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

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

0.030-0.070 IN.

(0.762-1.778 MM)

INTERRUPTER

GAP (TYP)

SUPPORT

NOTE 2

(NOTE 3)

BRACKET

ADJUSTMENT

JAMNUT

TEST EQUIPMENT

PROTECTIVE CAP

CABLE RECEPTACLE

INTERRUPTER-TO-MAGNETIC PICKUP GAP

PICKUP INSTALLATION

6G18-014-2

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

C. Tracking Tip Cap Installation

D. Main Rotor System Balancing Equipment

Installation

(1). The helicopter is originally equipped

with six tip caps that must be removed

and replaced with six tracking tip caps

Refer to Chadwick-Helmuth Operation and

(ST901).

Service Instruction Handbook to install that

(2). When blade tracking has been accom

portion of the balancing equipment (ST903)

plished or verified, the tracking tip caps

needed to balance the main rotor.

must be removed and original tip caps

installed.

When working near engine air

(3). Torque the screws that secures the tip

CAUTION

inlet, comply with precautions

cap to 15 - 20 inch-pounds (1.69 -

to prevent entry of foreign material. During

2.26 Nm).

main rotor balancing the helicopter will be

NOTE: Position interrupter over magnetic

airborne. Carefully observe precautions in

pickup. The blade positioned forward is

the Tracking and Balancing Manual relat

number 6. By rotating rotor head in operat

ing to the placement and security of equip

ing direction, the next blade pointing for

ment (especially cables) fastened to the ex

ward will be 5 then 4, 3, 2 and 1.

terior of the helicopter.

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CSP-HMI-2

MAINTENANCE MANUAL

MAIN ROTOR TRACK AND BALANCE (600N)

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

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

ONE BLADE APPROX. 1 IN. (25.4

6G18-016A

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

62-20-60) 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 phas

(4). Ground tracking is basically track-ob

ing. Do not adjust blade phasing in an at

servation and adjustment of idle and

tempt to equalize spacing. Slight tilting of

flight rpm. Improper track at idle rpm

magnetic interrupters or balance of the

is corrected by adjusting length of pitch

main 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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MD Helicopters, Inc.

MAINTENANCE MANUAL

during stabilized autorotation flight

sometimes E, are used for tracking at higher

and adjusting rpm to specified limits as

airspeeds. Zone B is used to supplement zone

necessary. Autorotation rpm check

A track correction when maximum tab (5

must be accomplished to ensure that

degrees) has been applied to zone A; if

track adjustments do not alter rotor

necessary, zone B may also be used for

performance necessary for safe power-

correction in 0-110 knot airspeed range.

off landings.

Special Tools

A. Blade Track Adjustment

(Ref. Section 91−00−00)

Although adjustment of pitch control links

Item

Nomenclature

affects blade track at all rotor speeds, they

ST902

Main rotor blade fixture and tab bending

should be adjusted only when necessary to

tool

establish acceptable track at ground idle

speed; blade tabs are used for all other track

Minimize bending and restrict

corrections.

CAUTION

adjustments to very small incre

ments so that bonded trailing edge joint be

NOTE: Blade tab and/or track can make the

tween upper and lower skins is not dam

collective heavy or light.

aged. Tabs must never be displaced more

than five degrees above or below neutral po

B. Pitch Control Link Adjustment

sition (parallel to chordline).

Repeat this adjustment procedure as necessary

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

to establish ground idle track:

during ground tracking at high rpm or

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

during forward flight, bend appropriate

control link assembly. To raise a blade

tab section slightly downward; to raise

tip, lengthen pitch control link assem

tip of blade that tends to descend, bend

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

tab slightly upward. If only slight track

raises or lowers blade tip approximately

correction is necessary, limit tab

1/4 inch (6.35 mm).

bending to width of bending tool. If

more correction is necessary, bend a

Center each rod end or pitch

slightly wider section of tab. Use small

CAUTION

case and/or swashplate wear

adjustments to avoid excessive rebend

will result. Ensure there is no binding in full

ing of tabs.

up travel position.

NOTE: Tab zones on same blade can require

(2). After adjusting pitch control link

bending in opposite directions. For example,

length, center each rod end in its fitting

after bending tab zone A downward to get

and hold while tightening jam nuts;

good tracking at 60-90 knots, it might be

safety with lockwire.

come necessary to bend tab zone D or E (Ref.

Figure 502) upward to correct track at red

C. Blade Tab Adjustment

line airspeed. In any case, do not use larger

tab corrections than are actually necessary.

(Ref. Figure 502) Once ground idle track is

obtained, all remaining tracking correction is

(2). Each time blade tabs are adjusted,

accomplished by very slight bending of various

recheck ground idle track and readjust

blade tab zones with tab bending tool (ST902).

if necessary.

Different zones of tabs are used to adjust blade

track at different airspeeds. In general, tab

(3). After completion of forward flight

zone A is used for high-rpm, flat pitch ground

tracking, balance and check autorota

tracking (100% N₂) and zones C, D, and

tion rpm.

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CSP-HMI-2

MAINTENANCE MANUAL

BLADE STATIONS

105

111

117

124

130

148

164

MAIN ROTOR BLADE

(TOP VIEW)

71 IN.

(180 CM)

65 IN.

(165 CM)

59 IN.

(150 CM)

53 IN.

(135 CM)

47 IN.

(119 CM)

40 IN.

(102 CM

34 IN.

(86 CM)

16 IN.

(41 CM)

NOT USED

(NOTE 1)

TAB ZONES

TO END OF

NOTE 2

BLADE NOT USED

SHOCK CORD

HIGH RPM GROUND

(NOTE 1)

MEDIUM SPEED

TRACKING AND UP TO

(OR EQUIVALENT)

FLIGHT TRACKING

110 KNOTS IN FLIGHT

130-145 KNOTS

(100% N₂)

110-130 KNOTS

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

6G18-017A

Figure 502. Adjustment − Main Rotor Blade Tab

D. Main Rotor Ground Tracking

NOTE: On new (untracked) blades, check that

all tab areas are straight and in neutral po

sition (centered on chordline 0.0° ±0.5°).

For best results, tracking should be performed

under calm air conditions. Wind velocity

(2). Load helicopter to a gross weight of

should not exceed six knots during adjust

approximately 2350 pounds (1066.9 kg);

ments. Accurate adjustment of initial ground

then ground idle (approximately

track is very important. In most instances,

64-65% N₁) with collective pitch stick

forward flight tracking problems can be

full down.

avoided or greatly reduced by setting initial

(3). Observe tracking tip cap reflector image

track as nearly perfect as possible. Tolerances

by directing strobe light beam toward

specified in following instructions should be

blade tip path and sweeping beam

considered maximum permissible deviation

slowly back and forth until reflector

rather than desired goal.

images are clearly seen. Tracking image

should appear directly in front of

NOTE: If main rotor hub or a pitch control rod

helicopter or slightly off helicopter

end bearing has been replaced, adjust pitch

centerline.

control link(s) before proceeding with

(4). If blades are in track, tip cap reflector

ground tracking.

image pattern should resemble image

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

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

than 1/4 of one tracking reflector

check that normally straight (not to be

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

used) tab areas are in neutral position

below adjacent reflectors). If blades are

(centered on chordline) and straight.

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

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MAINTENANCE MANUAL

blades are out of track, adjust pitch

Use of the tracking strobe

WARNING

control links and repeat step (3). above.

light in night flight is not

recommended. Such use can result in

(5). With collective pitch stick full down,

pilot disorientation or loss of vision

increase engine speed to 100% N2 and

with resultant damage to the helicop

observe tip cap reflector image to see if

ter and personal injury.

blade track is changed from ground idle

F. Forward Flight Tracking

track. When all six blades are in track

within 1/4 of one reflector diameter,

(Ref. Figure 502 and Figure 506 thru

ground track is correct; proceed with

Figure 508) Forward flight tracking should be

hover verification. When a blade is out

performed whenever vertical flight vibrations

of track, adjust blade tab zone A until

indicate that blades may be out of track.

high rpm ground track is within

tolerance.

(1). Verify helicopter gross weight of

2000-2500 pounds (908-1135 kg).

E. Hover Track Verification

NOTE: When bending trim tabs, do not bend

(Ref. Figure 504)

more than 1.5° between six inch sections.

(1). Hover track verification must be

(2). Perform flight tracking from hover up

performed after ground tracking and

to 110 knots at 100% N₂. If flight track

before forward flight tracking. Verifica

varies from hover track more than 1/2

tion is only a check of hover track. Do

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

not adjust pitch control links or blade

degrees maximum) to limit variation to

tabs because of track images observed

tab zone B (five degrees maximum).

during hovering. Tab adjustments often

(3). Check autorotation percentage; per

cause variation between ground track

centage must not be less than 480

and hovering track. A large track

(90%).

variation may indicate that one or more

blades is beyond its chordwise balance

Do not attempt to adjust chord

tolerance, but this can only be deter

CAUTION

wise balance of a blade found to

mined during forward flight tracking.

be faulty when performing banked turns.

Perform hover track verification as

Chordwise balance corrections must be ac

follows.

complished by manufacturer (MDHI).

NOTE: Collective pitch stick may be ``heavy” af

(4). Perform a series of 45 degree banked

ter tracking reflectors are mounted on blade

turns at 100 knots and observe track

tips. This condition is not unusual and may

change from level flight. If any blade

be disregarded.

climbs or dives more than one inch

(2.54 cm) out of track with others,

(2). Verify helicopter gross weight of

chordwise balance (center of gravity) of

2000-2500 pounds (908-1135 kg).

that blade is beyond its tolerance and

blade must be replaced or balanced by

(3). With collective pitch stick full down,

an MDHI Field Representative. (Hover

increase N₂ to 100%.

track variations of this type that do not

(4). Observe tracking reflector images to

repeat during banked-turn maneuver

verify that ground track is within

may be disregarded.)

limits.

(5). Perform flight tracking at 100% N₂. If

necessary, adjust tab zone B (five

(5). With helicopter in a stable hover,

degrees maximum) to limit track

observe reflector images. If one or more

blades are out of track, record condi

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

tion(s) for reference during forward

and to minimize excessive vertical

flight tracking.

(one-per revolution) vibration. If

variation is excessive, bend tab zone C

(6). Proceed with forward flight tracking.

or D (five degrees maximum).

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CSP-HMI-2

MAINTENANCE MANUAL

NOTE: When determining whether blade track

D All autorotation percentage adjustments

is acceptable, overall vibration level of heli

shall be made at the main rotor pitch con

copter should be determining factor. Some

trol links only. Do not re-adjust mixer

combinations of rotor blades might produce

control rods after rigging is accomplished.

higher six-per-revolution vibration as

Failure to observe this precaution may re

blade tips are brought into close track; in

sult in serious damage to rotor system

such cases, lowest vibration level is pre

and controls. Do not adjust control rod

ferred, even though observed blade track

end beyond witness hole.

may be beyond specified tolerances.

