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

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

WOODEN OR

PLASTIC IN

SPECTION

PHENOLIC

PROBE

TOOL

0.125 INCH

(3.175 MM)

LEAD LEG

LAMINATE HAS FAILED IF CRACK OCCURS

ON BOTH LEAD AND LAG LEGS OF SAME

LAMINATE.

0.250 INCH

(6.35 MM)

LAG LEG

LAMINATE HAS FAILED IF CRACK OCCURS

IN TONGUE OF LAMINATE (SHADED AREA

TONGUE

SHOWN BEYOND JOINT OF STRAP PACK

6.00 INCH

LEGS).

(15.24 CM)

1.5 INCH

4.00 INCH

(3.81 CM)

10.16 CM)

(REF)

TWO LAMINATE FAILURES AS DEFINED IN 1

1.00 INCH

AND/OR 2 ARE ALLOWED IN EACH STRAP

(2.54 CM)

0.50 INCH

PACK ASSEMBLY. (TOTAL OF TEN LAMINATE

(12.7 MM)

FAILURES PER HUB ASSEMBLY.)

0.050-0.125 INCH

FIELD FABRICATION INSPECTION TOOLS

(1.27-3.175 MM)

ALUMINUM CHISEL NOT SHOWN

(REF. TABLE 601, NOTE 2)

STRAP PACK IS REJECTED IF THREE OR MORE

LAMINATES IN SAME PACK HAVE FAILED AS

DEFINED IN 1 AND/OR 2 ABOVE.

STRAP PACK IS REJECTED IF THREE OR MORE

LAMINATES IN SAME PACK ARE CRACKED IN

THE LEG (LEAD OR LAG).

FAILED LAMINATE IF CRACK IS

FOUND ON EITHER EDGE OF

LAMINATE. IF ONE LAMINATE

HAS FAILED IN THIS AREA, RE

PLACE HUB.

CAUTION:

DO NOT DISASSEMBLE STRAP PACK ASSEMBLY,

LAMINATIONS ARE SHOWN SEPARATED ONLY TO

DEPICT POSSIBLE CRACK LOCATIONS.

NOTE:

ANY CRACK IN LAMINATE IS CONSIDERED A BREAK.

THE LAMINATE HAS NOT FAILED HOWEVER, UNLESS

BOTH LEAD AND LAG LEGS ARE CRACKED, CRACK

1.50 INCH

IS LOCATED IN TONGUE AREA OF LAMINATE OR IS

(3.81 CM)

UNDER SHOES (SEE DETAIL 6).

G62-2007-2B

Figure 602. Strap Pack Lamination Inspection (Sheet 2 of 2)

Page 606

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

Table 601. Strap Pack Inspection

Replace or Return

Inspect

Procedure (1)

For

Acceptable

Hub for Overhaul

Outboard end.

Visually. Use blunt nosed

Failed laminates

Two or less per

Three or more laminate

wooden or phenolic probe

(3).

pack.

failures in one pack.

(Figure 602). Probe at

upper and lower end of

pack. Failed laminate in

lead or lag leg will move

away from other

laminates.

Visually.

Gaps between

Single straight

More than one gap

laminates.

gap not exceed-

found; gap exceeds

ing 0.030 inch

acceptable limit.

(0.762 mm) within

pack or next to

either upper or

lower outer shoe.

Visually using light and

Cracks or breaks.

None.

Cracks or breaks are

mirror (2).

noted.

In area of and

Visually with light and

Cracks or breaks.

Two or less

Three or more laminate

within pitch

mirror (2).

laminate failures

failures (2) in a pack;

housing assem-

per strap pack (2).

three or more laminates

blies.

in pack with crack in

same leg (lead or lag).

Shims at each of

Visually with light and

Crack or break.

Inspect top

Top laminate is cracked

two attach

mirror.

laminate around

in area of cracked or

points.

shim (4).

broken shim.

NOTES:

(1) Conduct visual inspections indoors or in shaded area to eliminate glare of sun or bright outdoor light.

(2) Removal of teflon covering is required for visual inspection of laminate edges. Use aluminum chisel,

fabricated from stock 0.025 x 6.00 x 0.100 inch (0.635 x 152.4 x 25.4 mm) to carefully scrape excess

interlaminate teflon sheets from both sides of strap pack between top and bottom shoes at outboard

attachment bolt of all five strap packs. Remove excess teflon from a point 1/2 inch (12.70 mm) outboard of

bolt centerline to 1−1/2 inches (38.1 mm) inboard of bolt centerline. Field fabricate and use plastic tool

(Ref. Figure 602). Run plastic tool in both directions along each laminate feeling for cracked laminate. Use

of plastic tool will ensure that shreds of teflon still hanging free does not obscure small cracks.

(3) Laminate has failed if crack is found in tongue area or if crack is found in both legs (lead and lag).

(4) Pay particular attention to shim installed at upper side of lead leg of each strap pack assembly. Maximum

of two shims may have been installed on top side of lead leg of strap pack to accommodate tolerance

buildup during strap pack assembly. If more than one shim is installed, pay particular attention to lower

shim when checking for cracks or breaks.

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

NOTE: Laminate failures are defined in step

(1).

Install cyclic lateral rigging fixture

(6).

(ST506 or ST507), cyclic longitudinal

rigging fixture (ST504 or ST505), and

(9). Inspect upper, lower and center lami

collective rigging fixture (ST501 or

nates for cracks and breaks (Ref.

ST502).

Figure 601).

(2).

Rotate main rotor to position one blade

NOTE: Cracks, breaks or other noticeable dam

over tailboom.

age to the laminate/shims require main ro

(3).

Raise and support other four blades

tor hub overhaul/replacement.

until four corresponding droop stop

(10). Install main rotor blades.

rollers no longer contact their striker

plates.

(11). Perform tracking of main rotor blades

(4).

Place accurate propeller protractor on

(Ref. Sec. 18-20-00).

top of main rotor drive shaft. Adjust

The maximum allowable bal

protractor to zero setting.

CAUTION

ance weight per pitch case hous

(5).

Place protractor on machined surface of

ing on the main rotor hub assembly is 150

outboard end of blade pitch housing,

grams.

alongside lead-lag bolthead. Measure

and record static droop angle.

(12). Record location of all cracked/broken

laminates in helicopter Log Book

(6).

Repeat (2). thru (5). above for remain

including strap serial number, blade

ing blades.

color, leg, lead or lag, and laminate

position, if possible numbering from the

(7).

Maximum allowable static droop angle

top down.

is six degrees. If measured droop angle

exceeds six degrees, inspect striker

6. Main Rotor Hub Droop Angle Check

plate and roller for excessive wear and

adjust droop angle (Ref. Main Rotor

(Ref. Figure 805) Whenever new or replacement

Hub Droop Angle Adjustment).

main rotor hub is installed or whenever excessive

droop angle is suspected, measure static droop

7. Main Rotor Damper and Attachments

angle of all five rotor blades. Droop angle must be

Inspection

5.5 ±0.5 degrees.

Excessive lead-lag load applied

CAUTION

to the main rotor blades during

Special Tools

ground handling can result in damage to the

(Ref. Section 91−00−00)

elastomeric damper buns and failure of the

Item

Nomenclature

damper assembly. Operators and mainte

nance personnel should use extra caution to

Left−Hand Command:

avoid lead-lag loads in excess of 35 pounds

ST501

Collective rigging fixture

(155.68 N) at the tip of the main rotor

(LH command)

blades.

ST504

Longitudinal rigging fixture

(LH command)

(1). Inspect bearing in rotor blade and

bearing in the pitch housing for

ST506

Lateral rigging fixture

looseness around outer race. No degree

(LH command)

of radial or axial play is permitted.

Right−Hand Command

ST502

Collective rigging fixture

(2). Inspect pitch housing and blade

(RH command)

bearings for binding, galling, or scoring

in bore and for wear. No radial play is

ST505

Longitudinal rigging fixture

permitted. Maximum allowable axial

(RH command)

play is 0.015 inch (0.381 mm).

ST507

Lateral rigging fixture

(RH command)

(3). Inspect clevis bushings for wear and

looseness.

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CSP-HMI-2

MAINTENANCE MANUAL

(4). Inspect damper flange bushing for wear

(2). Attach dial indicator or equivalent to

and play.

outer case of damper; position indicator

arm on center aluminum disc as shown.

(5). Inspect lower bolt hole in damper

flange for wear.

NOTE: Fabricate holding bar or fixture capable

of sustaining 100 pound (45.359 kg) static

(6). Inspect damper housing (including

load (Ref. Figure 603).

flanges) for damage.

(3). Attach damper end cap to holding bar

(7). Inspect damper turnbuckle, jamnuts

or fixture.

and safetywire for security. No end play

is permitted when manually tested.

NOTE: Perform weight loading and extension

check at ambient temperature of 70° ±l0°F

NOTE: When performing lead-lag of main ro

(21° ±5°C). Apply total 100 pound (45.359

tor blades, apply rotor brake (if installed) or

kg) weight load to damper at one time, not in

have assistant hold main rotor hub from

weight increments.

moving. A second assistant is recommended

to measure approximate damper extension

(4). Using hydraulic jack or equivalent,

and compression.

raise and attach 100 pound (45.359 kg)

weight load at damper clevis end.

(8). Lead-lag each main rotor blade in turn

Slowly lower jack to avoid shock

to provide approximately 0.10 inch

loading. After period of two minutes

(2.54 mm) extension and compression of

under load, measure damper extension

the damper elastomer.

on dial indicator.

(9). Visually check each damper in turn for

(5). If extension exceeds 0.056 inch (1.4224

cracks in elastomer or in elastomer-to-

mm) for M50452 damper, or 0.063 inch

metal bond at end face of damper: If

(1.6002 mm) for 369D21400-503

bonding or elastomer cracks are noted,

damper, replace the damper assembly.

measure depths of cracks, using depth

gage fabricated of shim stock or

(6). Reinstall existing damper; or as

equivalent having a 0.20 inch (5.08

required; install replacement damper of

mm) indication. If depth of crack

same type and part number (Ref. Main

exceeds 0.20 inch (5.08 mm), remove

Rotor Damper Installation). Do not

and check damper.

intermix PN 369D21400-503 damper

with any other part number damper

8. Main Rotor Damper Weight Loading and

assemblies.

Extension Check

NOTE: If replacement damper is installed, re

(Ref. Figure 603)

cord part number, serial number, and other

(1). Remove damper assembly (Ref. Main

pertinent information in Components Re

Rotor Damper Removal).

cord of helicopters Log Book.

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Revision 20

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

MAIN ROTOR HUB

REPAIRS

1. Main Rotor Retention Strap Pack Repair

(2). After smoothing (removal of all sharp or

raised edges) repair depth must not

exceed 0.010 inch (0.254 mm) in any

Consumable Materials

area of housing except inner surfaces of

(Ref. Section 91−00−00)

arm clevis lugs.

Item

Nomenclature

CM234

Solvent, dry-cleaning

(3). Maximum repair depth of 0.050 inch

CM725

Tape, electrical, plastic

(1.27 mm) is acceptable in clevis lug

with sleeve bushing.

(Ref. Table 601) Where accessible, ends of

permissible cracks or broken laminates should

(4). On opposite clevis lug repair depth of

be taped to prevent scratching and damaging

0.030 inch (0.762 mm) is permissible in

adjacent laminates.

area of spot faces and maximum of

0.050 inch (1.27 mm) in area outside

Do not bend broken ends exces

spot faces.

CAUTION

sively and scratch adjacent

straps.

(5). Touch up repaired areas with chemical

film (CM206) followed by primer

(1). Carefully wipe ends of broken strap

(CM318) and remove main rotor hub for

with a clean soft cloth moistened with

pitch housing replacement.

solvent (CM234).

(2). Use mild blast of filtered air to dislodge

3. Unbushed Outboard Clevis Lug Hole

any foreign particles between broken

Repair

strap ends and adjacent strap.

(3). Carefully tape broken ends of strap

(Ref. Figure 801) Repair elongated outboard hole

with plastic electrical tape (CM725).

in unbushed side of clevis lug if inside diameter of

hole exceeds 0.3135 inch (7.9629 mm).

2. Pitch Housing Repair

(Ref. Figure 801)

Consumable Materials

(Ref. Section 91−00−00)

Item

Nomenclature

Consumable Materials

CM118

Grease

(Ref. Section 91−00−00)

Item

Nomenclature

CM318

Primer

CM206

Chemical coating

CM431

Sealing, locking and retaining compound

CM318

Primer

CM802

Abrasive cloth, aluminum oxide

(1). Remove existing bushing from inboard

lug.

During repair of pitch housing,

CAUTION

comply with precautions for cov

(2). Drill elongated hole in outboard lug to

ering engine air inlet fairing opening to pre

0.3680 inch (9.3472 mm). Use drill

vent entry of foreign objects into air intake.

bushing as guide.

(1). Use grade 320 abrasive cloth (CM802)

to smooth scratches, nicks and chafing

(3). Line ream hole to 0.3760-0.3770 inch

wear in pitch housing.

(9.5504-9.5758 mm) diameter.

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Revision 20

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

0.360 IN. (9.144 MM) MINI

MUM WALL WIDTH

AROUND LUG (NOTE 1)

OUTBOARD LUG

PITCH HOUSING

OUTBOARD LUG

0.250 IN. (6.35 MM)

MINIMUM LUG WIDTH

(NOTE 1)

INBOARD LUG

0.220 IN.

(5.588 MM)

MINIMUM LUG

INBOARD LUG

THICKNESS

(NOTE 1)

0.146 IN. (3.7084 MM) MINI

MUM LUG THICKNESS AT

0.20 IN. (5.08 MM)

SPOTFACE

LUG THICKNESS

(NOTE 1)

NOTES:

MAINTAIN MINIMUM WALL THICKNESS AROUND LUG AND MINIMUM

LUG THICKNESS FOR FIELD REPAIR OF CLEVIS LUG.

NO PAINT OR PRIMER PERMISSIBLE IN THIS AREA.

BRUSH CADMIUM PLATE GROUND SURFACE BEFORE INSTALLATION

IF POSSIBLE. IF NOT, COAT GROUND SURFACE THOROUGHLY WITH

PRIMER (CM318) AND INSTALL WHILE WET.

G62-2012-1B

Figure 801. Field Repair of Main Rotor Hub Pitch Control Lugs (Sheet 1 of 2)

Page 802

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CSP-HMI-2

MAINTENANCE MANUAL

BUSHING 0.44 IN. (11.176 MM) O.D. X 0.25 IN. (6.35 MM) I.D. X 0.31 IN. (7.874 MM) LONG

BUSHING 0.75 IN. (19.05 MM) O.D. X 0.56 IN. (14.224 MM) I.D. X 0.31 IN. (7.874 MM) LONG

BOLT 0.25 IN. (6.35 MM) DIA X 1.38 IN. (3.5052 CM) LONG

WASHER 0.25 IN. (6.35 MM) I.D. X 0.75 IN. (19.05 MM) O.D. X 0.06 IN. (1.524 MM) THICK (2 EA.)

SECTION A - A

REMOVAL OF HS610 SP 5010 R 313 X 290 SOLID BUSHING

DRILL BUSHING

0.4990-0.4995 INCH

0.3775-0.3780 INCH

1.13 INCH

O.D. X

I.D. X

(12.6746-12.6873 MM)

(9.5885-9.6012 MM)

(2.8702 CM)LONG

0.3760-0.3770 INCH

REAMER

DIA

(9.5504-9.5758 MM)

0.3689 INCH

DRILL NO. U

DIA

(9.37006 MM)

DRILL BUSHING

DRILL THEN REAM

0.875 INCH

DRILL BUSHING

(22.225 MM)

0.375 X 0.250 X 0.31 IN.

(9.525 X6.35 X 7.874 MM) LONG

DRILL AND REAM OUTBOARD LUG

NOTE 2

BACK SPOTFACE

0.875 IN. (22.225 MM) DIA X

TREAT SPOTFACE SURFACE AND REAMED

0.250 IN. (6.35 MM) DIA SHAFT

HOLE WITH SEALING COMPOUND (CM431)

0.020-0.030 INCH

0.010-0.030 INCH

FILLET RADIUS

(0.508-0.762 MM)

(0.254-0.762 MM)

0.146 INCH (3.7084 MM) MIN.

0.20 INCH (5.08 MM) MIN.

BACK SPOTFACE OUTBOARD LUG

AFTER INSTALLATION OF BUSHING,

SEAL EDGES WITH PRIMER (CM318).

