HANDBOOK OF MAINTENANCE INSTRUCTIONS FOR MDHI 369D/E/FF-500/600N HELICOPTERS (ISSUED: 1990)

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

PLACARDS AND MARKINGS

MAINTENANCE PRACTICES

1. General

be cut out to provide proper draining or

ease of opening or removing of doors,

(Ref. Figure 201 thru Figure 203 for placards

plates, etc.

and markings most common to Model 600N

helicopters). Nomenclature corresponds to that

used in the IPC. (Ref. Illustrated Parts Catalog

(2). Where a decal is applied over a skin lap

for each decal part number and the quantity

(one skin overlapping another), the

required.)

decal must be cut so that it lies flat and

The following illustrations cover different

makes a positive bond.

areas of decal placement on the helicopter:

(1). Exterior - Figure 201.

(3). Seal edges of all exterior decals, and

(2). Interior - Figure 202.

only those interior decals in the engine

compartment and cargo compartment

(3). Instrument panels - Figure 203.

aft of the transmission, with epoxy

adhesive. Edge sealing to be a mini

2. Decal Application

mum of 1/32 inch (0.8mm) and a

(1). Where a decal overlaps or covers drain

maximum of 1/8 inch (3mm) around

holes, access doors, etc., the decal shall

perimeter of decal.

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MD Helicopters, Inc.

MAINTENANCE MANUAL

LOCK

MCDONNELL DOUGLAS LOGO

600N IDENTIFICATION

LOCKED

CAUTION

WARNING

SAFELOCK

INNER HANDLE

FAILURE TO PROPERLY INSTALL,ALIGN

OPEN

AND TORQUE,FUEL,OIL AND AIR TUBES

NO PUSH

IN POSITION

AND FITTINGS COULD RESULT IN AN

ENGINE FAILURE.REFER TO THE APPLI

SHOWN BEFORE

DOOR

CABLE MANUAL FOR PROPER INSTAL4

FLIGHT

ATION AND TORQUE PROCEDURES

INSTRUCTIONS

OIL

PUSH

WARNING

PUSH

LOCK BEFORE FLIGHT

LEFT AND RIGHT HAND SIDES

OIL

DURING OPERATIONS IN TEMPERATURES OF 40 _F (4 _C)

OR COLDER, FUEL ADDED TO THE TANK MUST CONTAIN

EITHER ANTI-ICING ADDITIVE PFA-55MB OR ANTI-ICING

ADDITIVE PER MIL-I-27868 OR MIL-I-85470 WITH A

MINIMUM CONCENTRATION OF .06% BY VOLUME

JIG POINT

AND A MAXIMUM CONCENTRATION OF .15% BY VOLUME.

SEE FLIGHT MANUAL FOR MIXING PROCEDURES.

STA 92.64

11. DECAL, FUEL

12. DECAL, ANTI-ICE ADDITIVE

13. JIG POINT

10. REGISTRATION NUMBER

CAP. 12.0 U.S. PTS.

SEE FLT MANUAL

AND LOG BOOK FOR

ATTACH JACK PAD

OIL USAGE

14. ATTACH JACK PAD

15. PLATE IDENTIFICATION

16. GROUND SYMBOL

17. MAIN ROTOR

TRANSMISSION OIL

SERVICED

WITH

MOBIL

CAUTION

AGL

DISCONNECT ELECTRICAL WIRING

BEFORE REMOVING BOOM

19. OIL USAGE

18. FUEL DRAIN

20. ELECTRICAL DISCONNECT

CAUTION

21. CAUTION - CABLE

22. LIGHT ACCESS

23. TRANSMISSION CHECK

24. CAUTION-JACK LOAD

6G11-010-3B

Figure 201. Exterior Placards and Markings (Sheet 3 of 4)

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MAINTENANCE MANUAL

OFF

IF MOISTURE VISIBLE

CONTROLS ACCESS DOOR

BYP

AND O.A.T. BELOW 5o C

24 VOLT DC

DOOR

USE ANTI-ICE

WARNING

24 VOLT DC

REPLACE DOOR BEFORE FLIGHT

CABIN

OUTSIDE AIR

HEAT

TEMPERATURE

OPEN

CONTROLS ACCESS DOOR

WARNING-REPLACE DOOR

BEFORE FLIGHT

NO SMOKING/SEAT BELT

CABIN HEAT AND

FUEL ACCESS DOOR

ENGINE ANTI-ICE

WARNING

REPLACE DOOR BEFORE FLIGHT

LONG TRIM

LAT TRIM

AND JACKING AIRCRAFT

LEVEL HERE

LONGITUDINAL TRIM

FUEL ACCESS DOOR

LATERAL TRIM

LEVEL HERE

10. EXIT INSTRUCTIONS

11. FORWARD DAMPER

12. AFT DAMPER

WARNING

OPEN

CAUTION - TO ASSURE PROPER RESTRAINT. ADJUST SHOULDER

FRICTION

HARNESS SLIDE SO HARNESS IS SNUG AGAINST TORSO

13.

THROTTLE

WHILE SEATED UPRIGHT. FULL BACK IN THE SEAT

OPEN

INCREASE

16. CAUTION SHOULDER HARNESS

14. FRICTION INCREASE

DANGER

WHEN EXITING, WALK AWAY FROM THE

TANK

COOLER

HELICOPTER, KEEP HANDS AND HEAD LOW,

LOCK

DO NOT WALK TO THE REAR.

ENGINE OIL DRAINS

15. EXIT

22. ENGINE OIL DRAINS

17. DOOR

INSTRUCTIONS

LONG RANGE TANK CONN

19. LONG RANGE TANK CONNECTION

M/R

OIL TANK OUTLET

XMSN

23. OIL TANK OUTLET

OIL

CAUTION

WARNING

COOLER

SAFELOCK

DRAIN

OIL TANK VENT

HANDLE IN

FAILURE TO PROPERLY INSTALL,ALIGN

AND TORQUE,FUEL,OIL AND AIR TUBES

POSITION

AND FITTINGS COULD RESULT IN AN

24. OIL TANK VENT

SHOWN BEFORE

ENGINE FAILURE.REFER TO THE APPLI

CABLE MANUAL FOR PROPER INSTAL4

FLIGHT

ATION AND TORQUE PROCEDURES

OIL TANK INLET

21. MAIN ROTOR

TRANSMISSION OIL

18. LOCK BEFORE EXIT

20. WARNING

COOLER DRAIN

25. OIL TANK INLET

6G11-011-3

Figure 202. Interior Placards and Markings (Sheet 3 of 4)

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CSP-HMI-2

MAINTENANCE MANUAL

TABLE OF CONTENTS

Para/Figure/Table

Title

Page

12-00-00 Helicopter Servicing

Servicing

301

Servicing (General)

301

Servicing (Special)

301

A. Main Rotor Hub Wash Procedure

301

B. Main Rotor Blades Washing and Waxing

301

C. Engine Compressor Wash

301

Fuel System Servicing

301

A. Fuel System Servicing Precautions

301

B. Approved Fuels

301

C. Fuel System Filling

301

D. Fuel System Draining

302

E. Fuel System Bleeding

302

F. Engine Fuel Filter Replacement

302

Engine Oil System Servicing

302

A. Approved Lubricants

302

B. Engine Oil Changing

302

C. Engine Oil System Filling

302

D. Engine Oil System Draining (Helicopters With Sta. 137.50 Bulkhead Drain

Ports Installed)

302

E. Engine Oil System Draining (Helicopters with Drain Valve Installed)

303

F. Engine Oil System Flushing

303

Main Rotor Transmission Servicing

303

A. Main Rotor Transmission Filling

303

Figure 301. Servicing Points - Standard Equipment

304

Figure 302. Servicing Points - Optional Equipment

305

B. Main Rotor Transmission Draining

306

C. Main Rotor Transmission Oil System Flushing

306

Tail Rotor Transmission Servicing

306

A. Tail Rotor Transmission Filling

306

B. Tail Rotor Transmission Draining

306

C. Tail Rotor Transmission Flushing

306

Anti-Torque Fan Transmission Servicing

307

A. Anti-Torque Fan Transmission Filling

307

B. Anti-Torque Fan Transmission Draining

307

C. Anti-Torque Fan Transmission Flushing

307

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12 Contents

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MAINTENANCE MANUAL

TABLE OF CONTENTS (Cont.)

Para/Figure/Table

Title

Page

8. One-Way Lock Control System Servicing

307

9. Overrunning Clutch Servicing and Oil Leak Analysis

307

Figure 303. Checking Oil Level - Overrunning Clutch

309

10. Miscellaneous Component Servicing

310

A. Rotor Brake Servicing

310

B. Landing Gear Damper Servicing

310

C. Component Lubrication Chart

310

D. Tail Rotor Swashplate Dual Bearings Repack

310

E. Main Rotor Swashplate Bearing Repack

310

F. Main Rotor Hub Tapered Bearings

310

G. Ground Handling Wheels Bearing Repack

310

11. Overrunning Clutch Subassembly Bearing Repack

310

12. Component Fluid Leak Analysis

311

A. Main Rotor Transmission or Anti-Torque Transmission Oil Leaks

311

B. Engine Oil Leaks

311

C. Landing Gear Damper Hydraulic Fluid Leak

311

D. One-Way Lock Hydraulic Fluid Leak

311

Figure 304. Lubrication Chart

312

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12 Contents

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

HELICOPTER SERVICING

SERVICING

1. Servicing (General)

Fuel Cell Capacities 600N

Total Fuel

116.2 U.S. Gal. (440 Liters)

Servicing of helicopter includes replenishment

of fuel, changing or replenishment of oil and

Usable Fuel

114.6 U.S. Gal. (434 Liters)

other such maintenance functions.

A. Fuel System Servicing Precautions

For locations of servicing points of standard

Comply with following precautions when

equipment Refer to Figure 301. For optional

servicing fuel system.

equipment servicing points Refer to

Figure 302. For lubrication points Refer to

Turn off electrical switches

Figure 304.

WARNING

and disconnect any external

power from helicopter. Electrically

NOTE: The servicing intervals designated

ground helicopter prior to refueling or

herein are the maximum allowable and

defueling. Static discharge spark in

should not be exceeded. When unusual local

presence of fuel vapors can cause fire

conditions such as environmental condi

or an explosion.

tions, utilization, etc., dictate, it is the pre

rogative and responsibility of the operator to

(1). Refueling vehicle should be parked a

increase the scope and frequency of the in

minimum of 20 ft. (6 M) from helicopter

spections as necessary to ensure safe opera

during fueling operation.

tion.

(2). Before starting fueling operation,

always ground fueling nozzle or fuel

2. Servicing (Special)

truck to GROUND HERE receptacle or

Whenever helicopter operation has taken place

to another bare metal location.

over or around salt water environments and

B. Approved Fuels

other environments found to be corrosive, the

following wash procedures must be performed.

Service the helicopter with one of the autho

rized fuels listed in the applicable Allison

A. Main Rotor Hub Wash Procedure

Engine Operation and Maintenance Manual

(Ref. Table 201, Sec. 01-00-00). For operation

(Ref. Main Rotor Hub Corrosion Prevention

under emergency conditions where authorized

Tri-Flow Wash Procedure, Sec. 20-40-00)

fuel is not available, or for operation under

cold weather conditions, refer to same manual.

B. Main Rotor Blades Washing and Waxing

C. Fuel System Filling

(Ref. Main Rotor Blades Corrosion Arresting,

Sec. 20-40-00)

The fuel system has two fuel cells that are

interconnected for simultaneous flow and

C. Engine Compressor Wash

venting. Fuel system filler is on right side of

helicopter.