D Tracking targets reduce blade to tailboom

clearance, performing autorotations to

(6). After flight tracking is completed,

the ground could result in boom strikes.

perform a Main Rotor System Balance

Procedure and Main Rotor Autorotation

RPM Check.

NOTE: Change length of all six pitch control

links as necessary to adjust autorotation

percentage. Be sure to lengthen or shorten

2. Main Rotor System Balance Procedure

all six links exactly same amount or blade

track is changed. One flat (1/6-turn) of con

Balance the main rotor system according to

trol link body causes approximately one per

instructions in the Chadwick-Helmuth

cent change in autorotation percent.

Operation and Service Instruction Handbook.

(1).

Autorotation Percentage Check (Ref.

The maximum allowable bal

CAUTION

Table 502) Load helicopter to a gross

ance weight per lead-lag bolt on

weight of 2800 ±25 pounds (1270 ±11

the main rotor hub assembly is 143 grams.

kg). Perform a practice autorotative

descent (Ref. RFM), taking care not to

3. Main Rotor Autorotation Percentage

allow percentage to exceed rotor speed

Check

limitations. During autorotation, take

careful note of stabilized autorotation

(Ref. Table 502) An autorotation percentage

percentage at one of the gross weight/

check is required after each blade tracking

density altitude combinations. After

operation and whenever rpm is outside limits

landing, compare observed percentage

listed. Check rotor rpm and make adjustments

with values. If observed percentage is

as follows.

within limits in table, percentage

setting is correct. If limits were exceed

ed, make corrective adjustments

CAUTION

according to Autorotation Percentage

Adjustment, until percentage is within

D Autorotation rpm is critical to a success

limits.

ful autorotation landing. When full main

rotor rpm is not available, autorotation

(2).

Autorotation Percentage Adjustment:

function is decreased. At high gross

Change length of all six pitch control

weights and/or density altitudes, the

links as required to adjust autorotation

main rotor rpm will try to overspeed. The

percentage. Make certain all six links

pilot must increase collective pitch to

are shortened or lengthened exactly the

keep main rotor rpm within limits. At

same amount or blade track will be

lower gross weights and/or density alti

altered.

tudes, the main rotor rpm will be under

speed. The pilot has less rotor energy

available to do the autorotation landing.

NOTE: After autorotation percentage adjust

Set the autorotation rpm within the lim

ments are satisfactorily accomplished, re

its of the Autorotation Percentage Chart

move tracking equipment before returning

to make sure sufficient autorotation rpm

helicopter to service. Be sure to correctly

is available at the helicopter minimum

tighten and safety all bolts after they are re

gross weight.

installed.

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TR12-001

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

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 rods and blade tabs

Action.

as required. Repeat track observation.

(2) Perform hover verification.

Go to step (3). Ref. Corrective Record track verification and proceed with

Action.

forward flight tracking.

(3) Perform forward flight

Go to step (4). Ref. Corrective Adjust blade tabs and repeat forward

tracking.

Action.

flight tracking.

(4) Perform autorotation

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

percentage check.

Action.

repeat percentage 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.

Table 502. Autorotation Percentage Chart

Stabilized Autorotation Percentage at Density Altitude

Gross Wt

1000 Ft

2000 Ft

3000 Ft

4000 Ft

5000 Ft

lb/kg

Sea Level

(305 M)

(610 M)

(915 M)

(1220 M)

(1525 M)

2500/1134

93.8 − 95.8

94.6 − 96.6

95.4 − 97.4

96.3 − 98.3

97.1 − 99.1

98.0 − 100.0

2600/1179

95.6 − 97.6

96.4 − 98.4

97.3 − 99.3

98.1 − 100.1

99.0 − 101.0

99.9 − 101.9

2700/1224

97.4 − 99.4

98.2 − 100.2

99.1 − 101.1

100.0 − 102.0

100.9 − 102.9

101.8 − 103.8

2800/1270

99.2 − 101.2

100.0 − 102.0

100.9 − 102.9

101.8 − 103.8

102.7 − 104.7

103.6 − 105.6

2900/1315

101.0 − 103.0

101.8 − 103.8

102.7 − 104.7

103.6 − 105.6

104.6 − 106.4

3000/1361

102.7 − 104.7

103.6 − 105.6

104.5 − 106.4

105.4 − 106.4

NOTE: Perform autorotation percentage checks at gross weight/density altitude combinations for which percent-

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

overspeed.

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MAINTENANCE MANUAL

ROTATION

BLUE

MD600N HOVER PITCH LINK ADJUSTMENT

VELO.

TAKE READINGS AT IGE HOVER USING VERTICAL

WHITE

YELLOW

VELOCIMETER ON CONSOLE.

ADJUST PITCH CHANGE LINK IN FLATS. 1 FLAT=1/6 TURN

OF PITCH CHANGE BARREL.

BLADE SEQUENCE IS SHOWN WITH SINGLE INTERRUPTER

MAG P/U

ATTACHED TO DRIVE LINK OF ROTATING SWASHPLATE.

TAKE READINGS FROM VERTICAL VELOCIMETER MOUNTED

RED

ON INSTRUMENT PEDESTAL POINTING DOWN.

ADJUST PITCH CHANGE LINK BEFORE BALANCING AT HOVER.

GREEN

BLACK

ADJUSTMENT IN FLATS

OF PITCH LINKS

BLADE ORIENTATION WITH

DRIVE LINK INTERRUPTER

MOVE

RED

GREEN

MOVE

AIRCRAFT VIEWED FROM ABOVE

BLACK

1 1/2

12:00

MOVE

11:00

1:00

BLACK

1 1/2

MOVE

IPS

1 1/2

YELLOW

ADJUST

CLOCK

2:00

10:00

1 1/2

MOVE

WHITE

1 1/2

9:00

3:00

MOVE

1 1/2

GREEN

1 1/2

4:00

8:00

1 1/2

MOVE

7:00

5:00

BLUE

6:00

MOVE

1 1/2

BLUE

1 1/2

MOVE

YELLOW

MOVE

WHITE

NOTES:

ARROWS INDICATE DIRECTION POINT SHOULD GO WHEN

ADJUSTMENT TO NOTED BLADE IS MADE.

MOVE TO OPPOSITE BLADE IN OPPOSITE DIRECTION HAS

SAME EFFECT.

6G18-099

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

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MAINTENANCE MANUAL

ROTATION

BLUE

MD600N HOVER BALANCE CHART

WHITE

YELLOW

TAKE READINGS AT IGE HOVER AFTER PCL TRACK.

USE WEIGHT, IN GRAMS, AT HUB LOCATION.

BLADE SEQUENCE IS SHOWN WITH SINGLE INTERRUPTER

ATTACHED TO DRIVE LINK OF ROTATING SWASHPLATE.

LATERAL VELOCIMETER READINGS USING VELOCIMETER

AT LEADING SIDE OF CONTROLS COVER POINTING TO

LEFT OF AIRCRAFT.

GREEN

RED

BLACK

BLADE ORIENTATION WITH

DRIVE LINK INTERRUPTER

OVER MAGNETIC PICKUP

AIRCRAFT VIEWED FROM ABOVE

ADD TO

200

BLACK

YELLOW

200

100

ADD TO

12.00

100

GREEN

1.00

IPS

ADD TO

11.00

ADJUST

100

CLOCK

GREEN

ADD TO

BLUE

2.00

10.00

100

ADD TO

200

RED

100

200

3.00

9.00

200

100

200

ADD TO

100

YELLOW

ADD TO

8.00

4.00

BLACK

100

7.00

5.00

ADD TO

100

WHITE

ADD TO

6.00

WHITE

100

200

100

200

ADD TO

200

ADD TO

BLUE

RED

G18-1007

Figure 505. Main Rotor System Balance Chart

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MAINTENANCE MANUAL

MD600N VERTICAL TAB CHART 100-130 KIAS

ROTATION

TAKE READINGS AT 100-130 KIAS.

TAB MEASUREMENTS ARE IN 0.001 IN. (0.0254 MM).

BLUE

BLADE SEQUENCE IS SHOWN WITH SINGLE INTERRUPTER

VELO.

ATTACHED TO DRIVE LINK OF ROTATING SWASHPLATE.

TAKE READINGS FROM VERTICAL VELOCIMETER MOUNTED ON

WHITE

INSTRUMENT PEDESTAL POINTING DOWN.

YELLOW

GREEN

RED

NO BEND

BLACK

AREA

INNER TAB TWO WIDTHS OF BENDER (STA. 97 - 111)

MIDDLE TAB TWO WIDTHS OF BENDER (STA. 111 - 130)

BLADE ORIENTATION WITH

OUTER TAB ONE WIDTH OF BENDER (STA. 130 - 142)

DRIVE LINK INTERRUPTER

OVER MAGNETIC PICKUP

MOVE

AIRCRAFT VIEWED FROM ABOVE

WHITE UP

MOVE

BLACK UP

MOVE

RED UP

12.00

11.00

1.00

MOVE

IPS

RED UP

BLUE UP

ADJUST

2.00

CLOCK

10.00

MOVE

GREEN UP

9.00

3.00

MOVE

WHITE UP

8.00

4.00

MOVE

BLACK UP

YELLOW UP

7.00

5.00

6.00

MOVE

YELLOW UP

BLUE UP

MOVE

GREEN UP

NOTE:

ARROWS INDICATE DIRECTION POINT SHOULD GO

WHEN ADJUSTMENT TO NOTED BLADE IS MADE.

G18-1006A

Figure 506. Main Rotor Tracking at 100 − 130 KIAS (Inner Tab Adjustment)

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MAINTENANCE MANUAL

ROTATION

MD600N VERTICAL TAB CHART 100-130 KIAS

BLUE

TAKE READINGS AT 100-130 KIAS.

VELO.

TAB MEASUREMENTS ARE IN .001 INCH.

BLADE SEQUENCE IS SHOWN WITH SINGLE INTERRUPTER

WHITE

YELLOW

ATTACHED TO DRIVE LINK OF ROTATING SWASHPLATE.

TAKE READINGS FROM VERTICAL VELOCIMETER MOUNTED ON

INSTRUMENT PEDESTAL POINTING DOWN.

RED

GREEN

ÉÉÉÉ

NO BEND

AREA

ÉÉÉÉ

BLACK

TAB BENDER TWO WIDTHS

UNDER TAB TWO WIDTHS OF BENDER (STA 97 - 111)

MIDDLE TAB TWO WIDTHS OF BENDER (STA 111 - 130)

OUTER TAB ONE WIDTH OF BENDER (STA 130 - 142)

BLADE ORIENTATION WITH

DRIVE LINK INTERRUPTER

OVER MAGNETIC PICKUP

.010

WHITE

AIRCRAFT VIEWED FROM ABOVE

RED

.005

BLACK

.005

IPS

ADJUST

.010

CLOCK

1.0 IPS

12:00

.005

BLUE

11:00

1:00

.005

RED

.010

.005

10:00

2:00

WHITE

.005

9:00

.005

1.0 IPS

GREEN

8:00

4:00

.005

.010

.005

YELLOW

7:00

5:00

BLACK

.005

6:00

.010

BLUE

.005

YELLOW

GREEN

.010

6G18-100

Figure 507. Main Rotor Tracking at 100 − 130 KIAS (Mid Tab Adjustment)

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

ROTATION

MD600N VERTICAL TAB CHART 100-130 KIAS

BLUE

VELO.