FLANGE TO BE FLUSH WITH SURFACE.

369D21309-3 BUSHING

GRIND OFF TO 0.000-0.015 IN. (0.000-0.381 MM)

BELOW 0.75 IN. (19.05 MM) DIA. SPOTFACE

SURFACE (NOTE 3)

INSTALL WITH LOCTITE.

0.015-0.025 INCH

369D21306 SPLIT BUSHING, COAT WITH

X 455 CHAMFER (TYP)

(0.381-0.635 MM)

LUBRIPLATE (CM118) AT INSTALLATION.

0.360 IN.

0.000-0.015 INCH

0.814-0.818 INCH

(9.144 MM) MIN.

(0.000-0.381 MM)

(20.6756-20.7772 MM)

INSTALLATION OF 369D21306 AND 369D21309-3 BUSHINGS

G62-2012-2B

Figure 801. Field Repair of Main Rotor Hub Pitch Control Lugs (Sheet 2 of 2)

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Revision 20

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

NOTE: Check outboard lug two places for mini

4. Pitch Control Bearing Housing Assembly,

mum wall thickness of 0.146 inch (3.7084

Spacer or Striker Strip Replacement

mm) and 0.20 inch (5.08 mm).

(Ref. Figure 802)

(4). Back spotface inside surface of outboard

Consumable Materials

lug to 0.875 inch (22.225 mm) diameter

(Ref. Section 91−00−00)

and 0.020-0.030 inch (0.508-0.762 mm)

Item

Nomenclature

depth. Use drill bushing as guide for

spotface pilot. Add chamfer to clear

CM222

1,1,1-Trichloroethane

bushing two places.

CM425

Sealing compound

NOTE: Measure height of bushing and thick

(1). Support blade and pitch housing from

ness of lug prior to installation. Grind off

beneath. Remove nuts. washers, and

end surface of bushing as required to secure

bolts that secure bearing housing.

0.000-0.015 inch (0.000-0.381 mm) clear

If droop shim washers are in

ance. Brush cadmium plate ground end of

CAUTION

stalled between spacer and

bushing before installation. If equipment is

striker strip, they must be retained for rein

not available coat ground end thoroughly

stallation to establish correct static droop

with primer (CM318) and install while wet.

angle between pitch housing and hub.

If primer is used check for corrosion around

lug hole and bushing.

(2). Carefully remove spacer by sliding it

downward past striker strip. Retain

exact number of droop shim washers, if

(5). Install flanged bushing using loctite

installed.

(CM431). Use attach bolt or assembly

pin as guide to ensure proper align

(3). Slide bearing housing assembly off

ment. Seal edges with loctite.

pivot pin. Inspect pivot pin for grooving

or excessive wear.

(6). Install slotted bushing with grease

NOTE: Do not remove tetrafluoroethylene

(CM118) in inboard lug.

(TFE) debris which works out of pitch bear

ing edge. Debris is normal and helps lubri

cate bearing. Removal of debris increases

NOTE: Check outboard and inboard lugs of

bearing wear rate.

pitch control horn for interference with up

per jamnut on pitch control rod. Use file or

(4). Remove and discard pitch bearing if

portable grinder to carefully trim off interf

defective, total radial looseness of

ering corner of pitch housing lugs to provide

assembled ball and pivot pin must not

sufficient pitch control rod clearance. It is

exceed 0.010 inch (0.254 mm).

not necessary to trim to minimum wall

thickness. Do not exceed rework limitations.

(5). Replace striker strip if it is cracked or

Touch up reworked area with chemical film

lead-lag contact areas are worn

and primer. Paint with matching color.

through hard anodized surface.

(6). Remove sealant between pitch housing

(7). Reconnect pitch control rod assembly.

and striker strip. use care not to scratch

Check for proper clearance between

pitch housing. Remove striker strip

outboard lug and upper jamnut on pitch

from pitch housing.

control rod.

(7). Cut old striker strip to facilitate

removal from retention strap assembly.

Use care during removal of

Do not scratch strap assembly.

CAUTION

parts from around strap pack.

Any nicks or scratches on straps require

(8). Clean old sealant from pitch housing

scrapping of strap pack.

using 1,1,1, trichloroethane (CM222).

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CSP-HMI-2

MAINTENANCE MANUAL

(9). Cut out area of new striker strip (Ref.

(1). Remove housing, striker plate and pitch

Figure 803). Deburr, smooth and radius

control bearing.

cut edges.

(2). Place housing on drill press, striker

(10). Apply sealant (CM425) to faying

surface down.

surfaces of the striker strip and pitch

housing.

(3). Drill rivet hole out to 0.192-0.198 inch

(4.8768-5.0292 mm) dia.

(11). Position pitch control bearing housing

on pivot pin (Ref. Figure 802).

(4). Using a 0.453 inch (11.5062 mm) dia.

counterbore, counterbore rivet hole

0.396 inch (10.0584 mm) deep.

If droop shim washers were re

CAUTION

moved from between spacer and

NOTE: The screw-held striker plate is dimen

striker strip, same exact thickness removed

sionally thicker.

must be reinstalled. There must be an equal

number of washers on each of all three bolts.

(5). Counterbore should have a 0.030 inch

These washers establish correct static droop

(0.762 mm) radius. Deburr counterbore.

between pitch housing and hub.

(6). Clean drilled and counterbored surfaces

(12). Slide spacer into position between

with solvent (CM234) and treat with

bearing housing assembly and striker

chemical film (CM206).

strip on pitch housing. Install exact

thickness of droop shim washers

(7). Prime and paint counterbored surface

removed at time of disassembly. Align

with primer (CM318) and black paint

holes for all three bolts.

(CM305).

(13). Install bolts, washers and nuts; torque

(8). Reinstall pitch control bearing and

to 50 - 70 inch-pounds (5.65 - 7.91

striker plate and reinstall housing.

Nm) and install safety wire.

6. Pitch Control Bearing Replacement

(14). Seal all parting lines (joints) of the

assembly with bead of sealing com

(Ref. Figure 802)

pound (CM425).

(15). Perform droop angle check (Ref. Main

Consumable Materials

Rotor Hub Droop Angle Adjustment).

(Ref. Section 91−00−00)

Item

Nomenclature

5. Pitch Control Bearing Housing

CM206

Chemical coating

Modification

CM219

Methyl-ethyl-ketone

CM318

Primer

(Ref. Figure 802) To replace riveted striker plate

with screw held striker plate, refer to following

CM425

Sealing compound

instructions.

CM803

Crocus cloth

Consumable Materials

(1). To remove striker plate, remove screw,

(Ref. Section 91−00−00)

nut and washer or drill out rivets as

Item

Nomenclature

required. Discard striker plate if

CM206

Chemical coating

brinnelling or pits exceed 0.030 inch

(0.762 mm) depth.

CM234

Solvent, dry-cleaning

CM305

Lacquer, acrylic

(2). Press bearing from housing bore. Clean

CM318

Primer

any residual primer from housing bore

with MEK solvent (CM219).

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Revision 20

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

CAUTION: WASHERS ARE INSTALLED BETWEEN SPACERS AND STRIKER

STRIP TO ESTABLISH CORRECT STATIC DROOP ANGLE BETWEEN HOUSING

AND HUB. EXACT NUMBER REMOVED MUST BE REINSTALLED. THREE PITCH

BEARING HOUSING BOLTS MUST EACH HAVE SAME NUMBER (THICKNESS) OF

WASHERS WHEN SHIMMING IS NECESSARY.

HUB

LEAD-LAG

BOLT

LEAD-LAG

DROOP SHIM WASHERS

LINKS

(SEE CAUTION)

SLEEVE

BUSHING

SPACER

PIVOT PIN

STRIKER STRIP

PITCH CONTROL BEAR

ING HOUSING AS

MAIN ROTOR

SEMBLY

STRAP PACK

PITCH BEARING HOUSING AND

SPACER - INSTALLATION (CUR

RENT CONFIGURATION)

ELONGATED HOLE LINE REAMED (USING

SLEEVE BUSHING AS GUIDE) TO PROVIDE 0.001

NOTE 1

NOTE 2

-0.0015 IN. (0.0254-0.0381 MM) INTERFERENCE

LEAD-LAG

FIT FOR 0.3675-0.3685 IN. (9.3345-9.3599 MM)

STOP

OUTSIDE DIAMETER REPAIR BUSHING

LEAD-LAG LINK AND STOP

PITCH HOUSING ARM

REPAIR BUSHING (2024-T3 OR 7075-T6

(CLEVIS LUG)

ALUMINUM PRESS FIT

PRESS-FITTED REPAIR BUSHING LINE

DRILLED AND LINE REAMED USING SLEEVE

SLEEVE

BUSHING AS GUIDE:

BUSHING

FINAL ID; 0.3125-0.3135 IN. (7.9375-7.9629 MM)

PITCH HOUSING BUSHINGS - REPAIR

NOTES:

NOTES: (CONT)

FOR REMOVAL, WOOD DOWEL PLACED HERE AND

COUNTERSUNK RIVET HEAD OR SCREW HEAD MUST BE

STRUCK SHARPLY WITH HAMMER TO BREAK STOP BOND.

FLUSH WITH HOUSING. UPSET END MUST BE FLUSH

ALL STOP-TO-LINK SHADED CONTACT SURFACES

WITH PLATE.

BONDED WITH ADHESIVE (CM405 OR CM410).

UPSET END MUST BE FLUSH WITH PLATE.

INSTALL WITH WET PRIMER (CM318).

MANUFACTURED RIVET HEAD MUST BE FLUSH WITH

WET PRIMER (CM318) ON WASHER AND MATING SURFACES

PLATE IN ALTERNATE RIVET INSTALLATION.

BEFORE INSTALLATION.

10. REPLACEMENT HOUSING FOR BOTH VERSIONS

NUT RETAINING BRACKET IS BONDED TO HUB.

ATTACHED TO STRIKER PLATE WITH SCREW, WASHER

EARLY CONFIGURATION MODIFIED BY HUGHES SERVICE

AND NUT FOR EASE OF REMOVAL.

NOTICE DN-3.

G62 2013 1A

Figure 802. Main Rotor Hub Components − Repair and Installation (Sheet 1 of 2)

Page 806

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CSP-HMI-2

MAINTENANCE MANUAL

NOTE 7

HOUSING

NOTE 10

SCREW

NUT

WASHER

PITCH BEARING

NUT

STRIKER

PLATE

WASHER

THREADED

(2 PLACES)

COUNTERSUNK

HEAD SCREW

SUPPORT NUT

PITCH BEARING -

MODIFIED CONFIGURATION (RO

INSTALLATION

TATED) (NOTE 6)

MAXIMUM ALLOWABLE WEAR IS 90%

CIRCUMFERENCE OF 0.4328 INCH

0.4328 INCH

(10.99312 MM) MINIMUM DIAMETER

(10.99312 MM)

MINIMUM DIA.

SPECIAL WASHER

NOTE 7

(NOTE 4)

HOUSING

0.125 INCH (3.175 MM)

MAXIMUM WEAR

NUT RETAINING

PITCH PIVOT PIN

BRACKET (NOTE 5)

(CURRENT CONFIGURATION)

CURRENT CONFIGURATION

(NOTE 3)

HUB

STRIKER

RETAINING NUT

PLATE

BRACKET (NOTE 5)

ROUND HEAD RIV

CAPTIVE NUT

EARLY CONFIGURATION

ET (NOTE 8)

MAXIMUM ALLOWABLE WEAR IS 90%

CIRCUMFERENCE OF 0.4328 INCH

0.4328 INCH

(10.99312 MM) MINIMUM DIAMETER

(10.99312 MM)

PITCH

MINIMUM DIA.

BEARING

PITCH PIVOT PIN

0.125 INCH (3.175 MM)

COUNTERSUNK HEAD RIVET

(EARLY CONFIGURATION)

MAXIMUM WEAR

(ALTERNATE) (NOTE 9)

(NOTE 3)

EARLY CONFIGURATION

PIVOT PITCH PIN - INSTALLATION

62-2013-2A

Figure 802. Main Rotor Hub Components − Repair and Installation (Sheet 2 of 2)

Page 807

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MD Helicopters, Inc.

MAINTENANCE MANUAL

NOTE: Diameter of bearing bore, after cleanup,

(1).

Provide a backup support for link

should not exceed 1.1880 inch (3.01752 cm).

assembly. Use 0.5 inch (12.7 mm) wood

Localized areas of clean up should not ex

dowel and hammer to drive stop from

ceed 0.003 inch (0.0762 mm) within an area

link. Strike dowel sharply to break

of 25% of the circumference.

adhesive bond.

(3). Rework minor surface abrasion in

housing bore by polishing with crocus

(2).

Using sharp-edge metal scraper,

cloth (CM803). Restore chemical film

carefully scrape any adhesive residue

(CM206), where removed.

from link. If scraper penetrates through

paint and chemical surface film, surface

(4). Press bearing into bore using wet

must be refinished. Depth of gouges or

primer (CM318). Wipe away any excess

nicks is limited to 0.010 inch (0.254

primer using care to keep it out of

mm) maximum after rework. Rework

bearing. Check teflon linings of bearing

by smooth blending into surrounding

after installation to determine that no

area with grade 320 abrasive cloth

damage occurred from pressing opera

(CM802). Final polish with crocus cloth

tion.

(CM803). Restore chemical film protec

tion (CM206).

NOTE: Ensure bearing is seated completely in

bore of housing and striker plate fits flush

on housing.

(3).

Clean bond area of all contact surfaces

by wiping with cleaner (CM228).

(5). Apply sealant (CM425) to faying

Flush-wipe cleaned surface four times

surfaces and install striker plate with

with mixture of equal parts of distilled

screw, washer and nut or rivets. Head

water and isopropyl alcohol (CM217) to

of countersunk screw or rivet must be

remove all traces of phosphoric acid.

completely flush.

Rinse cleaned surface with tap water,

followed by a rinse of distilled water

7. Lead−Lag Link Blade Stop Replacement

until surface is ”water break” free. Dry

for 30 minutes minimum at 150°F

(Ref. Figure 802) Replace blade stop if it is

(66°C).

broken, cracked, has broken spring, or if there

are visible bond line cracks.

(4).

Check fit of stop in link. Flange and

radius contact surfaces of stop must

Consumable Materials

mate with link within 0.010 inch (0.254

(Ref. Section 91−00−00)

mm). Maximum clearance between stop

Item

Nomenclature

and inside surfaces of link ears is

CM206

Chemical coating

limited to 0.020 inch (0.508 mm). This

tolerance applies to both sides of stop.

CM217

Isopropyl alcohol

CM228

Surface cleaner

CM411

Adhesive, epoxy

(5).

Prepare mixture of epoxy adhesive

CM802

Abrasive cloth, aluminum oxide

(CM411). Apply uniform coating of

mixed adhesive to all contact surfaces.

CM803

Crocus cloth

Hand press stop into place between link

ears until all mating surfaces are in

Lead-lag link assembly must

firm contact. Apply a clamping device

CAUTION

not be removed from pitch con

so that contact is maintained. Cure for

trol housing for this repair, since retention

minimum of eight hours at room

bolt cannot be retorqued without special

temperature, or two hours at 150°F

adapter.

(66°C).