(Ref. Chap. 71 and applicable Allison Engine

Operation and Maintenance Manual, Table

(1). Refuel helicopter with correct fuel as

201, Sec. 01-00-00)

soon after landing as possible to

prevent moisture condensation and to

3. Fuel System Servicing

keep helicopter as heavy as possible in

case of winds.

Fuel Cell Capacities 369D/E/FF − 500N

Nonself−Sealing

64.0 U.S. Gal. (242 Liters)

(2). Keep fueling nozzle free of all foreign

Usable Fuel

62.7U.S. Gal. (237 Liters)

matter.

Self−Sealing

62.0 U.S. Gal. (234 Liters)

(3). Check filler cap for security after

Usable Fuel

60.7 U.S. Gal. (229 Liters)

fueling.

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MAINTENANCE MANUAL

D. Fuel System Draining

NOTE: If the type of engine oil or the oil group

is changed, remove and inspect the oil filter

Fuel draining should be accomplished with

each 25 hours of engine operation (Ref.

helicopter as level as possible.

applicable Allison Engine Operation and

Maintenance Manual for further informa

(1). Fuel system may be defueled in either

tion).

of two ways:

B. Engine Oil Changing

To avoid possible damage to fuel

(Ref. Applicable Allison Engine Operation and

CAUTION

pump, do not operate fuel pump

Maintenance Manual, Table 201, Sec.

with fuel tanks drained.

01-00-00)

C. Engine Oil System Filling

(a). Defuel through filler port using a

pump.

The engine oil tank filler is on the right side of

the helicopter. A liquid level sight gauge for

(b). Open system drain valves on fuselage

checking oil level in tank is visible through a

underside and in engine compart

transparent window near the filler.

ment.

NOTE:

D Before adding oil, the oil container must

(2). Fuel supply line drain valves are spring

be shaken to ensure proper mixture of the

loaded type and open by pushing valve

anti-foaming additive.

and attached drain line.

D If sight gauge does not permit positive de

(3). Fuel cells drain valve is spring-loaded

termination, remove filler cap and visual

closed and is opened by pressing

ly check the oil level.

internal plunger.

(1). Check oil level within 15 minutes of

engine shutdown; replenish if low.

E. Fuel System Bleeding

(2). If engine oil level is low after helicopter

(Ref. Chap. 28 and applicable Allison Engine

has set for more than 15 minutes;

Operation and Maintenance Manual, Table

(a). Run engine for at least 1 minute at

201, Sec. 01-00-00) Purge entrapped air from

ground idle.

the fuel system, if necessary.

Ensure engine oil pressure is at

CAUTION

F. Engine Fuel Filter Replacement

tained when starting engine

(Ref. applicable Pilot's Flight Manual).

(Ref. Applicable Allison Engine Operation and

(b). Shut down engine, check oil level,

Maintenance Manual, Table 201, Sec.

replenish if low.

01-00-00)

NOTE:

4. Engine Oil System Servicing

D Motoring engine can draw oil from the oil

tank to the gearbox, giving low oil level

Oil Tank Capacity

3.0 U.S. Qt. (2.84 Liter)

indications.

D If engine oil level indicates a low condi

A. Approved Lubricants

tion after setting overnight, engine check

valve may be leaking oil from tank to en

Service the helicopter with one of the autho

gine gearcase.

rized oils listed.

(3). Ensure oil tank filler cap is securely

For operation under emergency conditions

tightened immediately after servicing.

where different oils must be mixed, or for

D. Engine Oil System Draining (Helicopters

operation under cold weather conditions, use

With Sta. 137.50 Bulkhead Drain Ports

alternate lubricants (Ref. applicable Allison

Installed)

Engine Operation and Maintenance Manual,

Table 201, Sec. 01-00-00).

(1). Open engine access doors.

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MAINTENANCE MANUAL

(2). Place suitable container under engine

(1). Drain oil from engine, oil tank and oil

oil tank drain and remove engine oil

cooler (Ref. Engine Oil System Drain

tank filler cap.

ing).

(3). Remove engine oil tank drain cap.

(2). Replace engine oil filter(s) (Ref. Appli

cable Allison Operation and Mainte

(4). After draining oil from tank, reinstall

nance Manual).

engine oil tank drain cap and filler cap.

(3). Refill engine oil system (Ref. Engine Oil

(5). To drain residual oil from engine

System Filling).

accessory gearbox drain, remove wire

lead and lower chip detector. Use

(4). Operate engine for five minutes and

suitable container to catch oil. Check

repeat above procedures.

that detector O-ring is serviceable

5. Main Rotor Transmission Servicing

(replace as required); reinstall detector;

torque to 50 - 60 inch-pounds (5.65 -

Service the helicopter with one of the autho

6.78 Nm); lockwire and reconnect wire

rized oils listed (Ref. Sec. 91-00-00).

lead.

NOTE: Mobil oil AGL can be formulated such

E. Engine Oil System Draining (Helicopters

that it may have two different colors. The oil

with Drain Valve Installed)

can still be mixed with no adverse affects.

(1).

Remove interior trim and aft bulkhead

Main Transmission Capacities

right access cover.

369D25100

12.0 U.S. Pt. (5.67 Liter)

369F5100

14.0 U.S. Pt. (6.62 Liter)

(2).

Place a suitable container under

overboard oil drain line where it exits

A. Main Rotor Transmission Filling

fuselage underside at firewall.

Transmission (gearbox) oil should be replaced

(3).

Remove cap from engine oil tank filler.

with new oil whenever it is drained. A liquid

Pull out knurled spring-loaded button

level sight gauge for checking main rotor

to open valve in engine oil drain line

transmission oil level is located on the

just below engine oil cooler (Ref.

right-hand side and visible through the clear

Figure 301). Rotate button and valve

panel of the main transmission interior cover.

poppet so that locking pin rests on

NOTE:

shoulders of pin slot.

D Replacement of oil pump filter (Ref. Sec.

(4).

After draining oil from tank, reinstall

63-21-00) is required after oil is drained

filler cap and close oil drain valve;

from main rotor transmission and at in

ensure that poppet pin is in stop slot.

tervals specified (Ref. Sec. 05-20-20).

(5).

Reinstall access cover and interior trim.

D If oil was drained from transmission cool

er, ground-operate helicopter for 15 min

(6).

To drain residual oil from engine

utes after replenishing oil (Ref. applicable

accessory gearbox drain, remove wire

PFM, Table 201, Sec. 01-00-00). Recheck

lead and lower chip detector (Ref. Sec.

oil level at liquid level sight gauge and re

79-00-00). Use suitable container to

plenish as necessary. This purges air from

catch oil. Check that detector O-ring is

oil cooling system and ensures that entire

serviceable (replace as required);

oil cooling system is full.

reinstall detector, torque to 50 - 60

inch-pounds (5.65 - 6.78 Nm) and

(1). Replenish with correct oil until oil level

reconnect wire lead.

is at FULL on sight gauge by lifting

breather-filler cap and inserting spout

F. Engine Oil System Flushing

of oil can into opening.

The following procedure is for flushing oil that

(2). Check that spring-loaded cap closes

has been contaminated or when changing the

when oil can spout is removed. Replace

type of oil.

trim cover.

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MAINTENANCE MANUAL

BATTERY ELECTROLYTE

WATER

MAIN XMSN FILLER

MIL-L-23699/MOBIL AGL

NOTE 1

EXTERNAL POWER

RECEPTACLE

ONE-WAY LOCK

RESERVOIR MIL-H-5606

FUEL FILTER 5 MICRON

FUEL CELL SUMP DRAIN

L/G DAMPERS, 4 PLACES

FUEL SYSTEM FILLER

ENGINE OIL TANK FILLER

NITROGEN/MIL-H-5606

JP4/JP5

MIL-L-23699

NOTE 2

NOTES 1, 2

FAN XMSN FILLER

FAN GEARBOX

MIL-L-23699/MOBIL AGL

DRAIN (500/600N)

NOTE 1

ENGINE OIL

TRANS. OIL

COOLER DRAIN

ENGINE OIL

TANK DRAIN

OIL DRAINS FOR MAIN TRANSMISSION, ENGINE OIL COOLERS,

NOTES:

ENGINE OIL TANK AND FAN GEARBOX

DO NOT MIX OILS.

REFER TO APPLICABLE ALLISON OPERATION MAINTENANCE

MANUAL FOR FREQUENCY OF OIL CHANGE, AUTHORIZED

FUELS AND OILS AND SERVICE CHECKS.

FAN TRANSMISSION

FREQUENCY SYMBOL

REQUIREMENTS

BREATHER FILLER

MIL-L-23699/MOBIL AGL

DAILY

INSPECT PRIOR TO FIRST FLIGHT OF THE DAY

NOTE 1

PREFLIGHT

INSPECT PRIOR TO EACH FLIGHT

100 HOURS

REMOVE BATTERY AND SERVICE PER THE MANUFACTURER'S

MAINTENANCE MANUAL

INSPECT AND REPLENISH ONE-WAY LOCK RESERVOIR AS

APPLICABLE

YEARLY

DRAIN AND REFILL T/R GEARBOX, FAN TRANSMISSION

300 HRS / YEARLY . . 2.

DRAIN AND REFILL 369D25100 M/R G/B SERVICED WITH

MIL-L-23699;

REPLACE OIL FILTER ELEMENT

600HRS / YEARLY . . 3.

DRAIN AND REFILL 369D25100 M/R G/B SERVICED WITH MOBIL

AGL

TAIL ROTOR

OR 369F5100 M/R G/B; REPLACE OIL FILTER ELEMENT

TRANSMISSION

REPLACE ENGINE FUEL FILTER (5 MICRON)

G12-0001D

ON CONDITION

ON CONDITION OR EVERY 9 MONTHS IF ON SHELF

Figure 301. Servicing Points − Standard Equipment

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MAINTENANCE MANUAL

ROTOR BRAKE RESERVOIR

MIL-H-5606

MIST ELIMINATOR

PARTICLE SEPARATOR

ANTI-ICE FILTER

SCAVENGE OIL FILTER

NOTE

NOTE:

APPLICABLE TO ALL ALLISON 250C20R/2 AND C47 ENGINES.

OPTIONAL EQUIPMENT FOR ALLISON 250C20B, C30 ENGINES.

REFER TO ALLISON OPERATION AND MAINTENANCE MANUAL

FOR FILTER ELEMENT REPLACEMENT SCHEDULE.

FREQUENCY SYMBOL

REQUIREMENT

100 HOURS

CHECK ROTOR BRAKE RESERVOIR

FOR

PROPER LEVEL; REPLENISH IF LOW.

REMOVE AND CLEAN THE MIST

ELIMINATOR.

NOTE

REPLACE SCAVENGE OIL FILTER

ELEMENT.

300 HOURS

REPLACE ANTI-ICE FILTER ELEMENT.

SERVICING MATERIAL

REMOVE AND CLEAN PARTICLE

SPEC:

MATERIAL:

SEPARATOR ASSEMBLY.

REF:

MIL-L-23699

LUBRICATING OILS

TABLE 1, 91-00-00

MOBIL AGL

ITEMS CM125 & CM126

JET A/JP4/JP5/JP8

ENGINE FUEL, TURBINE

TABLE 201, 01-00-00

ALLISON OPERATION AND MAINTENANCE MANUAL

G12-0002C

Figure 302. Servicing Points − Optional Equipment

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MAINTENANCE MANUAL

B. Main Rotor Transmission Draining

6. Tail Rotor Transmission Servicing

Service the helicopter with one of the autho

Special Tools

rized oils listed (Ref. Table 1, Sec. 91-00-00).

(Ref. Section 91−00−00)

NOTE: Mobil oil AGL can be formulated such

Item

Nomenclature

that it may have two different colors. The oil

ST301

Main transmission drain hose

can still be mixed with no adverse affects.

