9-11........................... 12-43 - 2-50...................... 0 9-12....................................... 0*2-51...............................1 *9-13 - 9-15........................... 12-52 - 2-56......................0 *9-16 Blank ........................... 0*2-57............................... 1 *Appendix 1 .......................... 12-58 - 2-65...................... 0 *Appendix 2 Blank ................ 02-66 Blank ......................0 *Index 1 - Index 9.................. 13-1 - 3-3.......................... 0 *Index 10 Blank..................... 1*3-4 - 3-5......................... 1

3-6 .................................. 0*3-7................................. 13-8 - 3-33........................ 03-34 Blank ...................... 0*4-1................................. 14-2 - 4-4.......................... 0*4-5................................. 14-6 .................................. 0*The asterisk indicates pages changed, added, or deleted by the current change.

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TECHNICAL MANUAL HEADQUARTERSNO. 55-1520-228-10 DEPARTMENT OF THE ARMY

WASHINGTON, D.C., 17 JANUARY 1989

OPERATOR’S, MANUAL

FOR

ARMY MODEL OH-58AIC HELICOPTER

REPORTING ERRORS AND RECOMMENDING IMPROVEMENTSYou can help improve this manual. If you find any mistakes, or if you know of a way to improve theseprocedures, please let us know. Mail your letter or DA Form 2028 (Recommended Changes toPublications and Blank Forms), or DA Form 2028-2 located in the back of this manual directly to:Commander, US Army Aviation and Troop Command, ATTN: AMSAT-I-MP, 4300 Goodfellow Blvd., St.Louis, MO 63120-1798. You may also submit your recommended changes by E-mail directly to. A reply will be furnished directly to you.

TABLE OF CONTENTSChapter/Section Page

CHAPTER 1 INTRODUCTION ........................................................................................... 1-1CHAPTER 2 HELICOPTER AND SYSTEMS DESCRIPTION AND OPERATIONSection I Helicopter ....................................................................................................... 2-1

II Emergency Equipment................................................................................. 2-18III Engines and Related Systems..................................................................... 2-18IV Fuel System ................................................................................................. 2-28V Right Controls .............................................................................................. 2-30VI Hydraulic System......................................................................................... 2-32VII Power Train System..................................................................................... 2-33VIII Main and Tail Rotor Groups......................................................................... 2-34IX Utility System................................................................................................ 2-35X Heating and Ventilation................................................................................ 2-35XI Electrical Power Supply and Distribution System......................................... 2-40

XII Lighting......................................................................................................... 2-43XIII Right Instruments ......................................................................................... 2-45XIV Servicing, Parking, and Mooring.................................................................. 2-48

CHAPTER 3 AVIONICSSection I Communications ............................................................................................ 3-5

II Navigation .................................................................................................... 3-17III Transponder and Radar ............................................................................... 3-24

CHAPTER 4 MISSION EQUIPMENT -Section I Mission Avionics (Not Applicable).................................................................. 4-1

II Armament ...................................................................................................... 4-1CHAPTER 5 OPERATING LIMITS AND RESTRICTIONSSection I General .......................................................................................................... 5-1

II Systems Limits ............................................................................................... 5-1III Power Limits................................................................................................... 5-7IV Load Limits..................................................................................................... 5-8V Airspeed Limits .............................................................................................. 5-8VI Maneuvering ................................................................................................ 5-10VII Environmental Restrictions .......................................................................... 5-11

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CHAPTER 6 WEIGHT/BALANCE AND LOADINGSection I General .......................................................................................................... 6-1

II DD Form 365 ................................................................................................. 6-9

CHAPTER 7 PERFORMANCE DATASection I Introduction .................................................................................................... 7-1

II Temperature Conversion ............................................................................... 7-6III Torque Available A...................................................................................... . 7-8IV Hover A ...................................................................................................... . 7-17V Takeoff A ................................................................................................... . 7-22VI Cruise A ..................................................................................................... . 7-24VII Drag A......................................................................................................... . 7-38VIII Climb - Descent A...................................................................................... . 7-40IX Idle Fuel Flow A .......................................................................................... . 7-45X Torque Available C...................................................................................... . 7-47Xl Hover C ....................................................................................................... . 7-56XII Takeoff C .................................................................................................... . 7-60XIII Cruise C ...................................................................................................... . 7-62XIV Drag C.......................................................................................................... 7-76XV Climb - Descent C....................................................................................... . 7-78XVI Idle Fuel Flow C .......................................................................................... . 7-83

CHAPTER 8 NORMAL PROCEDURESSection I Mission Planning............................................................................................ 8-1

II Operating Procedures and Maneuvers.......................................................... 8-2III Instrument Flight .......................................................................................... 8-11IV Flight Characteristics ................................................................................... 8-11V Adverse Environmental Conditions.............................................................. 8-14

CHAPTER 9 EMERGENCY PROCEDURESSection I Helicopter Systems........................................................................................ 9-1Section II Mission Equipment....................................................................................... 9-13

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LIST OF ILLUSTRATIONS

Figure Title Page

2-1. General Arrangement A ..................2-22-2. General Arrangement......................2-4

2-3. Compartment Diagram A ................2-62-4. Pilot and Copilot/ObserverStation Diagram C......................... ..2-8

2-5. Principal Dimensions.....................2-112-6. Turning Radius and Ground

Clearance......................................2-132-7. Float Gear Equipped

Helicopter A.................................. .2-142-8. Locking Devices for Doors ............2-152-9. WSPS Configuration .....................2-172-10. Engine A...................................... ..2-192-11. Engine C .................................... ...2-202-12. Overhead Console ........................2-222-13. Instrument Panel and Console

(Typical) A ................................... ..2-252-14. Instrument Panel and

Console C ................................... ..2-262-15. Auxiliary Fuel System....................2-292-16. Heating and Ventilation A..............2-362-17. Heater Control and Vent Pull

Knobs C ..................................... ..2-382-18. Electrical System Schematic.........2-412-19. Warning and Caution Panels ........2-472-20. Servicing Diagram A ................... ..2-492-21. Servicing Diagram C ....................2-512-22. Gravity Refueling With Closed

Circuit Receiver.............................2-59

2-23. Refueling Receptacle....................2-612-24. Ground Handling Equipment,

Covers, Rotor Tiedowns, andMooring Diagram...........................2-65

3-1. Antenna Locations ..........................3-43-2. Communication System Control

Panel C-6533/ARC..........................3-63-3. AN/ARC-114 and AN/ARC-

114A Control Panel .........................3-73-4. AN/ARC-115 Control Panel.............3-93-5. AN/ARC-116 Control Panel...........3-103-6. UHF/AM Radio Set

AN/ARC-164 .................................3-11

3-7. AN/ARC-51 BX ControlPanel A....................................... ..3-13

3-8. Voice Security EquipmentTSEC/KY-58................................. .3-15

3-9. AN/ARN-89 (ADF) ControlPanel .............................................3-18

3-10. Radio Bearing HeadingIndicator ........................................3-20

Figure Title Page

3-11. CONUS Navigation ReceiverControl Panel C.......................... ..3-22

3-12. Course Deviation Indicator(CDI) C....................................... ..3-23

3-13. Transponder APX-72 ControlPanel A ....................................... ..3-25

3-14. Transponder Set ControlPanel C ...................................... ..3-28