Page 808

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CSP-HMI-2

MAINTENANCE MANUAL

2.50 INCH

(6.35 CM)

CAUTION:

DO NOT SCRATCH STRAP PACK WHEN INSTALLING

THROUGH STRAP ASSY.

NOTE:

CUT OUT 0.25-0.50 IN. (6.35-12.70 MM) PIECE OF THE

0.25-0.50 IN.

STRIKER STRIP BETWEEN LOWER BOLT HOLES.

(6.35-12.70 MM)

DEBURR AND RADIUS-CUT EDGES.

(NOTE)

G62-2009A

Figure 803. Striker Strip Replacement

8. Damper Attach Lug Bearing Replacement

(4).

Using 10-power magnifying glass,

inspect fitting bore for cracks. No

cracks are permitted.

Consumable Materials

(Ref. Section 91−00−00)

(5).

Measure fitting bore diameter. Accept

Item

Nomenclature

able limits are 0.6548-0.6552 inch

CM216

Loctite remover

(16.63192-16.64208 mm).

CM219

Methyl-ethyl-ketone

CM318

Primer

(6).

Apply thin coat of primer (CM318) to

fitting bore.

Special Tools

(7).

Press bearing into fitting with arbor

(Ref. Section 91−00−00)

press and fixture (ST706). Wipe away

Item

Nomenclature

excess primer.

ST706

Arbor press fixture

ST707

Staking tool

(8).

Stake bearing at both sides of fitting

with staking tool (ST707) in hydraulic

press with 6000-8000 pounds

(1). Use fly or circle cutter with 0.25 inch

(26688-35584 N) of force. When staked,

(6.35 mm) pilot to remove staked lip

outer race of bearing shall be flush to

from one side of bearing without

not more than 0.010 inch (0.254 mm)

removing any material from fitting. If

above fitting surface (both sides). Gap

fitting is damaged by cutter, blade must

between staked lip of bearing race and

be replaced.

chamfered surface of fitting bore shall

not exceed 0.002 inch (0.0508 mm) as

(2). Use an arbor press to press bearing

checked with feeler gage. Staking

from fitting.

operation shall produce no cracks in

(3). Clean primer residue from fitting bore

fitting or bearing.

with MEK (CM219). Remove locking

compound residue (if any) with locking

(9).

Fill staking gap (if any) with primer

compound remover (CM216).

(CM318).

Page 809

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MD Helicopters, Inc.

MAINTENANCE MANUAL

9. Lead−Lag Bolt Corrosion Control

NOTE: Torque pivot pin to 70 - 80 inch-

pounds (7.91 - 9.04 Nm), then use 0.002

inch (0.0508 mm) feeler gage and check for

Consumable Materials

gap between pin flange and washer on

(Ref. Section 91−00−00)

mounting lug surface. No gap is allowed.

Item

Nomenclature

CM219

Methyl-ethyl-ketone

(3). Install pivot pin in mounting lug with

washer (Ref. Figure 802). Torque pivot

CM318

Primer

pin to 250 - 280 inch-pounds (28.25 -

CM425

Sealing compound

31.64 Nm). Apply sealant (CM420) at

CM802

Abrasive cloth, aluminum oxide

junctures of pivot pin flange, washer

and hub.

Do not disturb torque on lead-

CAUTION

11. Droop Stop Roller Repair or Replacement

lag bolts. Special adapter is

needed to retorque lead-lag bolts.

(Ref. Figure 804) Replace defective droop stop

roller if clearance between roller bearing liner

(1). Remove and tag or color-code each set

and shaft is more than 0.015 inch (0.381 mm).

of balance hardware that is installed.

Roller shaft outside diameter must not be less

(2). Remove corrosion with grade 180

than 0.4370 inch (11.0998 mm).

abrasive cloth (CM802) and finish with

grade 400 abrasive cloth.

Consumable Materials

(Ref. Section 91−00−00)

(3). Swab cleaned surface with MEK

Item

Nomenclature

(CM219) and apply unthinned zinc

chromate primer (CM318).

CM217

Isopropyl alcohol

(4). Reinstall original balance hardware

that was removed. Using sealant

(1). Remove pitch control bearing housing

(CM425), reseal balance hardware.

that contacts lower shoe roller to be

removed.

10. Pitch Control Bearing Pivot Pin Repair or

NOTE: Only one roller can be removed at one

Replacement

time. Two opposing droop stop followers

(Ref. Figure 802) Minimum allowable pin

must be pressed against droop stop ring to

diameter is 0.4328 inch (10.99312 mm). Pivot

force opposite follower out and expose roller

pin grooving or excessive side wear may be

shaft for removal. Same condition exists at

polished to original finish as long as minimum

installation.

allowable pin diameter, 0.4328 inch (10.99312

(2). Press down on pitch housing that is

mm), remains after rework. Replace any pin

opposite roller that is to be removed.

requiring more rework as follows.

Remove cotter pin and shaft.

Consumable Materials

(3). Remove droop stop roller.

(Ref. Section 91−00−00)

(4). Wet down and clean plunger and

Item

Nomenclature

mating shoe bushing with isopropyl

CM318

Primer

alcohol (CM217).

CM420

Sealant

(5). To install replacement roller, press

down on pitch housings at opposite

(1). Remove pivot pin.

sides of hub from roller to be installed.

Install roller, shaft and new cotter pin.

(2). Install replacement pivot pin wet with

primer (CM318).

(6). Install pitch control bearing housing.

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CSP-HMI-2

MAINTENANCE MANUAL

12. Droop Stop Ring Repair

When T-head is free of ring channel,

turn it perpendicular (vertical) to

(Ref. Figure 804)

channel.

NOTE: Followers can be easily rotated by use of

Consumable Materials

nonmetallic drift in hole for droop stop roller

(Ref. Section 91−00−00)

shaft.

Item

Nomenclature

(6). Push droop stop ring toward number 4

CM103

Solid film lubricant

and 5 followers. Pull number 2 follower

T-head from droop stop ring channel.

(1). Repair depth limit for corrosion, nicks

When T-head is free of channel, turn it

or scratches in droop stop ring is 0.007

perpendicular to channel.

inch (0.1778 mm) for all surfaces except

(7). Push droop stop ring toward number 1

outer edges of ring outer flanges. Depth

and 5 followers. Pull number 3 follower

limit is 0.030 inch (0.762 mm). All

T-head from droop stop ring channel.

reworked areas must be blended

When T-head is free of channel, turn in

smoothly with 15 to 1 ratio into sur

perpendicular to channel.

rounding area.

(8). Tilt ring up on number 1, 2, and 3

(2). Spray repaired areas of rings with solid

T-heads as far as possible.

film lubricant (CM103).

(9). While pulling upward on ring, rotate (in

(3). Replace droop stop ring if repair limits

succession) number 1, 2, and 3 T-heads

are exceeded.

so that they are out of, and below, droop

stop ring.

13. Droop Stop Ring Replacement

(10). Withdraw number 4 and 5 T-heads

(Ref. Figure 804)

from droop stop ring channel and

remove ring.

(1).

With hub upside down, support hub so

When installing droop stop ring,

that pitch housings unload cam follow

CAUTION

droop stop followers T-Heads

ers and provide maximum clearance

must be offset away from lower shoe to pre

between striker plates and droop stop

vent damage to lower shoe.

rollers.

(11). Install replacement droop stop ring by

(2).

Release retaining (snap) ring of each

reversing removal procedure, steps (1).

droop stop restrainer from its groove.

through (10)., making certain to

Move retaining ring flush against droop

reinstall followers according to mark

stop follower (T-head) to provide

ings placed thereon prior to removal.

additional clearance and reduce spring

tension.

(12). Compress follower spring and install

retaining (snap) ring in its groove on

(3).

Remove five droop stop rollers.

each follower.

(4).

Starting from either scissors crank

(13). Reinstall droop stop rollers.

attach lug, number all five droop stop

14. Droop Stop Follower (T−Head)

follower assemblies in clockwise

Replacement

direction for location identification at

replacement. This number code should

(Ref. Figure 804) Replace the droop stop

be placed on outer, upper end of plunger

follower (T-head) if it is worn, scored or is

and on adjacent area of lower shoe.

causing damage to the droop stop ring. After

Make sure codes are not accidentally

the droop stop ring has been removed, the

removed during remaining steps.

droop stop follower assemblies may be

removed from hub.

(5).

Push droop stop ring toward number 3

and 4 followers. Pull number 1 follower

(1). Remove droop stop follower assembly

T-head from droop stop ring channel.

from hub.

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MD Helicopters, Inc.

MAINTENANCE MANUAL

(2). Remove pins that secure follower to

(c). The maximum wear condition may

plunger.

exist in one spot or in several spots

totaling 2.1 square inches (13.55

Droop stop followers T-Heads

cm²).

CAUTION

must be offset away from lower

shoe to prevent droop stop ring from damag

(6). Wet down and clean plunger and

mating shoe bushing with isopropyl

ing lower shoe.

alcohol (CM217).

(3). Insert new follower. T-head must be at

(7). Install droop stop plunger into lower

right angle to roller shaft in plunger.

shoe.

(4). Drill two 0.156-0.158 inch

(8). Install roller, shaft and new cotter pin.

(3.9624-4.0132 mm) diameter holes

through follower in line with holes in

(9). Complete droop stop ring installation.

plunger.

16. Main Rotor Hub Droop Angle Adjustment

(5). Insert pins and stake ends. No burrs or

(Ref. Figure 802) If static droop angle exceeds

roughness permissible after staking.

six degrees, adjust as follows.

(6). Install follower assembly in hub.

(1). Remove main rotor blade.

(7). Reinstall droop stop ring.

(2). Use flat washers of thickness required

to adjust spacing between spacer and

15. Droop Stop Plunger Removal, Inspection

striker strip. Any one type, or combina

and Installation

tion, of correct part number washers

(IPC) may be used; however, an identi

(Ref. Figure 804)

cal washer selection must be installed

on each of three bolts that secure pitch

Consumable Materials

control bearing assembly to pitch

(Ref. Section 91−00−00)

housing.

Item

Nomenclature

(3). Remove nuts and washers and separate

CM217

Isopropyl alcohol

spacer from striker strip. The use of one

0.016 inch washer raises static droop

angle approximately one-half degree.

(1). Remove droop stop ring.

Add sufficient washers to adjust droop

(2). Remove pitch control bearing housing

angle within range of 5.5 ±0.5 degrees.

assembly that contacts the lower shoe

Reinstall nuts and washers.

roller.

(4). If more than 0.063 inch (1.6002 mm)

spacing is required (above factory

(3). Remove cotter pin and shaft from droop

spacing), inspect striker plate and

stop follower assembly.

droop stop roller or follower and droop

(4). Remove droop stop roller.

stop ring for excessive wear. Replace as

required.

(5). Check droop stop plunger for wear by

NOTE: The average factory spacing on new and

using the following criteria:

rebuilt hubs is 0.063 inch (1.6002 mm).

(a). The minimum acceptable diameter

(5). Reinstall blade. Repeat measurement of

after wearing in service should be

static droop angle.

0.996 inch (25.2984 mm).

(6). As required, repeat above procedures

(b). The acceptable amount of wear

for remaining blades.

though the anodized coating shall not

exceed 40% or 2.1 square inches

(7). Following reinstallation or replacement

(13.55 cm²) of the total sliding

of parts, check track of main rotor

surface area of the cylinder.

blades.

Page 812

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CSP-HMI-2

MAINTENANCE MANUAL

LOWER

SHOE

PINS

DROOP STOP

0.007 INCH (0.1778 MM)

PLUNGER

DROOP STOP

MAX. DEPTH (15 TO 1

FOLLOWER

RADIUS) AFTER REWORK

(T-HEAD) (NOTE)

COTTER

DROOP STOP

SNAP RING

ROLLER

15 TO 1

SHAFT

SPRING

RADIUS

DROOP STOP FOLLOWER - INSTALLATION

0.007 INCH (0.1778 MM)

MAX. DEPTH (15 TO 1

0.030 IN. MAX.

RADIUS) AFTER

DROOP STOP RING

AFTER REWORK

REWORK

DROOP STOP RING - REPAIR LIMITS

DROOP STOP FOLLOWER

ASSEMBLY (5 PLCS)

SCISSORS CRANK

BEARING ROTATIONAL DRAG

ATTACH LUG

1.0 - 2.0 IN-LBS

(0.113 - 0.226 NM)

LOWER SHOE - INVERTED

NOTE: DROOP STOP FOLLOWER T-HEADS TO

G62 2011C

Figure 804. Main Rotor Hub Assembly − Repair

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

17. Main Rotor Hub Tapered Bearing Grease

(4). Check bearing cup hub bore for scoring.

Repack, Inspection and Replacement

Smooth out any roughness with grade

400-600 abrasive cloth (CM802).

(Ref. Figure 805) Replace tapered roller

Restore chemical film protection where

bearing cup or cone if it has any flat spots,

removed. Maximum diameter of hub

scoring, pitting, grooving, discoloration (blue)

bore for upper bearing cup (Ref.

or if it feels rough when rotated.

Figure 805) is 4.4335 inch (11.26109

cm), measured in any direction.

Maximum diameter of hub bore for

Consumable Materials

lower bearing cup is 4.3095 inch

(Ref. Section 91−00−00)

(10.94613 cm), measured in any

Item

Nomenclature

direction.

CM111

Grease, aircraft

CM121

Preservation oil

(5). Check upper seal retainer. No cracks,

sharp nicks or burrs are allowed. Minor

CM234

Solvent, dry-cleaning

corrosion or other surface defects may

CM802

Abrasive cloth, aluminum oxide

be polished out using crocus cloth

CM803

Crocus cloth

(CM803). Grooving on seal contact

surfaces must not exceed 0.004 inch

Special Tools

(0.1016 mm) depth after polishing.

(Ref. Section 91−00−00)

Bearing cups are installed in

Item

Nomenclature

WARNING

hub by differential tempera

ST701

Main rotor wrench assembly

ture (shrink-fit) method. Take appro

priate precautions to prevent burns

when handling parts that are cooled to

Do not intermix Timken or NTN

CAUTION

sub-zero temperatures.

bearing cups and cones at upper

and lower tapered roller bearing locations of

(6).

Place bearing cups in closed container

main rotor hub.

of dry ice and cool for not less than 20

minutes to -40°F (-40°C).

NOTE:

(7).

Coat bore of hub with grease (CM111).

D Roller bearing cones and cups should al

Use care to maintain cup-to-hub bore

ways be replaced as a set.

alignment and press cup into bore,

D Replace tapered roller bearing cup and

using tools D and E (Ref. Figure 806),

cone if it has any flat spots, scoring, pit

until cup is seated.

ting, grooving, discoloration (blue) or if it

(8).

Apply film of grease to sleeve bushing.

feels rough when rotated.

Use pressing tool equivalent to tool C,

(1). Use pressing tools equivalent to items

and press bearing cone onto sleeve

A and B (Ref. Figure 806) to press

bushing.

upper and lower bearing cups from hub.

(9).

With lip on center seal up, hand press it

A press ram of one to two tons is

into hub (Ref. Figure 805).

sufficient for removal.

(10).

Apply film of grease on mast. Install

(2). Press lower bearing cone from sleeve

preassembled sleeve bearing and

bushing.

bearing cone on mast. Do not apply any

additional lubricant to roller bearing

In next step, do not spin reus

CAUTION

set. Wipe any excess preservative oil

able bearings while cleaning.

from bearing cone and cup.

Coat bearings lightly with oil (CM121) after

cleaning.

(11).

Place assembled hub over mast and

seat on lower roller bearing cone.

(3). Clean hub bore, sleeve bushing, seal

retainer and reusable bearings using

(12).

Install lead spacer 369A1224-5 (thick

filtered solvent (CM234) spray.

ness gage substitute for recessed

Page 814

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CSP-HMI-2

MAINTENANCE MANUAL

spacer) over mast. Rest spacer on top of

pounds (1.13 - 1.69 Nm). This will be

sleeve bushing.