Tail Rotor Transmission Capacity

369D25300

0.530 U.S. Pt. (0.250 Liter)

(1).

Remove main rotor transmission cooler

369D25400

0.530 U.S. Pt. (0.250 Liter)

drain cap and drain oil into suitable

container.

A. Tail Rotor Transmission Filling

Tail rotor transmission oil should be replaced

(2).

Remove main rotor transmission drain

with new oil whenever it is drained. A liquid

access covers, wire leads and chip

level sight gauge for checking oil level is

detectors.

located on the transmission housing.

(3).

Using main rotor transmission drain

(1). Check oil level.

hose (ST301), drain oil into suitable

(2). Remove lockwire and unscrew brea

container.

ther-filler cap.

(4).

If damaged, replace O-rings used with

(3). Fill with proper oil by pouring oil into

chip detectors and self-closing valves.

transmission until oil level shows

FULL on sight gauge.

(5).

If removed, reinstall self-closing valve.

(4). Check that filler O-ring is serviceable

Torque valve to 50 - 60 inch-pounds

(replace if necessary). Reinstall brea

(5.65 - 6.78 Nm) and chip detector to

ther-filler and torque to 45 - 55

40 - 50 inch-pounds (4.52 - 5.65

inch-pounds (5.08 - 6.21 Nm) with

Nm). Lockwire valve to gearbox and

breather hole aft (Ref. Sec. 63-25-10)

detector to valve. Reconnect wire leads.

at completion of torquing. Secure with

lockwire.

(6).

Reinstall main rotor transmission

access covers.

B. Tail Rotor Transmission Draining

(1). Position suitable container under tail

C. Main Rotor Transmission Oil System

rotor transmission drain.

Flushing

(2). Remove wire lead, lockwire, chip

The following procedure is for flushing oil that

detector and self-closing valve (Ref.

has been contaminated or when changing the

Sec. 63-25-10).

type of oil.

(3). If damaged, replace O-rings used with

chip detector and self-closing valve.

(1). Drain oil from transmission and oil

cooler (Ref. Main Rotor Transmission

(4). After oil drains, install self-closing

Draining).

valve. Torque valve to 50 - 60 inch-

pounds (5.65 - 6.78 Nm) and chip

(2). Replace transmission oil filter (Ref. Sec.

detector to 40 - 50 inch-pounds (4.52

63-21-00, Main Transmission Filter

- 5.65 Nm). Lockwire valve to gearbox

Replacement).

and detector to valve; reconnect wire

leads.

(3). Refill transmission oil system (Ref.

C. Tail Rotor Transmission Flushing

Main Rotor Transmission Filling).

The following procedure is for flushing oil that

(4). Operate aircraft for five minutes, shut

has been contaminated or when changing the

down and repeat steps (1). thru (3).

type of oil.

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MAINTENANCE MANUAL

(1). Drain oil from tail rotor transmission

transmission drain and remove cap.

(Ref. Tail Rotor Transmission Drain

(Ref. Figure 301).

ing).

(4). After draining oil from transmission,

(2). Refill tail rotor transmission (Ref. Tail

reinstall drain cap.

Rotor Rotor Transmission Filling).

C. Anti−Torque Fan Transmission Flushing

(3). Operate aircraft for five minutes, shut

The following procedure is for flushing oil that

down and repeat steps (1). and (2).

has been contaminated or when changing the

type of oil.

7. Anti−Torque Fan Transmission Servicing

(1). Drain oil from fan transmission (Ref.

Service the helicopter with one of the autho

Anti-Torque Fan Transmission Drain

rized oils listed (Ref. Sec. 91-00-00).

ing).

NOTE: Mobil oil AGL can be formulated such

(2). Refill fan transmission (Ref. Anti-

that it may have two different colors. The oil

Torque Fan Transmission Filling).

can still be mixed with no adverse affects.

(3). Operate aircraft for five minutes, shut

Fan Transmission Capacity

8 U.S. Oz. (236 cc)

down and repeat steps (1). and (2).

A. Anti−Torque Fan Transmission Filling

8. One−Way Lock Control System Servicing

Anti-torque fan transmission oil should be

Service the helicopter with one of the autho

replaced with new oil whenever it is drained. A

rized hydraulic oils listed (Ref. Sec. 91-00-00).

liquid level sight gage for checking oil level is

located on the transmission housing.

One−Way Lock Capacity

0.67 U.S. Oz. (20 cc)

(1). To check oil level, remove control access

(1). Check oil level.

cover.

(2). If servicing is required, remove fan

NOTE: Reservoir should be 1/2 to 3/4 full.

inlet screen and fan hub transmission

fairing.

(2). If oil level in reservoir is low, lift filler

cap and add oil as needed.

(3). Remove lockwire and remove filler

plug.

(3). Reinstall pilot's seat cover.

(4). Fill by pouring oil into transmission

NOTE: If oil level is consistently low, one-way

filler plug hole, until oil level shows

lock should be repaired to stop oil leakage

FULL on sight gauge.

(Ref. Component Overhaul Manual).

(5). Check that plug O-ring is serviceable

9. Overrunning Clutch Servicing and Oil

(replace as required). Reinstall filler

Leak Analysis

plug and torque to 45 - 55 inch-

pounds (5.08 - 6.21 Nm). Secure with

(Ref. Figure 303) When oil leakage or seepage

lockwire.

is noticed at oil seals or assembly joint lines of

overrunning clutch, clutch requires further

B. Anti−Torque Fan Transmission Draining

inspection and investigation as follows.

(1). Remove fan inlet screen and transmis

NOTE: Mobil oil AGL can be formulated such

sion fairing.

that it may have two different colors. The oil

can still be mixed with no adverse affects.

(2). Cut lockwire and remove fan transmis

Overrunning Clutch Capacities

sion filler plug.

369A5350−11, −21, −31

1.52 U.S. Oz. (45cc)

(3). Open engine access doors and place

369A5350−41, −51

1.01 U.S. Oz. (30 cc)

suitable container under the fan

369F5450

3.64 U.S. Oz. (110 cc)

Page 307

12-00-00

TR12-001

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(b). Read scale to determine oil level and

Consumable Materials

servicing required. Full oil level is

(Ref. Section 91−00−00)

indicated by oil level of 2 7/8 inches

Item

Nomenclature

(7.30 cm) on scale. Minimum allow

able quantity (13 cc) is 7/8 inch

CM112

Anti-seize compound high temperature

(22.23 mm) on scale. Recheck reading

CM125

Oil

a minimum of three times.

CM126

Oil, turbine

If oil quantity is less than 7/8

CAUTION

inch (22.23 cm) on scale, the

CAUTION

clutch subassembly must be removed and

inspected for evidence of overheating (Ref.

D Checking clutch oil level requires removal

CSP-DEF-5).

of main rotor transmission drive shaft.

Use care not to stress drive shaft dia

(6). For a 369F5450 clutch, there is two

phragms (early type) or flexible couplings

methods for checking the oil level:

(current type) during removal and instal

lation. Deflection in these areas are lim

ited due to material hardness.

(a). First Method: Full oil level is indi

cated by oil level of 3 1/8 inches (9.84

D The 369F5450 clutch is only to be serviced

cm) on a 6 inch (15 cm) machinists

with Mobil AGL oil (CM125).

scale, 1/2 inch (12.7 mm) width,

inserted into clutch exactly 5 inches

D The 369A5350 clutch is only to be ser

(12.7 cm). Minimum allowable

viced with MIL-L-23699 oil (CM126).

quantity (60 cc) is 5/8 inch (15.88

mm) on scale. Recheck reading a

(1). Remove trim and blower access door.

minimum of three times.

(2). Remove main rotor transmission drive

shaft (Ref. Sec. 63-10-00). Carefully

(b). Second Method: Full oil level is

slide shaft from drive couplings; do not

indicated by oil level of 4 5/8 inches

strike shaft against any object.

(11.77 cm) on a 12 inch (30 cm)

machinists scale, 1/2 inch (12.7 mm)

(3). Remove coupling bolt and O-ring from

width, inserted to bottom of inner

end of clutch.

race. Minimum allowable quantity

(60 cc) is 2 1/8 inch (5.40 cm) on

(4). Check that the three drain holes in

scale. Recheck reading a minimum of

clutch housing are clean and free of

three times.

obstruction. Oil leakage may indicate

engine power output seal leakage if

If oil quantity is less than 5/8

clutch oil level is checked and within

CAUTION

inch (15.88 mm) on scale for the

limits.

first method or 2 1/8 inches (5.40 cm) for the

second method, the clutch subassembly

(5). For a 369A5350 Clutch:

must be removed and inspected for evidence

of overheating.

(a). Using a clean 6 inch (15 cm) machi

nists scale, 1/2 inch (12.7 mm) width,

(7). Service clutch with lubricating oil

slowly insert scale into center of

(CM125 or CM126). If oil level readings

clutch output shaft until scale

indicate less than full level. Do not

bottoms. Scale must be inserted 4 7/8

overfill. Recheck oil level as in previous

inches (12.38 cm).

step.

NOTE: Trim edge of scale as required to reduce

width of scale and allow scale to bottom in

NOTE: Always check oil level after installing

clutch.

clutch in the helicopter.

Page 308

TR12-001

12-00-00

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

CLUTCH CENTERLINE

CLUTCH OUTPUT SHAFT

SCALE

CLUTCH

MINIMUM OIL LEVEL

FULL OIL LEVEL

7/8 IN. (22.23 MM)

2-7/8 IN. (7.30 CM)

ENGINE

4-7/8 IN. (12.38 CM)

SCALE BOTTOMED

COUPLING

DRAIN HOLES

O-RING

COUPLING

369A5350 CLUTCH OIL

MAIN TRANSMISSION

LEVELS - SCALE INDICATIONS

DRIVE SHAFT

COUPLING BOLT

CLUTCH CENTERLINE

SCALE

ENGINE

3 1/8 IN.

“FULL” OIL LEVEL

CLUTCH

(9.84 CM)

110 CC

CENTERLINE

5/8 IN.

MINIMUM OIL LEVEL

SCALE

(15.88 MM)

60 CC

4 5/8 IN.

“FULL” OIL LEVEL

ENGINE

(11.77 CM)

110 CC

2 1/8 IN.

MINIMUM OIL LEVEL

6 INCH (15 CM) SCALE METHOD

(5.40 CM)

60 CC

12 INCH (30 CM) SCALE METHOD

369F5450 CLUTCH

OIL LEVELS - SCALE INDICATIONS

G12-3001B

Figure 303. Checking Oil Level − Overrunning Clutch

Page 309

12-00-00

Revision 23

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(8). If coupling shimming was disturbed,

C. Component Lubrication Chart

shim coupling so that there is

(Ref. Figure 304 for required lubrication

0.035-0.055 inch (0.889-1.397 mm)

points, lubricants to be used, and lubrication

O-ring gap. (Ref. Sec. 63-10-00 for

intervals.)

clutch installation and shimming

requirement details.)

Use extreme care when apply

CAUTION

ing any type of lubrication

When installing clutch coupling

(grease, oil, dry-film, etc) in vicinity of te

CAUTION

bolt in next step, installation

flon bearings. Most lubricants allow a dirt-

torque on the bolt must not be less than 250

retaining film to form or have other detri

- 300 inch-pounds (28.25 - 33.90 Nm)

mental effects that can cause rapid

plus drag torque. Torquing to lower value

deterioration of bearing surface.

reduces clutch bearing clamp-up and may

result in bearing race spinning.

D. Tail Rotor Swashplate Dual Bearings

Repack

(9). Coat bolt threads with oil (CM112).

