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

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

B. Fan Hub and Transmission Cover

(2). Install hardware attaching plenum

Installation

cover to structure.

(1). Inspect fairing for cracks and general

9. Tailboom Attach Fitting Inspection

condition.

(2). Install attaching hardware.

(Ref. Figure 203) Inspect the upper left-hand

and right-hand tailboom attach fittings,

(3). Check for minimum run-on torque of

angles and nutplates as follows:

attaching screws, 2 inch-pounds

(0.226 Nm) minimum.

(1). Remove button plug from attach fitting

access cover.

8. Engine Plenum Access Cover

Replacement

(2). Using a bright light, inspect fitting and

Avoid FOD, Cover compressor

angle:

CAUTION

inlet prior to working in plenum

chamber area. Vacuum all FOD debris out of

(a). Inspect attach fittings for cracks.

the plenum chamber before removing the

protective cover from the inlet bell. Severe

NOTE: Pay particular attention to area around

damage to the engine may result from entry

aft rivet holes. No cracks are allowed.

of foreign objects.

(b). Inspect angle for cracks.

A. Engine Plenum Access Cover Removal

(c). If any cracks are found in attach

NOTE: If particle separator is installed, ejector

fitting or angle, contact MDHI Field

ducting is not removed with plenum access

Service Dept. for replacement

cover.

instructions.

(1). Remove hardware that attaches engine

plenum access cover to supporting

(3). Inspect nutplate for thread damage and

structure.

cracks.

(2). Remove plenum cover.

NOTE: Cracks would appear from top of self-

locking nut split to base of nut.

B. Engine Plenum Access Cover Installation

(1). Position engine plenum access cover to

(a). Replace nutplate if threads are

align with mounting holes in fuselage.

damaged or cracked.

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MAINTENANCE MANUAL

10. Lower Longeron Inspection (L158, R158)

11. Forward Upper Longeron Inspection

(L137, R137)

(Ref. Figure 204) Inspect the lower left-hand

and right-hand longerons as follows:

(Ref. Figure 204) Inspect the foreword upper

left-hand and right-hand longerons as follows:

Consumable Materials

(Ref. Section 91−00−00)

Consumable Materials

Item

Nomenclature

(Ref. Section 91−00−00)

CM425

Sealing compound

Item

Nomenclature

CM425

Sealing compound

(1). Remove button plugs (L158, R158) from

side of helicopter.

(1). Remove button plugs (L137, R137) from

(2). Using bright light and mirror, or

side of helicopter.

borescope, inspect the longeron, Sta.

(2). Using a borescope, inspect the longeron

155.75 frame and Cant. Sta. 159.97

and Sta. 137.50 frame for cracks.

frame for cracks.

(3). If any cracks are found, contact MDHI

Field Service Dept. for repair instruc

tions.

(4). Install button plugs in inspection hole

and seal with sealing compound

(CM425).

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CSP-HMI-2

MAINTENANCE MANUAL

TAILBOOM

MAINTENANCE PRACTICES

1. Tailboom − General

(8). Remove nuts and washers from bolts

that attach boom to fuselage. Remove

(Ref. Figure 201) The tailboom assembly, a

lower bolts first and top bolt last; then

monocoque structure of aluminum skin over

remove boom.

forged aluminum frames, houses the tail rotor

drive shaft and tail rotor control rod, and

B. Tailboom Installation

supports the horizontal and vertical stabiliz

ers.

Consumable Materials

(Ref. Section 91−00−00)

2. Tailboom Replacement

Item

Nomenclature

CM103

Solid film lubricant

A. Tailboom Removal

Special Tools

(Ref. Section 91−00−00)

Item

Nomenclature

Item

Nomenclature

ST2010

Adapter, torque wrench

ST1005

Insertion/extraction tool

ST1006

Insertion/extraction tool

(1). Support tailboom so that mating

bulkheads are flush.

(1). Remove vertical stabilizer (Ref. Sec.

NOTE: Prior to tailboom installation, coat

53-50-10).

threads of external wrenching bolts and at

(2). Remove tail rotor transmission and tail

taching nuts with lubricant (CM103).

rotor drive shaft as a unit (Ref. Sec.

(2). Slide countersunk washers on external

63-15-00).

wrenching bolts with countersunk side

facing bolt heads.

(3). Remove tail rotor control rod (Ref. Sec.

67-20-10).

If washers are installed back

CAUTION

wards, structural failure may

(4).

(369FF Model Only) Remove tailboom

result due to insufficient surface in bearing

extension (Ref. Tailboom Extension

that can cause spreading or cracking of

Replacement).

washers and result in loss of clamp-up

(5). Position suitable cradles under tail

torque.

boom at Cant. Sta. 209.78 frame fitting

(3). Install bolts through aft section

and the forward stabilizer boom

fuselage frame into boom frame and

mounting frame (Cant. Sta. 273.00)

place flat washer(s) on each bolt as

(Ref. Figure 202).

required for correct bolt grip. Use no

more than three flat washers under

To avoid damage, ensure that

CAUTION

each nut. Install nuts and torque only

boom is properly supported be

the nuts to 380 - 410 inch-pounds

fore removing boom attach bolts.

(42.93 - 46.32 Nm).

(6). Open boom bolts access doors and

NOTE: Bolts may be reversed for access to

remove bond jumper from boom.

torque nuts. Torque wrench adapter

(7). Disconnect connector of chip detector

(ST2010) or a thin-walled deep socket is

wiring and night lighting system

used for torquing.

wiring. Disconnect knife splice by hand

(4). Install vertical stabilizer.

or use appropriate connector insertion/

extraction tool (ST1005 or ST1006) for

(5).

(369FF Model Only) Install tailboom

wire mate type connector.

extension.

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MAINTENANCE MANUAL

STABILIZER MOUNTING

FITTINGS

GROMMET

GEARBOX AND STABILIZER

WIRING CONDUIT

MOUNT FRAME

GROMMET

FORWARD STABILIZER BOOM

RIGHT SKIN PANEL

MOUNTING FRAME

GROMMET

STA. 264.32

CANT. FRAME

STA. 209.78

CANT. FRAME

STA. 242.14

CANT. FRAME

NUT

WASHER

LEFT SKIN PANEL

STA. 219.96

CANT. FRAME

FORWARD STABILIZER

TAILBOOM

BOOM MOUNTING FRAME

EXTENSION

STA. 197.78 CANT.

GEARBOX AND STABILIZER

FRAME FITTING

MOUNT FRAME

369FF ONLY

G53-4000

Figure 201. Tailboom Assembly and Tailboom Extension

(6).

Install tail rotor transmission and tail

(3). Remove tailboom extension from

rotor drive shaft as a unit.

tailboom assembly.

(7).

Install control rod.

(4). Apply primer (CM318) in holes, on

faying surfaces and on the grip area of

(8).

Perform tail rotor control rigging (Ref.

the mounting studs and install tail

Sec. 67-20-10).

boom extension while primer is still

wet.

(9).

Install bond jumper to boom and

connect chip detector wiring. Connect

NOTE:

night lighting wiring.

D Note the drag torque for each nut and it's

location on the extension, in the helicop

Tailboom Extension Replacement (369FF)

ter for later use.

(Ref. Figure 201)

D Torque nuts while primer is still wet.

(5). Install tailboom extension on tailboom

Consumable Materials

assembly and secure with four washers

(Ref. Section 91−00−00)

and four nuts.

Item

Nomenclature

CM318

Primer

(6). Torque nuts to 75 - 95 inch-pounds

(8.47 - 10.73 Nm) plus drag torque.

(1). Remove tail rotor transmission and tail

(7). Apply torque stripe paint.

rotor drive shaft as a unit (Ref. Sec.