TAKE READINGS AT 100-130 KIAS.

WHITE

TAB MEASUREMENTS ARE IN .001 INCH

YELLOW

BLADE SEQUENCE IS SHOWN WITH SINGLE INTERRUPTER

ATTACHED TO DRIVE LINK OF ROTATING SWASHPLATE.

TAKE READINGS FROM VERTICAL VELOCIMETER MOUNTED ON

INSTRUMENT PEDESTAL POINTING DOWN.

RED

NO BEND

GREEN

ÉÉÉ

AREA

ÉÉÉ

BLACK

ONE WIDTH OF TOOL

UNDER TAB TWO WIDTHS OF BENDER

(STA. 97 TO 111)

BLADE ORIENTATION WITH

MIDDLE TAB TWO WIDTHS OF BENDER

DRIVE LINK INTERRUPTER

(STA. 111 TO 130)

OVER MAGNETIC PICKUP

OUTER TAB ONE WIDTH OF BENDER

(STA. 130 TO 142)

BLACK

AIRCRAFT VIEWED FROM ABOVE

WHITE

.016

RED

.008

RED

IPS

ADJUST

.008

CLOCK

12:00

.008

11:00

1:00

10:00

2:00

GREEN

.008

1.0 IPS

BLUE

.008

1.0 IPS

.016

9:00

3:00

.016

.008

1.0 IPS

BLACK

.008

8:00

WHITE

4:00

7:00

5:00

.008

6:00

YELLOW

.008

YELLOW

.016

GREEN

BLUE

Figure 508. Main Rotor Tracking at 100 − 130 KIAS (Outer Tab Adjustment)

Page 512

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

TAIL ROTOR BALANCE

MAINTENANCE PRACTICES

1. Tail Rotor Balancing

procedure. Tail rotor balance spare kit

contains extra tip weights and screws.

Special Tools

(2). Install combination of weights required.

(Ref. Section 91−00−00)

Maximum weight permitted is thirty-

Item

Nomenclature

four grams at each tip (Ref. Table 201).

Torque screws to 21 - 24 inch-pounds

ST903

Balancer/analyzer instrument kit

(2.37 - 2.71 Nm).

B. Balance at Blade Pitch Arm

Balancing is accomplished by use of a balanc

ing kit (ST903). The carrying case of this kit

(Ref. Figure 201) Weight increase at light pitch

contains all instrumentation, balance charts

arm may be obtained by removal of equivalent

and miscellaneous items needed to balance the

washer weight from opposite pitch arm.

tail rotor. Also included is a track and balance

Always remove washers from opposite pitch

handbook for use with the equipment to

arm, if installed, and subtract from weight to

correct balance when such can be obtained by

be added before adding more weight. For

addition or subtraction of weight at pitch-arm

washer data, refer to Table 201. Main rotor

studs or at blade tips.

and tail rotor balancing spare kit contains

extra washers. Maximum washer weight

Since vibration reduction by weight adjust

allowed at either pitch arm bolt is 26.91 grams

ment is dependent on proper mechanical

(23 washers).

condition of the tail rotor and tail rotor drive

system, troubleshooting information (Ref.

NOTE:

Chap. 64) should be used with balancing kit

D A tail rotor out-of-balance condition that

instructions. Acceptance criteria for balance

cannot be corrected by standard balanc

and vibration are contained in the balancing

ing procedures may be an indication of ex

kit and on each balance chart. Main rotor and

cessive play in tail rotor hub components.

tail rotor balancing spare kit contains spare

D There is possibility of slight weight varia

screws, washers and tip weights.

tion between pitch control links.

NOTE: If tail rotor balance is difficult to

(1). If tail rotor has maximum balance

achieve and horizontal stabilizer resonance

washer weight allowed on one pitch

is noted refer to 421-087-505 Horizontal

arm, compare the two links.

Stabilizer Tab Weight Installation.

(2). If pitch link opposite the weight

A. Balance at Blade Tip

requirement appears larger, exchange

one link for the other and repeat

When balancing procedures indicate that

vibration analysis.

weight should be added to a tip, it is prefer

able, if possible, to instead remove an equiva

(3). If, as a result of parts peculiarity,

lent amount from the opposite tip to keep

maximum allowable weight at one pitch

overall weight to a minimum. Installation of

arm does not correct assembly balance,

tip weights is not mandatory. However, open

tail rotor hub may be shifted in fork

screw holes are not permitted; screws must be

and hub-to-fork shimming adjusted, if

installed. Shorter than normal screws may be

maximum allowable play in fork

used for balance if minimal thread engage

bearings is not exceeded. This is done

ment of 5/16 inch (7.9375 mm) exists.

by transferring fork-to-hub spacing

shims from balance weighted side to

(1). Remove tip-weight screws and weights

opposite side of hub, according to hub

(Ref. Figure 201). Select balancing

and fork assembly procedures (Ref.

hardware indicated by balancing

COM).

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(a). Chordwise weight shift resulting

(6). Initially balance the tail rotor until

from each 0.001 inch (0.0254 mm) of

vibration level is 0.1 IPS (0.85 MIL) or

spacing thickness transferred

less as follows:

reduces weight requirement at

(a). Add weights to blade tips only. For

weighted pitch arm by one

four-bladed tail rotor, divide weights

HS306-227L balance washer.

as necessary between the two lower

blades to make the total weight

(b). Transferring one 369A1717-53

vector in the downward direction.

spacing shim, 0.010 inch (0.254 mm)

thickness, allows initial removal of

NOTE: If more than 15 grams of tip weight (in

10 thin washers from pitch arm and

cluding screw) is necessary on any one

thereby allows more flexibility for

blade, use the ``long method'' balance proce

further balance correction during

dure.

vibration analysis.

(7). After initial balance, reset RPM TUNE

(4). It should be noted that spanwise

dial, according to Chadwick-Helmuth

balance is probably affected by any

Handbook for final balancing. Direct

chordwise shift of fork.

strobe at tail rotor and adjust per

Chadwick-Helmuth instructions for

(5). If maximum allowable play in fork

VERIFY TUNE. Apply the same

bearings is exceeded, bearings must be

method used for initial balance to

replaced (Ref. COM).

balance until vibration level is 0.1 IPS

(0.85 MIL) or less.

(6). Replacement or adjustment of parts

requires balancing of tail rotor follow

D. Long Method Balance Check

ing re-assembly.

(Four−Bladed Tail Rotor)

C. Short Method Balance Check

(Ref. Figure 203 and Figure 204) A long

method balance check must be accomplished

(Ref. Figure 201 and Figure 202) Use tail rotor

each time hubs and fork of four-bladed tail

vibration analyzer (ST903) throughout this

rotor are reassembled. Use tail rotor vibration

procedure.

analyzer (ST903) throughout the procedure.

First runup of tail rotor assem

(1). Mount accelerometer into tail rotor

CAUTION

bly should be accomplished in a

gearbox breather plug as noted in

cautious manner, increasing tail rotor rpm

Chadwick-Helmuth Operation and

slowly so that vibrations from out-of-ba

Service Handbook.

lance tail rotor assembly will not cause dam

age.

(2). Connect accelerometer and balancer DC

power cables as noted in the Chadwick-

NOTE: Prior to performing long method bal

Helmuth Operation and Service

ance check, ensure hub is centered on fork

Handbook.

and elastomeric bearings are preloaded cor

rectly.

(3). Apply a retro-reflective target material

on blade root fitting. For four-bladed

(1). With outboard blade removed, balance

tail rotor, one blade of the outboard tail

inboard blade by adjusting tip weights

rotor assembly.

and washers at pitch arm bolt to

achieve 0.10 IPS (0.85 MIL) or less

(4). Connect cables and instruments and

vibration level at 2100 rpm (input shaft

adjust settings as noted in Chadwick-

of transmission). This corresponds to

Helmuth Handbook.

tail rotor rpm of 2168.

(5). Direct strobe at tail rotor and adjust

(2). Install outboard blade and hub assem

per Chadwick-Helmuth instructions for

bly; check balance of outboard blades by

VERIFY TUNE.

adjusting weights to obtain 0.10 IPS

Page 202

Revision 23

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

(0.85 MIL) vibration or less, using same

assembly and balance the tail rotor

method as used for inboard blade

assembly.

balancing, except as shown in

(3). After balancing the tail rotor assembly,

Figure 204.

reinstall the horizontal stabilizer.

2. Horizontal Stabilizer Tuning

(4). Run engine at 102%-105% N₂ and

observe horizontal stabilizer tab.

Installation of tab weight is optional on the

(5). If tab resonance occurs and tail rotor

421-087 -505 horizontal stabilizer if difficulty

balance is no longer acceptable, install

in tail rotor balance and horizontal stabilizer

tab weight to horizontal stabilizer right

tab resonance vibration is encountered.

tab (Ref. Sec. 53-50-10, Horizontal

Stabilizer Tab Weight Installation).

(1). With helicopter on flat smooth surface,

operate engine at 102%-105% N₂ and

(6). If needed, a one ounce weight may also

observe horizontal stabilizer tab.

be installed on left tab.

(2). If tab resonance vibration occurs,

(7). A maximum of two ounces may be

remove the horizontal stabilizer

installed on each tab.

Page 203

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

ACCELEROMETER/VELOMETER

FOR TAIL ROTOR BALANCING.

INSTALL ON BREATHER PLUG

OF TAIL ROTOR GEAR BOX

TAPE

SECURE UNDER LATCH

REFLECTIVE

TAPE

KIT LOCATION FOR TAIL

28VDC POWER CABLE

ROTOR BALANCING

TO AUXILIARY OUTPUT

RECEPTACLE

BALANCE WASHERS

RETAINING NUT

PITCH ARM BOLT

CABLE

SPRING WASHER

PITCH CONTROL

ACCELEROMETER/VELOMETER

LINK

(NOTE 1)

PITCH ARM

BREATHER/FILLER

BALANCE WASHER

INSTALLATION

TIP WEIGHT

NOTE 3

WEIGHT INSTALLATION

ROTATED

NOTES:

INSTALLED ONLY FINGER TIGHT.

FOR INFORMATION ON MAXIMUM WEIGHT, NUMBERS, TYPES AND

EXACT LOCATIONS OF BALANCING HARDWARE TO BE USED,

REFER TO ASSOCIATED TEXT AND TABLES.

TORQUE SCREWS TO 21 - 24 INCH-POUNDS (2.37 - 2.71 NM).