1.5 - 3 pounds (0.681 - 1.362 kg) on

spring scale used as in step (15). above.

NOTE: If lead spacer is not available, fabricate

its equivalent from lead sheet. Spacer di

(18). Remove hub and sleeve bushing with

mensions are; 2.96 inch (7.5184 cm) outside

lower bearing cone from mast.

diameter;

2.68 inch

(608072 cm) ID;

(19). Position hub upside-down. Hand-pack

0.075-0.085 inch (1.905-2.159 mm) thick.

lower hub cavity (Ref. Figure 805) and

bearing cone on sleeve bushing with

(13). Install upper bearing cone into hub and

grease.

on top of lead spacer.

(20). Install sleeve bushing with bearing

(14). Install steel ring washer, equivalent to

cone in hub. Hand-pack cavity between

tool F (Ref. Figure 806), as substitute

bearing and hub liner with grease; then

for seal retainer (Ref. Figure 805).

press in lower seal with seal lip toward

top of hub. Wipe off excess grease.

NOTE: Step (14). is not required. However, use

of substitute washer for retainer prevents

(21). Turn hub assembly right side up.

unnecessary scoring of retainer. Several

(22). Complete reassembly of hub by install

tightening and loosening actions may be re

ing recessed spacer, upper bearing cone,

quired to get correct rotational drag on hub

upper seal and seal retainer in hub at

bearings.

installation of hub on mast.

(15). Install mast nut on mast using mast

18. Main Rotor Hub Scissors Attach Lug

nut wrench (ST701), tighten until

Bearing Replacement

bearings are preloaded to 10 - 12

inch-pounds (1.13 - 1.36 Nm) of

rotational drag. Measure rotational

Consumable Materials

drag using 0 - 10 pound (0 - 4.536 kg)

(Ref. Section 91−00−00)

spring scale hooked over one of hub

Item

Nomenclature

support web bosses, 6.5 inch (16.51 cm)

CM206

Chemical coating

from hub centerline). A 1.50 - 1.75

CM216

Loctite remover

pound (0.681 - 0.7945 kg) pull with hub

CM304

Enamel, epoxy

in motion indicates correct rotational

CM321

Surface primer locking compound

drag.

CM431

Sealing, locking and retaining compound

(16). Remove mast nut, tool F (Ref.

Figure 806), (or seal retainer), and

(1). Remove main rotor hub (Ref. Main

upper bearing cone. Remove lead spacer

Rotor Hub Replacement).

and measure compressed thickness.

Obtain serviceable recessed spacer of

(2). Invert hub and place on work bench.

same thickness, or grind new recessed

(3). Remove droop stop ring (Ref. Droop

spacer to required dimension. Discard

Stop Ring Replacement).

lead spacer after recessed spacer is

correctly ground.

(4). Press bearing from hub lug.

NOTE: To insure that hub is seated onto mast

(5). Clean bearing bore with Loctite

properly before torquing, 2 - 4 threads

remover (CM216).

should be showing above the mast nut with

(6). Inspect bearing bore for nicks,

nut installed finger tight.

scratches and grooves.

(17). Install recessed spacer, recess down, on

(7). Inspect bore for diameter of

top of sleeve bushing. Reinstall upper

0.6551-0.6556 inch (16.63954-16.65224

bearing cone, seal retainer and mast

mm).

nut. Torque nut to 200 - 250 foot-

pounds (271 - 339 Nm) and check for

(8). Touch up bearing bore with chemical

rotational drag of 10 - 15 inch-

coating (CM206).

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MD Helicopters, Inc.

MAINTENANCE MANUAL

(9). Apply surface primer (CM321) to

room temperature or heat to 140° -

mating surfaces of bearing and bores

160°F (60° - 72°C) for one hour.

per manufacturer's instructions.

(13). As required, touch up bearing lug with

NOTE: Do not allow primer to enter bearing.

paint (CM304).

(10). Apply locking compound (CM431) to

(14). Check bearing for a no-load rotational

faying surfaces of bearing and bore,

drag of 1.0 - 2.0 inch-pounds (0.113 -

press bearing into bore while locking

0.226 Nm).

compound is wet.

(15). Reinstall droop stop ring (Ref. Droop

(11). Remove excess sealant, do not allow

Stop Ring Replacement).

sealant to enter bearing.

(12). Apply a small fillet of sealant around

(16). Reinstall main rotor hub (Ref. Main

bearing and allow to dry for 24 hours at

Rotor Hub Replacement).

Page 816

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CSP-HMI-2

MAINTENANCE MANUAL

STRIKER

STRIP

SEALANT

(NOTE 2)

PITCH BEARING

(NOTE 1)

PITCH

(NOTE 1)

HOUSING

DROOP SHIM

WASHER (NOTE 9)

SPACER

LAMINATED

STRAP PACK

SEALANT

STRIKER

(NOTE 2)

PLATE

PITCH CONTROL

DROOP RESTRAINER

BEARING HOUSING

AND ROLLER

SEAL

UPPER BEARING CUP

(NOTE 4)

(NOTE 10)

UPPER BEARING CONE

HUB

(NOTE 10)

SEAL

RECESSED SPACER

RETAINER

(NOTE 3)

SEAL

(NOTE 4)

PIVOT PIN

SEALANT

(NOTE 2)

LOWER

SHOE

NOTE 1

NOTE 11

NOTES:

DROOP STOP

HEAVY LINES INDICATE REINFORCED

NOTE 5

RING

SEAL

TEFLON BEARINGS (TYPICAL)

(NOTE 4)

SEALANT (CM425) APPLIED TO LOCATIONS SHOWN.

HUB OUTER

LOWER BEARING CUP

RECESSED SPACER SPECIALLY GROUND TO ESTABLISH CORRECT

LINER

(NOTE 10)

ROTATIONAL DRAG ON TAPERED BEARINGS, INSTALLED RECESS

DOWN ON TOP OF SLEEVE BUSHING.

SEAL TO BE UPWARD.

BEARING AND CAVITY TO BE FILLED WITH GREASE (CM111).

EARLY CONFIGURATION MODIFIED BY HUGHES SERVICE NOTICE DN-3.

ON CURRENT CONFIGURATION, RIVET IS REPLACED BY SCREW, WASHER, AND NUT.

SEALANT (CM420) APPLIED TO SURFACES SHOWN.

DROOP SHIM WASHERS ARE INSTALLED AS REQUIRED TO OBTAIN PROPER ROTOR

DROOP ANGLE.

10. DO NOT INTERMIX TIMKEN AND NTN BEARING CUPS AND CONES AT UPPER AND LOWER

TAPERED BEARING LOCATIONS.

11. DROOP STOP FOLLOWER T-HEAD TO BE OFFSET AWAY FROM LOWER SHOE.

G62-2014-1B

Figure 805. Main Rotor Hub − Cross Section (Sheet 1 of 2)

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

2.875 IN. (7.3025 CM)

CUT OUT AFTER

0.50 IN.

OUTSIDE DIAMETER

BEVELING

(12.7 MM)

3.50 IN. (8.89 CM)

OUTSIDE DIAMETER

3.875 IN.

(9.8425 CM)

11.0 IN.

(27.94 CM)

5.75 IN.

3.375 IN.

(14.605 CM)

0.375 IN.

(8.5725 CM)

(9.525 MM)

0.1875 IN. (4.7625 MM)

0.203125 IN. (5.159375 MM)

4130 STEEL PLATE

WALL STEEL PIPE

4.40 IN.

4.30 IN.

(11.176 CM)

(10.922 CM)

2.58 IN.

0.30 IN.

(6.5532 CM)

(7.62 MM)

3.50 IN.

(8.89 CM)

2.0 IN.

(5.08 CM)

ALUMINUM ALLOY

STEEL RING WASHER

TOOL USE:

A & B - PRESS BEARING CUPS OUT OF HUB

C - PRESS LOWER BEARING CONE ON SLEEVE BUSHING

D - PRESS UPPER BEARING CUP INTO HUB

E - PRESS LOWER BEARING CUP ONTO HUB

F - IN PLACE OF UPPER SEAL RETAINER WHILE ADJUSTING ROTATIONAL DRAG

G - HUB BEARING REMOVAL - FABRICATION

G62-2010-1

Figure 806. Tapered Bearing Tools − Main Rotor Hub (Sheet 1 of 2)

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

MAIN ROTOR HUB

REMOVAL/INSTALLATION

1. Main Rotor Hub − General

(3). Remove lockwire and disconnect

flexible boot from lower end of hub

(Ref. Figure 402) The main rotor hub consists

liner.

of a central hub, six identical pitch housings

(4). Disconnect each pitch control rod from

spaced 60 degrees apart horizontally around

pitch housing.

the hub with associated mechanisms and

linkages. Lead-lag links, a lead-lag damper, a

(5). Disconnect scissors crank from main

droop stop striker strip and spacer, and a pitch

rotor hub or scissors link.

control bearing with each pitch housing

produce the pivoting axis, blade flapping stop

NOTE: To facilitate assembly, color code each

contact surfaces and lead-lag hinge function

pitch control rod to match pitch housing to

for the rotor blades. Six laminated retention

which it is attached.

strap assemblies that are flexible both

(6). Remove two screws securing retainer to

vertically and torsionally extend through the

main rotor hub nut.

pitch housings and connect to the lead-lag

links. A lower shoe, attached to the central

(7). Remove nut retainer.

hub, contains a droop stop ring and droop

restrainers that support the blades at rest and

(8). Using main rotor mast nut wrench

distribute droop loads at low blade rpm. The

(ST701), remove nut from mast.

following instructions provide field mainte

(9). Using hub puller (ST702), break loose

nance and repair procedures for the main rotor

main rotor hub. Remove hub puller.

hub.

(10). Attach hoisting adapter (ST201), to

2. Main Rotor Hub Replacement

eyebolts and hoist hub from mast.

B. Main Rotor Hub Installation

A. Main Rotor Hub Removal

(Ref. Figure 402)

(Ref. Figure 401)

Consumable Materials

Special Tools

(Ref. Section 91−00−00)

Item

Nomenclature

Item

Nomenclature

CM111

Grease, aircraft

ST201

Hoisting adapter

CM115

Grease, oscillating bearing

ST701

Main rotor wrench assembly

CM204

Compound, corrosion preventative

ST702

Hub puller

CM702

Lockwire CRES

Special Tools

(1). Remove main rotor blades.

(Ref. Section 91−00−00)

Item

Nomenclature

(2). Remove main rotor drive shaft; then

ST201

Hoisting adapter

reinstall hoisting eyebolts, washers and

nuts in rotor hub. Locate them to

ST701

Main rotor wrench assembly

correspond with lugs of hoisting

ST703

Main rotor hub driver

adapter (ST201).

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MAINTENANCE MANUAL

Main rotor hub is a highly

(5). Hand-pack hub cavity, between sleeve

CAUTION

stressed component. Use ex

bushing and hub, with grease (CM111).

treme care to prevent it from striking any

(6). Place recessed spacer, recess down, on

object. Any impact damage may require re

top of sleeve bushing.

placement of hub.

(7). Hand-pack upper bearing cup and cone

NOTE:

with grease; then install cone on mast

D Removal of recessed spacer, upper bear

and use hub driver (ST703), to fully

ing cone, upper seal and seal retainer is

seat cone.

not mandatory for installation of the

main rotor hub. If these items are in

(8). Fill remaining cavity to upper seal with

stalled, perform steps (1). thru (4). and

grease.

(11). thru (22). Caution should be used

(9). Position upper seal in seal retainer

when installing hub to prevent damage to

with lip up; then press seal and retain

these parts.

er in hub counterbore.

D If recessed spacer, upper bearing cone,

upper seal and seal retainer have been re

(10). Using a soft drift, carefully tap seal

moved, these parts should not be as

outer ring to seat in counterbore. Wipe

sembled in hub before installation of hub

away any excess grease.

on helicopter. These items are reas

(11). Apply grease (CM111) to exposed

sembled in hub after seating hub on mast.

threads on mast.

Prior to installing main rotor hub, insure

that all bearings are adequately serviced

Ensure that seal is properly po

CAUTION

with grease (CM111).

sitioned against seal retainer

and that seal retainer does not pinch seal.

D Replacement main rotor hubs do not come

Check by inserting a loop of approximately

balanced from MDHS. If installing a re

0.050 inch (1.27 mm) diameter lockwire,

placement hub, perform a main rotor sys

tem balance (Ref. Sec. 18-10-60, Main

round feeler gage or other suitable tool with

Rotor System Balance Procedure).

out sharp edges between seal lip and retain

er.

(1). Attach hoisting adapter (ST201) to

NOTE: To insure that hub is seated onto mast

eyebolts in main rotor hub and connect

properly before torquing, two to four threads

suitable hoist.

should be showing above the mast nut with

If hub assembly (with sleeve

nut installed finger tight.

CAUTION

bushing, spacer, upper bearing

(12). Install mast nut, using wrench (ST701);

and seal retainer installed) does not seat

torque nut to 200 foot-pounds (271

properly onto mast, do not attempt to force it

Nm). Apply coat of corrosion preventive

into position. Remove hub assembly from

compound (CM204) to screw holes in

mast and determine cause of hub not seat

mast nut.

ing, correct the problem and follow the pro

cedures for reinstallation.

(13). Place retainer on nut and check

retainer-to-nut screw hole alignment.

(2). Check that rotor mast is clean. Hoist

main rotor hub and position over mast;

(14). Increase nut torque to not more than

then lower hub onto mast.

250 foot-pounds (339 Nm) to align

holes in retainer and nut.

NOTE: To inhibit mast corrosion when operat

ing in salt water environment, lightly coat

NOTE: If holes cannot be aligned in 200 - 250

bearing journals of mast with grease

foot-pound (271 - 339 Nm) torque range,

(CM115).

remove and invert nut and repeat proce

dures in (12). thru (14). to align holes.

(3). Remove adapter, hoist and eyebolts.

(15). Secure retainer to nut with two screws;

(4). Check that hub is fully seated on mast.

safety screws with lockwire (CM702).

Page 402

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CSP-HMI-2

MAINTENANCE MANUAL

MAIN ROTOR

PULLER

ROTOR HUB

6G62-009A

Figure 401. Pulling Hub Assembly

Ensure that no washers are

(21). Install main rotor blades.

CAUTION

used under screw heads and

that screw heads are free of burrs.

(22). Perform main rotor blade droop angle

check if hub is new or replacement.

(16). Verify that screwheads do not project

more than 0.020 inch (0.508 mm) above

hub upper surface, for adequate

(23). Perform main rotor system balance

clearance between screw heads and

(Ref. Sec. 18-10-60, Main Rotor System

driveshaft flange.

Balance Procedure) if a new or rebuilt

hub is installed.

(17). Connect scissors crank to main rotor

hub lower shoe and/or to scissors link.

3. Main Rotor Damper

NOTE: Ensure pitch control rods are installed

at same locations from which removed.

(Ref. Figure 603) A main rotor damper is

(18). Install pitch control rods to pitch

attached to each pitch housing of the rotor

housings (Ref. Sec. 62-30-60, Pitch

hub. The damper is connected to the inboard

Control Rod Replacement).

trailing edge of the associated main rotor blade

by an adjustable clevis to prevent lateral

(19). Connect flexible boot to lower end of

vibrations from occurring in main rotor blades.

rotor hub liner and secure with lock

Neither damper travel nor stiffness is adjust

wire (CM702).

able on the helicopter. Phasing of rotor blades

is affected by turnbuckle adjustment. Any

(20). Install main rotor drive shaft (Ref. Sec.

phasing problem caused by a defective damper

63-10-00).

should be corrected by replacing damper.

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MD Helicopters, Inc.