3-15. Operating Controls forProximity Warning System............3-30

3-16. Radar Altimeter C ...................... ..3-313-17. Radar Warning Indicator

and Control ...................................3-334-1. Components of Armament

System A ....................................... .4-24-2. Gun Assembly Mounted A .............4-34-3. Armament Control Panel A............4-44-4. Reflex Sight M70E1 Control

and Reticle A ................................ .4-54-5. Bullet Trap Assembly......................4-64-6. Air-To-Air Stinger (ATAS)

Missile System CS ...................... .4-104-7. Pilot Display Unit (PDU)

Controls CS ................................. 4-124-8. Pilot Display Unit (PDU)

Symbology and Displays CS........4-134-9. ATAS Control Panel Switches

and Functions CS ........................ .4-184-10. ATAS Cyclic Switches CS.............4-19

5-1. Instrument Markings A...................5-25-2. Instrument Markings C ..................5-45-3. Airspeed Operating Limits

Chart ...............................................5-95-4. Practice Autorotation Landing

Limits Crosswind Components.....5-116-1. Helicopter Station Diagram.............6-16-2. Center of Gravity Limit Chart ..........6-36-3. Cargo Space...................................6-46-4. Fuel Loading Chart .........................6-56-5. Personnel Loading..........................6-66-6. Ammunition Table A ...................... .6-76-7. Armament Table A......................... .6-8

6-7.1. ATAS Missile System Table CS ....6-86-8. Cargo Moment Chart ......................6-87-1. Temperature Conversion Chart ......7-77-2. Maximum Torque Available

(30 Minute Operation)Chart A........................................... .7-9

7-3. Torque Available (ContinuousOperation) Chart A...................... ..7-13*

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LIST OF ILLUSTRATIONS (Cont)

Figure Title Page

7-4. Hover Chart A ............................. .7-197-5. Takeoff Chart A.......................... ..7-237-6. Cruise Chart A............................ ..7-25

7-7. Drag Chart A .............................. ..7-397-8. Climb - Descent Chart A ..............7-417-9. Climb Performance A...................7-437-10. Idle Fuel Flow Chart A..................7-467-11. Maximum Torque Available

(30 Minute Operation)Chart C ....................................... ..7-48

7-12. Torque Available (ContinuousOperation) Chart C..................... ..7-52

7-13. Hover Chart C ........................... ...7-577-14. Takeoff Chart C........................... ..7-617-15. Cruise Chart C .................................. .a

7-63

Figure Title Page

7-16. Drag Chart C............................... ..7-777-17. Climb - Descent Chart C...............7-797-18. Climb Performance C ...................7-81

7-19. Idle Fuel Flow Chart C ..................7-858-1. Exterior Check Diagram .................8-48-2. Effects of Wind Azimuth

on Aircraft .....................................8-139-1. Emergency Exits and

Equipment...................................... .9-39-2. Autorotational Glide

Characteristics Chart ......................9-5

9-3. Minimum Height for SafeLanding After Engine FailureChart A.......................................... .9-6

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CHAPTER 1

INTRODUCTION

1-1. GENERAL.

These instructions are for use by the operator. Theyapply to Army OH-58A/C Helicopters.

1-2. WARNING, CAUTIONS, AND NOTES DEFINED.

Warnings, cautions, and notes are used to emphasizeimportant and critical instructions and are used for thefollowing conditions:

WARNING

An operating procedure, practice,etc., which if not correctly followed,could result in personal injury or lossof life.

CAUTION

An operating procedure, practice,etc., which, if not strictly observed,could result in damage to ordestruction of equipment.

NOTE

An operating procedure, condition, etc.,

which it is essential to highlight.

1-3. DESCRIPTION - MANUAL.

This manual contains the complete operating instructionsand procedures for the Army OH-58A/C helicopter. Theprimary mission of this helicopter is that of observationand is designed for landing and take off from preparedand unprepared surfaces. The observance ofprocedures is mandatory except when modification isrequired because of multiple

emergencies, adverse weather, terrain, etc. Your flyingexperience is recognized, and therefore, basic fligh

principles are not included. It is required that THISMANUAL BE CARRIED IN THE HELICOPTER AT ALLTIMES.

1-4. APPENDIX A, REFERENCES.

Appendix A is a listing of official publications cited withinthe manual applicable to and available for flight crews.

1-5. INDEX.

The index lists, in alphabetical order, every titledparagraph, figure (F), and table (T) contained in thismanual. Chapter 7 performance data has an additiona

index within the chapter.

1-6. ABBREVIATIONS.

Designator symbols and abbreviations shall be used inconjunction with text contents, headings, and titles toshow effectivity of the material. Chapter 7 contains a listof abbreviations used in this publication.

1-7. ARMY AVIATION SAFETY PROGRAM.

Reports necessary to comply with the safety program areprescribed in AR 385-40.

1-8. DESTRUCTION OF ARMY MATERIAL TOPREVENT ENEMY USE.

For information concerning destruction of Army materieto prevent enemy use, refer to TM 750-244-1-5.

1-9. FORMS AND RECORDS.

Army aviators flight record and helicopter maintenancerecords which are to be used by crewmembers areprescribed in DA PAM 738-751 and TM 55-1500-342-23.

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1-10. HELICOPTER DESIGNATIONSYSTEM.

The designation system prescribed by AR70-50 is usedin helicopter designations as follows:

EXAMPLE OH-58A

The designation system prescribed by AR70-50 isused in helicopter designations as follows:

1-11. DESIGNATOR SYMBOLS.

Designator symbols A OH-58A and C OH-58C are usedin conjunction with text contents, text headings

and illustration titles to show limited effectivity of thematerial. One or more designator symbols may follow atext heading or illustration title to indicate propereffectivity, unless the material applies to all series andconfigurations within the manual. If the material appliesto all series and configurations, no designator symbolswill be used. Where practical, descriptive information iscondensed and combined for all models to avoidduplication.

The designator symbol CS is used to identify datapeculiar to the Air-To-Air Stinger (ATAS) missile systeminstalled on the OH-58C.

1-12. USE OF WORD SHALL, SHOULD, AND MAY.

Within this technical manual the word “shall” is used toindicate a mandatory requirement. The word “should” isused to indicate a nonmandatory but preferred method oaccomplishment. The word “may” is used to indicate an

acceptable method of accomplishment.

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CHAPTER 2

HELICOPTER AND SYSTEMS DESCRIPTIONAND OPERATION

SECTION I. HELICOPTER

2-1. GENERAL.