G18-2000B

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

Page 204

Revision 34

18-20-00

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

Table 201. Tail Rotor Balance Weight − Value Chart

At Blade Tip (4)

At Blade Pitch Arm (3)

Screw (5)

Washer (1)(2)

Length

Weight

Thickness

Weight

Part Number

(in./mm)

(Grams)

Part Number

(in./mm)

(Grams)

(in./mm)

NAS1352−08−12P

0.75/19.05

2.22

HS306−227L

0.016/0.4064

1.17

0.800/20.32

NAS1352−08−14P

0.875/22.23

2.44

Weight

Thickness

Weight

(In./mm)

(Grams)

369A1622−3

0.016/0.4064

0.29

369A1622−5

0.036/0.9144

1.76

NOTES:

(1) Used on balance bolt.

(2) Maximum of 23 washers is permitted on each balance bolt.

(3) Minimum of two threads must extend past nut securing balance washers on balance bolt.

(4) Maximum weight, including screws, is 34 grams.

(5) Minimum screw thread engagement is 5/16 inch (7.9375 mm).

TOTAL

WEIGHT

TOTAL

WEIGHT

SMALLER

VECTOR

WEIGHT

VECTOR

WEIGHT

VECTOR

EQUAL

WEIGHT

LARGE WEIGHT

WEIGHT

NOTE:

IF, WHEN ADDING WEIGHTS, OUT-OF-BALANCE VIBRATION

LEVEL INCREASES, ADD WEIGHTS TO THE TOP BLADE(S).

G18-2001

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

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18-20-00

Revision 39

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

BALANCE WASHERS

(NOTE 1)

SHIMS

(NOTE 2)

NOTES:

SHIM

MAXIMUM ALLOWABLE NUMBER OF WASHERS AT

PITCH ARM BOLT IS 23. WHENEVER THIS LIMIT IS

REACHED AND REQUIRED BALANCE CANNOT BE

MET, SHIFT THE CENTER OF THE HUB BY

TRANSFERRING SHIMS, THICKNESS OF 0.010 IN.

(0.254 MM), FROM WEIGHTED PITCH ARM SIDE TO

THE OPPOSITE SIDE AS SHOWN AND RE-CHECK

BALANCE, STARTING FROM ZERO WASHERS.

REMOVE 0.010 IN. (0.254 MM) THICK SHIM FROM

G18-2002A

PITCH ARM SIDES AND TRANSFER THE SHIM TO

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

BALANCE WASHERS

(MAX. 23)

SHIMS

(NOTE 2)

SHIM

NOTES:

REMOVE 0.010 IN. (0.254 MM) THICK SHIM

FROM WEIGHTED PITCH ARM SIDE AND

TRANSFER THE SHIM TO THE OPPOSITE SIDE.

DURING BALANCE OF OUTBOARD BLADES,

WEIGHTS ON INBOARD BLADES MUST NOT

G18-2003A

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

Page 206

Revision 23

18-20-00

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

NOTARR ANTI−TORQUE SYSTEM FAN BALANCE

MAINTENANCE PRACTICES

1. Fan Balancing

(4). Install velometer on bracket located at

the 6:00 o'clock position (Ref.

The NOTARr anti-torque system uses a

Figure 203).

fan-driven air circulation system within the

(5). Install magnetic pick-up and velometer

tailboom to control the directional heading of

wiring (Ref. Figure 203).

the helicopter. The rudder pedals in the cockpit

control the blade angle of the fan assembly.

Wiring must be secured to pre

The fan assembly operates at a constant speed

CAUTION

vent them from being ingested

of 5388 RPM at 100% N₂.

into the fan assembly during run-up.

Balancing is accomplished by use of a balanc

(6). Position the anti-torque pedals at

ing kit. The carrying case of this kit contains

neutral during fan balancing.

all instrumentation, balance charts and

miscellaneous items needed to balance the fan

NOTE: The neutral position is 62% from full

assembly. Also included is a track and balance

left or approximately one inch of right pedal

handbook for use with the equipment to

from pedals centered. This pedal position

correct balance when such can be obtained by

produces minimum fan pitch and closes the

addition or subtraction of weight at studs on

thruster.

the fan assembly.

WARNING

Since vibration reduction by weight adjust

ment is dependent on proper mechanical

D Damage could occur if the anti-

condition of fan drive system, troubleshooting

torque pedals are not kept at neutral

information (Ref. Chap. 64) should be used

while the helicopter is operating

with balancing kit instructions. Acceptance

with the fan/hub transmission fair

criteria for balance and vibration are con

ing removed.

tained in the balancing kit and on each

D Operators and authorized observers

balance chart.

should remain in the designated

areas during balancing operations.

2. Fan Balance Check

D Wearing loose clothing or having ma

terials in shirt pockets during opera

(Ref. Figure 201)

tions can result in injury to person

nel and/or damage to aircraft.

Special Tools

(7). Run helicopter to establish N2 speed of

(Ref. Section 91−00−00)

100% percent.

Item

Nomenclature

ST903

Balancer/analyzer instrument kit

(8). Observe vibration reading.

(a). If vibration reading is greater than

0.2 ips, shut down helicopter and

NOTE: Use the vibration analyzer (ST903)

proceed with step (9).

throughout this procedure.

(b). If vibration level is 0.2 ips or less,

(1). Remove fan inlet screen.

proceed with step (11).

(2). Remove upper portion of the fan/hub

(9). Add hardware to the balancing studs in

transmission fairing.

any combination as required using

Table 201 and Figure 202. Torque nuts

(3). Number balancing studs as shown in

on studs to 30 - 40 inch pounds (3.39

Figure 201 using a permanent marker.

- 4.52 Nm).

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MD Helicopters, Inc.

MAINTENANCE MANUAL

Do not over torque the nuts on

(11). Remove balancing equipment wiring

CAUTION

the balancing studs. An over-

and attachments.

torqued nut may cause the stud locking col

(12). Install the fan/hub transmission fairing

lar to become loose the next time the nut is

and fan inlet screen.

removed.

(10). Repeat steps (6). thru (9). until fan

dynamic balance is 0.2 ips or less.

Table 201. Preferred Hardware for Balancing Fan Assembly

Washer

Weight (grams)

Stainless

Thickness

Stainless

Aluminum

Steel

(in/mm)

Aluminum

Steel

AN960KD416L

0.016 / 0.406

0.265 / 6.731

0.500 / 12.700

0.103

AN960C416L

0.016 / 0.406

0.265 / 6.731

0.500 / 12.700

0.572

AN960KD416

AN960C416

0.063 /1.600

0.265 / 6.731

0.500 / 12.700

0.407

1.144

HS306−325L

HS306−225L

0.016 / 0.406

0.263 / 6.680

0.528 / 13.411

0.121

0.339

HS306−325

HS306−225

0.032 / 0.813

0.263 / 6.680

0.528 / 13.411

0.241

0.677

HS306−325H

HS306−225H

0.063 / 1.600

0.263 / 6.680

0.528 / 13.411

0.482

1.355

HS306−326L

HS306−226L

0.016 / 0.406

0.263 / 6.680

0.619 / 15.723

0.181

0.507

HS306−326

HS306−226

0.032 / 0.813

0.263 / 6.680

0.619 / 15.723

0.361

1.015

HS306−326H

HS306−226H

0.063 / 1.600

0.263 / 6.680

0.619 / 15.723

0.723

2.029

HS306−327L

HS306−227L

0.016 / 0.406

0.263 / 6.680

0.800 / 20.320

0.329

0.922

HS306−327

HS306−227

0.032 / 0.813

0.263 / 6.680

0.800 / 20.320

0.657

1.844

HS306−327H

HS306−227H

0.063 / 1.600

0.263 / 6.680

0.800 / 20.320

1.314

3.689

NOTE: Maximum washer stack−up thickness = 0.20 inch (5.08 mm).

Page 202

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

TABLE OF CONTENTS

Para/Figure/Table

Title

Page

20-10-00 Torque

Maintenance Practices

201

1. Torque Wrenches

201

2. Application of Torque Wrench Loads

201

3. Bearings Installation, Staking or Swaging Force

201

4. Control Tube Jam Nut Torquing

202

5. Standard Hardware Torque Values

202

Table 201. Recommended Standard Torques for Tension-Type Fasteners

203

Table 202. Recommended Standard Torques for Shear-Type Fasteners

204

Table 203. Locking (Drag) Torque for Self-Locking Fasteners

205

20-20-00 Cleaning

Maintenance Practices

201

1. Cleaning

201

2. Fuselage Interior Trim and Upholstery Cleaning

201

3. Airframe Exterior and Rotor Blades Cleaning

201

4. Transparent Plastic Cleaning

201

5. Engine Compressor Contamination Removal

202

6. Cleaning Of Engine Air Inlet Screens

202

20-30-00 Painting

Maintenance Practices

201

1. Paint Finish

201

2. Paint Removal

201

3. Paint Touchup

201

A. Touchup - Small Sanded Areas

201

B. Touchup - Flaking or Dried Paint or Primer

201

C. Touchup - Primer Not Adhering to Metal Finish

201

D. Touchup - Glass Fiber Laminate Parts

202

E. Touchup - Polycarbonate Plastic Parts

202

F. Touchup - ABS Thermoplastic Parts

202

4. Main Rotor Blade Paint

203

A. Main Rotor Blade Paint Removal

203

B. Main Rotor Blade Paint Application

203

5. Tail Rotor Blade Paint

204

A. Tail Rotor Blade Paint Removal

204

B. Tail Rotor Blade Paint Application

204

20-40-00 Corrosion Prevention

Maintenance Practices

201

1. Corrosion Control

201

Page i

20 Contents

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

TABLE OF CONTENTS (Cont.)

Para/Figure/Table

Title

Page

2. Magnesium Alloys - Insulation Against Corrosion

201

3. Sealing Compound Application

201

4. Main Rotor Hub Corrosion Prevention (Tri-Flow Wash Procedure)

201

5. Main Rotor Blades Corrosion Arresting

202

A. Main Rotor Blade and Damper Attach Pins - Corrosion Prevention

202

6. Magnesium Alloy Exterior Surface Touchup Treatment

203

7. Aluminum Alloy Exterior Surface Touchup Treatment

203

8. Steel Alloy Exterior Surface Touchup Treatment

203

9. Splitter Bungee Spring Corrosion Control (500N)

204

Table 201. Anti-Corrosion Chemical Finishes - Aluminum

204

20-90-00 Nondestructive Inspection

Maintenance Practices

201

1. Nondestructive Inspection Methods

201

A. Visual Inspection

201

Figure 201. Visual Inspection Technique

201

B. Dye Penetrant Inspection

202

C. Coin Tap Inspection

202

D. Fluorescent Penetrant Inspection

202

E. Magnetic Particle Inspection

202

Figure 202. Coin Tap Inspection

203

F. Eddy Current Inspection - General

203

Page ii

Revision 41

20 Contents

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

TORQUE

MAINTENANCE PRACTICES

1. Torque Wrenches

(5). Torque values specified in this manual

are special torque values that apply

Torque wrenches should be of good quality and

instead of those listed.

calibration should be verified at regular

intervals to verify accuracy. Torque wrench

(6). If adapters are used such that adapter

accuracy at room temperature, 70°F (22 °C)

and torque wrench are not at right

must be within following limits.

angles (90 degrees) to each other,

wrench or indicator reading must be

(1). From zero through 19 percent of torque

corrected.

wrench range, error may not exceed ±7

percent of load applied.