MAINTENANCE MANUAL

Excessive lead-lag load applied

NOTE: Ensure that bushing is installed in

CAUTION

to the main rotor blades during

large hole of damper ears.

ground handling can result in damage to the

(2). With damper rotational direction decal

elastomeric damper buns and failure of the

facing outboard so it can be read, attach

damper assembly. Operators and mainte

damper ears to pitch housing lug with

nance personnel should use extra caution to

bolt (head up), washers, and nut.

avoid lead-lag loads in excess of 35 pounds

Torque nut to 30 - 60 inch-pounds

(155.68 N) at the tip of the main rotor

(3.39 - 6.78 Nm) and install cotter pin.

blades.

NOTE: If one or more main rotor blades strike

(3). Adjust main rotor blade phasing for

an object while rotating or the drive system

associated main rotor blade.

has been subjected to sudden stop, inspect

(4). After final phasing adjustments, torque

damper.

jamnuts to 95 - 110 inch-pounds

(10.73 - 12.43 Nm). Safety jamnuts to

4. Main Rotor Damper Replacement

turnbuckle with new lockwire. Lock

A. Main Rotor Damper Removal

wire must be located out-board, away

from pitch housing.

(1). Note and record location from which

damper is to be removed from main

NOTE: Threaded end of damper turnbuckle

rotor hub.

shaft must protrude through clevis base a

minimum of two full threads and must clear

NOTE: At reinstallation, if damper is not rein

blade damper attach fitting.

stalled at same location, a check of and/or

blade phasing is required.

(5). Connect damper to blade.

(2). Support blade parallel to ground.

(6). Remove blade support.

(3). Remove damper.

5. Main Rotor Damper Nominal Adjustment

NOTE: If damper is to be reinstalled at same lo

(1). Remove main rotor blade dampers from

cation, do not disturb damper clevis, jam

helicopter if installed.

nuts or turnbuckle setting. Otherwise, blade

phasing is required at reinstallation of

(2). Store all dampers together in horizontal

damper.

position for minimum of six hours.

(4). If damper is not to be reinstalled,

Preferred ambient temperature during

remove bushing from damper ear and

storage is 55° to 85°F (13° to 30°C).

retain with hub.

(3). Set damper length, centerline-to-cent

B. Main Rotor Damper Installation

erline of bolt attach holes, for initial

installation.

(1). Check, and if necessary, preset main

600N

rotor damper length (Ref. Nominal

8.132 ±0.005 inch (206.553 ±0.127 mm.

Damper Adjustment Procedure). Leave

jamnuts fingertight.

(4). Install dampers on helicopter.

Page 404

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CSP-HMI-2

MAINTENANCE MANUAL

MAIN ROTOR HUB

INSPECTION/CHECK

1. Main Rotor System Balancing − General

(3). Inspect droop stop ring for corrosion,

dents and scratches. If defects are

Main rotor system balancing is accomplished

found, repair or replace.

by adding or removing weight (flat washers) as

NOTE: To inhibit corrosion, spray droop stop

required at the lead-lag bolts. Analysis of

ring, rollers and pitch bearings with spray

main rotor system balance is accomplished

lubricant (CM104).

using instrumentation that measures and

localizes vibrations due to main rotor system

(4). Inspect droop stop roller for flat spots,

imbalance. Data provided by the instrumenta

pit marks and looseness on roller shaft.

tion is plotted on a chart designed to indicate

(5). Inspect striker plate for dents and pit

how much weight must be added or removed

marks that exceed 0.030 inch (0.762

from the lead-lag bolt. No other means of

mm) depth. Damage exceeding this

balancing is to be used. If there is ground

limit requires replacement of striker

rocking, or if one-per-rev lateral (main rotor)

plate.

vibration occurs during flight refer to Sec.

18-10-60, Main Rotor System Balance

(6). Press each pitch housing downward

Procedure.

several times and check for evidence of

binding pitch bearing or droop restrain

er follower. Inspect visible portion of

2. Main Rotor Hub Inspection

droop restrainer for cracks and follower

spring for breaks.

Consumable Materials

NOTE: Do not remove tetrafluoroethylene

(Ref. Section 91−00−00)

(TFE) debris which works out of pitch bear

Item

Nomenclature

ing edge. Debris is normal and helps lubri

CM104

Lubricant, spray

cate bearing. Removal of debris increases

bearing wear rate.

(7). Use bright light and 5-power magnify

(1).

Inspect pitch housing for scratches,

ing glass to inspect all main rotor hub

nicks and cracks. No cracks are permis

lead-lag links (Ref. Figure 805) for

sible. Scratches and nicks must be

discoloration, pitting, intergranular

cleaned up before measuring depth of

cracks or stress corrosion cracks. Any

damage to determine housing service

discoloration or pitting is evidence of

ability.

more than superficial corrosion and

main rotor hub must be removed for

(2).

Inspect sleeve bushing (Ref. Figure 805)

replacement of lead-lag links.

for snug fit in pitch housing arm clevis

lug; if bushings are loose, remove and

NOTE: Normal or premature overhaul requires

inspect. Inspect lug for evidence of wear

visual inspection plus dye-penetrant in

caused by bushing movement. Maxi

spection of links for same conditions.

mum allowable diameter for hole in

each lug is 0.4380 inch (11.13 mm).

(8). Inspect lead-lag link stop for broken

Inspect inner surfaces of all pitch

spring, cracks, breaks or visible bond

housing arm clevis lugs for chafing

line cracks.

caused by misaligned pitch control rod

(9). Inspect interiors of lead-lag bolts using

end bearings. Chafing is in form of

bright light and 5X glass for cracks or

crescent-shaped grooves. If chafing

corrosion per Lead-Lag Bolt Inspection.

wear exists, repair or replace. Chafed

area must be cleaned up before measur

(10). Inspect each striker strip for cracks,

ing depth of damage to determine

deformation and badly worn contact

housing serviceability.

surfaces.

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CSP-HMI-2

MAINTENANCE MANUAL

(11). Inspect all parts of main rotor hub for

NOTE: Excessive amount of sealant can unbal

cracks, breaks, scratches and nicks.

ance rotor system. Apply light but thorough

(Refer all questionable damage to

coat of sealant.

MDHI for disposition.)

(f). Install new cotter pin to secure nut to

(12). Inspect lower shoe scissors attach

lead-lag bolt.

bearings for binding, looseness in bore

and wear. Maximum wear limits are

4. Main Rotor Strap Pack Lamination

0.010 inch (0.254 mm) radial and 0.020

Inspection

inch (0.508 mm) axial.

(13). Inspect each of six main rotor retention

CAUTION

strap packs (Ref. Main Rotor Strap

Pack Lamination Inspection) at

D Figure 601 and Figure 602 depict the

specified intervals (Ref. Section 05-10).

main rotor hub and strap pack assembly

disassembled for clarity of location and

3. Lead−Lag Bolt Inspection

area to be inspected for cracks. Under no

circumstances should the strap pack or

Consumable Materials

main rotor hub assembly ever be disas

(Ref. Section 91−00−00)

sembled in the field. MDHI and MDHI

Item

Nomenclature

Approved Licensees are the only ap

proved repair stations for main rotor hub

CM318

Primer

assembly overhaul.

CM425

Sealing compound

D If a hub assembly or strap pack assembly

(other than new parts in storage) are sub

(1). Inspect interiors of lead-lag bolts using

jected to extended periods of non-use,

bright light and 5X glass for cracks or

whether installed on the helicopter or not,

corrosion.

the strap assembly should be inspected

critically for corrosion and pitting before

(a).

Remove cotter pin securing nut to

return to service. If corrosion is found on

lower end of lead-lag bolt. Do not

the strap pack assemblies, contact MDHI

disturb torque on nut or remove nut.

for disposition.

(b).

Remove screw, nut, washers and

D It is acceptable to operate a helicopter

balance hardware, if installed, from

with a hub assembly having a strap pack

lead-lag bolt.

with one failed laminate in any one leg of

the strap assembly. When a laminate in

(c).

Inspect bolt interior. Treat minor

the strap assembly fails, the remaining

surface corrosion if noted (Ref.

laminates pick up and carry the load. This

Lead-Lag Bolt Corrosion Control). If

increased load causes slightly more elon

corrosion pitting or cracks are noted

gation in the remaining laminates of that

remove and replace hub.

leg thus shifting the mass of the rotor sys

tem. Any time a vibration develops or

(d).

Swab entire ID of bolt with primer

there is an increase in vibration level over

(CM318).

a short period of time, the main rotor

(e).

Reinstall screw, nut, washers and

strap pack assembly should be inspected

balance hardware removed in step 2.

for cracked or failed laminates.

Ensure hardware is installed exactly

as removed. Torque MS21042L08

NOTE: Conduct inspection indoors, if possible,

locknut on screw to 20 - 35 inch-

or in a shaded area to eliminate glare of sun

pounds (2.26 - 2.82 Nm). Torque

or bright outdoor light. To facilitate inspec

MS21042L3 locknut on screw to 30 -

tion, field fabricate and use plastic inspec

60 inch-pounds (3.39 - 6.78 Nm).

tion tool and wooden probe (Ref Figure 602).

Coat exposed screw threads, washers

and nut with sealant (CM425).

(1). Remove main rotor blades.

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CSP-HMI-2

MAINTENANCE MANUAL

PLASTIC

WOODEN OR

INSPECTION TOOL

PHENOLIC PROBE

0.125 INCH

(3.175 MM)

LEAD LEG

LAMINATE HAS FAILED IF CRACK OCCURS

ON BOTH LEAD AND LAG LEGS OF SAME

LAMINATE.

0.250 INCH

(6.35 MM)

LAG LEG

LAMINATE HAS FAILED IF CRACK OCCURS

IN TONGUE OF LAMINATE (SHADED AREA

TONGUE

SHOWN BEYOND JOINT OF STRAP PACK

6.00 INCH

LEGS).

(15.24 CM)

4.00 INCH

1.5 INCH

10.16 CM)

(3.81 CM)

(REF)

ONE LAMINATE FAILURE AS DEFINED IN 1

1.00 INCH

AND/OR 2 ARE ALLOWED IN EACH STRAP

0.50 INCH

(2.54 CM)

PACK ASSEMBLY. (TOTAL OF SIX LAMINATE

(12.7 MM)

FAILURES PER HUB ASSEMBLY.)

0.050-0.125 INCH

(1.27-3.175 MM)

FIELD FABRICATION INSPECTION TOOLS

ALUMINUM CHISEL NOT SHOWN

(REF. TABLE 601, NOTE 2)

STRAP PACK IS REJECTED IF TWO OR MORE

LAMINATES IN SAME PACK HAVE FAILED AS

DEFINED IN 1 AND/OR 2 ABOVE.

STRAP PACK IS REJECTED IF THREE OR MORE

LAMINATES IN SAME PACK ARE CRACKED IN

THE LEG (LEAD OR LAG).

FAILED LAMINATE IF CRACK IS

FOUND ON EITHER EDGE OF

LAMINATE. IF ONE LAMINATE

HAS FAILED IN THIS AREA,

REPLACE HUB.

CAUTION:

DO NOT DISASSEMBLE STRAP PACK ASSEMBLY,

LAMINATIONS ARE SHOWN SEPARATED ONLY TO

DEPICT POSSIBLE CRACK LOCATIONS.

NOTE:

ANY CRACK IN LAMINATE IS CONSIDERED A BREAK.

1.50 INCH

THE LAMINATE HAS NOT FAILED HOWEVER, UNLESS

(3.81 CM)

BOTH LEAD AND LAG LEGS ARE CRACKED, CRACK

IS LOCATED IN TONGUE AREA OF LAMINATE OR IS

UNDER SHOES (SEE DETAIL 6).

6G62−078−2B

Figure 602. Strap Pack Lamination Inspection (Sheet 2 of 2)

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MD Helicopters, Inc.

MAINTENANCE MANUAL

Table 601. Strap Pack Inspection

Replace or Return

Inspect

Procedure (1)

For

Acceptable

Hub for Overhaul

Outboard end.

Visually. Use blunt nosed

Failed laminates

One or less per

Two or more laminate

wooden or phenolic probe

(3).

pack.

failures in one pack.

(Figure 602). Probe at

upper and lower end of

pack. Failed laminate in

lead or lag leg will move

away from other

laminates.

Visually.

Gaps between

Single straight

More than one gap

laminates.

gap not exceed-

found; gap exceeds

ing 0.03 inch

acceptable limit.

(0.762 mm) within

pack or next to

either upper or

lower outer shoe.

Visually using light and

Cracks or breaks.

None.

Cracks or breaks are

mirror (2).

noted.

In area of and

Visually with light and

Cracks or breaks.

One or less

Two or more laminate

within pitch

mirror (2).

laminate failures

failures (2) in a pack;

housing assem-

per strap pack (2).

two or more laminates

blies.

in pack with crack in

same leg (lead or lag).

Cushioning

Visually with light and

Crack or break.

None

Cracks or breaks are

laminates at

mirror.

noted.

each of two

attach points.

NOTES:

(1) Conduct visual inspections indoors or in shaded area to eliminate glare of sun or bright outdoor light.

(2) Removal of teflon covering is required for visual inspection of laminate edges. Use aluminum chisel,

fabricated from stock 0.025 x 6.00 x 0.100 (6.35 x 152.4 x 25.4 mm) to carefully scrape excess

interlaminate teflon sheets from both sides of strap pack between top and bottom shoes at outboard

attachment bolt of all six strap packs. Remove excess teflon from a point 0.50 inch (12.7 mm) outboard of

bolt centerline to 1.50 inches (38.1 mm) inboard of bolt centerline. Field fabricate and use plastic tool (Ref.

Figure 602). Run plastic tool in both directions along each laminate feeling for cracked laminate. Use of

plastic tool will ensure that shreds of teflon still hanging free does not obscure small cracks.

(3) Laminate has failed if crack is found in tongue area or if crack is found in both legs (lead and lag).

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MAINTENANCE MANUAL

(2). If required, trim teflon from edges of

(6). Use the following as acceptance/rejec

laminates using a aluminum chisel.

tion criteria for laminate inspection:

Fabricate chisel from stock, 0.250 x 6.00

(a). A laminate has failed if cracked in

x 0.100 inch (6.35 x 152.4 x 25.4 mm).

tongue area or in lead and lag legs of

Carefully scrape excess interlaminate

the same laminate.

teflon sheets from both sides of strap

pack between top and bottom shoes at

(b). Reject strap pack and return hub

outboard attachment bolt of all six

for overhaul when:

strap packs.

1). Two or more laminates in a single

NOTE:

strap pack have failed.

D Do not pry at strap pack assemblies with

sharp or hard edged tools. If edges become

2). Two or more laminates in a single

nicked or laminates get scratched, addi

strap pack are cracked in the same

tional cracking can occur thus causing

lead or lag leg.

hub replacement.

3). One laminate is cracked at the

D Where accessible, ends of acceptable

outboard end in the area between

cracked or broken laminates should be

outboard shoes (Ref. Figure 602).

taped to prevent scratching and damag

ing of adjacent laminates.

4). There are two or more gaps in the

same strap pack. A single gap in

(3).

(Ref. Figure 602 for field fabricate

any one strap pack assembly is

plastic tool) Run plastic inspection tool

allowed.

in both directions along each laminate,

feeling for a ``catch'' from a crack on a

(7).

Visually inspect strap pack assemblies

single laminate. Use the wooden or

for evidence of corrosion. If corrosion is

phenolic probe and probe at upper and

found on strap pack laminates contact

lower end of pack. Failed laminate in

MDHI service department for disposi

lead or lag will move away from the

tion.

other laminates. If the adjacent upper

and lower laminates remain in tension

(8).

Inspect upper, lower and center cush

under the probing operation, no

ioning laminates for cracks and breaks

laminate failures have occurred.

(Ref. Figure 601).

(4).