63-15-00).

(8). Between 2 and 10 hours of helicopter

operation (to allow parts to seat), check

(2). Remove four nuts and four washers

the torque of each mounting nut as

from tailboom assembly.

follows:

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CSP-HMI-2

MAINTENANCE MANUAL

(a). Using the drag torque previously

(4). Inspect bond jumper for security and

measured and noted, apply a torque

corrosion.

load of 95 ±3 inch-pounds (10.73

±0.34 Nm) plus the noted drag

(5). Inspect boom exterior for loose or

torque (noted at each individual

missing rivets.

nut) to each mounting nut of the

extension.

(6). Inspect boom and gearbox stabilizer

mounting frames for cracks, security of

(b). Re-apply torque stripe paint.

attachment, elongated holes or condi

tion of mounting studs.

(9). Install tail rotor driveshaft and tail

rotor transmission as a unit.

(7). Replace damaged or deformed studs

(Ref. CSP-SRM-6, Structural Repair

4. Tailboom Inspection

Manual).

(Ref. Figure 201)

5. Tailboom Repair

(1). Inspect boom interior skin and frames

for corrosion and cracks.

There is no damage that can be

CAUTION

considered negligible. All dam

(2). Check attaching nuts and bolts in boom

age must be repaired upon detection (Ref.

Cant. Sta. 197.78 frame fitting for

CSP-SRM-6, Structural Repair Manual).

security.

(3). Inspect tail rotor control rod grommets

NOTE: The skins forming the monocoque boom

in boom frames for evidence of deterio

assembly are highly stressed

(Ref.

ration.

Figure 201).

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MD Helicopters, Inc.

MAINTENANCE MANUAL

FORWARD STABILIZER

BOOM MOUNTING FRAME

(CANTED STA 273.00)

CANT. STA 209.78

SELF-LOCKING NUT

FLAT WASHER (CRES)

NUT

PLAIN HEX NUT

(NOTE 4)

FLAT WASHER (AL-ALY

UNTREATED)

SPRING LOCKWASHER

FLAT WASHER(S)

BOND JUMPER

(NOTE 2)

SPRING LOCKWASHER

(NOTE 1)

FLAT WASHER

(AL-ALY UNTREATED)

FLAT WASHER

(NOTE 2)

ACCESS HOLE

COUNTERSUNK WASHER

CHIP DETECTOR WIRING

TAIL LIGHT WIRING

BOOM FITTING

EXTERNAL WRENCHING BOLT (NOTE

JUMPER CONNECTION

ACCESS HOLE

TAILBOOM ATTACHMENT

BRACKET

FLAT

NOTES:

WASHER

ENSURE THAT GROUND CONTACT SURFACE IS CLEAN

BEFORE BOND JUMPER INSTALLATION. AFTER

SPRING LOCKWASHER

INSTALLATION, COAT EXPOSED BARE METAL GROUNDED

FLAT WASHER (CRES)

AREA WITH LACQUER (CM306).

(NOTE 1)

BOND JUMPER

THREE FLAT WASHERS MAXIMUM UNDER NUT. WASHERS

FLAT WASHER

ADDED UNDER BOLT HEAD. COUNTERSUNK WASHER IS

(AL-ALY UNTREATED)

REQUIRED.

BOOM FITTING BRACKET AND

CRES-CORROSION RESISTANT STAINLESS STEEL.

JUMPER-INSTALLATION

PRIOR TO INSTALLATION, COAT THREADS

WITH LUBRICANT (CM103).

G53-4001A

Figure 202. Tailboom Installation and Removal

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CSP-HMI-2

MAINTENANCE MANUAL

TAILBOOM (500/600N)

MAINTENANCE PRACTICES

1. Tailboom Description

(8). A Strake, a composite strip bonded to

the left side of the tailboom, breaks up

(Ref. Figure 201) The tailboom assembly is a

airflow on the left side of the boom for

fully monocoque construction of graphite

hovering stability.

composites, it provides directional control for

the helicopter.

(9). A Stator located directly behind the fan

and mounted inside the tailboom

The tailboom for the Model 600N helicopter is

straightens low pressure air flowing

a similar version to that on the Model 500N

through the boom. The stator has

helicopter. One of the obvious differences is the

eleven composite removable blades, and

length, approximately 28 inches (71.12 cm)

is accessible by removing the tailboom.

longer on the 600N. Also, two of the four

mounting bolts that hold the boom to the

(10). A tail skid mounted bottom aft on the

fuselage are a larger diameter. These two

tailboom is constructed of aluminum

points have been reinforced both on the boom

tubing.

and on the fuselage for added strength.

(11). A jack pad is located on the tailboom

(1).

The tailboom converts energy from the

underside. The jackpad can be accessed

main rotor downwash to an anti-torque

by removing the tail skid.

force. In order to accomplish this, a

variable pitch fan pushes low pressure

(12). The tailboom provides for the mounting

air through two longitudinal slots on

of the horizontal stabilizer and a control

the right side of the tailboom and two

cable conduit for the flight controls.

thrusters ports at the end of the

tailboom. These slots located at 130°

2. Tailboom Replacement

and 76° degrees, direct low pressure air

(Ref. Figure 201)

downward over the tailboom surface.

NOTE: When removing tailboom as an assem

(2).

Slot air flow mixes with main rotor

bly with the horizontal and vertical stabiliz

downwash air, delaying its separation

ers installed, precaution should be taken to

at the bottom of the tailboom and

adequately support and balance the tail

effectively creating a lifting force.

boom assembly equally due to the mass of

(3).

Air from the main rotor passing over

the stabilizers.

the boom provides directional control to

neutralize the main rotor torque.

A. Tailboom Removal

(4).

Approximately 60% of the anti-torque

(1). Remove tailboom fairing.

force required in a hover, is provided by

(2). Disconnect the forward end of the

the tailboom lift, the remaining 40% is

anti-torque control cable by turning

by metered air flowing out the end of

outside collar sleeve counter-clockwise

the tailboom rotating thruster cone.

and back to expose the inner cable.

(5).

A stationary thruster cone port directs

Apply sufficient right pedal to expose

air flow to the left or to the right.

engagement pin and pull collar sleeve

outward.

(6).

The rotating thruster cone (a can-

shaped structure) meters exit air for

(3). Disconnect electrical connector.

left or right directional control.

(4). Have assistants support tailboom.

(7).

Pedal movement opens and closes the

thruster cone ports and changes fan

(5). Remove four mounting bolts and

blade pitch angle for engine power

washers and remove tailboom. Inspect

changes.

bolts for corrosion.

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MAINTENANCE MANUAL

B. Tailboom Installation

- 150 inch-pounds (14.68 - 16.94

Nm) plus drag torque and the two

Before tailboom installation, in

larger diameter bolts to 180 - 220

CAUTION

spect radius blocks for brinnel

inch-pounds (20.33 - 24.85 Nm)

ing, corrosion, cracks and indication of in

plus drag torque. Safety bolts.

dent on face; none allowed.

RN003 - RN059 with TB600N-007

NOTE: If installing a new tailboom, the

complied with and RN060 & subs;

500N3500-5 cover will have to be installed

torque bolts to 180 - 220 inch-

after internal tailboom components are

pounds (20.33 - 24.85 Nm) plus

installed (Ref. 500N3500-5 Cover Installa

drag torque. Safety bolts.

tion).

(5). Check for a minimum of two threads

protruding from nutplates.

(1). Support tailboom so that the mating

bulkhead surfaces are flush.