Check ball bearing for excessive loss of grease

Install coupling bolt and O-ring (Drag

and serviceability and relubricate (repack)

torque for bolt self-locking serviceabili

(Ref. Sec. 64-30-00).

ty is 25 inch-pounds (2.82 Nm)

minimum, 200 inch-pounds (22.60

E. Main Rotor Swashplate Bearing Repack

Nm) maximum). Torque bolt to 250 -

300 inch-pounds (28.25 - 33.90 Nm)

Check seals for evidence of deterioration and

plus actual drag torque.

grease leakage. Inspect bearing assembly for

serviceability and repack (Ref. COM, Sec.

(10). Position main rotor transmission drive

62-30-10).

shaft between drive couplings. Install

F. Main Rotor Hub Tapered Bearings

four bolts and washers each end of

drive shaft and torque bolts to 50 - 75

Clean, inspect, and relubricate (repack). (Ref.

inch-pounds (5.65 - 8.47 Nm).

Sec. 62-20--00).

(11). Reinstall blower access door and trim.

G. Ground Handling Wheels Bearing Repack

10. Miscellaneous Component Servicing

Consumable Materials

(Ref. Section 91−00−00)

A. Rotor Brake Servicing

Item

Nomenclature

CM111

Grease, aircraft

(Ref. Sec. 63-22-00 for information on adding

hydraulic fluid to the rotor brake master

cylinder and bleeding the hydraulic system.)

At regular intervals, repack wheel bearings

with grease (CM111).

B. Landing Gear Damper Servicing

11. Overrunning Clutch Subassembly Bearing

Repack

Servicing of the landing gear damper is

performed by overhauling the damper assem

For 369A5350 overrunning clutch, repack

bly, or if equipped with schrader valve,

bearing per CSP-COM-5, Sec. 63-10-10.

servicing with nitrogen if it does not meet the

minimum extension requirements (Ref.

For 369F5450 overrunning clutch, repack

32-10-00).

bearing per CSP-COM-5, Sec. 63-10-15.

Page 310

Revision 32

12-00-00

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

12. Component Fluid Leak Analysis

01-00-00) for definition of permissible engine

oil leakage.

A. Main Rotor Transmission or Anti−Torque

Transmission Oil Leaks

C. Landing Gear Damper Hydraulic Fluid

Leak

Oil leakage, seepage, or capillary wetting at oil

seals or assembly joint lines of main or

Hydraulic fluid leakage from any of landing

anti-torque transmissions are permissible if

gear dampers is not permissible. If leakage is

leakage rate does not exceed 2 cc per hour (one

present, damper assembly should be over

drop per minute). An acceptable alternate rate

hauled (Ref. Component Overhaul Manual) as

of leakage from either transmission is, if oil

required and a serviceable unit installed. If

loss is not more than from the full to the add

leaking landing gear damper is not replaced

mark on the sight gauge within 25 flight hours

when leakage is noticed, continuation of

(Repair leaks according to instructions in

damper in service can result in unequal and/or

Component Overhaul Manual).

unacceptable dampening and/or ground

resonance.

NOTE:

D On gearbox oil seals with less than 2

NOTE: It is normal for a thin hydraulic oil film

hours of operation, some seepage or wet

to remain on damper piston as a result of

ting of adjacent surfaces is normal until

wiping contact with piston seal. Newly in

seal is wetted and worn-in (seated). If

stalled dampers may also have slight oil

seepage continues at rate of one drop per

seepage from oil trapped in end cap threads

minute or less, seal may be continued in

during damper assembly. Neither of these

service. Check transmission oil level and

should be considered damper leakage or

observe seepage rate after every 2 hours

cause for damper replacement.

of operation. Shorter inspection periods

may be required if seal leakage appears to

D. One−Way Lock Hydraulic Fluid Leak

be increasing.

Hydraulic fluid leakage from any part of

D If excessive gearbox oil seepage occurs,

one-way lock is not permissible. When leakage

check breather filler for proper installa

is observed, assembly should be overhauled

tion and operation (Ref. Component Over

(Ref. Component Overhaul Manual) as

haul Manual for cleaning procedures).

required and a serviceable unit installed. If

leaking one-way lock is not replaced when

B. Engine Oil Leaks

leakage occurs, continuation in service may

(Ref. Applicable Allison Engine Operation and

result in mechanical malfunction that could be

Maintenance Manual (Ref. Table 201, Sec.

hazardous to flight safety.

Page 311

12-00-00

Revision 32

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

TABLE OF CONTENTS

Para/Figure/Table

Title

Page

18-10-00 Main Rotor Track and Balance

Maintenance Practices

201

1. Main Rotor Blade Tracking

201

A. Main Rotor Hub Balancing

201

B. Main Rotor System Balancing

201

C. Balancing Equipment and Balance Spare Kit

202

Table 201. Isolating Tracking Problems

202

Removal/Installation

401

1. Main Rotor System Tracking Equipment Installation

401

A. Interrupter Installation

401

B. Magnetic Pickup Installation

402

C. Tracking Tip Cap Installation

402

D. Main Rotor System Balancing Equipment Installation

402

Figure 401. Blade Tracking Equipment

403

Figure 402. Main Rotor Balancing Equipment Installation

404

Adjustment/Test

501

1. Blade Tracking Procedure

501

Figure 501. Typical Track Conditions and Adjustments

501

A. Blade Track Adjustment

502

B. Pitch Control Link Adjustment

502

C. Blade Tab Adjustment

502

D. Main Rotor Ground Tracking

502

E. Hover Track Verification

503

Figure 502. Main Rotor Blade Tab Adjustment

504

F. Forward Flight Tracking

505

2. Main Rotor Blade Tab Adjustment

505

3. Main Rotor System Balance Procedure

505

4. Main Rotor Autorotation RPM Check

505

5. Main Rotor Hub Balancing Procedure

506

Table 501. Summary Procedure for Blade Tracking

507

Table 502. Autorotation Rpm Chart (369D/E)

508

Table 503. Autorotation Rpm Chart (369FF/500N)

508

Figure 503. Main Rotor Hub Balancing Chart

509

Figure 504. Main Rotor Hub Balancing

510

18-10-60 Main Rotor Track and Balance (600N)

Maintenance Practices

201

1. Main Rotor Blade Tracking

201

Page i

18 Contents

Revision 23

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

TABLE OF CONTENTS (Cont.)

Para/Figure/Table

Title

Page

2. Main Rotor System Balancing

201

3. Balancing Equipment and Balance Spare Kit

201

Table 201. Isolating Tracking Problems

202

Removal/Installation

401

1. Main Rotor System Tracking Equipment Installation

401

A. Interrupter Installation

401

B. Magnetic Pickup Installation

401

Figure 401. Blade Tracking Equipment - Main Rotor Components

(Sheet 1 of 2)

402

C. Tracking Tip Cap Installation

403

D. Main Rotor System Balancing Equipment Installation

403

Figure 402. Main Rotor Balancing Equipment Installation

404

Adjustment/Test

501

Blade Tracking Procedure

501

Figure 501. Typical Track Conditions and Adjustments

501

A. Blade Track Adjustment

502

B. Pitch Control Link Adjustment

502

C. Blade Tab Adjustment

502

Figure 502. Adjustment - Main Rotor Blade Tab

503

D. Main Rotor Ground Tracking

503

E. Hover Track Verification

504

F. Forward Flight Tracking

504

Main Rotor System Balance Procedure

505

Main Rotor Autorotation Percentage Check

505

Table 501. Summary Procedure for Blade Tracking

506

Table 502. Autorotation Percentage Chart

506

Figure 503. Main Rotor System Balancing

507

Figure 504. Main Rotor Track at Hover (Pitch Change Link Adjustment)

508

Figure 505. Main Rotor System Balance Chart

509

Figure 506. Main Rotor Tracking at 100 - 130 KIAS

(Inner Tab Adjustment)

510

Figure 507. Main Rotor Tracking at 100 - 130 KIAS

(Mid Tab Adjustment)

511

Figure 508. Main Rotor Tracking at 100 - 130 KIAS

(Outer Tab Adjustment)

512

18-20-00 Tail Rotor Balance

Maintenance Practices

201

1. Tail Rotor Balancing

201

Page ii

Revision 23

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CSP-HMI-2

MAINTENANCE MANUAL

TABLE OF CONTENTS (Cont.)

Para/Figure/Table

Title

Page

A. Balance at Blade Tip

201

B. Balance at Blade Pitch Arm

201

C. Short Method Balance Check

202

D. Long Method Balance Check (Four-Bladed Tail Rotor)

202

2. Horizontal Stabilizer Tuning

203

Figure 201. Tail Rotor Assembly Balancing (Two-Bladed Tail Rotor)

204

Table 201. Tail Rotor Balance Weight - Value Chart

205

Figure 202. Short Method Tail Rotor Balancing (Four-Bladed Tail Rotor)

205

Figure 203. Long Method Tail Rotor Balancing (Inboard Blade)

206

Figure 204. Long Method Tail Rotor Balancing (Outboard Blade)

206

18-20-30 NOTARr Anti-Torque System Fan Balance

Maintenance Practices

201

1. Fan Balancing

201

2. Fan Balance Check

201

Table 201. Preferred Hardware for Balancing Fan Assembly

202

Figure 201. Fan Balancing Stud Numbering

203

Figure 202. Fan Balance Chart

204

Figure 203. Fan Balancing Equipment Installation

205

Page iii

18 Contents

Revision 23

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

MAIN ROTOR TRACK AND BALANCE

MAINTENANCE PRACTICES

1. Main Rotor Blade Tracking

(e). Forward flight tracking (Ref. For

ward Flight Tracking).

Main rotor blade track is observed by means of

(f). Autorotation rpm adjustment (Ref.

reflective tip caps temporarily installed on

Main Rotor Autorotation RPM

each blade and a high-intensity strobe light.

Check).

Blade track is determined by observing the

apparent tip cap pattern created by strobe

(2). No attempt should be made to verify or

light pulses synchronized with the rotating

adjust blade track without first check

blades. Strobe light electrical power is supplied

ing and adjusting blade phasing, a

by the helicopter electrical system.

function of main rotor damper adjust

ment (Ref. Sec. 62-20-00).

Immediately investigate the

WARNING

Understand the blade tracking

cause of a sudden onset of

CAUTION

sequence and related adjust

excessive or unusual main rotor vibra

ments before attempting blade track proce

tion prior to continued flight. Under no

dures.

circumstance should main rotor track

ing be attempted to correct the prob

If main rotor hub balance is suspect, balance ro

lem until a thorough inspection of the

tor hub prior to performing blade track.

main rotor blades, hub assembly and

A. Main Rotor Hub Balancing

strap pack assembly has been per

formed.

Main rotor hub balancing is accomplished by

adding or removing weight (flat washers) as

When working near engine air

required at the lead-lag bolts (Ref. Main Rotor

CAUTION

inlet, comply with all precau

Hub Balancing Procedure). Analysis of main

tions to prevent entry of foreign material.

rotor hub balance is accomplished using

Carefully observe precautions in the Track

instrumentation that measures and localizes

ing and Balancing Manual relating to the

vibrations due to main rotor hub imbalance.

placement and security of equipment (espe

Data provided by the instrumentation is

cially cables) fastened to the exterior of the

plotted on a chart designed to indicate how

helicopter.

much weight must be added or removed from

the lead-lag bolt. No other means of balancing

NOTE: Refer to Table 201 to isolate ground or

is to be used.

in-flight blade tracking problems.

B. Main Rotor System Balancing

(1). Tracking must be accomplished in the

Main rotor system balancing is accomplished

following sequence of six steps:

by adjusting the turnbuckle on the elastomeric

damper. Analysis of main rotor system balance

(a). Verification of proper blade phasing

is accomplished using instrumentation that

(Ref. Main Rotor Blade Phasing

measures and localizes vibrations due to main

Check and/or Adjustment, Sec.

rotor imbalance (Ref. Main Rotor System

62-20-00).