(7). Any re-use of self-locking nuts over 3/8

inch is governed by values listed in

(2). From 20 thru 79 percent of torque

Table 203.

wrench range, error may not exceed ±4

(8). Castellated nuts aretorqued to the

percent load applied.

minimum side of the recommended

(3). From 80 to 100 percent of torque

torque range. Continue to tighten the

wrench range, error may not exceed ±5

nut until the hole of the cotter pin lines

percent of load applied.

up with the castellation without

exceeding the maximum specified

torque.

2. Application of Torque Wrench Loads

(9). Bolt must not be rotated during

(Ref. Table 201 thru Table 203) Recommended

application of torque to mating nut.

tightening torque values and minimum drag

torque values for fine and coarse thread nuts,

3. Bearings Installation, Staking or Swaging

and minimum breakaway torque for used

Force

self-locking bolts or screws are listed in

Table 201 and Table 202. Requirements

The following procedure explains how to

governing application of torque loads follow.

convert from a given `Force` which is required

These requirements apply throughout this

to perform a task to a proper hydraulic

manual except where otherwise specifically

pressure reading.

indicated.

(1). Determine the diameter of the ram

(1). Values apply to cadmium-plated bolts,

(staking or swaging contact surface) on

cadmium-plated nuts coated with

the hydraulic press to be used.

molybdenum disulfide (MoS₂).

NOTE: The hydraulic press to be used must

(2). Manufacturer applied lubricant must

have a pressure gauge.

not be removed nor additional lubricant

added.

(2). Divide the ram diameter by two to get

the radius.

(3). Bolts, nuts and surfaces they bear on

must be clean, dry and free of lubricant

(3). Multiply 3.14159 (pi) times the Radius

except as stated in requirement above.

squared (R²). This will give the area of

the ram.

(4). Turning (drag) torque required to

install self-locking nut or bolt up to

(4). Divide the force required for the task by

point of final tightening must always be

the area of the ram. This gives the

added to final torque value specified or

actual PSI reading for the hydraulic

the maintenance instruction, as

press pressure gauge needed to perform

applicable.

the task.

Page 201

20-10-00

Revision 38

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

EXAMPLE:

5. Standard Hardware Torque Values

Ram Diameter = 2.65 in. (6.731 cm)

The following tables list torque values for

standard hardware by part number.

Ram Radius (R) = 1.325 in. (3.366 cm)

Radius squared (R²) = 1.756 in.² (8.548 cm²)

NOTE: If unsure of hardware type, refer to

CSP-IPC-4.

R² X 3.1416 = 5.517 in. (26.854 cm) (Area of

ram)

(1). Table 201 lists self-locking tension-

type fastener torque values.

Force required = 7500-8500 lbs. (3402-3856

kg) (variable)

(2). Table 202 lists shear-type fastener

7500-8500 lbs. (3402-3856 kg) / 5.517 in.

torque values.

(26.854 cm) = 1359-1540 PSI (9370-10618

kPa)

(3). Table 203 lists maximum and minimum

self-locking fastener drag (run-on)

PSI required =1359 PSI (9370 kPa) Min.

torque values.

1540 PSI (10618 kPa) Max.

Force needed/(R²) X 3.1416 = Pressure Gauge

Table 203 lists self-locking

CAUTION

Reading

(run-on) torque values, i.e.;

torque required to overcome the friction of

4. Control Tube Jam Nut Torquing

the self-locking feature of fastener threads

prior to clamp-up and final tightening. Any

(1). Tighten jam nuts against control rods

self-locking fastener that can be run down

by holding rodend with wrench.

with the fingers after the locking feature en

gages must be replaced. Determine final

NOTE: Do not tighten with rodend against fit

torque value by adding the run-on torque to

ting.

the specified final clamping torque. Final

(2). Ensure rodends are not preloaded after

clamping torque values are listed in

torquing jam nuts.

Table 201 and Table 202.

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CSP-HMI-2

MAINTENANCE MANUAL

Table 201. Recommended Standard Torques for Tension−Type Fasteners

Diameter

Thread

Recommended

Maximum

Thread

Recommended

Maximum

inch

Size

Torque

Allowable

Size

Torque

Allowable

(mm)

(Fine)

in. lb (Nm)

(Coarse)

in. lb (Nm)

0.1640

12 − 15

8 − 36

8 − 32

(4.1656)

(1.13 − 1.36)

(2.26)

(1.36 − 1.69)

(2.26)

0.1900

20 − 25

10 − 32

10 − 24

(4.8260)

(2.26 − 2.82)

(4.52)

(2.26 − 2.82)

(3.95)

0.250

50 − 70

100

40 − 50

1/4 − 28

1/4 − 20

(6.350)

(5.65 − 7.91)

(11.30)

(4.52 − 5.65)

(8.47)

0.3125

100 − 140

225

80 − 90

160

5/16 − 24

5/16 − 18

(7.9375)

(11.30 − 15.82)

(25.42)

(9.04 − 10.17)

(18.08)

0.3750

160 − 190

390

160 − 185

275

3/8 − 24

3/8 − 16

(9.5250)

(18.08 − 21.47)

(44.06)

(18.08 − 20.90)

(31.07)

0.4375

450 − 500

840

235 − 255

475

7/16 − 20

7/16 − 14

(11.1125)

(50.84 − 56.49)

(94.91)

(26.55 − 28.81)

(53.67)

0.50

480 − 690

1100

400 − 480

880

1/2 − 20

1/2 − 13

(12.70)

(54.23 − 77.96)

(124.3)

(45.19 − 54.23)

(90.39)

0.5625

800 − 1000

1600

500 − 700

1100

9/16 − 18

9/16 − 12

(14.2875)

(90.39 − 112.98)

(180.8)

(56.49 − 79.09)

(124.3)

0.6250

1100 − 1300

2400

700 − 900

1500

5/8 − 18

5/8 − 11

(15.8750)

(124.3 − 146.9)

(271.2)

(79.09 − 101.69)

(169.5)

0.750

2300 − 2500

5000

1150 − 1600

2500

3/4 − 16

3/4 − 10

(19.050)

(259.9 − 282.5)

(565.0)

(129.95 − 180.8)

(282.5)

0.8750

2500 − 3000

7000

2200 − 3000

4600

7/8 − 14

7/8 − 9

(22.2250)

(282.5 − 339.0)

(791.0)

(248.6 − 339.0)

(542.4)

1.00

3700 − 5500

10000

3700 − 5000

7600

1 − 12

1 − 8

(25.40)

(418.1 − 621.5)

(1130.0)

(418.1 − 565.0)

(858.8)

1.1250

5000 − 7000

15000

5500 − 6500

12000

1−1/8 − 12

1−1/8 − 8

(28.5750)

(565.0 − 791.0)

(1695.0)

(621.5 − 734.5)

(1356.0)

1.250

9000 − 11000

25000

6500 − 8000

16000

1−1/4 − 12

1−1/4 − 8

(31.750)

(1017.0 − 1243.0)

(2825.0)

(734.5 − 904.0)

(1469.0)

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MAINTENANCE MANUAL

Table 202. Recommended Standard Torques for Shear−Type Fasteners

Diameter

Thread

Recommended

Maximum

Thread

Recommended

Maximum

inch

Size

Torque

Allowable

Size

Torque

Allowable

(mm)

(Fine)

in. lb (Nm)

(Coarse)

in. lb (Nm)

0.1640

7 − 9

8 − 36

8 − 32

(4.1656)

(0.79 − 1.02)

(1.36)

(0.79 − 1.02)

(1.36)

0.1900

12 − 15

10 − 32

10 − 24

(4.8260)

(1.36 − 1.69)

(2.82)

(1.36 − 1.69)

(2.37)

0.250

30 − 40

25 − 30

1/4 − 28

1/4 − 20

(6.350)

(3.39 − 4.52)

(6.78)

(2.82 − 3.39)

(5.08)

0.3125

60 − 85

140

48 − 55

100

5/16 − 24

5/16 − 18

(7.9375)

(6.78 − 9.60)

(15.82)

(5.42 − 6.21)

(11.30)

0.3750

95 − 110

240

95 − 110

170

3/8 − 24

3/8 − 16

(9.5250)

(10.73 − 12.43)

(27.12)

(10.73 − 12.43)

(19.21)

0.4375

270 − 300

500

140 − 155

280

7/16 − 20

7/16 − 14

(11.1125)

(30.51 − 33.90)

(56.49)

(15.82 − 17.51)

(31.64)

0.50

290 − 410

660

240 − 290

520

1/2 − 20

1/2 − 13

(12.70)

(32.77 − 46.32)

74.57)

(27.12 − 32.77)

(58.75)

0.5625

480 − 600

960

300 − 420

650

9/16 − 18

9/16 − 12

(14.2875)

(54.23 − 67.79)

(108.47)

(33.90 − 47.45)

(73.44)

0.6250

660 − 780

1400

420 − 540

900

5/8 − 18

5/8 − 11

(15.8750)

(74.57 − 88.13)

(158.2)

(47.45 − 61.01)

(101.69)

0.750

1300 − 1500

3000

700 − 950

1500

3/4 − 16

3/4 − 10

(19.050)

(146.9 − 169.5)

(339.0)

(79.09 − 107.34)

(169.5)

0.8750

1500 − 1800

4200

1300 − 1800

2700

7/8 − 14

7/8 − 9

(22.2250)

(169.5 − 203.4)

(474.6)

(146.9 − 203.4)

(305.1)

1.00

2200 − 3300

6000

2200 − 3000

4500

1 − 12

1 − 8

(25.40)

(248.6 − 372.9)

(678.0)

(248.6 − 339.0)

(508.5)

1.1250

3000 − 4200

9000

3300 − 4000

7200

1−1/8 − 12

1−1/8 − 8

(28.5750)

(339.0 − 474.6)

(1017.0)

(372.9 − 452.0)

(813.6)

1.250

5400 − 6600

15000

4000 − 5000

10000

1−1/4 − 12

1−1/4 − 8

(31.750)

(610.2 − 745.8)

(1695.0)

(452.0 − 565.0)

(1130.0)

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CSP-HMI-2

MAINTENANCE MANUAL

Table 203. Locking (Drag) Torque for Self−Locking Fasteners

Diameter

Thread

Maximum

Minimum

Thread

Maximum

Minimum

inch

Size

in. lb

Size

in. lb

(mm)

(Fine)

(Nm)

(Coarse)