(6). Using a 0.002 inch (0.051 mm) feeler

gauge, check for gap between tailboom

(2). Slide countersunk/chamfered washers

and fuselage flange within 0.60 inch

on external wrenching bolts with

(15.3 mm) of centerline of each of the

countersunk side facing bolt head.

four attach bolts; no gap allowed.

If washers are installed back

(7). Re-connect electrical connectors.

CAUTION

wards, structural failure may

(8). Re-connect control cable assembly.

result due to insufficient surface in load

(9). Install tailboom fairing.

bearing area that can cause spreading or

cracking of washers and result in loss of

3. Tailboom Inspection

clamp-up torque.

(Ref. Figure 201)

(3).

600N:

(1). Inspect tailboom exterior as follows:

(a). Inspect tailboom fairing for cracks

Install washer on bolt after the counter

and delaminations.

sunk washer.

(b). Inspect tailboom flange and mount

(a). Install either an AN960C516 or

ing bolt holes attachment area for

NAS1149C0563R washer on -5 bolts.

cracks at Sta. 168.20.

(b). Install either an AN960C616 or

(c). Inspect radius blocks for brinneling,

NAS1149C0663R washer on -6 bolts.

corrosion and indication of indent on

face; none allowed. If found, scrap

Do not lubricate tailboom attach

radius block and install new radius

CAUTION

bolts or nutplates, this will

block.

cause a false torque reading and lead to bolt

(d). Inspect strake for cracks, delamina

loosening.

tions, debonding, dents, nicks and

(4). With the tailboom supported in place,

separation.

install four bolts with washers.

NOTE: Damage to slots can cause significant

degradation of aircraft performance in a

(a).

500N:

hover.

Torque bolts to 130 - 150 inch-

(e). Inspect tailboom surface area and

pounds (14.69 - 16.95 Nm) plus

tailboom circulation control slots

drag torque. Verify minimum run

surface area for cracks, voids, dents,

on torque of 6.5 inch-pounds (0.73

holes, scratches, separation, delami

Nm).

nations at tailboom and security.

1). Using a bright light, inspect fore

(b).

600N:

and aft radii of the lower portion of

RN003 - RN059 without

the three upper slot bridges for

TB600N-007 complied with; torque

cracks, illuminate area under the

the two smaller diameter bolts to 130

flap.

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MAINTENANCE MANUAL

1.25 IN. (3.175 CM) CRACK

LENGTH PERMISSIBLE

1.25 IN. (3.175 CM) CRACK

LENGTH PERMISSIBLE

6G53-102A

Figure 202. Tailboom Flap Inspection

NOTE: The flap may be raised slightly, using

to the forward inboard legs) and

finger pressure only, to aid in checking this

attachment fittings for cracks, voids,

area.

separation and delamination.

(h). Inspect stabilizers (Ref. Sec.

(f). Inspect flaps for cracking and

53-50-30).

debonding (Ref. Figure 202):

(i). Inspect (tail-skid) for cracks, dents,

1). A crack of any length, in line with

holes and delamination.

aft edge of flap, is permissible at

interface between flap and tail

(j). Inspect rotating thruster cone for

boom.

freedom of operation, cracks, holes,

separation and delamination.

2). A crack of 1.25 inch (3.175 cm)

maximum length, in line with the

(k). Inspect tailboom grommets (2) places

forward edge of flap, is permissible

for cracks and proper fit.

at interface between flap and

(2). Inspect tailboom interior as follows:

tailboom.

(a). Check stator vanes and stator

NOTE: If crack in forward edge of flap is longer

diffuser cone for cracks, delamina

than 1.25 inch (3.175 cm), contact your local

tions and separation.

MDHI Field Service Representative for dis

position.

1). Maximum allowable cracks found

emanating from stator vane inserts

(g). Inspect horizontal stabilizer mount

should not exceed 0.10 inch (2.54

ing brackets (pay particular attention

mm) span-wise.

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MAINTENANCE MANUAL

2). No cracks allowed running cord-

6. Stator Blade Replacement

wise towards leading or trailing

(Ref. Figure 201, View E)

edge

(1). Stator Blade Removal: Remove two

(b). Inspect slot air foils for cracks,

self-locking screws and two surface

delamination and separation from

washers.

boom.

(2). Stator Blade Installation: Install two

(c). Inspect control cable assembly

surface washers and two self-locking

attachment points for looseness,

screws. Torque screws to 3 - 6 inch-

cracks and condition.

pounds (0.34 - 0.68 Nm) plus drag

torque. Total torque should not exceed

(d). Inspect cable conduit for cracks,

15 inch-pounds (1069 Nm) total

separation and delamination.

torque.

(e). Inspect air circulation area for FOD

7. Rotating Thruster Cone Replacement

and cleanliness. If necessary, clean

with mild soap and water.

(Ref. Figure 201, View H)

(3). Inspect rotating thruster cone collar

A. Rotating Thruster Cone Removal

strap ring rivets for looseness, strap for

(1). Remove cone tip cap by removing eight

cracks and condition.

screws and washers.

Tailboom Repair

(2). Support rotating thruster cone and

remove three bolts and washers that

Minor repair procedures for the tailboom are

attach the rotating thruster cone,

in the Repair section (Ref. Sec. 53-40-30).

carefully slide rotating cone aft to clear

stationary cone, bearings and followers

5. Stator Replacement

and the cable and drum assembly.

(Ref. Figure 201, View D)

B. Rotating Thruster Cone Installation

A. Stator Removal

(1). Carefully slide rotating thruster cone

over stationary cone, bearings, rollers

(1). Remove tailboom.

and followers.

(2). Note or index top of stator for reas

(2). With the thruster supported in place,

semble. Support stator and remove

install three bolts with washers

seven exterior screws and washers

attaching the rotating thruster to

mounted around the forward part of the

thruster gear box. Torque bolts 70 - 90

tailboom.

inch-pounds (7.91 - 10.17 Nm).

Safety wire bolts.

B. Stator Installation

(3). Install cone tip cap with eight screws

(1). Support stator and align stator vanes in

and washers, torque screws per general

tailboom, install seven screws and

aircraft practices.

washers, torque screws to 3 - 6 inch-

pounds (0.34 - 0.68 Nm) plus drag

8. Rotating Thruster Cone Inspection

torque. Total torque should not exceed

(1). Inspect for cracks and separation of

15 inch-pounds (1069 Nm) total

composite laminates.

torque.

(2). Check for freedom of rotational move

(2). Install tailboom.

ment within the control range of

thruster.

(3). Verify that stator does not rub against

the fan and for clearance of 0.020-0.080

(3). When the thruster is removed from

inch (0.508-2.032 mm) between stator

helicopter, check roller surface area

and fan.

(strap) for cracks and condition.

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MAINTENANCE MANUAL

NOTE: Refer to MD Helicopters Inc. Represen

washer and bolt, torque bolt per

tative for structural repairs, cracks, etc.

standard aircraft torque values and

safety wire.

9. Stationary Thruster Cone Replacement

(4). Install thruster cone fairings.

(Ref. Figure 201)

(5). Install rotating thruster (Ref. Rotating

A. Stationary Thruster Cone Removal

Thruster Cone Installation).

(1). Remove rotating thruster cone (Ref.

10. Stationary Thruster Cone Inspection

Rotating Thruster Cone Removal).

(1).

Inspect for cracks and delamination of

(2). Remove eight off wing screws from pan

composites structure for the following:

cover, remove cotter pin, nut and

Internal ducts, air foil supports, pan

washer from sector input shaft and

cover and pan (hat section).

remove pan cover. Remove washer and

bushing from sector bellcrank input

(2).

Inspect rollers and bearings for condi

shaft.

tion and freedom of rotation. Inspect for

cleanliness.