Using a light and mirror, visually

NOTE: Cracks, breaks or other noticeable dam

inspect each of the main rotor strap

age to the cushioning laminates require

pack assemblies for evidence of cracks

main rotor hub overhaul/replacement.

or breaks in strap pack laminates in the

areas of the outboard shoes and pitch

(9). Record location of all cracked/broken

housing assemblies.

laminates in Helicopter Log Book

including strap serial number, blade

(5).

Using a 10X magnifying glass, visually

color, leg (lead or lag) and laminate

inspect the edge of strap pack lami

position, if possible, numbering from

nates on both sides at outboard end of

the top down.

blade pitch housing (area between

outboard shoes).

(10). Install main rotor blades.

Page 607

62-20-60

Revision 33

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

5. Main Rotor Hub Droop Angle Check

(7). Maximum allowable static droop angle

is six degrees. If measured droop angle

(Ref. Figure 805) Whenever new or replacement

exceeds six degrees, inspect striker

main rotor hub is installed or whenever excessive

plate and roller for excessive wear and

droop angle is suspected, measure static droop

adjust droop angle (Ref. Main Rotor

angle of all six rotor blades. Droop angle must be

Hub Droop Angle Adjustment).

5.5 ±0.5 degrees.

6. Main Rotor Damper and Attachments

Inspection

Special Tools

(Ref. Section 91−00−00)

Excessive lead-lag load applied

CAUTION

Item

Nomenclature

to the main rotor blades during

ground handling can result in damage to the

ST206

Prop protractor

elastomeric damper buns and failure of the

Left−Hand Command:

damper assembly. Operators and mainte

ST501

Collective rigging fixture

nance personnel should use extra caution to

(LH command)

avoid lead-lag loads in excess of 35 pounds

ST504

Longitudinal rigging fixture

(155.68 N) at the tip of the main rotor

(LH command)

blades.

ST506

Lateral rigging fixture

(1). Inspect bearing in rotor blade and

(LH command)

bearing in the pitch housing for

Right−Hand Command

looseness around outer race. No degree

ST502

Collective rigging fixture

of radial or axial play is permitted.

(RH command)

(2). Inspect pitch housing and blade

ST505

Longitudinal rigging fixture

bearings for binding, galling, or scoring

(RH command)

in bore and for wear. No radial play is

ST507

Lateral rigging fixture

permitted. Maximum allowable axial

(RH command)

play is 0.015 inch (0.381 mm).

(3). Inspect clevis bushings for wear and

(1).

Install cyclic lateral rigging fixture

looseness.

(ST506 or ST507), cyclic longitudinal

rigging fixture (ST504 or ST505), and

(4). Inspect damper flange bushing for wear

collective rigging fixture (ST501 or

and play.

ST502).

(5). Inspect lower bolt hole in damper

flange for wear.

(2).

Rotate main rotor to position one blade

over tailboom.

(6). Inspect damper housing (including

flanges) for damage.

(3).

Raise and support other five blades

until five corresponding droop stop

(7). Inspect damper turnbuckle, jamnuts

rollers no longer contact their striker

and safetywire for security. No end play

plates.

is permitted when manually tested.

(4).

Place accurate prop protractor (ST206)

NOTE: When performing lead-lag of main ro

on top of main rotor drive shaft. Adjust

tor blades, apply rotor brake (if installed) or

protractor to zero setting.

have assistant hold main rotor hub from

moving. A second assistant is recommended

(5).

Place protractor on machined surface of

to measure approximate damper extension

outboard end of blade pitch housing,

and compression.

alongside lead-lag bolthead. Measure

and record static droop angle.

(8). Lead-lag each main rotor blade in turn

to provide approximately 0.10 inch

(6).

Repeat (2). thru (5). above for remain

(2.54 mm) extension and compression of

ing blades.

the damper elastomer.

Page 608

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

(9). Visually check each damper in turn for

(3). Attach damper end cap to holding bar

cracks in elastomer or in elastomer-to-

or fixture.

metal bond at end face of damper: If

NOTE: Perform weight loading and extension

bonding or elastomer cracks are noted,

check at ambient temperature of 70° ±l0°F

measure depths of cracks, using depth

(21° ±5°C). Apply total 100 pound (45.359

gage fabricated of shim stock or

kg) weight load to damper at one time, not in

equivalent having a 0.20 inch (5.08

weight increments.

mm) indication. If depth of crack

exceeds 0.20 inch (5.08 mm), remove

(4). Using hydraulic jack or equivalent,

and check damper.

raise and attach 100 pound (45.359 kg)

weight load at damper clevis end.

7. Main Rotor Damper Weight Loading and

Slowly lower jack to avoid shock

Extension Check

loading. After period of two minutes

under load, measure damper extension

(Ref. Figure 603)

on dial indicator.

(1). Remove damper assembly (Ref. Main

(5). If extension exceeds 0.063 inch (1.6002

Rotor Damper Removal).

mm), replace the damper assembly.

(2). Attach dial indicator or equivalent to

(6). Reinstall existing damper; or as

outer case of damper; position indicator

required; install replacement damper.

arm on center aluminum disc as shown.

NOTE: If replacement damper is installed, re

NOTE: Fabricate holding bar or fixture capable

cord part number, serial number, and other

of sustaining 100 pound (45.359 kg) static

pertinent information in Components Re

load (Ref. Figure 603).

cord of helicopters Log Book.

Page 609

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Revision 25

MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

MAIN ROTOR HUB

REPAIRS

1. Main Rotor Retention Strap Pack Repair

If droop shim washers are in

CAUTION

stalled between spacer and

Where accessible, ends of permissible cracks or

striker strip, they must be retained for rein

broken laminates (Ref. Table 601) should be

stallation to establish correct static droop

taped to prevent scratching and damaging

angle between pitch housing and hub.

adjacent laminates.

(2). Carefully remove spacer by sliding it

downward past striker strip. Retain

Consumable Materials

exact number of droop shim washers, if

(Ref. Section 91−00−00)

installed.

Item

Nomenclature

(3). Slide bearing housing assembly off

CM234

Solvent, dry-cleaning

pivot pin. Inspect pivot pin for grooving

CM725

Tape, electrical, plastic

or excessive wear.

NOTE: Do not remove tetrafluoroethylene

Do not bend broken ends exces

(TFE) debris which works out of pitch bear

CAUTION

sively and scratch adjacent

ing edge. Debris is normal and helps lubri

straps.

cate bearing. Removal of debris increases

bearing wear rate.

(1). Carefully wipe ends of broken strap

with a clean soft cloth moistened with

(4).

Remove and discard pitch bearing if

solvent (CM234).

defective, total radial looseness of

assembled ball and pivot pin must not

(2). Use mild blast of filtered air to dislodge

exceed 0.010 inch (0.254 mm).

any foreign particles between broken

(5).

Replace striker strip if it is cracked or

strap ends and adjacent strap.

lead-lag contact areas are worn

through hard anodized surface.

(3). Carefully tape broken ends of strap

with plastic electrical tape (CM725).

(6).

Remove sealant between pitch housing

and striker strip. use care not to scratch

2. Pitch Control Bearing Housing Assembly,

pitch housing. Remove striker strip

Spacer or Striker Strip Replacement

from pitch housing.

(Ref. Figure 801)

(7).

Cut old striker strip to facilitate

removal from retention strap assembly.

Consumable Materials

Do not scratch strap assembly.

(Ref. Section 91−00−00)

Item

Nomenclature

(8).

Clean old sealant from pitch housing

using 1,1,1, trichloroethane (CM222).

CM222

1,1,1-Trichloroethane

CM425

Sealing compound

(9).

Cut out area of new striker strip.

Deburr, smooth and radius cut edges.

(1). Support blade and pitch housing from

(10).

Apply sealant (CM425) to faying

beneath. Remove nuts. washers, and

surfaces of the striker strip and pitch

bolts that secure bearing housing.

housing.

Page 801

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

2.50 INCH

(6.35 CM)

CAUTION:

DO NOT SCRATCH STRAP PACK WHEN INSTALLING

THROUGH STRAP ASSY.

NOTE:

CUT OUT 0.25-0.50 IN. (6.35-12.70 MM) PIECE OF THE

0.25-0.50 IN.

STRIKER STRIP BETWEEN LOWER BOLT HOLES.

(6.35-12.70 MM)

DEBURR AND RADIUS-CUT EDGES.

(NOTE)

G62-2009A

Figure 801. Striker Strip Replacement

(11). Position pitch control bearing housing

3. Lead−Lag Link Blade Stop Replacement

on pivot pin (Ref. Figure 802).

Replace blade stop if it is broken, cracked, has bro

ken spring, or if there are visible bond line cracks

If droop shim washers were re

(Ref. Figure 802).

CAUTION

moved from between spacer and

striker strip, same exact thickness removed

Consumable Materials

must be reinstalled. There must be an equal

(Ref. Section 91−00−00)

number of washers on each of all three bolts.

Item

Nomenclature

These washers establish correct static droop

between pitch housing and hub.

CM206

Chemical coating

CM217

Isopropyl alcohol

(12). Slide spacer into position between

CM228

Surface cleaner

bearing housing assembly and striker

CM411

Adhesive, epoxy

strip on pitch housing. Install exact

CM802

Abrasive cloth, aluminum oxide

thickness of droop shim washers

removed at time of disassembly. Align

CM803

Crocus cloth

holes for all three bolts.

Lead-lag link assembly must

(13). Install bolts, washers and nuts; torque

CAUTION

not be removed from pitch con

to 50 - 70 inch-pounds (5.65 - 7.91

trol housing for this repair, since retention

Nm) and install safety wire.

bolt cannot be retorqued without special

adapter.

(14). Seal all parting lines (joints) of the

assembly with bead of sealing com

(1). Provide a backup support for link

pound (CM425).

assembly. Use 1/2 inch (12.7 mm) wood

dowel and hammer to drive stop from

(15). Perform droop angle check (Ref. Main

link. Strike dowel sharply to break

Rotor Hub Droop Angle Adjustment).

adhesive bond.

Page 802

Revision 20

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

LEAD-LAG

BOLT

LEAD-LAG LINKS

MAIN ROTOR

STRAP PACK

STRIKER STRIP

PITCH CONTROL BEARING

HOUSING ASSEMBLY

PITCH PIVOT PIN

SLEEVE

(NOTE 3)

BUSHING

SPECIAL WASHER

(NOTE 4)

DROOP SHIM WASHERS

(CAUTION)

HUB

SPACE

NUT RETAINING

PITCH

BRACKET

BEARING

(NOTE 5)

STRIKER

NUT

COUNTERSUNK

PLATE

NOTE 2

HEAD SCREW

PITCH BEARING HOUSING AND

NOTE 1

SPACER - INSTALLATION

0.4328 IN.

LEAD-LAG

(1.03872 MM)

STOP

DIA. MIN.

LEAD-LAG LINK AND STOP

CAUTION:

WASHERS ARE INSTALLED BETWEEN SPACERS AND STRIKER STRIP TO ESTABLISH

CORRECT STATIC DROOP ANGLE BETWEEN HOUSING AND HUB. EXACT NUMBER

REMOVED MUST BE REINSTALLED. THREE PITCH BEARING HOUSING BOLTS MUST EACH

HAVE SAME NUMBER (THICKNESS) OF WASHERS WHEN SHIMMING IS NECESSARY.

NOTES:

FOR REMOVAL, WOOD DOWEL PLACED HERE AND STRUCK SHARPLY WITH

HAMMER TO BREAK STOP BOND.

ALL STOP-TO-LINK SHADED CONTACT SURFACES BONDED WITH ADHESIVE.

THREADED SHANK LIGHTLY LUBRICATED WITH GREASE BEFORE INSTALLATION.

WET PRIMER ON WASHER AND MATING SURFACES BEFORE INSTALLATION.

NUT RETAINING BRACKET IS BONDED TO HUB.

6G62-029A

Figure 802. Main Rotor Hub Components Repair and Installation

Page 803

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Revision 20

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(2).

Using sharp-edge metal scraper,

Do not disturb torque on lead-

CAUTION

carefully scrape any adhesive residue

lag bolts. Special adapter is

from link. If scraper penetrates through

needed to retorque lead-lag bolts.

paint and chemical surface film, surface

(1). Remove and tag or color-code each set

must be refinished. Depth of gouges or

of balance hardware that is installed.

nicks is limited to 0.010 inch (0.254

mm) maximum after rework. Rework

(2). Remove corrosion with grade 180

by smooth blending into surrounding

abrasive cloth (CM802) and finish with

area with grade 320 abrasive cloth

grade 400 abrasive cloth.

(CM802). Final polish with crocus cloth

(3). Swab cleaned surface with MEK

(CM803). Restore chemical film protec

(CM219) and apply unthinned primer

tion (CM206).

(CM318).

(3).

Clean bond area of all contact surfaces

(4). Reinstall original balance hardware

by wiping with cleaner (CM228).

that was removed. Using sealant

Flush-wipe cleaned surface four times

(CM425), reseal balance hardware.

with mixture of equal parts of distilled

water and isopropyl alcohol (CM217) to

5. Pitch Control Bearing Pivot Pin Repair or

remove all traces of phosphoric acid.

Replacement

Rinse cleaned surface with tap water,

(Ref. Figure 802) Minimum allowable pin diame

followed by a rinse of distilled water

ter is 0.4328 inch (10.993 mm). Pivot pin grooving

until surface is ``water break'' free. Dry

or excessive side wear may be polished to original

for 30 minutes minimum at 150°F

finish as long as minimum allowable pin diameter

(66°C).

remains after rework. Replace any pin requiring

more rework as follows.

(4).

Check fit of stop in link. Flange and

radius contact surfaces of stop must

Consumable Materials

mate with link within 0.010 inch (0.254

(Ref. Section 91−00−00)

mm). Maximum clearance between stop

Item

Nomenclature

and inside surfaces of link ears is

limited to 0.020 inch (0.508 mm). This

CM115

Grease, oscillating bearing

tolerance applies to both sides of stop.

CM420

Sealant

(5).

Prepare mixture of epoxy adhesive

(CM411). Apply uniform coating of

(1). Remove pivot pin.

mixed adhesive to all contact surfaces.

(2). Lightly lubricate shank of replacement

Hand press stop into place between link

pivot pin with grease (CM115).

ears until all mating surfaces are in

firm contact. Apply a clamping device

NOTE: Torque pivot pin to 70 - 80 inch-

so that contact is maintained. Cure for

pounds (7.91 - 9.04 Nm), then use 0.002

minimum of eight hours at room

inch (0.0508 mm) feeler gage and check for

temperature, or two hours at 150°F

gap between pin flange and washer on

(66°C).

mounting lug surface. No gap is allowed.

(3). Install pivot pin in mounting lug with

Lead−Lag Bolt Corrosion Control

washer. Torque pivot pin to 250 - 280

inch-pounds (28.25 - 31.64 Nm).

Consumable Materials

Apply sealant (CM420) at junctures of

(Ref. Section 91−00−00)

pivot pin flange, washer and hub.

Item

Nomenclature

6. Droop Stop Roller Repair or Replacement

CM219

Methyl-ethyl-ketone

(Ref. Figure 803) Replace defective droop stop roll

CM318

Primer

er if clearance between roller bearing liner and

CM425

Sealing compound

shaft is more than 0.015 inch (0.381 mm). Roller

CM802

Abrasive cloth, aluminum oxide

shaft outside diameter must not be less than

0.4370 inch (11.0998).

Page 804

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

clearance between striker plates and

Consumable Materials

droop stop rollers.

(Ref. Section 91−00−00)

Item

Nomenclature

(2).

If necessary, release retaining (snap)

ring of each droop stop restrainer from

CM217

Isopropyl alcohol

its groove. Move retaining ring flush

against droop stop follower (T-head) to

(1). Move pitch control bearing housing out

provide additional clearance and reduce

of the way that contacts lower shoe

spring tension.

roller to be removed.

(3).

Remove six droop stop rollers.

NOTE: It may be easier if only one roller is re

(4).