The OH-58A/C helicopter (figure 2-1 A and figure 2-2 C)is a single engine, observation type helicopter designedfor landing and takeoff from prepared or unpreparedsurfaces. The fuselage consists of the forward section,intermediate or transition section, and the aft or tailboomsection. The forward section provides the cabin and fuelcell enclosure as well as pylon support. Entrance to thecabin is provided by two doors on each side. The pilotstation (figure 2-3 A and figure 2-4 C) is located on theright and the copilot/observer station is located on the leftside of the helicopter. The area aft of the pilot andcopilot may be used as a cargo/passenger compartment.It also provides support for the M27E1 armament systemA The intermediate section supports the engine andincludes the equipment and electronic compartment. Italso provides attaching points for Air-To-Air Stingermissile system CS. The tailboom supports the horizontalstabilizer, vertical stabilizer, and tail rotor. The basicstructure of the forward section consists of a lower-curved honeycomb sandwich panel and an upperlongitudinal aluminum beam. The core of the sandwichstructure is aluminum alloy throughout. The faces arealuminum alloy except in the fuel cell region, where they

are fiberglass. The aluminum alloy sandwich panel iscapable of withstanding the specified design cargoloadings, while the fiberglass sandwich supports the fuelcell pressures. The rotor, transmission, and engine aresupported by the upper longitudinal beam. The upperand lower structures are interconnected by threefuselage bulkheads and a centerpost to form anintegrated structure. The most forward and aftbulkheads act as carry-through structure for the skidlanding gear crosstubes. The tailboom is a monocoquestructure with aluminum skin and aluminum substructure.

a. Dimensions. Principal dimensions of thehelicopter areas are shown in figure 2-5.

b. Turning Radius and Ground Clearance.(Refer to figure 2-6.)

c. Weights. The helicopter weight empty andgross operating weight will change according to theconfiguration or equipment installed for the type omission to be performed. Refer to Chapter 6Weight/Balance and Loading.

d. Crew Configuration. The crew consists of thepilot alone, pilot and copilot, pilot and gunner [ or piloand observer.

2-2. PASSIVE DEFENSE.

The armor protection is a combination of ceramic andfiberglass composite with a small amount of duahardness steel. The armor protection is removable.

a. Crew Protection. Armor protection is furnishedfor the pilot and copilot and consists of panels on seatbottom, seat back, and outboard side of each seat.

b. A Component Protection. Armor protectionis furnished for the compressor section of the engine andconsists of a panel on each side of the engine. The fuelines and oil cell are self sealing.

2-3. LANDING GEAR SYSTEM.

a. Standard System. The landing gear system isa skid type, consisting of two laterally mounted archedcrosstubes, attached to two formed longitudinal skidtubes. The landing gear structure members are madefrom formed aluminum alloy tubing with steel skid shoesto minimize skid wear. The gear assembly is attachedwith straps/clamps at four points to the fuselagestructure, therefore, gear removal for maintenance caneasily be accomplished. The manually retractable andquickly removable wheel assemblies have been providedto facilitate helicopter ground handling operations.

b. High Skid Gear. The high skid gear, wheninstalled, will provide an approximate additional 14

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1. Anti-Collision Light 14. Horizontal Stabilizer2. Main Rotor Hub and Blades 15. Vertical Fin3. Engine Oil Tank Drain Access Door 16. Battery and Avionics Compartment Door4. Tail Rotor Hub and Blade 17. Passenger Door (Left)5. Position Light (White) 18. Copilot Door6. Tail Skid 19. Left Static Port7. Position Light (Red)8. Forward Transmission Fairing9. Pitot Tube10. Skid Gear11. Fuel Filter Cap12. Aft Engine Cowling13. Position Light (Green)

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Figure 2-1. General Arrangement A (Sheet 1 of 2)2-2


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20 Windshield 31. Lower Cutter Assembly21. Tail Rotor Driveshaft 32. Pilot Door22. Tail Rotor Gearbox 33. Passenger Door (Right)23. Tail Rotor Driveshaft and Cover (if installed) 34. FM Homing Antenna (Right Side)24. Engine Exhaust 35. Battery Vent26. Engine Air Inlet 36. External Power Receptacle26. Forward Transmission Fairing Inspection Door 37. Ground Receptacle

27. Upper Cutter Assembly 38. FM Homing Antenna (Left Side)28. Free Air Temperature (FAT) Gage 39. Landing Lights29. Windshield Deflector/Cutter Assembly30. Right Static Port

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Figure 2-1. General Arrangement A (Sheet 2 of 2)

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1. Position Light (Green) 15. Position Light (White)2. Horizontal Stabilizer 16. Tail Skid3. Engine Oil Tank Cowling 17. Vertical Fin4. Infrared Suppression Shield 18. Lower Anti-Collision Light5. Aft Engine Cowling 19. Aft Proximity Warning Antenna6. Upper Anti-Collision Light 20. ADF Sense Antenna7. Forward Transmission Fairing 21. ADF Loop Antenna7.1. Pilot Display Unit (PDU) E 22. Landing Gear8. Pitot Tube 23. Radar Warning Blade Antenna9. Right Forward Radar Warning Antenna 24. Radar Altimeter Antenna10. Door Lock 25. Marker Beacon Antenna

11. Fuel Filler Cap 26. Transponder Antenna12. Left Forward Radar Warning Antenna 27. UHF Antenna12.1. Air-To-Air Stinger (ATAS) 28. Landing Light

Launcher Assembly m 29. Upper Cutter Assembly13. Left Aft Radar Warning Antenna 30. Windshield Deflector/Cutter Assembly14. Position Light (Red) 31. Lower Cutter Assembly

206900-508-1A

Figure 2-2. General Arrangement C (Sheet 1 of 2)

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32 Infrared Engine Exhaust 44 Engine Oil Tank Drain Access Door33 FM No. 2 Antenna 45 Tail Rotor Driveshaft Cover34 Windshield (Flat Glass) 46 Tail Rotor Blade and Hub35 Right Static Port 47 Tail Rotor Gearbox36 Pilot Door 48 VOR Antenna37 Cabin Door 49 Battery and Avionics Compartment Door38 Battery Vent 50 Step39 External Power Receptacle 51 FM Homing Antenna40 Main Rotor Blades and Hub 52 Cabin Door41 Free Air Temperature (FAT) Gage 53 Copilot/Observer Door42 Forward Transmission Fairing Inspection Door 54 Left Static Port

43 Engine Air Inlet 55 NVG Position Lights

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Figure 2-2. General Arrangement C (Sheet 2 of 2)

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1. Copilot Door Emergency Jettison Handle 9. Pilot Cyclic Stick2. Overhead Console 10. Pilot Seat3. Fuel Shutoff Valve 11. Inertia Reel Control Handle4. Free Air Temperature (FAT) Gage 12. Pilot Collective Stick5. Pilot Door Emergency Jettison Handle 13. Collective Friction Control Adjustment6. Instrument Panel 14. Pedestal7. Magnetic Compass 15. Copilot Seat8. Anti-Torque Pedals 16. Ignition Key Lock Switch

206061-90-1

Figure 2-3. Compartment Diagram A (Sheet 1 of 2)

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17. Governor Switch 25. Radio Transmit Switch18. Landing Lights 26. Trigger Switch19. Starter Switch 27. Not Used20. Engine Idle Release Control 28. Not Used21. Inertia Reel 29. Depress/Elevate Gun Switch22. Inertia Reel Control Handle 30. Force Trim Release Switch23. Not Used 31. Throttle24. ICS Switch

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Figure 2-3. Compartment Diagram A (Sheet 2 of 2)

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1 Copilot Door Emergency Jettison Handle 11 Pilot Seat2 Overhead Console 12 Anti-Torque Pedal Adjuster3 Fuel ON/OFF Control Handle 13 Shoulder Harness Lock4 Free Air Temperature (FAT) Gage 14 Pilot Collective Lever4.1 Pilot Display Unit (PDU)r 15 Collective Friction Control Adjustment5 Pilot Door Emergency Jettison Handle 16 Console

6 Instrument Panel 17 Copilot/Observer Seat7 Magnetic Compass 18 Copilot Collective Lever8 Pilot Cyclic Stick 19 Copilot Anti-Torque Pedals9 Pilot Anti-Torque Pedals 20 Copilot Cyclic Stick10 Cyclic Friction Control Adjustment 21 Glareshield

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Figure 2-4. Pilot and Copilot/Observer Station Diagram C (Sheet 1 of 3)

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DETAIL A

22 Night Vision Goggles Light Switch 26 ICS Switch23 Not Used 27 Radio Trasmit Switch24 Not Used 28 Not Used25 Force Trim Switch 28.1 TRIGGER UNCAGE/FIRE Switch CS25.1 MSL ACT Switch CS

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29. Primary Directional Control Switch30. Starter Switch31. Governor Switch32. Search/Landing Lights33. Engine Idle Release Control34. IR/White (Dual) Landing/Searchlights35. Throttle

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Figure 2-5. Principal Dimensions (Sheet 1 of 2)

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STANDARD HIGH SKID FLOATHEIGHT SKID GEAR GEAR GEAR A

1. Forward Tip of Main Rotor(Static Position) to Groundwith Droop ..................................... 9 ft. 6.0 in 10 ft. 0.0 in 9 ft 7. 9 in.