(Nm)

0.1640

1.50

8−36

8 − 32

(4.1656)

(1.7)

(0.17)

(1.7)

(0.17)

0.1900

2.0

10 − 32

10 − 24

(4.8260)

(2.03)

(0.23)

(2.03)

(0.23)

0.250

3.50

4.50

1/4 − 28

1/4 − 20

(6.350)

(3.39)

(0.40)

(3.39)

(0.51)

0.3125

6.50

7.50

5/16 − 24

5/16 − 18

(7.9375)

(6.78)

(0.73)

(6.78)

(0.85)

0.3750

9.50

12.0

3/8 − 24

3/8 − 18

(9.5250)

(9.04)

(1.07)

(9.04)

(1.36)

0.4375

100

14.0

100

16.50

7/16 − 20

7/16 − 14

(11.1125)

(11.3)

(1.58)

(11.3)

(1.86)

0.50

150

18.0

150

24.0

1/2 − 20

1/2 − 13

(12.70)

(16.95)

(2.03)

(16.95)

(2.71)

0.5625

200

24.0

200

30.0

9/16 − 18

9/16 − 12

(14.2875)

(22.60)

(2.71)

(22.60)

(3.39)

0.6250

300

32.0

300

40.0

5/8 − 18

5/8 − 11

(15.8750)

(33.90)

(3.62)

(33.90)

(4.52)

0.750

400

50.0

400

60.0

3/4 − 16

3/4 − 10

(19.050)

(45.19)

(5.65)

(45.19)

(6.78)

0.8750

600

70.0

600

82.0

7/8 − 14

7/8 − 9

(22.2250)

(67.79)

(7.91)

(67.79)

(9.27)

1.00

800

90.0

800

110.0

1 − 12

1 − 8

(25.40)

(90.39)

(10.17)

(90.39)

(12.43)

1.1250

900

117.0

1−1/8 − 12

(28.5750)

(101.69)

(13.22)

1.250

1000

143.0

1−1/4 − 12

(31.750)

(112.98)

(16.16)

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CSP-HMI-2

MAINTENANCE MANUAL

CLEANING

MAINTENANCE PRACTICES

1. Cleaning

3. Airframe Exterior and Rotor Blades

Cleaning

Consumable Materials

(Ref. Section 91−00−00)

Consumable Materials

Item

Nomenclature

(Ref. Section 91−00−00)

Item

Nomenclature

CM234

Solvent, dry-cleaning

CM234

Solvent, dry-cleaning

General cleaning of oil and dirt deposits from

Use care to prevent scratching

the helicopter and its components must be

CAUTION

of aluminum skin when clean

accomplished by using dry-cleaning solvent

ing main rotor blades. Never use volatile

(CM234), standard commercial grade kerosene

solvents or abrasive materials. Never apply

or a solution of detergent soap and water.

bending loads to blades or blade tabs during

Exceptions that must be observed are specified

cleaning.

in the following cleaning paragraphs.

NOTE: Avoid directing soapy or clean water

concentrations toward engine air intake

Some commercial cleaning

area and instrument static source ports in

CAUTION

agents, such as readily avail

aft fairing.

able household cleaners, contain chemicals

(1). Wash helicopter exterior, including

that can cause corrosive action and/or leave

fiberglass components and rotor blades,

residue that can result in corrosion. Exam

when necessary, using solution of clean

ples of cleaning agents that are not to be

water and mild soap.

used are ``Fantastic” and ``409” type clean

ers, or locally made strong soap cleaners.

(2). Clean surfaces stained with fuel or oil

by wiping with soft cloth dampened by

Fuselage Interior Trim and Upholstery

solvent (CM234), followed by washing

Cleaning

with clean water and mild soap.

(3). Rinse washed areas with water and dry

(1). Clean dirt or dust accumulations from

with soft cloth.

floors and other metal surfaces with

vacuum cleaner or small hand brush.

4. Transparent Plastic Cleaning

(2). Sponge soiled upholstery and trim

(1). Clean outside surfaces of plastic panels

panels with a mild soap and lukewarm

by rinsing with clean water and

water solution. Avoid complete soaking

rubbing lightly with palm of hand.

of upholstery and trim panels. Wipe

(2). Use mild soap and water solution or

solution residue from upholstery with

aircraft type plastic cleaner to remove

cloth dampened by clean water.

oil spots and similar residue.

(3). Remove imbedded grease or dirt from

Never attempt to dry plastic

upholstery and carpeting by sponging

CAUTION

panels with cloth. To do so

or wiping with an upholstery cleaning

causes any abrasive particles lying on plas

solvent recommended for the ``applica

tic to scratch or dull surface. Wiping with

ble” fabric (nylon, vinyl, leather, etc).

dry cloth also builds up an electrostatic

charge that attracts dust particles from air.

NOTE: If necessary, seat upholstery may be

thoroughly dry-cleaned with solvent. When

(3). After dirt is removed from surface of

complete dry-cleaning is performed, uphol

plastic, rinse with clean water and let

stery must be re-flameproofed.

air-dry or dry with soft, damp chamois.

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CSP-HMI-2

MAINTENANCE MANUAL

PAINTING

MAINTENANCE PRACTICES

1. Paint Finish

Consumable Materials

Polyurethane paint is used for the helicopter

(Ref. Section 91−00−00)

exterior finish. The primary interior finish is

Item

Nomenclature

acrylic paint. A base coat of primer is used on

CM305

Lacquer, acrylic

most helicopter structure.

CM318

Primer

CM320

Thinner, lacquer

2. Paint Removal

(1). Apply applicable chemical surface

Consumable Materials

treatment (Ref. Sec. 20-40-00) if metal

(Ref. Section 91−00−00)

protection is not adequate. If chemical

Item

Nomenclature

surface treatment is undamaged, or has

CM229

Paint remover

already been applied, wipe surface

clean with thinner (CM320) and wipe

CM230

Paint remover

dry immediately.

CM236

Paint remover

(2). Apply coat of primer (CM318). Feather

primer coating onto surrounding color

Use paint remover (CM229, CM230 or CM236)

coat. Allow primer to air-dry for 30

when it becomes necessary to remove finish

minutes.

paint coatings. Ordinarily, use of paint

(3). Apply lacquer (CM305) color coats to

remover should be limited to stripping of paint

match original finish color.

from parts that require magnetic-particle or

fluorescent-penetrant inspection and to parts

B. Touchup − Flaking or Dried Paint or

that require removal of excessive paint

Primer

buildup. When possible, use high-pressure

water spray to rinse off paint remover and

Consumable Materials

paint particles and to neutralize paint

(Ref. Section 91−00−00)

remover. Solvent type paint remover usually

Item

Nomenclature

does not remove primer coating; acid type

CM801

Abrasive paper, silicon carbide

solvent removes primer.

If paint remover is used in vicin

(1). Sand non-adherent surface to smooth

CAUTION

ity of drive shaft couplings, be

featheredge with surrounding area,

sure couplings are completely masked and

using 320-grit or finer abrasive paper

covered. If paint remover contacts coupling

(CM801), and wet or dry sanding

diaphragms, rust spots will develop and cou

method. Do not sand beyond point

pling replacement is required. If acid type

where chemical film protection begins

paint remover is used, comply with all spe

to show through primer.

cial safety precautions listed on container.

(2). Touchup sanded area [Ref. Touchup -

Small Sanded Area).

3. Paint Touchup

C. Touchup − Primer Not Adhering to Metal

Following procedures apply to application of

Finish

both polyurethane and acrylic paints.

Consumable Materials

A. Touchup − Small Sanded Areas

(Ref. Section 91−00−00)

Item

Nomenclature

The following procedure is for rework of

scratches, nicks, gouges and other small

CM801

Abrasive paper, silicon carbide

blemishes.

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TR12-001

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(1). Use 320-grit or finer abrasive paper

(4). Lightly sand surface with 320-grit

(CM801) and wet or dry sanding

abrasive paper (CM801). Normal grain

method to sand through chemical film

appearance does not require further

to bare metal. Feather surrounding

filling or sanding.

surface with bare surface.

(5). Apply primer and color finish (CM305)

(2). Re-treat bare metal with applicable

[Ref. Touchup - Small Sanded Areas).

chemical film (Ref. Sec. 20-40-00)

using brush application.

E. Touchup − Polycarbonate Plastic Parts

(3). Touchup re-treated surface [Ref.

Touchup - Small Sanded Areas).

Consumable Materials

(Ref. Section 91−00−00)

D. Touchup − Glass Fiber Laminate Parts

Item

Nomenclature

CM220

Naphtha aliphatic

Consumable Materials

CM217

Isopropyl alcohol

(Ref. Section 91−00−00)

CM305

Lacquer, acrylic

Item

Nomenclature

CM317

Resin primer / Thinner

CM217

Isopropyl alcohol

CM219

Methyl-ethyl-ketone

CM305

Lacquer, acrylic

(1). Wipe surface clean with a 1:1 mixture

CM316

Epoxy coating / Thinner

of naphtha (CM220) and isopropyl

CM801

Abrasive paper, silicon carbide

alcohol (CM217). Mix equal parts (1:1)

of primer resin (CM317) and thinner.

Apply one coat to surface and allow to

(1). Remove all gloss from area requiring

air-dry minimum of 3 hours. Apply

finish with 100-grit or coarser abrasive

epoxy primer and color finish (CM305)

paper (CM801) until there is a uniform

[Ref. Touchup - Small Sanded Areas).

dull condition.

F. Touchup − ABS Thermoplastic Parts

MEK solvent is flammable.

WARNING

Use only in well-ventilated

area and away from heat and flame.

Consumable Materials

(Ref. Section 91−00−00)

(2). Wipe surface clean with 1:1 mixture of

Item

Nomenclature

MEK (CM219) and isopropyl alcohol

(CM217).

CM305

Lacquer, acrylic

(3). Squeeze one coat of Poly-EP (CM316),

thinned as required with thinner, into

Clean surface with mild soap and water. Dry

fiberglass pores until surface of fibers is

thoroughly. Apply one coat of lacquer (CM305)

smooth.

[Ref. Touchup - Small Sanded Areas).

Page 202

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CSP-HMI-2

MAINTENANCE MANUAL

4. Main Rotor Blade Paint

CAUTION

The following procedures is to be used whenev

D When sanding paint from the main rotor

er the main rotor blades require either

blade, take care to not damage rivet heads

repainting or paint touch-up.

and sealant.

D Do not sand through the paint and primer

NOTE:

into the base metal.

D Repaint main rotor blades only in sets to

(4). Using 320 grit, or finer, abrasive paper

maintain rotor balance. Never completely

(CM801) and wet or dry sanding

repaint only one main rotor blade

method, sand areas that require

installed on helicopter.

painting.

D New main rotor blades have the inboard

(5). Using a soft cloth, dampened in

24 inches (610 mm) painted gloss white.

isopropyl alcohol (CM217), thoroughly

This aids in inspection of the blade.

clean main rotor blade.