Balance Procedure). Data provided by the

instrumentation is plotted on a chart designed

(b). Ground tracking (Ref. Main Rotor

to indicate how much rotor blade shall be

Ground Tracking).

shifted in leading or lagging direction by

adjusting turnbuckle. No other means of

(c). Verification of proper rotor balance

balancing is to be used. Never add weight to,

(Ref. Main Rotor System Balance

subtract weight from or redistribute weight on

Procedure).

the main rotor blades. Do not attempt the

blade balancing procedure without first

(d). Hover verification (Ref. Hover Track

tracking the blades (Ref. Blade Tracking

Verification).

Procedure).

Page 201

18-10-00

Revision 23

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

C. Balancing Equipment and Balance Spare

Kit

The balancing equipment contains all equip

ment needed to analyze main rotor balance.

Table 201. Isolating Tracking Problems

Symptom

Probable Cause

Corrective Action

GROUND TRACKING

Rotor does not follow adjustments.

Turning turnbuckle wrong direction.

Adjust correctly.

Pitch link bearing worn. Trim tab

Replace bearing. Zero trim tabs.

bent excessively.

Excessive diving or climbing of

Trim tab bent excessively.

Zero trim tabs.

blade from low speed ground track

Pitch link control not coordinated

Set pitch link to 6.25 in. (15.875 cm)

to high speed ground track.

with trim tab bend (Intermixing

nominal and zero trim tabs.

control input).

Damage to blade or tabs.

Inspect for damage.

Excessive torque and erratic high

Pitch change links too long.

Set to nominal 6.25 in. (15.875 cm).

speed ground tracking.

IN−FLIGHT TRACKING

Blade track changes with power

Worn pitch bearing housing

Replace bearings.

and control changes.

bearings.

Missing pitch bearing liner.

Replace bearing.

Broken or loose feathering studs.

Repair or replace studs.

Binding rotating scissor crank at

Repair or replace crank.

lower main rotor hub shoe.

Play between longitudinal pitch

Re−bond collective pitch mixer

mixer bellcrank and collective pitch

bearings and install shims between

mixer bellcrank.

longitudinal pitch mixer bellcrank and

collective pitch mixer bellcrank

bearings (Ref. Sec. 62−30−00).

Helicopter has rough feeling with

Tilted tracking images, no blade in

Retrack blades.

some vibration while appearing to

track.

be in track.

Pitch link control not coordinated

Set pitch link to nominal 6.25 in.

with trim tab bend (intermixing

(15.875 cm) and zero trim tabs.

control input), with climbing or

diving blades within acceptable

track limits.

Page 202

Revision 31

18-10-00

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

Table 201. Isolating Tracking Problems (Cont.)

Symptom

Probable Cause

Corrective Action

Blades very erratic in response to

Tab bent too much in wrong area.

Correct by limiting bending.

tab bends.

Blade erosion, but within chordwise

Track erratic blade to other blades.

limits.

Tab bent too many degrees in one

Limit tab bending to smaller degree

area.

over larger area.

Blades climb or dive excessively at

Too much tab bending in outboard

Remove outboard bending and

high speeds.

tab areas.

increase inboard bending.

Ground track off at low speed and

Excessive tab bending and pitch

Zero trim tabs and set pitch links to

stick shake at 103% N₂.

link control not coordinated with tab

nominal 6.25 in. (15.875 cm)

bend (intermixing control input).

Helicopter in track but has stick

Blade out of phase.

Check phasing.

shake.

Feedback in collective control.

Main rotor hub out of balance.

Balance hub.

Loose or binding rotating scissors.

Check and repair as required.

Heavy collective stick − climb and

Overcenter adjustment set too low.

Adjust.

cruise.

Trim tab bent down excessively.

Adjust.

Light collective stick − climb and

Overcenter adjustment set too

Adjust.

cruise.

high.

Trim tabs bent up excessively.

Adjust.

Heavy collective lift-off − light flight.

Bungee spring adjusted too short.

Adjust to nominal.

Light collective lift-off − heavy flight.

Bungee spring adjusted too long.

Adjust to nominal.

Page 203

18-10-00

Revision 37

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

MAIN ROTOR TRACK AND BALANCE

REMOVAL/INSTALLATION

1. Main Rotor System Tracking Equipment

A. Interrupter Installation

Installation

(Ref. Figure 401)

(Ref. Figure 401 and Figure 402) Equipment

(1).

The helicopter is equipped with five

needed to track main rotor blades consists of

main rotor blade tracking interrupters

the main rotor tracking and tail rotor vibration

located immediately inboard of each

analyzer equipment, tracking and balancing

pitch control link attach clevis on the

equipment and the tip cap assembly. Instruc

rotating swashplate.

tions for equipment installation are contained

in Chadwick-Helmuth Operation and Service

(2).

The interrupter installation incorpo

Instruction Handbook.

rates a double interrupter which may

be used for both tracking and balanc

ing.

When working near engine air

CAUTION

inlet, comply with precautions

(3).

Each interrupter insert is attached to

to prevent entry of foreign material. During

the interrupter body at a different

main rotor balancing the helicopter will be

position (left, center, or right). The

airborne. Carefully observe precautions in

interrupters create five equally spaced

the Tracking and Balancing Manual relat

horizontal reflective images, as viewed

ing to the placement and security of equip

by the technician, when the main rotor

ment (especially cables) fastened to the ex

blade tips are illuminated with the test

terior of the helicopter.

strobe light.

(4).

Interrupter blade spacing separates the

NOTE: Main rotor tracking tip caps manufac

tured by the same firm that manufactures

image of each main rotor blade tip cap

the tracking and balance equipment, are

by approximately 0.25 inch (6.35 mm).

components of the tracking and balancing

This staggered relationship allows the

equipment and may be used instead of tip

technician to view the stopped image of

cap assembly. In procedures that follow, use

each blade in order of rotation.

of tip cap assembly is presumed. If tip caps

from the balancing equipment are used, re

(5).

The number one blade is seen on the

fer to the Tracking and Balancing Manual

extreme left, number two blade is seen

for tip cap data.

second from left, and so on through

number five which is seen on the

extreme right.

Special Tools

(6).

On current configuration helicopters,

(Ref. Section 91−00−00)

the pulse of the double interrupter is so

Item

Nomenclature

short that it appears as a single pulse

ST901

Tip cap assembly

to the strobe light amplifier. The second

pulse created by the double interrupter

ST903

Balancer/analyzer instrument kit

is used during main rotor balancing.

Consumable Materials

(7).

If counterweights are installed, coat the

(Ref. Section 91−00−00)

two interrupter bolts passing through

Item

Nomenclature

the swashplate counterweights with

grease (CM116) before installation.

CM116

Grease, aircraft and instrument

Torque nuts to 30 - 60 inch-pounds

(3.39 - 6.78 Nm).

Page 401

18-10-00

Revision 44

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(8). Torque the three remaining interrupter

(6). Ensure the interrupter passing closest

nuts to 15 - 20 inch-pounds (1.69 -

over either early or current configura

2.26 Nm).

tion magnetic pickup, clears pickup by

not less than 0.030 inch (0.762 mm).

B. Magnetic Pickup Installation

C. Tracking Tip Cap Installation

(Ref. Figure 401)

(1).

The helicopter is originally equipped

with a magnetic pickup support bracket

(1). The helicopter is originally equipped

installed with shim washers to prevent

with five tip caps that must be removed

distortion of the bracket when the nut

and replaced with five tracking tip caps

on the bolt that secures the link bearing

(ST901).

is torqued to 30 - 60 inch-pounds

(3.39 - 6.78 Nm).

(2). When blade tracking has been accom

plished or verified, the tracking tip caps

(2).

To preclude rocking movement of

must be removed and original tip caps

magnetic pickup support bracket when

installed.

installed on stationary swashplate,

check clearance between swashplate

(3). Torque the screw that secures the tip

and lower flange of bracket. If gap

cap to 15 - 20 inch-pounds (1.69 -

exists, tap bent tip of lower flange

2.26 Nm).

(typical both sides of bracket) until bent

tip touches swashplate.

NOTE: When installing tip cap targets, posi

(3).

Reinstall by forcing bracket until

tion double interrupter over magnetic pick

elongated bracket holes align with hole

up. The blade positioned forward is number

in stationary swashplate.

5. By rotating rotor head in operating direc

tion, the next blade pointing forward will be

(4).

Install the magnetic pickup and cable

4, then 3, 2 and 1.

as instructed in the Chadwick-Hel

muth Operation and Service Instruc

D. Main Rotor System Balancing Equipment

tion Handbook.

Installation

(5).

After final adjustment, torque the

(Ref. Figure 401 and Figure 402) and Chad

adjustment nut to 15 - 20 inch-

wick-Helmuth Operation and Service Instruc

pounds (1.69 - 2.26 Nm) and ensure

tion Handbook to install that portion of the

the cable is routed and tied down in

balancing equipment (ST903) needed to

such a manner as not to be dislodged or

balance the main rotor.

interfere with control components at

their extremes of travel.

Page 402

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MAINTENANCE MANUAL

ROTATION

PLACE DOUBLE INTERRUPTER

OVER MAGNETIC PICKUP AND

THEN ATTACH TIP TARGET

TAPE

NUMBERS EXACTLY AS SHOWN

TRACKING TARGET

(NOTE 1)

TIP CAP

INTERRUPTER

TRACKING TIP CAP INSTALLATION

(NOTE 4)

DOUBLE

ROTATION OF

(NOTE 5)

INTERRUPTER

HUB

(NOTE 4)

SUPPORT

NOTE 2

(NOTE 6)

SCISSORS

BRACKET

LINK

ADJUSTMENT

JAMNUT

ROTATING

SWASHPLATE

TEST EQUIPMENT

PROTECTIVE CAP

CABLE RECEPTACLE

PICKUP INSTALLATION (ROTATED)

INTERRUPTER

SPACER

INTERRUPTER

(NOTE 4)

INTERRUPTER

(NOTE 5)

INTERRUPTER

(NOTE 6)

(NOTE 3)

(NOTE 4)

STATIONARY

(NOTE 6)

SWASHPLATE

NOTES:

ALWAYS REMOVE TARGETS

0.030-0.070 IN.

AFTER TRACKING.

(0.762-1.778 MM)

INSTALL WASHERS BETWEEN

GAP TYP.

BRACKET AND SWASHPLATE

TO FILL GAP.

ADJUST AS REQUIRED FOR

GAP INDICATED.

REFER TO CSP-IPC-4 FOR

INTERRUPTER-TO-MAGNETIC PICKUP GAP

PART NO.

MAGNETIC PICKUP

TORQUE NUT TO 30-60 IN-LBS.

G18-1000C

TORQUE NUT TO 15-20 IN-LBS

Figure 401. Blade Tracking Equipment

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MAINTENANCE MANUAL

TAPE CABLE TO RIGHT HAND INBOARD

MAGNETIC PICKUP CABLE AND

SIDE OF INLET HOUSING AND ROUTE

VELOMETER/ACCELEROMETER

FORWARD ALONG FUSELAGE AS

LOCATION FOR MAIN ROTOR

CABLE MAY BE ROUTED

SHOWN. CABLE MUST CLEAR AL

BALANCING

THROUGH VENT DOOR

EXTREME MOVEMENTS OF CONTROLS.

KIT LOCATION

FOR MAIN ROTOR

BALANCING

INTERRUPTER

(TYP)

TORQUE NUT AFTER

SECURING GAP AND

SAFETY WIRE

0.030-0.070 IN.