(3). Remove bolt, washer and bushing from

thruster input sector bellcrank clevis

(3).

Inspect sector bellcrank, cable assem

(Ref. View J).

blies, pulleys and support brackets for

condition, inspect of cleanliness.

(4). Remove thruster cone fairings.

(4).

Inspect upper input shaft for damage

(5). Support stationary thruster cone and

and wear. Check for play in mounting

remove eight bolts and washers, with

pins. If mounting pins are found to

cable assembly attached to cone,

have play, replace with new pins and

carefully lift cone off tailboom so that

collars.

the control rod passes through the

(5).

Inspect thruster aft support shaft for

thruster cone cutout.

damage and wear. Check for play in

B. Stationary Thruster Cone Installation

mounting hardware. If top bolt is found

to be loose, retorque to 10 - 15 inch-

(1). Support stationary thruster cone to

pounds (1.13 - 1.69 Nm). If bottom

tailboom so that the control rod passes

mounting pins are found to be loose,

through the cutout of the stationary

replace with new pins and collars.

cone, and that the mating surfaces are

flush to the tailboom. Slide counter

11. Conduit and Support Strap Rebonding

sunk/chamber washers on external

wrenching bolts with countersunk side

(Ref. Figure 203) The following procedure is for

facing bolt head.

rebonding of the conduit supports.

If washers are installed back

CAUTION

Consumable Materials

wards, structural failure may

(Ref. Section 91−00−00)

result due to insufficient surface clamp-up

Item

Nomenclature

in load bearing areas that can cause spread

ing or cracking, resulting in loss of clamp-

CM217

Isopropyl alcohol

up torque.

CM402

Adhesive

(2). With the stationary thruster cone

support in place, install eight bolts and

(1). Lightly abrade faying surfaces with

washers. Torque bolts 30 - 40 inch-

Scotchbrite until surface gloss of the

pounds (3.39 - 4.52 Nm) plus drag

laminate is gone.

torque.

(2). Solvent-wipe parts using a clean

(3). Connect control rod to input sector

lint-free cloth dampened with isopropyl

bellcrank clevis and install bushing,

alcohol (CM217).

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MAINTENANCE MANUAL

(3). Wipe dry using a clean, lint-free, dry

NOTE: Adhesive must be applied within 2

cloth and allow to air dry for 15 min

hours of preparation. If more than 2 hours

utes at ambient temperature.

elapse before adhesive application, re-pre

pare surfaces.

Do not heat conduit to more

CAUTION

than 170°F (77°C). Conduit and

(5). Mix adhesive (CM402) according to

tailboom can be damaged from too much

manufacturer's instructions and apply

heat.

to faying surfaces.

(4). If conduit is bent away from tailboom,

(6). Secure parts together with light

heat conduit to make more flexible for

pressure and allow to cure for 24 hours

re-bonding.

at ambient temperature.

CANT

FS 168.200

CANT

0.000

38° 28′

APPLY ADHESIVE HERE

28° 20′

TAILBOOM

SUPPORT

APPLY

ADHESIVE

APPLY

HERE

ADHESIVE

HERE

CONDUIT

APPLY

ADHESIVE

HERE

SECTION B-B

SECTION A-A

LOOKING AFT

SECTION C-C

LOOKING FORWARD

500N TAILBOOM SHOWN

G53-4004A

Figure 203. Conduit and Support Strap Rebonding

Page 209

53-40-30

Revision 39

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

12. Horizontal Stabilizer Mount Fitting

(8). Locate new fitting on tailboom.

Replacement

(9). Back-drill fittings to 0.186-0.188 inch

(Ref. Figure 201)

(4.724-4.775 mm).

(10). Remove fitting and deburr rivet holes.

Empennage Fitting

Part No.

(11). Touch up rivet holes with solid film

L/H, Aluminum

500N3530−3, −7

lubricant (CM101) for steel fittings or

R/H, Aluminum

500N3530−4, −8

chemical coating (CM206) for alumi

L/H, CRES

500N3530−9

num fittings.

R/H, CRES

500N3530−10

(12). Steel fittings only:

(a). Using abrasive paper (CM801),

Consumable Materials

lightly abrade tailboom where fitting

(Ref. Section 91−00−00)

is to be mounted.

Item

Nomenclature

(b). Clean fitting and tailboom abraded

CM101

Solid film lubricant

area with 1,1,1-Trichloroethane

CM206

Chemical coating

(CM222).

CM222

1,1,1-Trichloroethane

CM304

Enamel, epoxy

(c). Prime fitting with adhesive primer

(CM315).

CM315

Adhesive primer

CM318

Primer

(d). Apply a thin layer of cement (CM418)

CM418

Cement, epoxy

between fitting and tailboom.

CM425

Sealing compound

NOTE:

CM801

Abrasive paper, silicon carbide

D Use HTS12-6-4/-5 pin rivets with

HTS1176DU-6AWU collars or alternate

HTS48-6-4/-5 pin rivets with

(1). Remove horizontal stabilizer (Ref. Sec.

HST2000-6AW collars.

53-50-30, Horizontal Stabilizer

Replacement).

D Gage rivet holes to ensure proper length

pin rivets.

(2). Remove rotating thruster cone (Ref.

Rotating Thruster Cone Replacement).

(13).

Relocate fitting on tailboom and install

with pin rivets wet with primer

(3). Remove stationary thruster cone (Ref.

(CM318).

Stationary Thruster Cone

(14).

Seal edges around fittings with sealing

Replacement).

compound (CM425).

(4). Remove collars from pins in mount

(15).

If installing steel fittings, prime with

fittings.

adhesive primer (CM315).

(5). Drive pins out of fittings.

(16).

Touch up with paint (CM304).

Do not allow fittings to reach

(17).

Reinstall stationary thruster cone (Ref.

CAUTION

200°F (94°C), damage to tail

Stationary Thruster Cone

boom composite material will occur.

Replacement).

NOTE: Heating the fitting to 150°F (66°C) may

(18).

Reinstall rotating thruster cone (Ref.

assist in removing them from tailboom.

Rotating Thruster Cone Replacement).

(6). Carefully pop fittings loose from

(19).

Reinstall horizontal stabilizer (Ref. Sec.

tailboom while not damaging fiberglass

53-50-30, Horizontal Stabilizer

sheets under fitting.

Replacement).

(7). Clean area with 1,1,1-Trichloroethane

(20).

Check rigging of thruster (Ref. Sec.

(CM222).

67-20-30).

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CSP-HMI-2

MAINTENANCE MANUAL

(21). Check rigging of vertical stabilizers

(a). If tailboom is not previously marked,

(Ref. Sec. 67-20-30).

place a mark every 2.0 inches (50.8

mm) around cover and tailboom.

13. 500N3500−5 Cover Installation

(b). Do not bond the bottom 8.0 inches

(Ref. Figure 204) New tailbooms come with the

(203.2 mm) on aft end of cover.

500N3500-5 cover separate. This cover must

be bonded in place after the wiring and cables

(4). Abrade around the cover mating

are installed.

surface with 240 grit abrasive cloth

(CM802) to remove gloss.

Consumable Materials

NOTE:

(Ref. Section 91−00−00)

Item

Nomenclature

D Use care to avoid damage to the fiber re

CM222

1,1,1-Trichloroethane

inforcement.

CM410

Adhesive, epoxy (parts A & B)

D Metallic faying surfaces do not require

CM802

Abrasive cloth, aluminum oxide

abrading.

CM819

Kimwipe

(5). Using 240 grit abrasive cloth (CM802),

lightly abrade spots, where marked,

(1). With cutout facing down and forward,

around the tailboom until the surface

gently role cover to shape of tailboom

gloss is removed.

and position inside aft end of tailboom.