D At owner-operators convenience, in-ser

(6). Inspect sanded areas for damage.

vice main rotor blades may have the in

board 24 inches (610 mm) painted gloss

B. Main Rotor Blade Paint Application

white.

NOTE: If inboard 24 inches (610 mm) of main

rotor blade is to be painted white, paint is to

be applied to the entire circumference of the

Consumable Materials

blade. There is to be no ridges in the paint

(Ref. Section 91−00−00)

when completed.

Item

Nomenclature

CM206

Chemical coating

(1). Inspect main rotor blade (Ref. Sec.

62-10-00, Main Rotor Blade Inspec

CM217

Isopropyl alcohol

tion).

CM304

Enamel, epoxy

(2). Ensure all bushings, bearing, data

CM318

Primer

plates and the abrasion strip are

CM729

Tape, masking, pressure sensitive

protected from paint with tape

CM801

Abrasive paper, silicon carbide

(CM729).

(3). Using a soft cloth, dampened in

isopropyl alcohol (CM217), thoroughly

A. Main Rotor Blade Paint Removal

clean main rotor blade.

(1). Position main rotor blade on a bench of

(4). Treat any bare metal areas of main

sufficient length to provide support.

rotor blade with chemical coating

(CM206).

(2). Inspect main rotor blade (Ref. Sec.

NOTE: Mix primer (CM318) according to

62-10-00, Main Rotor Blade Inspec

manufacturer's recommendations.

tion).

(5). Allow mixed primer to stand for 15 to

30 minutes prior to use.

When removing paint from

CAUTION

main rotor blade, do not use any

NOTE:

paint remover. Bonding agents used in

D Working life of mixed primer is four hours

manufacture of the blade may be damaged

maximum.

by the chemicals causing the blade to be un

serviceable.

D Primer allowed to stand for more than

two hours must be stirred or shaken be

fore use.

(3). Apply tape (CM729) to all bushings,

bearing, data plates and the abrasion

D Addition of freshly mixed primer to re

strip.

plenish an older mixture is not permitted.

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MAINTENANCE MANUAL

(6). Apply primer (CM318) to sanded areas,

When removing paint from tail

CAUTION

feather into surrounding color coat.

rotor blade, do not use any paint

remover. Bonding agents used in manufac

(7). Allow to air-dry for one hour minimum.

ture of the blade may be damaged by the

chemicals causing the blade to be unservice

NOTE: Mix paint

(CM304) according to

able.

manufacturer's recommendations.

(2). Apply tape (CM729) to all bushings,

(8). Allow mixed paint to stand for 20

data plates and the abrasion strip.

minutes minimum prior to use.

(3). Plug root end of tail rotor blade to

NOTE:

ensure no paint enters.

D Working life of mixed paint is four hours

maximum.

CAUTION

D Addition of freshly mixed primer to re

plenish an older mixture is not permitted.

D When sanding paint from the tail rotor

blade, take care to not damage rivet heads

(9). Apply paint (CM318) to primed areas.

and sealant.

Feather-edge paint while applying.

D Do not sand through the paint and primer

(10). Allow to air-dry for eight hours

into the base metal.

minimum.

(4). Using 320 grit, or finer, abrasive paper

(11). Remove protective tape from main rotor

(CM801) and wet or dry sanding

blade.

method, sand areas that require

painting.

NOTE: Main rotor assembly may need to be re-

balanced after painting.

(5). Using a soft cloth, dampened in

isopropyl alcohol (CM217), thoroughly

5. Tail Rotor Blade Paint

clean tail rotor blade.

The following procedures is to be used whenev

(6). Inspect sanded areas for damage.

er the tail rotor blades require either repaint

ing or paint touch-up.

B. Tail Rotor Blade Paint Application

NOTE: Repaint tail rotor blades only in sets to

(1). Inspect tail rotor blade (Ref. Sec.

maintain rotor balance. Never completely

64-10-00, Tail Rotor Blade Inspection).

repaint only one tail rotor blade installed on

helicopter.

(2). Ensure all bushings, data plates and

the abrasion strip are protected from

paint with tape (CM729).

Consumable Materials

(Ref. Section 91−00−00)

(3). Ensure root end of tail rotor blade is

Item

Nomenclature

plugged to prevent entry of paint.

CM206

Chemical coating

(4). Using a soft cloth, dampened in

CM217

Isopropyl alcohol

isopropyl alcohol (CM217), thoroughly

CM304

Enamel, epoxy

clean tail rotor blade.

CM318

Primer

CM729

Tape, masking, pressure sensitive

(5). Treat any bare metal areas of tail rotor

blade with chemical coating (CM206).

CM801

Abrasive paper, silicon carbide

NOTE: Mix primer (CM318) according to

A. Tail Rotor Blade Paint Removal

manufacturer's recommendations.

(1). Inspect tail rotor blade (Ref. Sec.

(6). Allow mixed primer to stand for 15 to

64-10-00, Tail Rotor Blade Inspection).

30 minutes prior to use.

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CSP-HMI-2

MAINTENANCE MANUAL

NOTE:

D Working life of mixed primer is four hours

D Working life of mixed paint is four hours

maximum.

D Primer allowed to stand for more than

D Addition of freshly mixed primer to re

two hours must be stirred or shaken be

plenish an older mixture is not permitted.

fore use.

D Addition of freshly mixed primer to re

(10). Apply paint (CM318) to primed areas.

plenish an older mixture is not permitted.

Feather-edge paint while applying.

(7). Apply primer (CM318) to sanded areas,

(11). Allow to air-dry for eight hours

feather into surrounding color coat.

minimum.

(8). Allow to air-dry for one hour minimum.

(12). Remove protective tape from tail rotor

NOTE: Mix paint

(CM304) according to

blade.

manufacturer's recommendations.

(9). Allow mixed paint to stand for 20

NOTE: Tail rotor assembly may need to be re-

minutes minimum prior to use.

balanced after painting.

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CSP-HMI-2

MAINTENANCE MANUAL

CORROSION PREVENTION

MAINTENANCE PRACTICES

1. Corrosion Control

(1). Coat contacting surfaces with layer of

sealing compound (CM425), in addition

The airframe is fabricated primarily of

to primer (CM318).

aluminum and some magnesium alloys, with

Do not use steel washers.

selective use of stainless steel and titanium,

CAUTION

and should be checked regularly for any signs

of corrosion, especially at points of dissimilar

(2). Use 5056S aluminum alloy washers

and overlapping metal contact. Corrosion of

under boltheads and nuts that would

dissimilar metals is the result of several

otherwise contact magnesium. If 5056S

conditions; lack of sufficient insulation in

aluminum is not available, use 5052S

areas of metal contact, tears or punctures in

alloy washers.

metal itself, and areas where protective

(3). Apply primer on attaching hardware

finishes have been scuffed, scratched, chipped

before installation.

or worn away. Perform corrosion control

according to MDHI Corrosion Control Manual

3. Sealing Compound Application

(CSP-A-3) and instructions in the following

paragraphs.

Use sealing compound (CM425) to replace

loose or missing sealant on exterior surfaces.

Do not apply potassium hydrox

Sealant is used to fill seams and joints that

CAUTION

ide to or near bolts, fasteners,

might trap water. Apply sealant as follows:

seams, or faying surfaces. Immediately af

ter completing the magnesium and alumi

Consumable Materials

num test (Ref. NOTE below), wash the

(Ref. Section 91−00−00)

tested area with water to prevent burns and

Item

Nomenclature

continued action on the material.

CM425

Sealing compound

NOTE: To differentiate between aluminum and

magnesium alloy, apply one drop of ordinary

(1). Check that seam or joint is clean and

potassium hydroxide (dropped from a glass

free of foreign matter and moisture.

rod) to the surface of the metal being tested.

(2). Apply sealant with putty knife or

If the alloy is aluminum, a foaming or boil

similar tool.

ing action of the liquid, accompanied by a

black discoloration of the metal, will imme

(3). Force sealant well down into seam to

diately occur. If the alloy is magnesium, no

eliminate any air pockets.

reaction will be evidenced.

(4). Fillet sealant to give joint or seam a

smooth appearance.

2. Magnesium Alloys − Insulation Against

Corrosion

4. Main Rotor Hub Corrosion Prevention

(Tri−Flow Wash Procedure)

To prevent galvanic corrosion between

The following procedure will help prevent

magnesium and any dissimilar metals:

corrosion of main rotor hub components,

especially on helicopters operated in marine

Consumable Materials

environments. The procedure should be

(Ref. Section 91−00−00)

accomplished following the last flight each day

Item

Nomenclature

for helicopters operated in marine or other

corrosive environments, and at each 25-hour

CM318

Primer

inspection (Ref. Chap. 05), or more often if

CM425

Sealing compound

desired, for helicopters not operated in

corrosive environments.

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MAINTENANCE MANUAL

(5). Wash remainder of helicopter exterior

Consumable Materials

using fresh water spray.

(Ref. Section 91−00−00)

Item

Nomenclature

(6). Wash main rotor blades with Zip Wax

(CM227) or equivalent, mixed per

CM104

Lubricant, spray

manufacturer's instructions.

CM227

Washing compound with wax

5. Main Rotor Blades Corrosion Arresting

Use care when working

The following procedure will help prevent

WARNING

around turning rotor blades.

corrosion of main rotor blades. The procedure

Stay low. Remain on right side of heli

should be accomplished following the last

copter to avoid tail rotor blades.

flight each day on helicopters operated in

marine or other corrosive environments, and

NOTE: Perform the first step below prior to en

weekly for helicopters not operated in corrosive

gine shutdown, following the last flight of

environments.

the day if possible. When the rotor stops

turning, the laminates of the strap-pack

Consumable Materials

spread apart slightly. Contaminates col

(Ref. Section 91−00−00)

lected on the edges of the strap-pack assem

Item

Nomenclature

bly can enter the area between the lami

nates as they spread apart. If the rotor

CM227

Washing compound with wax

continues turning until the contaminants

CM228

Surface cleaner

are washed away, centrifugal force will keep

the laminates compressed and not allow the

corrosive substances to enter the area be

Wear rubber gloves when us

tween the laminates.

WARNING

ing phosphoric solution in

next step.

(1). Bring engine to ground idle (64-65 %

N_l); set SCAV AIR to ON (Ref. applica

(1). Wipe down main rotor blades with

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

surface cleaner (CM228).

Perform the following:

(2). Rinse main rotor blades immediately

with water and dry. (Ref. Sec. 20-20-00

(a). Spray fine fresh water mist on main

for additional information on cleaning

rotor blades.

main rotor blades.)

(b). Direct a strong stream of fresh water

(3). Wax main rotor blades with Zip Wax

into main rotor hub and control

(CM227) or equivalent, mixed per

system at main rotor hub.

manufacturer's instructions.

(c). Spray entire rotor hub with lubricant

A. Main Rotor Blade and Damper Attach

(CM104).