2. Forward Tip of Main Rotorto Ground (Tie-down) ....................... 12 ft. 0.0 in 12 ft. 6.0 in 12 ft. 1.9 in.

3. Forward Tip of Main Rotorto Ground (Forward Down)............... .. 6 ft. 8.0 in 7 ft. 2.0 in 6 ft. 10 in.

4. Ground to Top of MainRotor Reservoirs .............................. 9 ft. 7.0 in 10ft. 9.0 in 10 ft. 5.4 in.

5. Bottom of Cabin................................ 13.0 in 27.0 in 28 in.5.1 Bottom of ATAS Launcher E ............ 13.0 in 27.0 in N/A6. Top of Vertical Stabilizer............. 8 ft. 1.5 in 10 ft. 1.5 in 11 ft. 1.0 in.7. Tail Skid to Ground........................... 1 ft. 4.4in 3 ft. 4.4 in 4 ft. 4.0 in.8. Lower Cutter to Ground.................... 12.0 in 2 ft. 2.0 in 2 ft. 3.0 in.9. Upper Cutter to Ground.................... 7 ft. 9.5 in 9 ft. 9.5 in 9ft. 10.5 in.

WIDTH

10. Skid Gear ......................................... 6 ft. 5.4 in 7 ft. 3.0 in 11 ft. 6.1 in.11. Horizontal Stabilizer.......................... 6 ft. 5.2 in No change No change

DIAMETERS

12. Main Rotor........................................ 35 ft. 4.0 in No change No change13. Tail Rotor.......................................... 5 ft. 2.0 in No change No change

LENGTH

14. Overall (Main Rotor Fore andAft) to Aft End of Tail Skid ................ 40 ft. 11.8 in No change No change

15. Nose of Cabin to Aft End of

Tail Skid............................................ 32 ft. 2.0 in No change No change16. Nose of Cabin to CenterLine of Main Rotor ............................ 8 ft. 10.1 in No change No change

17. Skid Gear ......................................... 8 ft. 1.3 in 10 ft. 4.2 in 19 ft. 5.0 in.18. Nose of Cabin to Center Line

of Forward Cross Tube..................... 6 ft. 0.0 in 5 ft. 9.4 in 5 ft. 11.7 in.19. Nose of Cabin to Center Line

of Aft Cross Tube ............................. 10 ft. 9.0 in 10 ft. 6.3 in 10 ft. 8.7 in.20. Pitot Tube ......................................... 6.8 in No change No change

*Check antennas that may protrude lower.

206900-509-2A

Figure 2-5. Principal Dimensions (Sheet 2 of 2)

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Figure 2-6. Turning Radius and Ground Clearance

inches of ground clearance. This will improve landingsto be accomplished in snow and rough terrain areas.

c. A Float Gear. The float landing gear (figure 2-7)consists of two streamlined multi-cell inflatable floats,float support tubes, crosstubes, and necessary fittings

required to equip the helicopter for water landings. Atriangular plate is attached to the tail skid for addedcontrollability and protection of the tail rotor in the eventof a tail low water landing. Landing may be made onsmooth surfaces that do not have protrusions that coulddamage floats.

d. Tail Skid. A tubular steel tail skid is attached tothe lower section of the vertical fin and providesprotection for the tail rotor in landings by indicating a taillow condition.

2-4. COCKPIT AND CABIN DOORS.

WARNING

Inadvertent jettisoning of cockpit doors ispossible if jettison handle is utilized as ahandhold, or hand rest during flight.

NOTE

The left cabin door will not open completely withATAS missile system installed. Access can begained by entering through right side cabin dooror by removing left side cabin door CS.

Four entrance doors are provided for access to theaircraft interior. The doors are of bonded sheet metaconstruction with acrylic plastic windows. Each door maybe jettisoned by means of emergency jettison handle. Al

four doors are provided with door lock devices. The pilodoor has a padlock while the other three doors have looplocking devices (figure 2-8)

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206050-18

Figure 2-7. Float Gear Equipped Helicopter A

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Figure 2-8. Locking Devices for Doors

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2-5. SEATS.

a. Pilot and Copilot/Observer Seats. The pilotand copilot/observer seats are constructed of tubing andstretched nylon material. Each seat is equipped withprovisions for cushions, safety belts, and shoulderharness. An inertia reel, with a manually operatedcontrol handle, is incorporated on each seat. The inertiareel is a mechanical restraining device that is designedto hold pilot in a normal seated position during anymaneuver which would tend to pitch the pilot forward.Each reel is connected to a shoulder harness with a webstrap. An automatic locking mechanism, a webbingroller, and a manual control are incorporated in each unit(figure 2-3).

b. Passenger Seats. The passenger seats areconstructed of aluminum honeycomb panels and form anintegral part of the airframe. The center panel of theseat back is removable to gain access to fuel cell. Seatsare equipped with shoulder harness, safety belts, and

cushions. Seating is provided for two passengers orwithout seats, space is provided for cargo (figure 2-3).

2-6. WIRE STRIKE PROTECTION SYSTEM (WSPS).

WARNING

Flight with the landing light in other than thefully stowed position on OH56A/C aircraftmay degrade the effectiveness of the WireStrike Protection System (WSPS). When useof the controllable landing light is notanticipated, it should be in the fully stowed

position.

The WSPS provides protection against frontal impactswith horizontally strung mechanical and

power transmission wires. The basic system consists ofan upper cutter assembly, a windshield deflector/cutterassembly, and a lower cutter assembly (figure 2-1 andfigure 2-2). The windshield deflector/cutter assembly,consisting of a sawtooth equipped aluminum extrusion,provides deflection mechanism into the upper cutterwhile simultaneously abrading thus weakening wire andprovides additional structural support for the upper cuttermounting. The mechanical cutter assembly (upper andlower) (figure 2-9) consists of a sawtooth equippeddeflector section, providing deflection/abrading featuresimilar to the windshield deflector section, leading intothe primary wire cutting mechanism wedge type cuttingblades positioned to provide the necessary mechanicaladvantage to cut the design objective wires whileminimizing load input into the airframe. The lower cutterassembly features a "Breakaway Tip" designed to shearwhen relatively large ground contact forces areexperienced and before helicopter structural damage isincurred. However, the tip shear rivets are designed towithstand the smaller forces experienced during wire

strikes and the tip will still effectively deflect wires into thecutter blades.

a. Wire Strikes. If avoidance is not possible or noteffective a wire strike will occur. The protection providedby the WSPS is 90% of frontal area. The cableimpact/deflection/cutting sequence of the designobjective cables does not have a significant effect onaircraft performance, control, crew functioning or bladeflapping.

b. Avoidance. The most effective defense againstwire strikes is avoidance. Because of the many different

encounters that can occur, it is not possible to provide aprocedure to cover every situation. The success incoping with emergency depends on quick analysis of thecondition and selection of the proper evasive maneuvers

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Figure 2-9. WSPS Configuration

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TM 55-1520-228-10SECTION II. EMERGENCY EQUIPMENT

2-7. FIRST AID KIT.