(0.762-1.778 MM)

GAP (TYP)

ENGINE AIR INLET

MAGNETIC PICKUP

FAIRING (LEFT

HAND SIDE)

VIEW LOOKING DOWN

MAGNETIC PICKUP INSTALLATION

TAPE

VELOMETER/ACCELEROMETER

VIEW LOOKING INBOARD

LOCATION FOR MAIN ROTOR

BALANCING

ACCELEROMETER INSTALLATION

G18-2005

Figure 402. Main Rotor Balancing Equipment Installation

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CSP-HMI-2

MAINTENANCE MANUAL

MAIN ROTOR TRACK AND BALANCE

ADJUSTMENT/TEST

1. Blade Tracking Procedure

TIP PATH PLANE

Table 501 is a summary of the sequence of

required procedures for blade tracking.

(1). Install strobe light, blade tip cap

IMAGE A:

ALL BLADES

reflectors and related equipment.

IN TRACK

(2). Use 1/2 inch (12.7 mm) diameter

tracking tip cap reflector as a guide for

estimating track accuracy. For example:

IMAGE B:

ONE BLADE APPROX. 1/2 IN. (12.7

MM) HIGH

(a). A tip cap reflector image displace

ment of 1/2 diameter up, or down,

indicates blade tip is approximately

1/4 inch (6.35 mm) out of track.

IMAGE C:

ONE BLADE APPROX. 1/2 IN. (12.7

(b). One full reflector diameter indicates

MM) HIGH

ONE BLADE APPROX. 1 IN. (25.4

G18-1001A

1/2 inch (12.7 mm) out of track.

CORRECTIVE ACTION

NOTE: Rocking or stick shake caused by a cor

HIGH RPM AND

rectly tracking rotor indicates improper

CONDITION

GROUND IDLE RPM

FWD FLIGHT

blade phasing.

IMAGE A

NONE REQUIRED

IMAGE B

SHORTEN PITCH CONTROL MOVE TAB DOWNWARD

(3). Accomplish blade phasing (Ref. Sec.

ROD (2ND BLADE)

(2ND BLADE) MOVE TAB

62-20-00) when installing new rotor

UPWARD (3RD BLADE)

blades or if ground rock or stick shake

IMAGE C

SHORTEN PITCH CONTROL

MOVE TAB DOWNWARD

is noted. This must be accomplished

ROD (2ND BLADE):

(2ND BLADE): MOVE TAB

prior to starting tracking procedure.

LENGTHEN CONTROL ROD

UPWARD (3RD BLADE)

(3RD BLADE)

NOTE: Final rotor system balance cannot be

accomplished until blades are in track.

NOTE: Chordwise spacing of tracking images

are not an accurate indication of blade

(4). Ground tracking is basically track-ob

phasing. Do not adjust blade phasing in an

servation and adjustment of idle and

attempt to equalize spacing. Slight tilting of

flight rpm. Improper track at idle rpm

magnetic interrupters or balance of the main

is corrected by adjusting length of pitch

rotor system can move the image

control links connecting rotating

Figure 501. Typical Track Conditions and

swashplate and blade pitch housing.

Adjustments

Ground track at flat pitch and flight

rpm is corrected by blade tab adjust

(6). Forward flight track is corrected only

ment.

by making blade tab adjustments.

Forward flight tracking requires track

(5). Hover track verification is essentially

observation during following airspeeds

an observation to check for track

and maneuvers: Flight at 0-100 knots.

variations between high rpm (flat pitch)

Forty-five degree banked turns at

ground track check and hovering.

80-100 knots. Flight at 100-155 knots.

NOTE: Track adjustments are not made on ba

(7). Check for proper balance of rotor

sis of track observations during hovering.

system prior to checking autorotation.

However, track variations should be noted

and recorded for use during check of track in

(8). Obtaining correct autorotation rpm

forward flight.

consists of checking main rotor rpm

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MAINTENANCE MANUAL

during stabilized autorotation flight

and adjusting rpm to specified limits as

Special Tools

necessary. Autorotation rpm check

(Ref. Section 91−00−00)

must be accomplished to ensure that

Item

Nomenclature

track adjustments do not alter rotor

ST902

Main rotor blade fixture and tab bending

performance necessary for safe power-

tool

off landings.

A. Blade Track Adjustment

Minimize bending and restrict

CAUTION

adjustments to very small incre

Although adjustment of pitch control links

ments so that bonded trailing edge joint be

affects blade track at all rotor speeds, they

tween upper and lower skins is not dam

should be adjusted only when necessary to

aged. Tabs must never be displaced more

establish acceptable track at ground idle

than five degrees above or below neutral po

speed; blade tabs are used for all other track

sition (parallel to chordline).

corrections.

(1). To lower blade tip that tends to climb

NOTE: Blade tab and/or track can make the

during ground tracking at high rpm or

collective heavy or light.

during forward flight, bend appropriate

tab section slightly downward; to raise

B. Pitch Control Link Adjustment

tip of blade that tends to descend, bend

Repeat this adjustment procedure as necessary

tab slightly upward. If only slight track

to establish ground idle track:

correction is necessary, limit tab

bending to width of bending tool. If

(1). To lower a blade tip, shorten pitch

more correction is necessary, bend a

control link assembly. To raise a blade

slightly wider section of tab. Use small

tip, lengthen pitch control link assem

adjustments to avoid excessive rebend

bly. One-sixth of a turn of link (one flat)

ing of tabs.

raises or lowers blade tip approximately

1/4 inch (6.35 mm).

NOTE: Tab zones on same blade can require

bending in opposite directions. For example,

Center each rod end or (fitting

after bending tab zone A downward to get

CAUTION

wear) results. Make sure there

good tracking at 60-90 knots, it might be

is no binding in full up travel position.

come necessary to bend tab zone D or E up

ward to correct track at redline airspeed. In

(2). After adjusting pitch control link

any case, do not use larger tab corrections

length, center each rod end in its fitting

than are actually necessary.

and hold while tightening jam nuts;

safety with lockwire.

(2). Each time blade tabs are adjusted,

recheck ground idle track and readjust

C. Blade Tab Adjustment

if necessary.

(Ref. Figure 502) Once ground idle track is

(3). After completion of forward flight

obtained, all remaining tracking correction is

tracking, balance and check autorota

accomplished by very slight bending of various

tion rpm.

blade tab zones with tab bending tool (ST902).

Different zones of tabs are used to adjust blade

D. Main Rotor Ground Tracking

track at different airspeeds. In general, tab

zone A is used for high rpm, flat pitch ground

(Ref. Figure 502) For best results, tracking

tracking (369D/E - 103% N₂, 369FF/500N -

should be performed under calm air conditions.

100% N₂) and zones C, D, and sometimes E,

Wind velocity should not exceed six knots

are used for tracking at higher airspeeds. Zone

during adjustments. Accurate adjustment of

B is used to supplement zone A track correc

initial ground track is very important. In most

tion when maximum tab (5 degrees) has been

instances, forward flight tracking problems

applied to zone A; if necessary, zone B may

can be avoided or greatly reduced by setting

also be used for correction in 0-110 knot

initial track as nearly perfect as possible.

airspeed range.

Tolerances specified in following instructions

Page 502

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CSP-HMI-2

MAINTENANCE MANUAL

should be considered maximum permissible

blade tab zone A until high rpm ground

deviation rather than desired goal.

track is within tolerance.

E. Hover Track Verification

NOTE: If main rotor hub or a pitch control rod

end bearing has been replaced, adjust pitch

control link(s) before proceeding with

(Ref. Figure 502)

ground tracking.

(1). Hover track verification must be

performed after ground tracking and

(1). Before tracking blades that are not new,

before forward flight tracking. Verifica

check that normally straight (not to be

tion is only a check of hover track. Do

used) tab areas are in neutral position

not adjust pitch control links or blade

(centered on chordline) and straight.

tabs because of track images observed

during hovering. Tab adjustments often

NOTE: On new (untracked) blades, check that

cause variation between ground track

all tab areas are straight and in neutral po

and hovering track. A large track

sition (centered on chordline 0° ±0.5°).

variation may indicate that one or more

blades is beyond its chordwise balance

tolerance, but this can only be deter

(2).

Load helicopter to a gross weight of

mined during forward flight tracking.

approximately 2350 pounds (1066 kg);

Perform hover track verification as

then ground idle (approximately

follows.

64-65% N₁).

NOTE: Collective pitch stick may be ”heavy” af

(3).

Observe tracking tip cap reflector image

ter tracking reflectors are mounted on blade

by directing strobe light beam toward

tips. This condition is not unusual and may

blade tip path and sweeping beam

be disregarded.

slowly back and forth until reflector

images are clearly seen. Tracking image

(2). Verify helicopter gross weight of

should appear directly in front of

2000-2500 pounds (908-1135 kg).

helicopter or slightly off helicopter

centerline.

(3). With collective pitch stick full down,

increase N₂ to 103% - 369D/E, 100% -

(4).

If blades are in track, tip cap reflector

369FF/500N.

image pattern should resemble image A

(Ref. Figure 501), (no blade tip more

(4). Observe tracking reflector images to

than 1/4 of one tracking reflector

verify that ground track is within

diameter, 1/8 inch (3.175 mm) above or

limits.

below adjacent reflectors). If blades are

in track, proceed with (5). below. If

(5). With helicopter in a stable hover,

blades are out of track, adjust pitch

observe reflector images. If one or more

control links and repeat step (3). above.

blades are out of track, record condi

tion(s) for reference during forward

flight tracking.

(5).

With collective pitch stick full down,

increase engine speed to 103% N₂ -

369D/E, 100% N2 - 369FF/500N and

(6). Proceed with forward flight tracking.

observe tip cap reflector image to see if

blade track is changed from ground idle

Use of the tracking strobe

WARNING

track. When all five blades are in track

light in night flight is not

within 1/4 of one reflector diameter, 1/8

recommended. Such use can result in

inch (3.175 mm), ground track is

pilot disorientation or loss of vision

correct; proceed with hover verification.

with resultant damage to the helicop

When a blade is out of track, adjust

ter and personal injury.

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MD Helicopters, Inc.

MAINTENANCE MANUAL

BLADE STATIONS

105

111

117

124

130

142

158

MAIN ROTOR BLADE

(TOP VIEW)

65 IN.

(165 CM)

59 IN.

(150 CM)

53 IN.

369D/E

(135 CM)

47 IN.

(119 CM)

41 IN.

(104 CM)

34 IN.

(86 CM)

28 IN.

(71 CM)

16 IN.

(41 CM)

TAB ZONES

NOT USED

(NOTE 1)

TO END OF

NOTE 2

BLADE NOT USED

HIGH RPM GROUND

MEDIUM SPEED

(NOTE 1)

TRACKING AND UP TO

FLIGHT TRACKING

110 KNOTS IN FLIGHT

130-145 KNOTS

(103 % N₂)

HIGH SPEED

110-130 KNOTS

FLIGHT TRACKING

IN FLIGHT

130-145 KNOTS

(103 % N₂)

MAIN ROTOR BLADE

BLADE STATIONS

105

111

117

124

130

148

164

(TOP VIEW)

71 IN.

(180 CM)

65 IN.

(165 CM)

59 IN.

369FF/500N

(150 CM)

53 IN.

(135 CM)

47 IN.

(119 CM)

40 IN.

(102 CM

34 IN.

(86 CM)

16 IN.

(41 CM)

TAB ZONES

NOT USED

(NOTE 1)

TO END OF

NOTE 2

BLADE NOT USED

HIGH RPM GROUND

(NOTE 1)

MEDIUM SPEED

TRACKING AND UP TO

FLIGHT TRACKING

110 KNOTS IN FLIGHT

130-145 KNOTS

(100% N₂)

SHOCK CORD

110-130 KNOTS

(OR EQUIVALENT)

HIGH SPEED

IN FLIGHT

FLIGHT TRACKING

(100% N₂)

145-152 KNOTS

(100% N₂)

NOTES:

UNUSED TAB ZONES MUST BE MAINTAINED

STRAIGHT, NEUTRAL AND PARALLEL.