Slide cover in until aft end is flush with

(6). Wipe abraded surfaces with kimwipes

tailboom.

(CM819) dampened with

1,1,1-Trichloroethane (CM222). Allow

NOTE: Right edge of cover should be just to the

to air dry for 15 minutes.

right of the torque tube housing (8° to the

right of centerline). Left edge should be un

(7). Mix adhesive according to manufactur

der the left horizontal stabilizer empennage

er's instructions.

fitting.

NOTE: Adhesive must be applied within two

(2). Check holes in cover to ensure they line

hours of cleaning. Repeat solvent prep if

up with electrical connectors on

more than two hours elapses before bond

tailboom.

ing.

(3). If holes do not line up with electrical

(8). Apply adhesive to abraded areas and

connectors, remove cover, role 180° and

position cover in tailboom. Clean up

reposition in tailboom.

excessive adhesive.

NOTE: Tailboom is manufactured with 1.0 x 1.0

inch (25.4 x 25.4 mm) spots marked for

(9). Allow to cure per manufacturer's

abrasion.

instructions.

Page 211

53-40-30

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

R/H HORIZONTAL

EMPENNAGE FITTING

RIGHT EDGE OF

-5 COVER

LEFT EDGE OF

-5 COVER

8°

TORQUE TUBE

HOUSING

RIGHT EDGE OF

-5 COVER

TAILBOOM

LEFT EDGE OF

-5 COVER

8.0 IN. (203.2 MM)

L/H HORIZONTAL

DO NOT BOND

EMPENNAGE FITTING

THIS AREA

VIEW LOOKING DOWN

VIEW LOOKING FORWARD

G53-4005

Figure 204. 500N3500−5 Cover Installation

14. Tail Skid Replacement

(a). Insert removed shims and install two

bolts and washers.

(Ref. Figure 205)

(b). Torque bolts to 36 - 40 Inch-pounds

A. Tail Skid Removal

(3.95 - 4.52 Nm) plus drag torque.

(1). Remove two bolts with washers from aft

(4). If installing a new tail skid:

tail skid brace.

(2). Retain shims between base and brace if

(a). Install bolts finger tight, ensure gap

same tail skid is to be reinstalled.

is even on both sides.

(3). Slide tail skid from forward bracket

(b). Measure gap between brace and

assembly.

base.

B. Tail Skid Installation

(c). Subtract 0.010 in. (0.254 mm) and

peel shims to that thickness.

(1). Slide tail skid into forward bracket

assembly.

(d). Insert shims between brace and base

and torque bolts to 36 - 40 Inch-

(2). Install aft brace onto aft base.

pounds (3.95 - 4.52 Nm) plus drag

(3). If reinstalling the same tail skid:

torque.

Page 212

Revision 39

53-40-30

MD Helicopters, Inc.

CSP−HMI−2

MAINTENANCE MANUAL

TAILBOOM (500/600N)

REPAIRS

1. Rotating Thruster Cone Strap Repair

A. Rotating Thruster Cone Strap Removal

For minor repairs not described in this section,

(1). Remove the rotating thruster cone

refer to MDHI Field Service Representative.

assembly. (Ref. Sec. 53-40-30).

(Ref. Figure 801)

(2). Remove rivets (2) from rotating

thruster cone (1).

Consumable Materials

(3). Remove strap (3) from rotating thruster

(Ref. Section 91−00−00)

cone.

Item

Nomenclature

CM235

Cleaner

(4). Remove any adhesive residue from

rotating thruster cone strap bonding

CM214

Releasing agent

area.

CM409

Adhesive, epoxy

CM441

Sealing compound, corrosion inhibiting

(5). Clean the bonding area with cleaner

(CM235).

2 (24 PL)

G53-4007

Figure 801. Rotating Thruster Cone

Legend (Ref. Figure 801)

1. ROTATING THRUSTER CONE

3. STRAP

2. RIVET

Page 801

53-40-30

Revision 44

CSP−HMI−2

MD Helicopters, Inc.

MAINTENANCE MANUAL

B. Rotating Thruster Cone Strap Installation

(9). Install the strap in the rotating

thruster cone.

NOTE: The rotating thruster cone strap bond

ing area must be smooth. Small surface de

(10). Apply releasing agent (CM214) to cleco

fects in the bonding area can be filled with

fasteners.

adhesive (CM409) before bonding. Do not let

excess adhesive change the contour of the

(11). Use cleco fasteners to align the rotating

bonding area.

thruster cone and strap rivet holes.

(1). Put the rotating thruster cone strap (3)

(12). Remove excess adhesive from rotating

in position on the rotating thruster cone

thruster cone strap and bonding area.

(1) bonding area.

(2). Transfer the 24 rivet hole locations in

Make sure the strap is not de

CAUTION

the rotating thruster cone to the strap.

formed or out-of-round when

installed in the rotating thruster cone. An

(3). Match drill the strap for the rivets (2).

out-of-round contour can cause the rotat

ing thruster cone to bind during operation.

(4). Remove the strap from the rotating

thruster cone.

(13). Cure adhesive for 24 hours at ambient

(5). Clean and deburr the rivet holes in the

temperature or heat to 170° to 190° F

strap.

(76.7 to 87.7° C) for 90 minutes.

(6). Inspect the rotating thruster cone strap

(14). Remove cleco fasteners from rivet holes.

bonding area for any surface defects.

(15). Wet install rivets with sealing com

(7). If necessary, fill bonding area surface

pound (CM441).

defects with adhesive (CM409).

(8). Apply adhesive (CM409) to the rotating

(16). Paint exterior of rotating thruster cone

thruster cone strap bonding area.

as required (Ref. Sec. 20-30-00).

Page 802

Revision 44

53-40-30

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

STABILIZER (T−TAIL) (369D/E/FF)

MAINTENANCE PRACTICES

1. Stabilizer − General

(1). Remove four screws securing tip plate

and tip weight (if applicable, right and

(Ref. Figure 201) The tail surfaces (empen

left tip plates and/or tip weights are

nage) stabilize the helicopter and maintain it

interchangeable) to horizontal stabiliz

in a relatively level attitude during high speed

er.

forward flight. The tail surfaces consist of a

vertical and horizontal stabilizer attached to

(2). Remove nuts and washers securing

the aft end of the tailboom.

horizontal stabilizer to vertical stabiliz

er fitting.

The horizontal stabilizer mounts atop of the

vertical stabilizer in a T-shaped arrangement.

(3). Disconnect position light electrical

Tip plates are attached to ends of the horizon

connection and bond jumper.

tal stabilizer with a steel tip weight between

each tip plate and the stabilizer. The horizon

NOTE: MDHI Notice DN-63 contains informa

tal stabilizer is constructed of aluminum alloy

tion relative to adding drain holes and seal

skins riveted to formed ribs and spars.

ing doubler edges on some 369D helicopters.

MDHI Notice DN-44.1 contains informa

The vertical stabilizer is constructed of

tion relative to replacement of trailing edge

aluminum alloy skins bonded to formed spars.

tabs, relocation of static pressure tube and

adding doublers to some 369D helicopters.

The vertical stabilizer includes fittings,

honeycomb core, and non-structural leading

(4). Inspect horizontal tip plates and

and trailing edges. The tip plates are con

stabilizer (Ref. Horizontal Stabilizer

structed of aluminum alloy skins bonded over

and Tip Plate Inspection).

a honeycomb core. The vertical stabilizer is

mounted aft right of the tail boom and is

B. Horizontal Stabilizer and Tip Plate

bolted to the gearbox and stabilizer mount

Installation

frame and a upper and lower mount fitting.