An aeronautical type first aid kit is located on the rightside of the center support column.

2-8. FIRE EXTINGUISHER

A portable fire extinguisher is mounted in a bracketlocated on the right side of the center support column(figure 9-1).

SECTION III. ENGINES AND RELATED SYSTEMS

2-9. ENGINE.

The OH-58A/C helicopter is equipped with a T63-A-700A. T63-A-720 C gas turbine engine (figure 2-10 A andfigure 2-11 C. The engine is designed for a low fuelconsumption, light weight, minimum size, maximumreliability and ease of maintenance. The engine isinstalled aft of the mast and the passenger compartment.The engine cowl aft of the engine air inlet is removableas a single unit or the hinged section the length of theengine on either side may be opened individually. Theaft fairing covers the engine oil cooler, provides tail rotor

driveshaft access and provides air intake for the engineoil cooler. The major engine components are as follows:

a. Compressor. Air enters the engine through theparticle separator to the compressor inlet and iscompressed by six axial compressor stages and onecentrifugal stage. The particle separator removes dirtand other contaminates from the incoming air and ejectsthe dirt out ducts on either side of the fairing. This allowscleaned air to enter the engine compressor section. Thecompressed air is discharged through the scroll typediffuser into two external ducts which convey the air tothe combustion section.

b. Combustion Section. The combustion sectionconsists of the outer combustion case and thecombustion liner. A spark igniter and a fuel nozzle aremounted in the aft end of the outer combustion case. Airenters the single combustion liner at the aft end, throughholes in the liner dome and skin. The air is

mixed with fuel sprayed from the fuel nozzle andcombustion takes place. Combustion gasses moveforward out of the combustion liner to the first-stage gasproducer turbine nozzle.

c. Turbine. The turbine consists of a gas producerturbine support, a power turbine support, a turbine andexhaust collector support, a gas producer turbine rotor,and a power turbine rotor. The turbine is mountedbetween the combustion section and the power andaccessory gearbox. The two-stage gas producer turbinedrives the compressor and accessory gear train. Gas

discharged from the gas producer turbine drives the two-stage power turbine which furnishes the output power ofthe engine. The gas from the power turbine dischargesin an upward direction through twin ducts in the turbineand exhaust collector support

d. Power and Accessories Gearbox. The mainpower and accessory drive gear train are enclosed in asingle gear case. The gear case serves as a structuralsupport of the engine. All engine components includingthe engine mounted accessories are attached to thecase. A two-stage helical and spur gear set is used toreduce rotational speed from the power turbine to the

output drive spline. Accessories driven by the powerturbine gear train are the power turbine tachometer-generator and the power turbine governor. The gasproducer drives the compressor and through anaccessory gear train drives the fuel pump, gas producertach generator, gas producer fuel control, startergenerator, and engine oil pump.

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Figure 2-10. Engine A

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1. Anti-Ice valve 12. Freewheeling Unit2. Oil Filter 13. Turbine Section3. Anti-Ice Control Actuator 14. Exhaust Stack4. Combustion Section 15. Compressor Section5. Compressor Discharge Tubes 16. Compressor Bleed Valve Assembly6. Air Filter 17. Tachometer Generator (Gas Producer)7. Power Turbine Governor 18. Starter Generator8. Fuel Pump and Filter 19. Oil Pressure Regulator9. Accessory Gearbox 20. TOT Harness

10. Tachometer Generator (Power Turbine) 21. Engine Oil Lines11. Ignition Exciter Assembly

206001-183

Figure 2-11. Engine C

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2-10. ENGINE COMPARTMENT COOLING.

Openings are provided on both sides of the engine andtop C cowling for compartment cooling. The center cowlsection houses the engine air inlet, the inlet bellmouthand the forward firewall. Suspended below the engine isa stainless fire shield. Below the fire shield is a titaniumfloor which acts as a drip pan and also gives insulationfrom heat.

2-11. INDUCTION SYSTEM.

The engine air inlet system consists of an inductionfairing with inlets on each outboard side. This fairingprovides mounting for the particle separator. Theparticle separator removes dirt and other contaminatesfrom the incoming air and ejects the dirt out eductortubes on either side of the fairing. This allows cleanedair to enter the engine compressor section. Removablereverse flow inlet fairings may be installed over the airinlets on modified induction fairings. These reverse flow

fairings minimize ram effect of falling or blowing snow,thus permitting effective operation of the particleseparator and preventing engine flame-out caused byingestion of snow.

a. Intake Ducting. The engine air intake ductingconsists of louvered openings and a large circular airinlet opening. The louvered openings are located on leftand right cowl panels.

b. Particle Separator. Foreign matter isremoved from the engine inlet air by a centrifugal typeparticle separator. The particle separator consists of a

group of separator tube assemblies arranged in rowsand positioned in a front and rear sheet metal panel anda scavenge system. The separator tube assembliesconsist of an inlet tube, a swirl tube which is bondedinside the inlet tube, and an outlet tube. The scavengesystem consists of a bleed air manifold, bleed airnozzles, and ejector tubes which are contained in twoejector boxes located beneath the separator tubeassemblies. The bleed air manifold is attached to theejector boxes and is connected directly to the enginecompressor scroll with bleed air inlet fittings. Air entersthe inlet tube and is spun by the swirl tube. Clean airthen enters the engine inlet plenum chamber through theoutlet tube while foreign material is centrifuged into thescavenge system. The foreign material is ejectedoverboard by the vacuum-cleaner effect created by

engine bleed air as it is discharged through venturies inthe eductor tubes. Reverse flow inlet fairings may beattached to the engine air inlets. These sheet metafairings make it impossible for air to enter the plenum

chamber without first making two 180° turns. These

abrupt changes in airflow greatly reduce the probability oengine flame-out associated with snow ingestion.

2-12. ENGINE INLET ANTI-ICING SYSTEM.

The compressor inlet guide vanes and front bearingsupport hub are the only engine components with anti-icing provisions. Anti-icing is provided by the use ocompressor bleed air. Anti-icing is actuated by placingENG DEICE switch on overhead console (figure 2-12) toENG DEICE position.

2-13. ENGINE FUEL CONTROL SYSTEM.

The system controls engine power output by controllingthe gas producer speed. Gas producer speed levels are

established by the action of the power turbine fuegovernor which senses power turbine speed. The poweturbine (load) speed is selected by the operator and thepower required to maintain this speed is automaticallymaintained by power turbine governor action on meteredfuel flow. The power turbine governor lever schedulesthe power turbine governor requirements. The poweturbine governor schedules the gas producer speed to achanged power output to maintain output shaft speed.

a. A Throttle. The throttle (figure 2-3) is a twistgrip type on the collective stick. The throttle is rotated tothe left to increase or to the right to decrease power.

b. C Throttle. Rotating the throttle (figure 2-4) tothe full open position allows the power turbine governorto maintain a constant rpm. Rotating the throttle towardthe closed position will cause the rpm to be manuallyselected instead of automatically selected by the powerturbine governor. Rotating the throttle past the engine-idle stop to the fully closed position shuts off fuel flow. Amanually operated idle stop is incorporated to preventinadvertent throttle closure. The idle stop is controlled bythe engine idle release control (figure 2-4).