USE ONLY AS NECESSARY TO SUPPLEMENT

ZONE D TO AVOID EXCESSIVE TAB BENDING

POINTER

IN ZONE D.

TAB BENDING TOOLS

BENDER

G18-1002C

Figure 502. Main Rotor Blade Tab Adjustment

Page 504

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MAINTENANCE MANUAL

F. Forward Flight Tracking

ferred, even though observed blade track

may be beyond specified tolerances.

(Ref. Figure 502) Forward flight tracking

should be performed whenever vertical flight

(4). After flight tracking is completed,

vibrations indicate that blades may be out of

perform a Main Rotor System Balance

track.

Procedure and Main Rotor Autorotation

RPM Check.

(1). Verify helicopter gross weight of

2000-2500 pounds (907-1134 kg).

3. Main Rotor System Balance Procedure

(2). Perform flight tracking from hover up

Balance the main rotor system according to

to 110 knots at 103% N₂ - 369D/E,

instructions in the Tracking and Balancing

100% N₂ - 369FF/500N. If flight track

Manual. Since vibration reduction is accom

varies from hover track more than 1/2

plished by slight adjustment in phasing, the

inch (12.7 mm), bend tab zone A (five

instruction outline in the Tracking and

degrees maximum) to limit variation to

Balancing Manual must be closely followed for

tab zone B (five degrees maximum).

best results. Safety damper turnbuckle after

completing phasing balance adjustments.

2. Main Rotor Blade Tab Adjustment

4. Main Rotor Autorotation RPM Check

(1). Check autorotation rpm; rpm must not

be less than 480.

(Ref. Table 502 for 369D/E and Table 503

369FF and 500N). An autorotation rpm check

Do not attempt to adjust chord

CAUTION

is required after each blade tracking operation

wise balance of a blade found to

and whenever rpm is outside limits listed.

be faulty when performing banked turns.

Check rotor rpm and make adjustments as

Chordwise balance corrections must be ac

follows.

complished by manufacturer (MDHI).

(2). Perform a series of 45 degree banked

CAUTION

turns at 100 knots and observe track

change from level flight. If any blade

D Autorotation rpm is critical to a success

climbs or dives more than one inch out

ful autorotation landing. When full main

of track with others, chordwise balance

rotor rpm is not available, autorotation

(center of gravity) of that blade is

function is decreased. At high gross

beyond its tolerance and blade must be

weights and/or density altitudes, the

replaced. (Hover track variations of this

main rotor rpm will try to overspeed. The

type that do not repeat during banked-

pilot must increase collective pitch to

turn maneuver may be disregarded.)

keep main rotor rpm within limits. At

lower gross weights and/or density alti

(3). Perform flight tracking at 110-155

tudes, the main rotor rpm will be under

knots and 103% N₂ - 369D/E, 100% N₂

speed. The pilot has less rotor energy

- 369FF/500N. If necessary, adjust tab

available to do the autorotation landing.

zone B (five degrees maximum) to limit

Set the autorotation rpm within the lim

track variation to 1/2 inch (12.7 mm) or

its of the Autorotation Percentage Chart

less and to minimize excessive vertical

to make sure sufficient autorotation rpm

(one-per revolution) vibration. If

is available at the helicopter minimum

variation is excessive, bend tab zone C

gross weight.

or D (five degrees maximum).

D All autorotation rpm adjustments shall

NOTE: When determining whether blade track

be made at the main rotor pitch control

is acceptable, overall vibration level of heli

links only. Do not re-adjust mixer control

copter should be determining factor. Some

rods after rigging is accomplished. Fail

combinations of rotor blades might produce

ure to observe this precaution may result

higher five-per-revolution vibration as

in serious damage to rotor system and

blade tips are brought into close track; in

controls. Do not adjust control rod end be

such cases, lowest vibration level is pre

yond witness hole.

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MD Helicopters, Inc.

MAINTENANCE MANUAL

D Tracking targets reduce blade to tailboom

5. Main Rotor Hub Balancing Procedure

clearance, performing autorotations to

the ground could result in boom strikes.

Balance the main rotor hub according to the

following instructions.

NOTE: Change length of all five pitch control

links as necessary to adjust autorotation

Consumable Materials

rpm. Be sure to lengthen or shorten all five

(Ref. Section 91−00−00)

links exactly same amount or blade track is

Item

Nomenclature

changed. One flat (1/6 turn) of control link

CM420

Sealant

body causes approximately four rpm change

in autorotation rpm.

Special Tools

(Ref. Section 91−00−00)

(1). Autorotation Rpm Check: Load 369D/E

Item

Nomenclature

helicopter to a gross weight of 2250

pounds (1021 kg): 2350 pounds (1066

ST903

Balancer/analyzer instrument kit

kg) for 369FF and 500N. Perform a

practice autorotative descent (Ref.

NOTE:

PFM), taking care not to allow rpm to

exceed rotor speed limitations. During

D If swashplate has weights removed, there

autorotation take careful note of

should be three AN970-3 washers at the

stabilized autorotation rpm at one of

green pitch housing bolt.

gross weight/density altitude combina

D In some instances, main rotor hub bal

tions. After landing, compare observed

ance may not be achieved without addi

rpm with values (Ref. Tables 502 and

tion of swashplate weights (Ref. Sec.

503). If observed rpm is within limits in

62-30-00,

Counterweight

and

table, rpm setting is correct. If limits

Interrupter Installation)

were exceeded, make corrective adjust

ments according to (2). below, until rpm

(1). Remove main rotor blades.

is within limits.

(2). Remove main rotor dampers.

NOTE: After autorotation rpm adjustments are

(3). Hook up Phazor. Refer to Chadwick-

satisfactorily accomplished, remove track

Helmuth Operation and Service

ing equipment before returning helicopter

Instruction Handbook (ST903).

to service. Be sure to correctly tighten and

safety all bolts after they are reinstalled.

NOTE: Refer to applicable Rotorcraft Flight

Manual, Section 7, for blades-off operating

(2). Autorotation Rpm Adjustment: Change

procedures.

length of all five pitch control links as

required to adjust autorotation rpm.

(4). Run engine at 103% N₂ - 369D/E,

Make certain all five links are short

100% N₂ - 369FF/500N.

ened or lengthened exactly the same

amount or blade track will be altered.

Observe N₂ speed avoid range

CAUTION

limits during this procedure and

exercise caution when increasing twistgrip

CAUTION

to flight idle position to avoid N₂ overshoots.

D Do not adjust (lengthen) pitch control link

(5). Record IPS reading and direction on

rodend threads beyond witness holes in

main rotor balance chart (Ref.

rods.

Figure 503).

D Do not readjust mixer control rods after

(6). Plot IPS reading and direction on main

rigging has once been accomplished. Fail

rotor balance chart (Ref. Figure 503).

ure to observe this precaution can result

in serious damage to rotor system and

(7). Analyze chart for weight location and

controls.

amount requirements.

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MAINTENANCE MANUAL

The maximum allowable bal

as applicable. Coat screw threads, nuts

CAUTION

ance weight per lead-lag bolt on

and washers with sealant (CM420). (To

the main rotor hub assembly is 150 grams.

prevent imbalance, do not use excessive

amount of sealant.)

(8). Install weights as follows: (Ref.

Figure 504).

NOTE: Intermixing of P/N 369D21400-503 and

M50452 main rotor blade damper assem

(a). Engage head of screw, inside lead-lag

blies in a shipset is not permitted. All damp

bolt, with Phillips screwdriver, then

ers in shipset must be of same type and part

loosen locknut with 1/4 inch wrench.

number.

(b). Hold screw in place with screwdriver

(11). Reinstall main rotor blades (Ref. Sec.

while adding or removing flat wash

62-10-00).

ers as required, then reinstall

locknut.

NOTE: If main rotor dampers require more

(9). Repeat steps (4). thru (8). until reading

than four flats adjustment, re-phase main

is 0.15 IPS, or less.

rotor dampers (Ref. 62-20-00, Main Rotor

Damper Phasing Procedure).

(10). After balance has been established

satisfactorily, torque MS21042L08

(12). Perform main rotor system balance.

locknuts to 20 - 35 inch-pounds (2.26

- 3.95 Nm) or MS21042L3 locknuts to

(13). Track main rotor blades (Ref. Blade

30 - 60 inch-pounds (3.39 - 6.78 Nm)

Tracking Procedure).

Table 501. Summary Procedure for Blade Tracking

Satisfactory

Unsatisfactory

Step

Result

Corrective Action

(1) Observe ground track.

Go to step (2). Ref. Corrective

Adjust pitch control links and blade

Action.

tabs as required. Repeat track

observation.

(2) Perform hover verification.

Go to step (3). Ref. Corrective

Record track verification and proceed

Action.

with forward flight tracking.

(3) Perform forward flight tracking. Go to step (4).

Ref. Corrective

Adjust blade tabs and repeat forward

Action.

flight tracking.

(4) Perform autorotation rpm

Go to step (5). Ref. Corrective Adjust autorotation rpm and repeat

check.

Action.

rpm check.

(5) Remove tracking equipment

and return helicopter to service.

NOTE: Ground rock or stick shake with rotor blades in track during ground track indicates rotor blades are not

properly phased.

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MAINTENANCE MANUAL

Table 502. Autorotation Rpm Chart (369D/E)

Stabilized Autorotation Rpm at Density Chart

Gross Wt

lb/kg

Sea Level

1000 Ft

2000 Ft

3000 Ft

4000 Ft

5000 Ft

2050/930

460 − 470

466.5 − 476.5

473 − 483

479.5 − 489.5

486 − 496

492.6 − 502.6

2150/975

470 − 480

476.5 − 486.5

483 − 493

489.5 − 499.5

496 − 506

502.6 − 512.6

2250/1021

480 − 490

486.5 − 496.5

493 − 503

499.5 − 509.5

506 − 516

−−−

2350/1066

490 − 500

496.5 − 506.5

503 − 513

509.5 − 519.5

−−−

NOTES:

(1) Chart values based upon 15°C (59°F) outside air temperature. At sea level, 8°C (14°F) temperature

change is equal to 1000 feet (305 M) of change in density altitude.

(2) Perform autorotation rpm checks at gross weight/density altitude combinations for which rpm values are

given. Blank spaces indicate that application of collective pitch may be necessary to avoid rotor

overspeed.

Table 503. Autorotation Rpm Chart (369FF/500N)

Stabilized Autorotation Rpm at Density Chart

Gross Wt

lb/kg

Sea Level

1000 Ft

2000 Ft

3000 Ft

4000 Ft

5000 Ft

2216/1005

459-469

465-475

471-481

477-487

483-493

489-499

2316/1051

466-476

472-482

478-488

484-494

490-500

496-506

2416/1096

473-483

479-489

485-495

491-501

497-507

---

2516/1189

480-490

486-496

492-502

498-508

---

NOTES:

(1) Chart values based upon 15°C (59°F) outside air temperature. At sea level, 8°C (14°F) temperature

change is equal to 1000 feet (305 M) of change in density altitude.

(2) Perform autorotation rpm checks at gross weight/density altitude combinations for which rpm values are

given. Blank spaces indicate that application of collective pitch may be necessary to avoid rotor

overspeed.