The vertical stabilizer fitting supports the

Consumable Materials

horizontal stabilizer. The lower end of the

(Ref. Section 91−00−00)

vertical stabilizer incorporates a tail skid

Item

Nomenclature

assembly.

CM425

Sealing compound

Lighting provisions are provided on both

vertical and horizontal stabilizers. (Ref. Sec.

(1). Support helicopter at rear jackpoint

96-40 contains information on exterior lights.)

(Ref. Sec. 07-00-00) when installing

A. Stabilizer Troubleshooting

horizontal stabilizer to ensure that

helicopter angle of incidence does not

(Ref. Table 201)

change during measurements.

(2). Measure inclination angle of horizontal

2. Horizontal Stabilizer and Tip Plate

stabilizer at B.L. 10.66 inches (27.076

Replacement

cm) to right (S RIGHT) and left (S

A. Horizontal Stabilizer and Tip Plate

LEFT) of horizontal stabilizer center

Removal

line (Ref. Figure 202). If angles S

RIGHT and S LEFT differ by more than

(Ref. Figure 201)

one degree, replace horizontal stabiliz

er.

NOTE: Tip weights are installed at manufac

turing and are only required to reduce T-

(3). For aircraft 0003D - 0286D (Ref.

Tail vibration.

Figure 204);

Page 201

53-50-10

Revision 19

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(a). Apply a 0.030 - 0.040 inch (0.762 -

(2). Torque bolts 190 - 220 inch-pounds

1.016 mm) bead of sealant (CM425)

(21.47 - 24.86 Nm); then lockwire bolts

around perimeter of top rib assem

in pairs.

blies and at attach fitting.

(3). Connect anti-collision light electrical

NOTE: Do not seal drain holes.

connection.

(b). Apply sealant around electrical

(4). Install horizontal stabilizer, refer to

conduit and seal over tooling holes.

(Ref. Horizontal Stabilizer and Tip

(4). Position horizontal stabilizer on vertical

Plate Installation).

stabilizer fitting (Ref. Figure 201).

4. Horizontal Stabilizer and Tip Plate

(5). Connect position light electrical

Inspection

connection and bond jumper.

(1).

Inspect metal skin for holes, cracks,

(6). Install nuts and washers. Torque nuts

loose rivets or corrosion. Any crack is to

to 90 - 110 inch-pounds (10.17 -

be stop drilled or patched.

12.43 Nm).

(2).

Inspect attach fittings and light

(7). Check angle of incidence (Ref. Angle of

mounting bracket for cracks, loose

Incidence Measurement).

rivets or corrosion.

(8). Install tip plates with tip weight

between tip plate and horizontal

(3).

Inspect attach studs and mating holes

stabilizer, using four screws.

for evidence of wear caused by loose

ness in service. Inspect questionable

(9). Remove support from rear jackpoint.

studs by dye-penetrant or magnetic

particle method, as applicable.

3. Vertical Stabilizer Replacement

(4).

Inspect drain holes on lower surface.

A. Vertical Stabilizer Removal

Ensure they are not blocked or clogged

(Ref. Figure 201)

with debris.

(1). Remove horizontal stabilizer (Ref.

(5).

Inspect seal around upper and lower

Horizontal Stabilizer and Tip Plates

doublers. Ensure all gaps/edges

Removal).

between doublers and stabilizer skin

are sealed.

(2). Disconnect anti-collision light electrical

connection.

(6).

Repair horizontal stabilizer and tip

(3). Remove bolts and washers securing

plates (Ref. Horizontal Stabilizer and

stabilizer to tailboom.

Tip Plates Repair).

(4). Inspect vertical stabilizer (Ref. Vertical

5. Vertical Stabilizer Inspection

Stabilizer Inspection).

(1). Inspect skin for holes, cracks, bonding

B. Vertical Stabilizer Installation

separation or corrosion.

(Ref. Figure 201)

(2). Inspect attach fitting for cracks, loose

rivets or corrosion.

Consumable Materials

(Ref. Section 91−00−00)

(3). Inspect tail skid for cracks, deformation

Item

Nomenclature

and loose or missing rivets.

CM109

Molybdenum disulfide powder lubricant

(4). Inspect anti-collision light bracket for

cracks, loose rivets or screws and

(1). Align stabilizer with mounting holes on

corrosion.

the tailboom fitting. Spray bolt threads

with lubricant (CM109) and install.

(5). Check condition of grommets.

Page 202

Revision 19

53-50-10

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

POSITION LIGHT

BRACKET

GROMMET

HORIZONTAL

STABILIZER

TIP WEIGHT

(NOTE 1)

HORIZONTAL

STABILIZER

VERTICAL

ELECTRICAL

STABILIZER

LEAD

POSITION LIGHT

BRACKET - ATTACHMENT

TIP PLATE

ANTI-COLLISION

LIGHT SUPPORT

SEAL

0.1 X 0.75 X 2.0 INCH

(2.54 X 19.05 X 50.8 MM)

1 OZ (28.35 G)

MS20470AD4 RIVET

LEAD WEIGHT

(2 REQD)

(NOTES 2, 3, 4)

HS306-318 WASHER

(2 REQD) (NOTE 3)

GROMMET

FORWARD

SEAL

VERTICAL

HORIZONTAL STABILIZER TAB

STABILIZER

WEIGHT INSTALLATION

FITTING

(421-087-505 STABILIZER ONLY)

NOTE:

TIP WEIGHTS ARE INSTALLED AT MANUFACTURING AND

ARE ONLY REQUIRED TO REDUCE T-TAIL VIBRATION.

COMMERCIAL 1 OZ (28.35 G). LEAD AUTOMOBILE

ALLOY WHEEL BALANCE WEIGHT.

INSTALL WEIGHT, RIVETS AND WASHERS WITH PRIMER

HORIZONTAL STABILIZER/VERTICAL

STABILIZER - ATTACHMENT

SEAL EDGES WITH SEALANT AFTER INSTALLATION.

G53-5000B

Figure 201. Stabilizer T−Tail Removal and Installation

Page 203

53-50-10

Revision 22

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(6). Check mount holes for elongation.

Special Tools

(7). For repair (Ref. Vertical Stabilizer

(Ref. Section 91−00−00)

Repair).

Item

Nomenclature

ST2014

Angle measuring tool

6. Horizontal Stabilizer and Tip Plate Repair

Consumable Materials

Table 201. Horizontal Stabilizer Angle of

(Ref. Section 91−00−00)

Incidence

Item

Nomenclature

Angle

Model

CM220

Naphtha aliphatic

8° 55’ − 9° 25’

369D

CM425

Sealing compound

8° 55’ − 9° 25’

369E

7° 30’ − 8° 00’

369FF

(1). Seal gaps/edges between doublers and

NOTE: It is not necessary to level helicopter

stabilizer skin with sealant (CM425).

when establishing horizontal stabilizer

Remove excess sealant with naphtha

angle of incidence.

(CM220).

D If the mast is tilted forward of 0°, add “H”

(2). Repaint sealed areas.

to “S”.

(3). Make other horizontal stabilizer repairs

D If the mast is tilted aft of 0°, subtract “H”

according to applicable instructions in

from “S”.

Structural Repair Manual.

(1).

Remove hub fairing from main rotor

NOTE: Support helicopter at rear jackpoint

hub assembly.

when installing horizontal stabilizer.

(2).

Measure incidence angle of horizontal

(4). Install horizontal stabilizer (Ref.

stabilizer (Ref. Figure 202) using angle

Horizontal Stabilizer and Tip Plate

measurement tool (ST2014) at B.L.

Installation).