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Figure 2-12. Overhead Console

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c. Droop Compensator. A droop compensatormaintains engine rpm (N2) as power demand isincreased. The compensator is a direct mechanicallinkage between the collective stick and the speedselector lever on the N2 governor. Droop is defined asthe speed change in N2 rpm as power is increased froma no-load condition. Without droop compensation,instability would develop as engine output is increased,resulting in N1 speed overshooting or hunting the valuenecessary to satisfy the new power condition. If N2power is allowed to droop, other than momentarily, thereduction in rotor speed could become critical.

d. Engine Idle Release Control. The engine idlerelease is a spring loaded plunger mounted on the switchbox of the pilot collective stick(figure 2-3 and figure 2-4).The plunger prevents the pilot from accidentally retardingthe throttle beyond engine idle position. This acts as asafety feature by preventing inadvertent engineshutdown. The plunger need not be depressed whenperforming an engine start or runup; however, the

plunger must be depressed when accomplishing anengine shutdown or when it is desired to retard thepower control below the engine idle position.

e. Governor RPM Switch. The GOV INCR/DECRswitch is mounted on the pilot collective stick (figure 2-3and 2-4). The switch is a three position momentary typeand is held in the INCR position (FWD) to increase thepower turbine (N2) speed or DECR position (AFT) todecrease the power turbine (N2) speed. Regulatedpower turbine speed may be adjusted in flight throughthe operating range by movement of the switch asrequired.

f. A Gas Producer Fuel Control. The gasproducer fuel control has a bypass valve, metering valve,acceleration bellows, governing and enrichment bellows,manually operated cutoff valve, maximum pressure reliefvalve, and a torque tube seal and lever assembly. Amaximum pressure relief valve is incorporated to protectthe system from excessive fuel pressure. The fuelcontrol incorporates a bleed air heating system,consisting of fittings, a manually actuated valve, and aheating element at the fuel control to prevent formationof ice in the pneumatic system.

g. Power Turbine Governor. The power turbinespeed is scheduled by the power turbine governor leverand the power turbine speed scheduling cam. The camsets a governor spring load

which opposes a speed-weight output. Overspeedprotection of the power turbine governor becomeseffective at approximately 108% N2. This governingaction will result in a pulsating increase/decrease ofengine power.

h. E Fuel Pump and Filter Assembly. The fuelpump and filter assembly incorporates two gear-typepumping elements arranged in tandem and driven by acommon driveshaft. Fuel enters the engine fuel systemat the inlet port of the pump and passes through a lowpressure filter before entering the gear elements. Thegear elements are arranged in parallel and eachpumping element has sufficient capacity to permit take-off power operation in the event of failure of the otherpump element. Two discharge check valves areprovided in the assembly to prevent reverse flow in eventof failure of one gear pumping element. A bypass valvein the pump assembly allows fuel to bypass the filterelement if it becomes clogged. The bypass return flowfrom the fuel control is passed back to the inlet of the

gear elements through a pressure regulating valve whichmaintains the bypass flow pressure above inlet pressureBy means of passages leading to auxiliary filling ports onthe periphery of the gear elements, a portion of thebypass flow is used to fill the gear teeth when vaporliquid conditions exist at the inlet to the gear elements.Paper filter is located inside the fuel pump assemblyupstream of the gear elements. It is retained by athreaded cover (distinguished by a hex) which can befound on the lower side of the pump.

i. C Fuel Pump and Filter Assembly. The fuelpump and filter assembly incorporates a single gear type

pumping element, a low pressure barrier filter, a filterbypass valve, and a bypass pressure regulating valve.Fuel enters the engine fuel system at the inlet port of thepump and passes through the low pressure filter beforeentering the gear element. The filter bypass valve allowsfuel to bypass the filter element if it becomes clogged.The bypass return flow from the fuel control is passedback to the inlet of the gear element through a pressureregulating valve which maintains the bypass flowpressure above inlet pressure.

j. A Fuel Nozzle. The fuel nozzle is a single entrydual-orifice type unit which contains an integral valve fordividing primary and secondary flow. This same valve

acts as a fuel shutoff valve when the fuel manifoldpressure falls below a predetermined pressure, thuskeeping fuel out of the combustion chamber atshutdown.

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TM 55-1520-228-10k. C Fuel Nozzle. The fuel nozzle is a single entry

dual-orifice type unit which contains an integral valve fordividing primary and secondary flow.

l. A Fuel Control Heater. The fuel control heaterimproves engine reliability by preventing autoacceleration during engine start operations after coldsoak. The fuel control heater valve is located on rightside of engine. With handle in vertical position, the valveis open. With handle in horizontal position, the valve isclosed.

2-14. INFRARED SUPPRESSION SYSTEM.

The infrared suppression system is specially formulatedto reduce detection of IR-seeking missiles. The systemconsists of two exhaust stacks located at the top of theengine cowling and two shields located on the sideengine cowling (figure 2-2). The exhaust stacks havecooling fins and a shield around them to reduce theinfrared signature of the hot engine exhaust. The shieldson the side engine cowling prevent detection of the hot

engine area from the sides.

2-15. TEMPERATURE MEASUREMENT SYSTEM.

The temperature measurement system consists of fourchromel-alumel single junction thermocouples in the gasproducer turbine outlet and an associated integralharness. The voltages of the four thermocouples areelectrically averaged in the assembly and delivered bythe assembly lead to the airframe terminal block forreference to the engine temperature indicating system.

2-16. COMPRESSOR BLEED AIR SYSTEM.

The 5th stage compressor bleed valve permits rapidengine response. The system consists of a compressordischarge pressure sensing port on the scroll, tubingfrom the sensing port to the bleed valve, a compressorbleed control valve, and a bleed air manifold on thecompressor case. Elongated slots between every othervane in the compressor 5th stage bleeds compressor airinto a manifold which is an integral part of thecompressor case. The manifold forms the mountingflange for the compressor bleed control valve when thecompressor case halves are assembled. Compressordischarge air pressure

sensing for bleed control valve operation is obtained at asensing port of the compressor scroll. The bleed controlvalve is normally open. It is closed by compressordischarge pressure.

2-17. ENGINE OIL SUPPLY SYSTEM.

The lubricating system is a dry sump type with anexternal reservoir and heat exchanger. A gear typepressure and scavenge pump assembly is mountedwithin the power and accessory gearbox. The oil filterfilter bypass valve, and pressure regulating valve are in aunit which is located in the upper right side of the poweand accessory gearbox housing and are accessible fromthe top of the engine. The oil tank is mounted aft of theengine rear firewall on top of the intermediate cabinsection. A check valve is located between the housingand the filter unit. Probe type magnetic clip detectors areinstalled at the bottom of the power accessory gearboxand the engine oil outlet connection. All engine oisystem lines and connections are internal with theexception of pressure and scavenge lines to the fron

compressor support, the gas producer turbine supportand the power turbine support. The oil cooler blower isan integral part of the tail rotor drive and is located aft ofthe freewheeling unit and adjacent to the oil tank.