Pins − Corrosion Prevention

(2). Shut down engine and allow rotor

If helicopter is subject to salt-laden atmo

blades stop turning.

sphere, lubricate mating surfaces of barrel nut

and cam handle at each periodic inspection,

NOTE: In the next step, spray directly between

using corrosion preventive oil (CM120) (Ref.

individual laminates.

Chap. 62).

(3). Lift main rotor blades to separate strap

Consumable Materials

pack laminates and spray strap-packs

(Ref. Section 91−00−00)

with lubricant.

Item

Nomenclature

(4). Perform engine water wash (Ref. Chap.

CM120

Oil, corrosion preventive

71).

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MAINTENANCE MANUAL

6. Magnesium Alloy Exterior Surface

(2). Using swab, liberally apply chemical

Touchup Treatment

film (CM206). Allow solution to remain

on surface for 1 to 3 minutes, or until

surface becomes amber to brown in

Consumable Materials

color.

(Ref. Section 91−00−00)

Item

Nomenclature

(3). Rinse treated surface thoroughly with

CM207

Chromic acid solution

clean water. After rinsing, wipe off

CM320

Thinner, lacquer

excess moisture with clean lint-free

cloth. If dry compressed air is available,

blow any moisture from joints or

(1). Wash affected area with solution of

crevices and allow to dry completely at

mild soap and clean fresh water. Rinse

room temperature for approximately 1

area with clean water and wipe dry

hour.

using clean soft lint-free cloth.

(4). Apply paint finish touchup (Ref. Sec.

(2). Use thinner (CM320) on damaged area

20-30-00).

to remove any grease and old paint.

8. Steel Alloy Exterior Surface Touchup

(3). Apply chromic acid solution (CM207) by

Treatment

swabbing exposed area for 10 to 30

minutes.

Consumable Materials

(4). Using clean cloth soaked in clean, fresh

(Ref. Section 91−00−00)

water, thoroughly rinse area where

Item

Nomenclature

solution was applied. Allow area to

thoroughly dry.

CM228

Surface cleaner

CM801

Abrasive paper, silicon carbide

(5). Apply paint finish touchup (Ref. Sec.

20-30-00).

(1).

Remove loose paint and corrosion

Aluminum Alloy Exterior Surface Touchup

products by scraping area with sharp

Treatment

phenolic scraper, brushing with heavy

fiber brush and light sanding with

320-grit or finer abrasive paper

Consumable Materials

(CM801).

(Ref. Section 91−00−00)

Item

Nomenclature

(2).

Wash off area with mild soap and clean

CM206

Chemical coating

fresh water; rinse thoroughly.

(3).

Treat surface with surface cleaner

NOTE: If there is any question of whether or

(CM228).

not the protective coating is removed, it

should always be assumed that bare metal

(4).

Allow solution to remain on surface for

is exposed.

approximately 5 minutes. Keep sur

faces wet.

(1). Wash affected area with solution of

mild soap and fresh water. Rinse area

(5).

Rinse thoroughly with clean water. Dry

with clean water and wipe dry with

with clean lint-free cloth and then

clean soft lint-free cloth.

allow to air-dry completely.

NOTE: Avoid letting chemical mixture dry on

surface in next step. If it has dried, re-wet

(6).

Apply paint finish touchup (Ref. Sec.

surface with solution.

20-30-00).

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9. Splitter Bungee Spring Corrosion Control

(1). After helicopter shut-down, insert

(500N)

absorbent cloth into area around

splitter bungee spring.

It is recommended that after shutdown from

the last flight of the day, for helicopters

operating in a corrosive environment, the

(2). Liberally spray spring with lubricant

splitter bungee spring be sprayed with

(CM104) until spring inner coils are

Tri-Flow.

coated.

Consumable Materials

(3). Remove absorbant cloth from around

(Ref. Section 91−00−00)

spring.

Item

Nomenclature

CM104

Lubricant, spray

(4). Wipe excess spray from aircraft.

Table 201. Anti−Corrosion Chemical Finishes − Aluminum

Process

Applicable Specification

Normal Coating Thickness and Color

Dow #1 (Chrome Pickel)

MIL−M−3171, Type I

Removes metal. Iridescent yellow or red;

gray coatings are unacceptable.

Dow #7 (Dichromate

MIL−M−3171, Type III

No dimensional change. Wrought or

Treatment)

extruded parts − chestnut brown; castings

− light brown to black; AZ91C−T6 and

AZ92A−T6 alloys − gray.

Dow #17 (Anodize)

MIL−M−45202, Type I − light coat Class C: 0.0002−0.0003 inch

(0.00508−0.00762 mm); light green.

Type II − heavy coat

Class D: 0.0002−0.0035 inch

(0.00508−0.08890 mm); dark green.

Dow #19 (Chromic Acid

MIL−M−3171, Type VI

No dimensional change; gray to black.

Brush−on Treatment)

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MAINTENANCE MANUAL

NONDESTRUCTIVE INSPECTION

MAINTENANCE PRACTICES

1. Nondestructive Inspection Methods

missing fasteners, security of parts,

corrosion, and damage.

A. Visual Inspection

(3). Treat any corrosion found during

(Ref. Figure 201)

preliminary inspection.

(1). Select applicable visual inspection aids

(4). Clean the areas or surface of parts to be

from the following list:

inspected.

(a). A flashlight with the correct explo

(a). Remove any contaminates that

sive atmosphere rating, beam spread,

might hinder surface indications.

efficiency, and brightness for the

inspection being performed.

(b). Do not remove protective finishes.

(b). An inspection mirror on a ball joint

(5). Using optical aids as required, inspect

for use in viewing an area that is not

area as follows:

in the normal line of sight.

(a). Examine surface for cracks using a

(c). A 2-10 power magnifying glass to

flashlight, and confirm with a

expose defects that cannot be seen by

magnifying glass.

the unaided eye.

(b). Examine surface for other disconti

(d). A borescope to allow remote visual

nuities, such as: discoloration from

inspection of internal surfaces or

overheating; buckled, bulging, dented

otherwise inaccessible areas.

skin; cracked, chafed, split, or dented

(2). Perform a preliminary inspection of

tubing; chafed electrical wiring;

overall general area for cleanliness,

delaminating of composites; and

presence of foreign objects, deformed or

damaged protective finishes.

EYE ABOVE REFLECTED

LIGHT BEAM

INCANDESCENT

LIGHT BEAM

LINE OF SIGHT

REFLECTED LIGHT BEAM

5° TO 45°

FAYING SURFACES

CRACK OPEN TO SURFACE

G20-0001

Figure 201. Visual Inspection Technique

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MAINTENANCE MANUAL

B. Dye Penetrant Inspection

Consumable Materials

(Ref. Section 91−00−00)

Consumable Materials

Item

Nomenclature

(Ref. Section 91−00−00)

CM234

Solvent, dry-cleaning

Item

Nomenclature

CM234

Solvent, dry-cleaning

The coin tap method of inspection is used

CM805

Dye penetrant kit

evaluate composite structures. The coin tap is

limited to detecting shallow defects.

When inspecting cored structure, two sided

(1). Using cleaning solvent (CM234), clean

access is required. When multiple laminates

area to be inspected.

are installed over core, the core bond-line

cannot be evaluated.

NOTE:

The sound of an acceptable part can vary

D Manufacturers instructions on Dye Pene

considerably and the entire area must be

trant Kit take precedence over the follow

tapped in order to detect any variance.

ing steps.

Compare the sound of the suspected area with

D Parts to be inspected must be dry and

the sound of a known acceptable area.

heated to at least 70°F (21.1°C) but not

An acceptable area will have a slightly sharper

over 130°F (54.4°C).

or crisper sounding response. A dead or flat

sound is unacceptable, and requires a more

(2).

Apply penetrant from dye penetrant kit

thorough type of NDI.

(CM805) by brushing, spraying or by

dipping. Allow to stand for a minimum

Any suspect areas must be in

CAUTION

of 2 minutes.

spected by person(s) qualified in

the appropriate NDI. Contact MDHI cogni

zant engineering for recommended NDI pro

(3).

Remove excess penetrant with remover

cedures and applications.

(available with dye penetrant kit

(CM805)), or by cleaning with plain

(1). Thoroughly clean area to be inspected

water. Allow part to dry.

with cleaning solvent (CM234).

(4).

Apply a light even layer of developer

(2). Perform a visual inspection for any

from dye penetrant kit (CM805) by

raised or blistered appearing areas.

brushing, spraying or by dipping. When

NOTE: Tap the entire area to be inspected in

dipping, avoid excess quantity.

cluding any surrounding area of like

construction.

(5).

Penetrant, which has penetrated into

cracks (or other openings) in the surface

(3). Using a coin, light hammer, or other

of the part will be drawn out by the

suitable blunt object, lightly tap the

developer resulting in a bright red

surface of the part to be inspected.

indication.

D. Fluorescent Penetrant Inspection

(6).

If part is serviceable or repairable,

Refer to the appropriate manufacturer's

clean part free of penetrant and

related instructions for type of equipment and

developer with cleaning solvent

materials being used.

(CM234).

E. Magnetic Particle Inspection

C. Coin Tap Inspection

Refer to the appropriate manufacturer's

related instructions for type of equipment and

(Ref. Figure 202)

materials being used.

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MAINTENANCE MANUAL

0.25 INCH

(6.35 MM)

2.00 INCH

(50.8 MM)

0.375 INCH

(9.52 MM)

DIA BALL

MATERIAL: MILD STEEL OR BRASS

G20-0002

Figure 202. Coin Tap Inspection

F. Eddy Current Inspection − General

(a). Personnel doing nondestructive tests

must be qualified and certified in of

This procedure includes general information

NAS 410 or ASNT SNT-TC-1A or

on material, equipment and procedures for the

equivalent. Personnel making must

detection of surface cracks.

be certified to Level 2 minimum.

The Eddy Current test instruments induce an

(b). The test facilities written procedure

Eddy Current into a conductive medium and

approved by the Level 3 technician

detect the change in the induced eddy current

must be followed.

field which is produced by a defect.

(2). Equipment

Related Publications

(Ref. Section 01−00−00 (Table 201)

Specification

Publication Title

Refer to equipment manufacturer's

instructions for type of material

NAS−410

inspected.

Nondestructive Testing Personnel

Qualification and Certification

ASNT−SNT−TC−1

(a). Electronic - Electronic - All electron

Nondestructive Testing Personnel

ic equipment must be calibrated

Qualification and Certification

annually or after repair. Records

must be kept and made available

ASTM E 1316

when requested. All calibration must

Standard Terminology for Non−destructive

be made to a national standard. The

Examinations

equipment must be approved for the

type of part examined. Maintain a

(1). Personnel Qualification and Certifica

3:1 signal to noise ratio during

tion.

inspection.

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HANDBOOK OF MAINTENANCE INSTRUCTIONS FOR MDHI 369D/E/FF-500/600N HELICOPTERS (ISSUED: 1990) - page 6