10.66 inches (27.076 cm) to right (S

RIGHT) and left (S LEFT) of horizontal

7. Vertical Stabilizer Repair

stabilizer centerline. If angles S RIGHT

and S LEFT differ by more than one

degree, replace horizontal stabilizer.

Consumable Materials

(Ref. Section 91−00−00)

(3).

Measure inclination of top of main rotor

Item

Nomenclature

hub (Ref. Figure 203). Record as angle

CM418

Cement, epoxy

(4).

Compute average of angles S RIGHT

and S LEFT. Record results as angle S.

(1). For allowable repairs and additional

inspection criteria, Ref. Structural

(5).

(D/E Only) Determine incidence of

Repair Manual.

stabilizer by adding angles H and S. If

H plus S is between 8 degrees 55

(2). Replace damaged or worn seals; bond

minutes and 9 degrees 25 minutes,

replacement seal with cement (CM418).

angle of incidence is correct.

(3). Replace damaged, worn or missing

(6).

(FF Only) Determine incidence of

grommets.

stabilizer by adding angles H and S. If

(4). Install vertical stabilizer (Ref. Vertical

H plus S is between 7 degrees 30

Stabilizer Installation).

minutes and 8 degrees 00 minutes,

angle of incidence is correct.

8. Angle of Incidence Measurement

(7).

If angle of incidence is not acceptable

(Ref. Figure 202 and Figure 203)

(Ref. Angle of Incidence Adjustment).

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CSP-HMI-2

MAINTENANCE MANUAL

(8). Install hub fairing onto main rotor hub

(1). Temporarily apply one ounce tab weight

assembly.

to upper right trailing edge of the right

tab using tape.

9. Angle of Incidence Adjustment

(2). Locate weight spanwise to the point of

(1). Remove bolts and washers attaching

observed maximum amplitude vibra

horizontal stabilizer to vertical stabiliz

tion.

er fitting.

NOTE: Tab weight can be made from commer

Do not add more than two wash

cial automobile alloy wheel balance weight

CAUTION

ers under each boss.

(0.100 x 0.75 x 2.00 inch).

(2). Lift horizontal stabilizer and add equal

(3). Run engine at 102% - 105% N₂ and

number of AN960PD416L washers

observe horizontal stabilizer tab,

under each of two front, or each of two

weight may be moved inboard or

rear bosses.

outboard on tab depending on response.

(3). Install horizontal stabilizer with

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

washers and bolts.

be installed on left tab.

(4). Torque bolts to 90 - 110 inch-pounds

(5). A maximum of two ounces may be

(10.17 - 12.43 Nm).

installed on each tab.

(5). Repeat angle of incidence measurement

(6). Once correct position and amount of

(Ref. Angle of Incidence Measurement).

weight has been established, install

weight(s) as follows:

10. Horizontal Stabilizer Tab Weight

Installation

(a). Cleco weight in place on stabilizer.

(b). Drill two #31 holes through each

Consumable Materials

weight and stabilizer.

(Ref. Section 91−00−00)

Item

Nomenclature

(c). Remove weight and deburr holes;

CM318

Primer

touch up stabilizer holes with primer

CM425

Sealing compound

(CM318).

(d). Install weight, rivets and washers

(Ref. Figure 201) Installation of tab weight is

with wet primer.

optional on the 421-087 -505 horizontal

stabilizer if difficulty in tail rotor balance and

(e). Seal mating edges of weight with

horizontal stabilizer tab resonance vibration is

sealing compound (CM425).

encountered (Ref. Sec. 18-20-00, Horizontal

Stabilizer Tuning).

(7). Touch up with paint to match.

Table 202. Troubleshooting Tailboom and Tail Surfaces

Symptom

Probable Trouble

Corrective Action

High frequency vibration.

Loose vertical stabilizer.

Retorque bolts to 190 − 220

inch−pounds (21.47 − 24.86 Nm).

NOTE: High frequency vibrations in

Loose horizontal stabilizer.

Retorque nuts to 90 − 110

helicopter can be caused by

inch−pounds (10.17 - 12.43 Nm).

components in other systems (Ref.

Chap. 63, 64 and 71).

Check angle of incidence, (Ref. Angle

of Incidence Measurement).

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

S LEFT

S RIGHT

HORIZONTAL

STABILIZER

B.L. 10.66 INCH

(27.076 CM)

NOTE

2.030 INCH

13.850 INCH

(5.1562 CM)

(35.179 CM)

0.50 INCH (12.7 MM)

0.50 INCH

RADIUS (3 PLACES)

(12.7 MM)

1.090 INCH (2.769 CM)

1.575 INCH (4.0005 CM)

CHORD PLANE

OML SKIN AT

14.015 INCH

STABILIZER STA. 10.66

(35.598 CM)

NOTE:

TOOL FUNCTION - TO CHECK STABILIZER INCIDENCE.

G53-5001B

Figure 202. Horizontal Stabilizer Incidence Angle Measuring Tool

HORIZONTAL STAB.

STAB. INCIDENCE

CHORD PLANE

TOP OF M/R

ANGLE ``I''

AVERAGE STAB. INCLINATION

HUB PLANE

ANGLE ``S'' AVERAGE

HUB INCLINATION ANGLE ``H''

GROUND LEVEL PLANE

MAST

G53-5002

Figure 203. Establishing Horizontal Stabilizer Angle of Incidence

Page 206

Revision 40

53-50-10

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

STABILIZER

MAINTENANCE PRACTICES

1. Stabilizers Description

a hollow core spar, retainer fittings and

nonstructural leading and trailing edges.

The tail surfaces consist of two verticals and a

horizontal stabilizer. The tail surfaces (empen

The differences on the 600N are that the

nage) stabilize the helicopter and maintain it

vertical stabilizers are slightly longer, the skin

in a relatively contain level attitude and

is thicker and on standard 600N helicopters,

heading during autorotation and forward

are both controlled by the directional control

flight.

pedals. The lower vertical stabilizer angle of

attack is eight degrees clockwise relative to the

A. Horizontal Stabilizer Description

upper vertical stabilizer. Refer to Section

67-20-30 for flight controls linkage details.

The horizontal stabilizer is constructed of

laminated fiber glass composite ribs and skin,

The left vertical stabilizer is mounted to the

bonded to a formed graphite composite spar.

horizontal on a torque tube fitting assembly

The horizontal stabilizer includes a non-struc

and has approximately 6.5 inches (16.51 cm) of

tural leading and trailing edges. hollow core

travel.

spar, sparbox fittings, access panels, torque

On the 500N and S.A.S. equipped 600N, the

tubes, bellcranks and control rods.

right vertical stabilizer, also mounted on a

On the 500N and optional on the 600N, a

torque tube, is controlled by the stability

stability augmentation system (S.A.S.) is

augmentation system. From the fully extended

attached to the right-hand vertical stabilizer,

to the fully retracted position on the S.A.S.

the early 600N does not have a S.A.S system.

actuator, the tip of the right vertical stabilizer

trailing edge will travel a minimum of 2.70

The horizontal stabilizer mounts atop the

inches (6.86 cm). The amount of travel is

tailboom. Four eye bolts from the horizontal

determine by the S.A.S. computer and gyro.

attach to clevis attachment points on the

NOTE: The anti-torque control system must be

tailboom. Access plates are attached to the

re-rigged immediately after removal or re

ends caps of the horizontal stabilizer and at

placement of control rods, linkages, and

center line for access to the control rods, S.A.S.

components or if helicopter operation re

and bellcranks. Two control rods, S.A.S. and

veals a rigging deficiency.

bellcranks are routed in the center aft of the

sparbox. The angle of incidence of the horizon

2. Vertical Stabilizer Replacement

tal stabilizer is preset at -2°. An anti-collision

light is mounted in the top center of the

(Ref. Figure 201, Figure 202)

stabilizer. Position lighting provisions are

provided on both ends of the stabilizers.