Starting from either scissors crank

moved at one time. The opposing pitch hous

attach lug, number, or color code, all six

ing may be pressed against it's follower to

droop stop follower assemblies in

force opposite follower out and expose roller

clockwise direction for location identifi

shaft for removal. Same condition exists at

cation at replacement. This number

installation.

code should be placed on outer, upper

(2). Remove droop stop roller.

end of plunger and on adjacent area of

lower shoe. Ensure codes are not

(3). Wet down and clean plunger and

accidentally removed during remaining

mating shoe bushing with isopropyl

steps.

alcohol (CM217).

(5).

Compress each droop stop follower and

(4). Install roller, shaft and new cotter pin.

insert a small wedge from the back side

(5). Install pitch control bearing housing.

to hold follower away from droop ring.

(6).

After all followers are compressed,

7. Droop Stop Ring Repair

remove droop stop ring.

(Ref. Figure 803)

When installing droop stop ring,

CAUTION

Consumable Materials

droop stop followers T-Heads

(Ref. Section 91−00−00)

must be offset away from lower shoe to pre

Item

Nomenclature

vent damage to lower shoe.

CM103

Solid film lubricant

(7). Install replacement droop stop ring by

reversing removal procedure, steps (1).

(1). Repair depth limit for corrosion, nicks

thru (6)., making certain to reinstall

or scratches in droop stop ring is 0.007

followers according to markings placed

inch (0.1778 mm) for all surfaces except

thereon prior to removal.

outer edges of ring outer flanges where

(8). Compress follower spring and install

the depth limit is 0.030 inch (0.762

retaining (snap) ring, if removed, in its

mm). All reworked areas must be

groove on each follower.

blended smoothly with 15 to 1 ratio into

surrounding area.

(9). Reinstall droop stop rollers, shafts and

cotter pins.

(2). Spray repaired areas of rings with solid

film lubricant (CM103).

9. Droop Stop Follower (T−Head)

(3). Replace droop stop ring if repair limits

Replacement

are exceeded.

(Ref. Figure 803) Replace the droop stop follower

(T-head) if it is worn, scored or is causing damage

8. Droop Stop Ring Replacement

to the droop stop ring. After the droop stop ring

(Ref. Figure 803)

has been removed, the droop stop follower assem

blies may be removed from hub.

(1). With hub upside down, support hub so

that pitch housings unload droop stop

(1). Remove droop stop follower assembly

followers and provide maximum

from hub.

Page 805

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Revision 37

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

LOWER SHOE

DROOP STOP

PINS

FOLLOWER

(T-HEAD) (NOTE)

SNAP RING

SPRING

COTTER PIN

DROOP STOP

ROLLER

DROOP STOP PLUNGER

SCISSORS CRANK

SHAFT

ATTACH LUG

BEARING ROTATIONAL DRAG

1.0 - 2.0 IN-LBS

(0.113 - 0.226 NM)

DROOP STOP FOLLOWER - INSTALLATION

DROOP STOP

0.007 IN. (0.178 MM) MAX. DEPTH

RING

(15 TO 1 RADIUS) AFTER REWORK

DROOP STOP FOLLOWER

ASSEMBLY (6 PLACES)

LOWER SHOE - INVERTED

0.030 IN. (0.762 MM)

MAX. AFTER REWORK

15 TO 1 RADIUS

DROOP STOP RING - REPAIR LIMITS

NOTE: DROOP STOP FOLLOWER T-HEADS TO

BE OFFSET AWAY FROM LOWER SHOE.

6G62-028C

Figure 803. Droop Stop Ring Replacement and Repair

Page 806

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

(2). Remove pins that secure follower to

(3). Wet down and clean plunger and

plunger.

mating shoe bushing with isopropyl

alcohol (CM217).

Droop stop followers T-Heads

CAUTION

(4). Install droop stop plunger into lower

must be offset away from lower

shoe.

shoe to prevent droop stop ring from damag

ing lower shoe.

(5). Complete droop stop ring installation.

(3). Insert new follower. T-head must be at

(6). Install roller, shaft and new cotter pin.

right angle to roller shaft in plunger.

11. Main Rotor Hub Droop Angle Adjustment

(4). Drill two 0.156-0.158 inch (3.962-4.013

(Ref. Figure 802) If static droop angle exceeds six

mm) diameter holes through follower in

degrees, adjust as follows.

line with holes in plunger.

(1).

Remove main rotor blade.

(2).

Use flat washers of thickness required

(5). Insert pins and stake ends. No burrs or

to adjust spacing between spacer and

roughness permissible after staking.

striker strip. Any one type, or combina

(6). Install follower assembly in hub.

tion, of correct part number washers

(IPC) may be used; however, an identi

(7). Reinstall droop stop ring.

cal washer selection must be installed

on each of three bolts that secure pitch

control bearing assembly to pitch

10. Droop Stop Plunger Removal, Inspection

housing.

and Installation

(Ref. Figure 803)

(3).

Remove nuts, washers and bolts, and

separate spacer from striker strip. The

Consumable Materials

use of one 0.016 inch (0.406 mm)

(Ref. Section 91−00−00)

washer raises static droop angle

Item

Nomenclature

approximately one-half degree. Add

sufficient washers to adjust droop angle

CM217

Isopropyl alcohol

within range of 5.5 ±0.5 degrees.

Reinstall nuts, washers and bolts.

(1). Remove droop stop ring (Ref. Droop

(4).

If more than 0.063 inch (1.6 mm)

Stop Ring Replacement).

spacing is required (above factory

spacing), inspect striker plate and

(2). Check droop stop plunger for wear by

droop stop roller or follower and droop

using the following criteria:

stop ring for excessive wear. Replace as

required.

NOTE: The minimum acceptable diameter af

ter wearing in service should be 0.996 inch

(5).

Reinstall blade. Repeat measurement of

(25.298 mm). The acceptable amount of

static droop angle.

wear though the anodized coating shall not

(6).

As required, repeat above procedures

exceed 40% or 2.1 square inches (28.45

for remaining blades.

square cm) of the total sliding surface area

of the cylinder. The maximum wear condi

(7).

Following reinstallation or replacement

tion may exist in one spot or in several spots

of parts, check track of main rotor

totaling 2.1 inches (28.45 square cm).

blades.

Page 807

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

12. Main Rotor Hub Tapered Bearing Grease

(b). Restore chemical film protection

Repack, Inspection and Replacement

where removed.

(Ref. Figure 805)

(c). Maximum diameter of hub bore for

upper bearing cup (Ref. Figure 805)

Consumable Materials

is 4.4335 inches (11.25 cm), measured

(Ref. Section 91−00−00)

in any direction.

Item

Nomenclature

CM111

Grease, aircraft

(d). Maximum diameter of hub bore for

lower bearing cup is 4.3095 inches

CM121

Preservation oil

(10.95 cm), measured in any direc

CM234

Solvent, dry-cleaning

tion.

CM802

Abrasive cloth, aluminum oxide

CM803

Crocus cloth

(5). Check upper seal retainer:

(a). No cracks, sharp nicks or burrs are

Special Tools

allowed.

(Ref. Section 91−00−00)

Item

Nomenclature

(b). Minor corrosion or other surface

ST701

Main rotor wrench assembly

defects may be polished out using

crocus cloth (CM803).

Do not intermix Timken or NTN

(c). Grooving on seal contact surfaces

CAUTION

bearing cups and cones at upper

must not exceed 0.004 inch (0.10 mm)

and lower tapered roller bearing locations of

depth after polishing.

main rotor hub.

Bearing cups are installed in

NOTE:

WARNING

hub by differential tempera

D Roller bearing cones and cups should al

ture (shrink-fit) method. Take appro

ways be replaced as a set.

priate precautions to prevent burns

when handling parts that are cooled to

D Replace tapered roller bearing cup and

sub-zero temperatures.

cone if it has any flat spots, scoring, pit

ting, grooving, discoloration (blue) or if it

(6).

Place bearing cups in closed container

feels rough when rotated.

of dry ice and cool for not less than 20

minutes to -40°F (-40°C).

(1). Use pressing tools equivalent to items

A and B (Ref. Figure 804) to press

(7).

Coat bores of hub with grease (CM111).

upper and lower bearing cups from hub.

A press ram of one to two tons is

(8).

Use care to maintain cup-to-hub bore

sufficient for removal.

alignment and press cup into bore,

using tools D and E (Ref. Figure 804),

(2). Press lower bearing cone from sleeve

until cup is seated.

bushing.

(9).

Apply film of grease (CM111) to sleeve

In next step, do not spin reus

CAUTION

bushing. Use pressing tool equivalent to

able bearings while cleaning.

tool C, and press bearing cone onto

Coat bearings lightly with oil (CM121) after

sleeve bushing.

cleaning.

(10).

With lip on center seal up, hand press it

(3). Clean hub bore, sleeve bushing, seal

into hub (Ref. Figure 805).

retainer and reusable bearings using

filtered solvent (CM234) spray.

(11).

Apply film of grease (CM111) on mast.

Install preassembled sleeve bearing

(4). Check bearing cup hub bore for scoring:

and bearing cone on mast. Do not apply

(a). Smooth out any roughness with

any additional lubricant to roller

grade 400-600 abrasive cloth

bearing set. Wipe any excess preserva

(CM802).

tive oil from bearing cone and cup.

Page 808

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

2.875 IN. (7.3025 CM)

CUT OUT AFTER

0.50 IN.

OUTSIDE DIAMETER

BEVELING

(12.7 MM)

3.50 IN. (8.89 CM)

OUTSIDE DIAMETER

3.875 IN.

(9.8425 CM)

11.0 IN.

(27.94 CM)

5.75 IN.

3.375 IN.

(14.605 CM)

0.375 IN.

(8.5725 CM)

(9.525 MM)

0.1875 IN. (4.7625 MM)

0.203125 IN. (5.159375 MM)

4130 STEEL PLATE

WALL STEEL PIPE

4.40 IN.

4.30 IN.

(11.176 CM)

(10.922 CM)

2.58 IN.

0.30 IN.

(6.5532 CM)

(7.62 MM)

3.50 IN.

(8.89 CM)

2.0 IN.

(5.08 CM)

ALUMINUM ALLOY

STEEL RING WASHER

TOOL USE:

A & B - PRESS BEARING CUPS OUT OF HUB

C - PRESS LOWER BEARING CONE ON SLEEVE BUSHING

D - PRESS UPPER BEARING CUP INTO HUB

E - PRESS LOWER BEARING CUP ONTO HUB

F - IN PLACE OF UPPER SEAL RETAINER WHILE ADJUSTING ROTATIONAL DRAG

G - HUB BEARING REMOVAL - FABRICATION

G62-2010-1

Figure 804. Tapered Bearing Tools − Main Rotor Hub (Sheet 1 of 2)

Page 809

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Revision 22

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

7.0 INCH (17.78 CM)

SQUARED

4.75 INCH

(12.065 CM)

10.0 INCH (25.40 CM)

0.75 INCH

MATERIAL: WOOD

SQUARED

(19.05 MM)

H62-2010-2A

Figure 804. Tapered Bearing Tools − Main Rotor Hub (Sheet 2 of 2)

If hub assembly does not seat

NOTE: When determining spacer thickness,

CAUTION

properly onto mast, do not at

start with thick spacer and work down to

tempt to force it into position. Remove hub

thinner spacer.

assembly from mast and determine cause of

hub not seating, correct the problem and fol

(a). Install subsequently thinner spacers,

low the procedures for reinstallation.

from kit K-600N-1200A, starting

with a thick spacer, along with cone,

(12). Place assembled hub over mast and

substitute washer for retainer and

seat on lower roller bearing cone.

locknut.

(13). Install upper bearing cone into hub.

(b). Torque nut to to 200 - 250 foot-

NOTE: Use of substitute steel ring washer for

pounds (271 - 339 Nm) until 10 -

retainer prevents unnecessary scoring of re

15 inch-pounds (1.13 - 1.69 Nm)

tainer. Several tightening and loosening ac

of rotational drag (not break-

tions may be required to get rotational drag

away torque) is obtained on hub.

on hub bearings.

(18). When proper torque has been reached,

(14). Install steel ring washer, equivalent to

disassemble and remove steel ring

tool F (Ref. Figure 804), as substitute

washer.

for seal retainer (Ref. Figure 805)

(19). Alternative method for determining

(15). Install mast nut on mast using mast

thickness required for spacer:

nut wrench (ST701), tighten until

bearings are preloaded to 10 - 12

(a). Install 369A1224-5 lead spacer in

inch-pounds (1.13 - 1.36 Nm) of

place of the 369A1224-3 spacer.

rotational drag. Measure rotational

drag using 0 - 10 pound (0 - 4.536 kg)

(b). Place steel ring washer for retainer

spring scale hooked over one of hub

and locknut on the mast and gradual

support web bosses, 6.5 inch (16.51 cm)

ly tighten the retaining nut until

from hub centerline). A 1.50 - 1.75

rolling torque of 10 - 15 inch-

pound (0.681 - 0.795 kg) pull with

pounds (1.13 - 1.69 Nm) of rota

hub in motion indicates correct rota

tional drag (not break-away

tional drag.

torque) is obtained on hub. If the 10

- 15 inch-pounds (1.13 - 1.69 Nm)

(16). Remove locknut, washer and cone.

of rotational drag is exceeded,

(17). To determine thickness required for

discard the lead washer, install new

spacer:

washer and continue.

Page 810

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

(c). When proper torque has been

reached, disassemble and measure

Consumable Materials

thickness of the lead washer in the

(Ref. Section 91−00−00)

bearing seat area. Grind the

Item

Nomenclature

369A1224-3 spacer to the same

CM111

Grease, aircraft

thickness as measured on the lead

CM204

Compound, corrosion preventative

washer. Check thickness of ground

CM121

Preservation oil

washer at six locations to ensure

CM234

Solvent, dry-cleaning

thickness does not vary by more than

CM702

Lockwire CRES

0.0005 inch (0.0127 mm).

CM802

Abrasive cloth, aluminum oxide

(d). Re-assemble with the ground steel

Special Tools

washer, steel ring washer and

(Ref. Section 91−00−00)

locknut and torque to 200 - 250

Item

Nomenclature

foot-pounds (271 - 339 Nm) until

ST701

Main rotor wrench assembly

10 - 15 inch-pounds (1.13 - 1.69

ST703

Main rotor hub driver

Nm) of rotational drag (not

break-away torque) is obtained on

hub.

(1). Remove main rotor hub assembly (Ref.

Main Rotor Hub Removal) and place on

bench.

(20).

Remove hub and sleeve bushing with

(2). Remove upper bearing cone.

lower bearing cone from mast.

Do not intermix Timken or NTN

CAUTION

bearing cups and cones at upper

(21).

Position hub upside-down. Hand-pack

and lower tapered roller bearing locations of

lower hub cavity (Ref. Figure 805) and

main rotor hub.

bearing cone on sleeve bushing with

NOTE:

grease (CM111).

D Roller bearing cones and cups should al

ways be replaced as a set.

(22).

Install sleeve bushing with bearing

D Replace tapered roller bearing cup and

cone in hub. Hand-pack cavity between

cone if it has any flat spots, scoring, pit

bearing and hub liner with grease

ting, grooving, discoloration (blue) or if it

(CM111); then press in lower seal with

feels rough when rotated.

seal lip toward top of hub. Wipe off

excess grease.

(3). Use pressing tools equivalent to items

A and B (Ref. Figure 804) to press

upper bearing cup from hub. A press

(23).

Turn hub assembly right side up.

ram of one to two tons is sufficient for

removal.

In next step, do not spin reus

(24).

Complete reassembly of hub by install

CAUTION

able bearing while cleaning.

ing recessed spacer, upper bearing cone,

Coat bearings lightly with oil (CM121) after

upper seal and seal retainer in hub at

cleaning.

installation of hub on mast.

(4). Clean hub bore, sleeve bushing, seal

retainer and reusable bearing using

filtered solvent (CM234) spray.