2-18. IGNITION SYSTEM.

a. The engine ignition system consists of a keylockignition switch, a low tension capacitor discharge ignitionexciter, a spark igniter lead, and a shunted surface gapspark igniter. The system derives its input power fromthe helicopter 28-volt DC electrical system.

b. The keylock ignition switch (figure 2-13 andfigure 2-14) locks out the starter system and preventsunauthorized use of the helicopter, thereby preventingpossible injury to personnel and/or damage to theequipment.

2-19. STARTER SWITCH.

The starter switch (figure 2-3 and figure 2-4), located inthe collective stick switchbox, is a pushbutton typeswitch. When the switch is pressed, the circuit to thestarter relay actuating coil, the igniter unit, and the fuelboost pump are energized. The switch is released whenthe engine starts cycle is completed or abort startprocedures is completed. The keylock ignition

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Figure 2-13. Instrument Panel and Console (Typical) A

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Figure 2-14. Instrument Panel and Console C

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switch must be ON to complete the ignition circuit. Thecircuit is protected by the START ENG, IGN ENG, andFUEL PUMP circuit breakers.

2-20. C ENGINE AUTOMATIC RELIGHT SYSTEM.

The engine automatic relight system will provide enginere-ignition capability in the event of an engine flameout.The ENGINE RELIGHT ON/OFF switch (figure 2-14) isspring loaded to the ON position and will actuate thesystem when bleed air has decayed as a result of aflameout or engine shutdown. The ENGINE RELIGHTlight (figure 2-14) will illuminate when the system isactuated. The system will recycle only if the engineignites after a flameout.

2-21. ENGINE INSTRUMENTS AND INDICATORS.

The engine instruments and indicators are mounted inthe instrument panel or the caution panel in the lowerconsole. They are described in the following paragraphs

and shown in figure 2-13 and figure 2-14.

a. Engine Out Warning. An RPM sensor isconnected to the gas producer tachometer. Power issupplied from the CAUTION PNL LTS circuit breakerand connections are made to the ENGINE OUT warninglight (figure 2-13 and figure 2-14), and to a tonegenerator which produces a tone in the pilot headset.The warning system is activated when N1 is below 55 +3% and is deactivated above that N1 speed. The audiosignal is the same as the low rotor audio signal.

b. Engine Out Audio Warning. A switch

connected to the collective lever disables the engine outaudio warning when the collective lever is in the full downposition.

c. Torquemeter. The torquemeter (figure 2-13and figure 2-14), located in the instrument panel,displays pounds of torque E, percent of torque E,produced by the engine. The torquemeter is a directreading, wetline indicator.

d. A Turbine Outlet Temperature Gage. Athermocouple harness assembly with four integralprobes is used to sense the temperature of the gases onthe outlet side of the gas producer turbine rotor. A DCvoltage, which is directly proportional to the gastemperature it senses, is generated by each thermo-

couple. The thermocouple and thermocouple harnessprovide an average of the four voltages representative ofthe turbine outlet temperature (TOT) and this is thetemperature indication on the TOT gage on theinstrument panel.

e. Turbine Outlet Temperature Indicator. Theturbine outlet temperature (TOT) indicator (figure 2-14),located in the instrument panel, displays temperature indegrees celsius of the exhaust gases in the N1 turbineoutlet area. The indicator is powered by 28 Vdc andprotected by TURB OUTLET TEMP circuit breaker.

f. Gas Producer Tachometer. The gas producertachometer generator, located on the engine, generatesan AC voltage with a frequency that is a function of gasproducer turbine rotor N1 RPM. The output of thetachometer generator is delivered to the gas producertachometer indicator which indicates the frequency interms of percent RPM of gas producer turbine speed.The power for the gas producer tachometer is engine

generated and does not depend on the helicopterelectrical system.

g. Dual Tachometer. The dual tachometer (figure2-13 A ,figure 2-14 C), located in the instrument paneldisplays the percent RPM of the power turbine and RPMof the main rotor A, both percent RPM C. The outerscale is marked TURB A, ENGINE C and the inner scaleis marked ROTOR. The TURB A, ENGINE C, andROTOR needles are synchronized at normal operatingrpm. Operating power for the engine portion of the dualtachometer is derived from the turbine tachometergenerator. Operating power for the rotor portion of the

dual tachometer is derived from the rotor tachometer.The circuit is powered by 28 Vdc and protected by theDUAL TACH circuit breaker.

h. A Oil Pressure Gage. The oil pressureindicator, located on the instrument panel, is a directreading, wet-line system. Pressure from the pressureside of the oil pump is indicated in psi. Refer to figure 2-13.

i. A Oil Temperature Gage. The engine oiltemperature gage, located on the instrument panel, isconnected to an electrical resistance type thermocoupleand indicates the temperature of the oil at the oil tankoutlet.

j. C Oil Pressure/Temperature Indicator. Theengine oil pressure/temperature indicator (figure 214),located in the instrument panel, displays engine oilpressure in psi and temperature in degrees Celsius.

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The temperature circuit is powered by 28 Vdc andprotected by ENG OIL TEMP circuit breaker. The oilpressure portion of the indicator is a direct readingwetline system.

WARNING

Illumination of the engine oil bypasslight may Indicate a severe leak Ispresent or developing which couldresult in total loss of engine oil In ashort period of time.

k. Engine Oil Bypass Caution Light. The ENGOIL BYPASS caution light (figure 2-13 and figure 214),located on the caution panel, will illuminate when the oiltank level is approximately 3 pints low. With the ENGOIL switch A , ENG OIL BYPASS switch C (figure 2-12)in the AUTO position the engine oil will

bypass the oil cooler. A significant rise in engine oitemperature will occur and engine failure can occur in afew minutes due to excessive engine oil temperatureand/or engine oil loss. The switch in AUTO position isdesigned for combat operations only (due to the potentiafor damage to the oil cooler by hostile fire) to provide thepilot a little additional time to fly out of the immediateenemy danger area only. The switch should be in theOFF position for operation in noncombat environmentThe circuit is powered by 28 Vdc and is protected by theCAUTION PNL LTS circuit breaker.

I. Engine Chip Detector. There are two electricalengine chip detectors located in the accessory gearcase, one at the lowest part and one on the forward rightside by the oil pump. The ENG CHIP DET caution light(figure 2-14), located on the caution panel will i lluminatewhen sufficient metal chips to complete the electricalcircuit are collected from the engine oil. The system ispowered by 28 Vdc and protected by CAUTION PNLLTS circuit breaker.

SECTION IV. FUEL SYSTEM

2-22. FUEL SUPPLY SYSTEM.

The OH-58A/C helicopter is equipped with a self-sealingCrashworthy Fuel System. This system is designed toretain fuel in a crash and provide improved ballisticprotection, and is located below and aft of the passengerseat. In addition, the fuel lines are self-sealing. Mountedin the bottom of the cell is one boost pump, one fuelquantity transmitter, one low fuel transmitter, and onefuel sump drain. Installed in top of the cell is one fuel

quantity transmitter, a vent line, and a boost pumppressure switch. A fuel filler cap is located on the rightside just aft of the passenger door. The fuel shut offvalve is mounted on the right side of the aircraft abovethe fuel cell cavity and is manually operated by the fuelvalve handle on the overhead console. A connector foran auxiliary fuel cell is located on the forward side of thefuel cell beneath the seat. Helicopters with crashworthyfuel systems also incorporate the closed circuit refuelingprovision.