A. Vertical Upper and Lower Stabilizer

Removal

On the 600N without S.A.S., gurney flaps were

(1). Remove nuts, washers, and bolts.

added to the trailing edge of the horizontal for

Remove by lifting vertical stabilizer off

the purpose of increasing lift without increas

torque tube.

ing the stabilizer area or weight.

B. Vertical Upper and Lower Stabilizer

Refer to Section 96-40-00 for information on

Installation

exterior lights and Section 67-20-30 for

rigging requirements.

(1). Installation with Standard Hardware:

B. Vertical Stabilizers Description

Do not over-torque nut. Over-

CAUTION

torquing nut can crack vertical

The vertical stabilizers (upper and lower) are

stabilizer fitting.

constructed of laminated fiber glass composite

ribs and skin, bonded to a formed fiberglass

(a). Install stabilizer onto torque tube

composite spar. The vertical stabilizers include

fittings.

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(b). Install bolts, washers and nuts.

NOTE: Horizontal stabilizer can be removed

Torque to 30 - 40 inch-pounds

with vertical stabilizers installed. Support

(3.39 - 4.52 Nm) plus drag torque.

stabilizer during removal.

(2). Installation with Expandable Bolts:

A. Horizontal Stabilizer Removal

(1). Remove seven screws securing center

Do not over-torque nut. Over-

CAUTION

access plate to horizontal stabilizer.

torquing nut can crack vertical

stabilizer fitting.

(2). Disconnect position light electrical

interconnect.

(a). Install bolt with washer under bolt

head and thick washer under nut.

(3). On 500N, disconnect S.A.S. electrical

interconnect.

NOTE:

(4). Remove cotter pin, nut, washer and bolt

D Do not remove any expanding elements

from center bellcrank shaft. Index mark

from bolt.

bellcrank with grease pencil in relation

D If 600N2012-5 spacers are not present,

ship to shaft. Disconnect bellcrank.

up to two spacers may be added to achieve

(5). Remove nuts, washers and expandable

proper installation.

bolts securing horizontal stabilizer to

(b). Remove one (1) or two (2)

tailboom attachment clevis fittings.

600N2012-5 spacers, as required) to

Remove horizontal stabilizer.

obtain 0.005-0.035 inch (0.127-0.889

B. Horizontal Stabilizer Installation

mm) gap between the washers and

the vertical stabilizer, equal on each

NOTE: When installing horizontal stabilizer it

side.

may be necessary to loosen eye bolts and

nuts to align with clevises, if so, install

(c). Install nut and note drag torque.

mounting expandable bolts first and torque

per step (2). below, then torque clevis nuts to

(d). Perform a break in cycle by torquing

80 - 120 inch-pounds (9.04 - 13.56 Nm).

the nut to 20 - 25 inch-pounds

(2.26 - 2.82 Nm) plus drag torque.

(1). Position horizontal stabilizer on

tailboom attach fittings.

(e). Back off nut until bolt moves freely

in hole.

(2). Install expandable bolts, washers and

nut. Torque to 30 - 40 inch-pounds

(f). Torque nut to 20 inch-pounds (2.26

(3.39 - 4.52 Nm). Install cotter pin.

Nm) plus drag torque.

(3). Connect position light/strobe light

(g). Check for equal gap of 0.005-0.035

electrical connector.

inch (0.127-0.889 mm) between the

(4). On 500N, connect S.A.S. electrical

washers and the vertical stabilizer.

interconnect.

NOTE: NAS1149C0332R or NAS1149C0363R

When installing bellcrank on

washers may be added under the nut for ad

CAUTION

center bellcrank shaft it is possi

equate cotter pin engagement.

ble to be one spline tooth off in either direc

tion, install bellcrank centered on shaft

(h). If necessary, tighten nut until cotter

(Ref. Sec. 67-20 -30).

pin hole aligns with castillation in

nut.

(5). Connect bellcrank to center bellcrank

shaft and install bolt, washers and nut.

(i). Install cotter pin.

Torque nut to 30 - 40 inch-pounds

(3.39 - 4.52 Nm) and install cotter pin.

3. Horizontal Stabilizer Replacement

(6). Install center access plate with seven

(Ref. Figure 201 and Figure 202)

screws and washers.

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4. Horizontal Stabilizer Eye Bolt

(2). Install control tubes and bellcranks as

Replacement

required, safety wire or cotter pin.

A. Horizontal Stabilizer Eye Bolt Removal

(3). Install center access plate with seven

screws and washers.

(1). Remove horizontal stabilizer.

6. Vertical Stabilizer Inspection

(2). Remove eye bolts by holding the flat

(Ref. Figure 201 and Figure 202)

surface of eye bolt with a wrench and

removing nut.

(1). Inspect skin for cracks, bonding

separation, delamanation and obvious

B. Horizontal Stabilizer Eye Bolt Installation

damage.

(1). Install eye bolts in horizontal stabilizer,

(2). Inspect stabilizer for freedom of

the short eye bolts in the forward holes

movement through pedal travel range,

and the longer eye bolts with spacer to

check for clearance between vertical to

the aft holes of horizontal stabilizer.

horizontal.

(2). Torque eye bolts to 80 - 120 inch-

(3). Check mounting fitting holes for

pounds (9.04 - 13.56 Nm) plus drag

elongation.

torque.

NOTE: Internal stabilizer fitting may display

cracking after installation of expandable

(3). Install horizontal stabilizer.

bolts. This cracking, internal fitting only, is

acceptable for continued service. Cracking

5. Horizontal/Vertical Stabilizer Control Tube

of the external skin from the mounting bolt

and Bellcrank Replacement

holes is unacceptable and stabilizer must be

removed from service and scrapped.

(Ref. Figure 201 and Figure 202)

7. Vertical Stabilizer Repair

A. Horizontal/Vertical Stabilizer Control Tube

and Bellcrank Removal

Refer to MDHI Field Service Representative.

(1). Remove horizontal stabilizer end tip

8. Horizontal Stabilizer Inspection

covers and center access cover for

access to bellcranks and control tubes.

(1). Inspect skin for cracks, bonding

separation, delamination and obvious

(2). Remove cotter pin, nut, washer and bolt

damage.

from center bellcrank shaft. Index mark

(2). Inspect mounting fitting and attach

bellcrank with grease pencil in relation

ship to shaft. Disconnect bellcrank.

ment hardware for condition.

(3). Inspect center access panel and nut

(3). Disconnect control tube from vertical

plate fasteners for condition, end tip

stabilizer torque tube bellcrank.

plate access covers and position lights

Remove controls from horizontal

for condition.

stabilizer as required for maintenance.

(4). Inspect vertical stabilizer torques tubes

B. Horizontal/Vertical Stabilizer Control Tube

for excessive axial and radial move

and Bellcrank Installation

ment, 0.010 inch (0.254 mm) axial end

play maximum allowable.

Refer to adjustment and test control rigging

during installation.

(5). Inspect torque tube bushings for wear

and security.

(1). Connect bellcrank to center bellcrank

shaft and install bolt, washers and nut.

(6). If the bushings are not bonded to the

Torque bolt to standard aircraft torque

horizontal stabilizer, rework Vertical

values and install cotter pin.

Stabilizer Torque Tube Bushings.

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HANDBOOK OF MAINTENANCE INSTRUCTIONS FOR MDHI 369D/E/FF-500/600N HELICOPTERS (ISSUED: 1990) - page 16