Page 508

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

MS21042L08 NUT

369D29935 MAIN ROTOR

NOTE 1

(NOTE 2)

HUB BALANCE WEIGHT

AN960C8, AN960C8L WASHERS

SUPPORT WASHER

AS REQUIRED TO BALANCE

(NOTE 5)

369D21220 LEAD-LAG BOLT

369D29934 WASHER

NAS602-64P, -72P OR -76P

SCREW

369D21300-501

LINK ASSY PITCH HOUSING

369A1219 NUT AND

MS24665-300 COTTER PIN

(NOTE 4)

A - A

SERIAL NO. 0260D AND SUBS

MS21042L3 LOCKNUT

(NOTE 3)

NOTE 1

AN960C10, AN960C10L WASHERS

AS REQUIRED TO BALANCE

(NOTE 5)

HS1555 WASHER

AN970-3 WASHER

369A1220 LEAD-LAG BOLT

HS1554 WASHER

369A1219 NUT AND

NAS603-56 OR -64

MS24665-300 COTTER PIN

SCREW

(NOTE 4)

A - A

SERIAL NO. 003D THRU 0259D

NOTES:

COAT SCREW THREADS, NUTS AND WASHERS

WITH PR-1436-G, CLASS B-2 SEALANT.

TORQUE MS21042L08 NUT TO 20 - 35 INCH-POUNDS

(2.26 - 3.95 NM).

TORQUE MS21042L3 NUT TO 30 - 60 INCH-POUNDS

(3.39 - 6.78 NM).

DO NOT REMOVE OR DISTURB TORQUE ON 369A1219 NUT.

THE MAXIMUM ALLOWABLE BALANCE WEIGHT PER LEAD-LAG

G18-1004B

BOLT ON THE MAIN ROTOR HUB ASSEMBLY IS 150 GRAMS

Figure 504. Main Rotor Hub Balancing

Page 510

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18-10-00

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

MAIN ROTOR TRACK AND BALANCE (600N)

MAINTENANCE PRACTICES

1. Main Rotor Blade Tracking

CAUTION

Immediately investigate the

D Understand the blade tracking sequence

WARNING

cause of a sudden onset of

and related adjustments before attempt

excessive or unusual main rotor vibra

ing blade track procedures.

tion prior to continued flight. Under no

D If main rotor hub balance is suspect, bal

circumstance should main rotor track

ance rotor hub prior to performing blade

ing be attempted to correct the prob

track.

lem until a thorough inspection of the

main rotor blades, hub assembly and

2. Main Rotor System Balancing

strap pack assembly has been per

formed.

Main rotor hub balancing is accomplished by

adding or removing weight (flat washers) as

required at the lead-lag bolts (Ref. Main Rotor

NOTE: Ref. Table 201 to isolate ground or in-

Hub Balancing Procedure). Analysis of main

flight blade tracking problems.

rotor hub balance is accomplished using

instrumentation that measures and localizes

Main rotor blade track is observed by means of

vibrations due to main rotor hub imbalance.

reflective tip caps temporarily installed on

Data provided by the instrumentation is

each blade and a high-intensity strobe light.

plotted on a chart designed to indicate how

Blade track is determined by observing the

much weight must be added or removed from

apparent tip cap pattern created by strobe

the lead-lag bolt. No other means of balancing

light pulses synchronized with the rotating

is to be used.

blades. Strobe light electrical power is supplied

by the helicopter electrical system.

3. Balancing Equipment and Balance Spare

Kit

a. Tracking must be accomplished in the follow

ing sequence of six steps:

Special Tools

1). Verification of proper blade phasing

(Ref. Section 91−00−00)

(Ref. Main Rotor System Balance Procedure).

Item

Nomenclature

2). Ground tracking

ST903

Balancer/analyzer instrument kit

(Ref. Main Rotor Ground Tracking).

3). Verification of proper rotor balance

(Ref. Main Rotor System Balance Procedure).

The balancing equipment (ST903) contains all

4). Hover verification

equipment needed to analyze main rotor

(Ref. Hover Track Verification).

balance.

5). Forward flight tracking

When working near engine air

(Ref. Forward Flight Tracking).

CAUTION

inlet, comply with all precau

6). Autorotation rpm adjustment

tions to prevent entry of foreign material.

(Ref. Main Rotor Autorotation RPM Check).

Carefully observe precautions in the Track

ing and Balancing Manual relating to the

b. No attempt should be made to verify or adjust

placement and security of equipment (espe

blade track without first checking and adjust

ing blade phasing, a function of main rotor

cially cables) fastened to the exterior of the

damper adjustment.

helicopter.

Page 201

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

Table 201. Isolating Tracking Problems

Symptom

Probable Cause

Corrective Action

GROUND TRACKING

Rotor does not follow adjustments.

Turning P/C link wrong direction.

Adjust correctly.

Pitch link bearing worn. Trim tab

Replace bearing. Zero trim tabs.

bent excessively.

Excessive diving or climbing of

Trim tab bent excessively.

Zero trim tabs.

blade from low speed ground track

Pitch link control not coordinated

Set pitch link to nominal 6.25 inches

to high speed ground track.

with trim tab bend (Intermixing

(15.88 cm) and zero trim tabs.

control input).

Damage to blade or tabs.

Inspect for damage.

Excessive torque and erratic high

Pitch change links too long or

Set to nominal 6.25 inches (15.88

speed ground tracking.

collective rigging too high.

cm). Check collective rigging.

IN−FLIGHT TRACKING

Blade track changes with power

Worn pitch bearing housing

Replace bearings.

and control changes.

bearings.

Missing pitch bearing liner.

Replace bearing.

Broken or loose feathering studs.

Repair or replace studs.

Binding rotating scissor crank at

Repair or replace crank.

lower main rotor hub shoe.

Play between longitudinal pitch

Re−bond collective pitch mixer

mixer bellcrank and collective pitch

bearings and install shims between

mixer bellcrank.

longitudinal pitch mixer bellcrank and

collective pitch mixer bellcrank

bearings (Ref. Sec. 62−30−60).

Helicopter has rough feeling with

Tilted tracking images, no blade in

Retrack blades.

some vibration while appearing to

track.

be in track.

Pitch link control not coordinated

Set pitch link to nominal 6.25 inches

with trim tab bend (intermixing

(15.88 cm) and zero trim tabs.

control input), with climbing or

diving blades within acceptable

track limits.

Blades very erratic in response to

Tab bent too much in wrong area.

Correct by limiting bending.

tab bends.

Blade erosion, but within chordwise

Track erratic blade to other blades.

limits.

Tab bent too many degrees in one

Limit tab bending to smaller degree

area.

over larger area.

Blades climb or dive excessively at

Too much tab bending in outboard

Remove outboard bending and

high speeds.

tab areas.

increase inboard bending.

Page 202

Revision 31

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

Table 201. Isolating Tracking Problems (Cont.)

Symptom

Probable Cause

Corrective Action

Ground track off at low speed and

Excessive tab bending and pitch

Set pitch link to nominal 6.25 inches

stick shake at 100% N₂.

link control not coordinated with tab

(15.88 cm) and zero trim tabs.

bend (intermixing control input).

Helicopter in track but has stick

Blade out of phase.

Check phasing.

shake.

Feedback in collective control.

Main rotor system out of balance.

Balance rotor system.

Loose or binding rotating scissors. Check and repair as required.

Heavy collective stick − climb and

Overcenter adjustment set too low. Adjust.

cruise.

Trim tab bent down excessively.

Adjust.

Light collective stick − climb and

Overcenter adjustment set too

Adjust.

cruise.

high.

Trim tabs bent up excessively.

Adjust.

Heavy collective lift-off − light flight. Bungee spring adjusted too short.

Adjust to nominal.

Light collective lift-off − heavy flight. Bungee spring adjusted too long.

Adjust to nominal.

Page 203

18-10-60

Revision 31

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

MAIN ROTOR TRACK AND BALANCE (600N)

REMOVAL/INSTALLATION

1. Main Rotor System Tracking Equipment

(4). The number one blade is seen on the

Installation

extreme left, number two blade is seen

second from left, and so on thru number

six which is seen on the extreme right.

(Ref. Figure 401 and Figure 402) Equipment

needed to track main rotor blades consists of

(5). Additional interrupters can be added to

the tracking and balancing equipment (ST903)

be compatible with the older balance/

and the tip cap assemblies (ST901). Instruc

analyzer instrument kits.

tions for equipment installation are contained

in Chadwick-Helmuth Operation and Service

(6). Torque the interrupter as shown in

Instruction Handbook.

Figure 401.

B. Magnetic Pickup Installation

Special Tools

(Ref. Section 91−00−00)

(1).

The helicopter is originally equipped

Item

Nomenclature

with a magnetic pickup support bracket

ST901

Tip cap assembly

installed with shim washers to prevent

distortion of the bracket when the nut

ST903

Balancer/analyzer instrument kit

on the bolt that secures the link bearing

is torqued to 30 - 60 inch-pounds

(3.39 - 6.78 Nm).

NOTE: Main rotor tracking tip caps manufac

tured by the same firm that manufactures

(2).

To preclude rocking movement of

the tracking and balance equipment, are

magnetic pickup support bracket when

components of the tracking and balancing

installed on stationary swashplate,

equipment and may be used instead of tip

check clearance between swashplate

cap assembly (ST901). In procedures that

and lower flange of bracket. If gap

follow, use of tip cap assembly is presumed.

exists, tap bent tip of lower flange

If tip caps from the balancing equipment are

(typical both sides of bracket) until bent

used, refer to the Tracking and Balancing

tip touches swashplate.

Manual for tip cap data.

(3).

Reinstall by forcing bracket until

A. Interrupter Installation

elongated bracket holes align with hole

in stationary swashplate.

(1). The helicopter is equipped with a main

(4).

Install the magnetic pickup and cable

rotor blade tracking interrupter located

as instructed in the Chadwick-Hel

on the rotating swashplate.

muth Operation and Service Instruc

tion Handbook.

(2). The interrupter creates six equally

spaced horizontal reflective images, as

(5).

After final adjustment, torque the

viewed by the technician, when the

adjustment nut to 15 - 20 inch-

main rotor blade tips are illuminated

pounds (1.69 - 2.26 Nm) and ensure

with the test strobe light.

the cable is routed and tied down in

such a manner as not to be dislodged or

(3). The balance analyzer separates the

interfere with control components at

image of each main rotor blade tip cap

their extremes of travel.

by approximately 0.25 inch (6.35 mm).

This staggered relationship allows the

(6).

Ensure the interrupter passing closest

technician to view the stopped image of

over magnetic pickup, clears pickup by

each blade in order of rotation.

not less than 0.030 inch (0.76 mm).

Page 401

18-10-60

Revision 44

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

PLACE DOUBLE INTERRUPTER

ROTATION

OVER MAGNETIC PICKUP AND

THEN ATTACH TIP TARGET

NUMBERS EXACTLY AS SHOWN.

TAPE

TRACKING TARGET

(NOTE 1)

SCISSORS

CRANK

TIP CAP

ROTATION

OF HUB

TRACKING TIP CAP

INSTALLATION

INTERRUPTER

(NOTE 4)

SCISSORS LINK

(NOTE 6)

INTERRUPTER

(NOTE 4)

(NOTE 5)

ROTATING

SWASHPLATE

STATIONARY

SWASHPLATE

NOTES:

ALWAYS REMOVE TARGETS AFTER TRACKING.

INSTALL WASHERS BETWEEN BRACKET AND

SWASHPLATE TO FILL GAP.

ADJUST AS REQUIRED FOR GAP INDICATED.

MAGNETIC PICKUP

REFER TO IPC FOR PART NUMBER.

TORQUE NUT TO 15-20 IN-LBS.

6G18-014-1A

TORQUE NUT TO 50 60 IN LBS

Figure 401. Blade Tracking Equipment − Main Rotor Components (Sheet 1 of 2)

Page 402

Revision 44

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HANDBOOK OF MAINTENANCE INSTRUCTIONS FOR MDHI 369D/E/FF-500/600N HELICOPTERS (ISSUED: 1990) - page 5