2-22.1. AIRFRAME MOUNTED FUEL FILTERASSEMBLY. After compliance with MWO 1-1520228-50-48.

The OH-58A/C helicopters have been equipped withan airframe mounted fuel filter. The fuel filter is acylindrical unit mounted on the engine deck on the leftside of the engine compartment. The fuel filter has a 30micron disposable filter element and electrical means ofindicating any impending bypass condition

which may occur. Fuel enters the inlet port of the filterfrom the fuel supply system and routes the fuel throughthe filter element, then exiting the outlet port of the filterto the engine fuel pump. If a clogging condition shoulddevelop in the filter element, a normally open switch isclosed by differential pressure, lighting FUEL FILTERcaution panel as warning that further clogging may causefuel to flow through the bypass valve in the filter and onto the engine pump without filtration.

2-23. AUXILIARY FUEL SYSTEM.

An auxiliary fuel cell (figure 2-15) can be installed in thehelicopter. The auxiliary fuel cell, when installed, issecured in the passenger compartment on the right halfof the cargo platform. The auxiliary fuel cell is a self-supporting, crashworthy self-sealing bladder type.

a. This fuel is delivered to the main fuel system bygravity only; the pilot has no control over the flow of fuelfrom the auxiliary cell into the main fuel cell.

b. The auxiliary fuel cell can be filled either at themain fuel cell filler or at a filler cap on the auxiliary fuelcell. The preferred method is to service the helicopterwith fuel at the main fuel filler.

c. When the auxiliary fuel cell is installed, a fuelcalibration card must be used to determine the amountof fuel on board (figure 2-15).

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Figure 2-15. Auxiliary Fuel System

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2-24. CONTROLS AND INDICATORS.a. Fuel Quantity Indicator. The FUEL QTY

indicator (figure 2-13 and 2-14) is located in theinstrument panel and displays the quantity of fuel in thefuel cell in pounds (O to 600 lbs.). The indicator ispowered by 28 Vdc and protected by INST CLUSTERcircuit breaker A, FUEL QTY circuit breaker C.

b. Fuel Boost Caution Light. The FUEL BOOSTcaution light (figure 2-13 and 2-14) is located on thecaution panel and illuminates if the fuel boost pressure isbelow safe operating limits when fuel boost switch is inthe ON position. To check FUEL BOOST caution lightwith engine running, move FUEL BOOST switch, to ON.The FUEL BOOST caution light should illuminate then goOFF. The system is powered by 28 Vdc and protectedby CAUTION PANEL LTS circuit breaker.

c. Fuel Boost Pump Switch. The FUEL BOOSTswitch (figure 2-13 and 2-14) is located in the lower rightcomer of the instrument panel. The fuel boost switch will

be in the fuel boost position for all normal conditionswhen the engine is operating and for starting. Thesystem is powered by 28 Vdc and protected by FUELPUMP circuit breaker.

NOTELow fuel caution systems alert the pilot that the fuelevel in the tank has reached a specified levelDifferences in fuel densities due to temperature andfuel type will vary the weight of the fuel remainingand the actual time the aircraft engine may operateDifferences in fuel consumption rates, aircrafaltitude and operational condition of the fuel systemwill also affect actual time the aircraft engine mayoperate.

d. Low Fuel Quantity Caution Light. The LOWFUEL caution light, (figure 2-13 and 2-14), located in thecaution panel, should illuminate when there isapproximately 20 minutes or 65 to 98 pounds of fuelremaining. The illumination of this light does not mean afixed time remains. When the 20 minute fuel cautionlight is on, the fuel remaining may not be availableexcept when the aircraft is in level or coordinated flight.The 20 minute fuel caution light in conjunction with a fuelboost caution light may indicate impending fuel

starvation. The system is powered by 28 Vdc andprotected by CAUTION PNL LTS circuit breaker.

e. Fuel Filter Caution Light. The FUEL FILTERcaution light (figure 2-13 and 2-14), located in the cautionpanel, will illuminate when the filter in the fuel supply linebecomes partially obstructed. The system is powered by28 Vdc and protected by CAUTION PNL LTS circuitbreaker. The light may illuminate momentarily when theboost pump is turned on, but it should extinguish withinapproximately ten seconds.

SECTION V. FLIGHT CONTROLS

2-25. DESCRIPTION.

CAUTION

When carrying non-rated passengersunfamiliar with the operation of thehelicopter, the pilot should evaluate themission as to the advantages anddisadvantages of stowing the copilotcontrols or accepting the responsibilityof the potential hazard when leaving thecontrols in place.

The flight control system is a positive mechanical type,actuated by conventional helicopter controls which, whenmoved, directs the helicopter in various modes of flight.Dual flight controls are provided. The system includes;the cyclic control stick, used for fore and aft and lateralcontrol; the collective pitch control lever, used for verticalcontrol; and the tail rotor anti-torque control pedals, usedfor heading control. The control forces of the main rotorflight control system are reduced to a near

zero pounds force, to lessen pilot fatigue, by hydraulicservo cylinders connected to the control systemmechanical linkage and powered by the transmissiondriven hydraulic pump. Force trims (force gradientsconnected to the cyclic controls are electrically operatedmechanical units used to induce artificial control feelinginto the cyclic controls and to prevent the cyclic stickmoving from a pre-set position.

2-26. CYCLIC CONTROL.

The pilot cyclic grip (figures 2-3 and 2-4) contains thefollowing switches: force trim release switch, ICS switchRADIO transmit switch, TRIGGER switch A, depresselevate gun switch A, night vision goggles light (LTGswitch C CS, TRIGGER UNCAGEIFIRE switch CS, andMSL ACT (missile activate) switch CS. The cycliccontrol system controls the fore and aft and lateramovement of the helicopter. Control feel is provided bythe force trim units.

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NOTE

Removal of copilot cyclic stick can cause pilotcyclic stick to creep slightly aft.

a. Copilot Cyclic Stick Stowage.

NOTE

Force trim will be lost when the electricalconnector is disconnected when stowing orremoving the copilot cyclic stick. Removal isauthorized by the pilot and/or commander. (Fuelquantity gage cannot be monitored with cyclicstick stowed C.)

(1) Unscrew retaining nut on cyclic stick.

(2) Secure cyclic stick on stowage pin andstrap located on the left outboard side of the centerconsole.

b. Copilot Cyclic Stick Installation.

(1) Remove cyclic stick from stowage.

(2) Insert cyclic stick into pivot assembly ontorque tube.

(3) Secure cyclic stick in pivot assembly withknurled nut.

(4) Ensure electrical connector is installed.

2-27. COLLECTIVE PITCH CONTROL.

WARNINGDo not use deck under collective forstorage. This could cause interference inthe full down position.

The pilot collective pitch control is located to the left ofthe pilot position and controls the vertical mode of flight.A rotating grip-type throttle and a switch box assemblyare located in the forward end of the pilot collective pitchlever (figure 2-3 and figure 2-4). The switch boxassembly contains the starter, governor engine idle

release and landing lights switches. Friction can beinduced into the collective system by

rotating a friction device located between the pilot andcopilot seats. The copilot collective lever, located on theleft of the copilot position, contains only a twist typethrottle at the forward end of the control.

a. Copilot Collecti

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