13. Main Rotor Hub Upper Bearing Grease

Repack, Inspection and Replacement

(5). Check bearing cup hub bore for scoring:

The following procedure is for greasing, inspection

(a). Smooth out any roughness with

and replacement of the main rotor hub upper

grade 400-600 abrasive cloth

bearing only.

(CM802).

Page 811

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Revision 22

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

(b). Restore chemical film protection

(13). Hand-pack hub cavity, between sleeve

where removed.

bushing and hub, with grease (CM111).

(c). Maximum diameter of hub bore for

(14). Apply film of grease (CM111) on upper

upper bearing cup (Ref. Figure 805)

bearing cone and place into hub.

is 4.4335 inches (11.25 cm), measured

in any direction.

NOTE: Use of substitute steel ring washer for

retainer prevents unnecessary scoring of re

(6). Check upper seal retainer.

tainer. Several tightening and loosening ac

tions may be required to get rotational drag

(a). No cracks, sharp nicks or burrs are

on hub bearings.

allowed.

(15). Install steel ring washer, equivalent to

(b). Minor corrosion or other surface

tool F (Ref. Figure 804), as substitute

defects may be polished out using

for seal retainer (Ref. Figure 805)

crocus cloth (CM803).

(16). Install mast nut on mast using mast

(c). Grooving on seal contact surfaces

nut wrench (ST701), tighten until

must not exceed 0.004 inch (0.10 mm)

bearings are preloaded to 10 - 12

depth after polishing.

inch-pounds (1.13 - 1.36 Nm) of

Bearing cups are installed in

rotational drag. Measure rotational

WARNING

hub by differential tempera

drag using 0 - 10 pound (0 - 4.536 kg)

ture (shrink-fit) method. Take appro

spring scale hooked over one of hub

priate precautions to prevent burns

support web bosses, 6.5 inch (16.51 cm)

when handling parts that are cooled to

from hub centerline). A 1.50 - 1.75

sub-zero temperatures.

pound (0.681 - 0.795 kg) pull with

hub in motion indicates correct rota

(7). Place bearing cup in closed container of

tional drag.

dry ice and cool for not less than 20

minutes to -40°F (-40°C).

(17). Remove locknut, washer and cone.

(8). Coat bore of hub with grease (CM111).

(18). To determine thickness required for

spacer:

(9). Use care to maintain cup-to-hub bore

alignment and press cup into bore,

NOTE: When determining spacer thickness,

using tools D and E (Ref. Figure 804),

start with thick spacer and work down to

until cup is seated.

thinner spacer.

If hub assembly does not seat

CAUTION

(a). Install subsequently thinner spacers,

properly onto mast, do not at

from kit K-600N-1200A, starting

tempt to force it into position. Remove hub

with a thick spacer, along with cone,

assembly from mast and determine cause of

steel ring washer for retainer and

hub not seating, correct the problem and fol

locknut.

low the procedures for reinstallation.

(b). Torque nut to to 200 - 250 foot-

(10). Check that rotor mast is clean. Hoist

pounds (271 - 339 Nm) until 10 -

main rotor hub and position over mast;

15 inch-pounds (1.13 - 1.69 Nm)

then lower hub onto mast.

of rotational drag (not break-

NOTE: To inhibit mast corrosion when operat

away torque) is obtained on hub.

ing in salt water environment, lightly coat

(19). When proper torque has been reached,

bearing journals of mast with grease

disassemble and remove steel ring

(CM111).

washer.

(11). Remove adapter, hoist and eyebolts.

(20). Alternative method for determining

(12). Check that hub is fully seated on mast.

thickness required for spacer:

Page 812

Revision 34

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

(a).

Install 369A1224-5 lead spacer in

(1).

Remove main rotor hub (Ref. Main

place of the 369A1224-3 spacer.

Rotor Hub Replacement).

(b).

Place steel ring washer for retainer

(2).

Invert hub and place on work bench.

and locknut on the mast and gradual

ly tighten the retaining nut until

(3).

Remove droop stop ring (Ref. Droop

rolling torque of 10 - 15 inch-

Stop Ring Replacement).

pounds (1.13 - 1.69 Nm) of rota

tional drag (not break-away

(4).

Press bearing from hub lug.

torque) is obtained on hub. If the 10

- 15 inch-pounds (1.13 - 1.69 Nm)

(5).

Clean bearing bore with locktite

of rotational drag is exceeded,

remover (CM216).

discard the lead washer, install new

washer and continue.

(6).

Inspect bearing bore for nicks,

scratches and grooves.

(c).

When proper torque has been

reached, disassemble and measure

(7).

Inspect bore for diameter of

thickness of the lead washer in the

0.6551-0.6556 inch (16.63954-16.65224

bearing seat area. Grind the

mm).

369A1224-3 spacer to the same

thickness as measured on the lead

(8).

Touch up bearing bore with chemical

washer. Check thickness of ground

coating (CM206).

washer at six locations to ensure

thickness does not vary by more than

(9).

Apply surface primer (CM321) to

0.0005 inch (0.0127 mm).

mating surfaces of bearing and boreas

per manufacturer's instructions.

(d).

Re-assemble with the ground steel

washer, steel ring washer and

NOTE: Do not allow primer to enter bearing.

locknut and torque to 200 - 250

foot-pounds (271 - 339 Nm) until

(10).

Apply locking compound (CM431) to

10 - 15 inch-pounds (1.13 - 1.69

faying surfaces of bearing and bore,

Nm) of rotational drag (not

press bearing into bore while locking

break-away torque) is obtained on

compound is wet.

hub.

(11).

Remove excess sealant, do not allow

(21). Complete reinstallation of main rotor

sealant to enter bearing.

hub assembly (Ref. Main Rotor Hub

Installation).

(12).

Apply a small fillet of sealant around

bearing and allow to dry for 24 hours at

room temperature or heat to 140° -

14. Main Rotor Hub Scissors Attach Lug

160°F (60° - 72°C) for one hour.

Bearing Replacement

(13).

As required, touch up bearing lug with

paint (CM304).

Consumable Materials

(Ref. Section 91−00−00)

(14).

Check bearing for a no-load rotational

Item

Nomenclature

drag of 1.0 - 2.0 inch-pounds (0.113 -

CM206

Chemical coating

0.226 Nm).

CM216

Loctite remover

(15).

Reinstall droop stop ring (Ref. Droop

CM304

Enamel, epoxy

Stop Ring Replacement).

CM321

Surface primer locking compound

CM431

Sealing, locking and retaining compound

(16).

Reinstall main rotor hub (Ref. Main

Rotor Hub Replacement).

Page 813

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Revision 34

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

SEAL

DROOP SHIM WASHER

(NOTE 4)

(NOTE 6)

SEAL RETAINER

HUB

STRIKER

STRIP

PIVOT PIN

SEALANT

PITCH

UPPER BEARING CONE

HOUSING

(NOTE 2)

(NOTE 7)

NOTE 1

UPPER BEARING CUP

(NOTE 7)

(NOTE 5)

SEAL

PITCH

(NOTE 4)

BEARING

SLEEVE

RECESSED

BUSHING

SPACER

SEALANT

STRAP

(NOTE 3)

(NOTE 2)

PACKS

LOWER SHOE

NOTE 5

STRAP

DROOP STOP RING

NOTE 8

ASSEMBLY

NOTE 1

SPRING

HUB OUTER LINER

ROLLER

SPACER

LOWER BEARING CONE

ASSEMBLY

SEAL

RETAINING

(NOTE 7)

FOLLOWER

PITCH CONTROL

(NOTE 4)

CLIP

ASSEMBLY

BEARING HOUSING

LOWER BEARING CUP

(NOTE 7)

BUSHING

LEAD-LAG PIVOT BOLT

PITCH HOUSING

SEALANT

BEARING

(NOTE 2)

(NOTE 1)

LEAD-LAG

LINKS

SHIM

STRAP ASSEMBLY

BUSHING

COTTER PIN

NUT

NOTES:

HEAVY LINES INDICATE REINFORCED TEFLON BEARING LININGS (TYPICAL).

SEALANT APPLIED TO LOCATIONS SHOWN.

RECESSED SPACER SPECIALLY GROUND TO ESTABLISH CORRECT ROTATIONAL

DRAG ON TAPERED BEARINGS. INSTALL RECESS DOWN ON TOP OF SLEEVE BUSHING.

SEAL TO BE UPWARD.

BEARING AND CAVITY TO BE FILLED WITH GREASE.

DROOP SHIM WASHERS ARE INSTALLED, AS REQUIRED, TO OBTAIN PROPER

ROTOR DROOP ANGLE.

DO NOT INTERMIX TIMKEN AND NTN BEARING CUPS AND CONES AT UPPER AND

LOWER TAPERED BEARING LOCATIONS.

DROOP STOP FOLLOWER T-HEAD TO BE OFFSET AWAY FROM LOWER SHOE.

6G62-030A

Figure 805. Main Rotor Hub − Cross Section

Page 814

Revision 37

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CSP-HMI-2

MAINTENANCE MANUAL

SWASHPLATE AND MIXER

REMOVAL/INSTALLATION

1. Main Rotor Swashplate

B. Swashplate Installation

(Ref. Figure 403) The main rotor swashplate

(1).

If swashplate lower boot was removed,

includes a rotating swashplate, stationary

install boot on mast (Ref. Figure 403).

swashplate, bearing and retainer and two

(2).

Position swashplate over main rotor

counterweights.

mast and carefully lower into place.

2. Swashplate Replacement

(3).

Engage upper end of boot in groove at

lower side of stationary swashplate.

A. Swashplate Removal

Secure boot with self-clinching nylon

strap (Ref. Figure 403).

(1). Tag or color-identify five pitch control

rods (Ref. Figure 401) to simplify

(4).

Align longitudinal link with stationary

replacement at same locations.

swashplate (Ref. Figure 402).

Failure to reinstall pitch control

CAUTION

(5).

Install flanged bushing, if removed,

rods at correct locations prob

bolt, two washers, nut and cotter pin to

ably will result in main rotor blades exces

secure upper end of longitudinal link.

sively out of track.

(6).

Align upper ends of mixer links with

(2). Disconnect pitch control rods from

stationary swashplate. Install slotted

rotating swashplate.

bushing (if removed), bolt, two washers,

nut and cotter pin to secure each link to

(3). Remove scissors.

swashplate.

(4). Remove main rotor hub.

(7).

Install scissors.

(5). Disconnect longitudinal link (Ref.

(8).

Using color code, reinstall pitch control

Figure 402) from stationary swash

rods at same locations from which

plate.

removed.

(6). Disconnect right and left side mixer

(9).

Check track of main rotor blades (Ref.

links (Ref. Figure 402) from stationary

Chap. 18) following any maintenance

swashplate.

activity that could result in a dimen

sional variation affecting rigging or

(7). Remove protective boot from groove in

tracking.

lower side of stationary swashplate

(Ref. Figure 403).

3. Mixer Controls

Do not strike rotating swash

CAUTION

Mixer controls consist of various links,

plate or bearing assembly (Ref.

bellcranks, idlers, support bracket and

Figure 403) with tools or in any way deface

associated fasteners that secure these compo

these components. Rotating swashplate is a

nents in place and to the control rods and main

stressed part; all surfaces are shot peened.

rotor swashplate.

Use particular care to protect teflon liner in

bearing bore. A damaged swashplate bear

4. Mixer Controls Replacement

ing must not be retained in service.

A. Mixer Controls Removal

(8). Lift swashplate carefully up and off of

mast.

(Ref. Figure 402)

(9). To remove boot from mast, remove

(1). Remove air intake forward fairing for

self-clinching nylon strap.

access.

Page 401

62-30-00

Revision 20

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

ROTOR HUB

6.25 IN.

CLOSE TOLERANCE

LOWER SHOE

(15.875 CM)

BOLT

WASHERS

SCISSORS CRANK

(NOTE 4)

PITCH CONTROL ROD - LENGTH

SLOTTED BUSHING

(NOTE 3)

(NOTE 1)

MAXIMUM ALLOWABLE LOOSENESS

0.040 IN. (1.016 MM)

AT INSTALLATION, ROD ENDS

TO BE PARALLEL WITH

MATING CLEVIS

BEARING

1.30 IN. (3.302 CM) TYPICAL

(UPPER BEARING ONLY)

WASHERS

(NOTE 4)

BUSHING

SCISSORS LINK

BEARING

PITCH CONTROL ROD

(NOTE 2)

ELASTOMER RING

SLOTTED BUSHING

(NOTE 6)

(NOTE 1)

ELASTOMER RING

(NOTE 5)

ROTATING

SWASHPLATE

INTERRUPTER

SLOTTED BUSHING

COLLECTIVE PITCH

(NOTE 1)

CONTROL ROD

LONGITUDINAL PITCH

CONTROL ROD

SLOTTED BUSHING

(NOTE 1)

LATERAL PITCH

CONTROL ROD

NOTES:

END OF SLOTTED BUSHING MUST PROTRUDE MINIMUM OF

0.010 IN. (0.254 MM) TO MAXIMUM OF 0.060 IN. (1.524 MM) ABOVE

OUTSIDE SURFACE OF PART AFTER NUT IS TIGHTENED.

COLOR CODED TO MATCH BLADE.

OPTIMUM INITIAL SETTING (FIVE PLACES).

AS REQUIRED TO FILL GAP.

THIS SIDE ONLY ON EARLY CONFIGURATION.

BOTH SIDES ON CURRENT CONFIGURATION.

DELETED

G62-3000D

Figure 401. Pitch Control Rods and Swashplate Scissors − Installation

Page 402

Revision 36

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

(2). Disconnect upper ends of collective

support bracket and bore in mast base

mixer, lateral mixer and longitudinal

lug is 0.015 inch (0.381 mm) or less.

mixer control rods (Ref. Figure 401).

NOTE: If necessary, loosen aft two bracket-to-

NOTE: Control rods are attached by slightly

fitting nuts, position support bracket to

different length bolts. Reinstall each bolt in

minimize misalignment and retighten nuts.

its bellcrank following control rod removal

(4).

Install mixer support attaching bushing

to simplify reinstallation at correct loca

in bracket and mast base lug.

tions.

(5).

Check that sleeve bushing is in place;

(3). Remove mixer links. (Mixer link

then install bolt, two washers and nut.

bearings are not replaceable.)

Torque nut to 80 - 100 inch-pounds

(4). Disconnect longitudinal link from

(9.04 - 11.30 Nm).

stationary swashplate.

(6).

Position longitudinal pitch idler and

(5). Remove longitudinal control mixer link.

collective pitch mixer bellcrank on

support bracket. Position washer

(6). Disconnect lateral bellcrank from

between right side of longitudinal pitch

collective pitch mixer bellcrank.

idler bearing and center bearing of

mixer support bracket. Install left-

(7). Remove connecting hardware (includ

hand bearing, with attaching hardware.

ing flanged bushing) from each side of

longitudinal pitch mixer bellcrank.

(7).

Position lateral bellcrank between

Carefully remove bellcrank. Retain any

collective pitch mixer bellcrank bear

shims that may be installed.

ings and install attaching hardware.

(8). Remove bolt from hingeline of support

(8).

Position longitudinal pitch mixer

bracket, longitudinal pitch idler and

bellcrank with collective pitch mixer

collective pitch mixer bellcrank.

bellcrank; insert two flanged bushings.

Separate the three parts.

Install two bolts.

(9). Remove mixer support bracket from

(9).

Push longitudinal bellcrank to one side

mast base.

and measure gap between bellcrank

and bearings in collective pitch bell

To prevent washing dirt into

crank.

CAUTION

bearings, or washing grease out

(10).

Using HS5079-2646 laminated wash

of bearings, do not permit solvent to enter

er(s), shim evenly to take up gap.

bearings when cleaning mixer control com

ponents.

(11).

Insert flanged bushings, bolts, six

washers (two under each nut) shims

B. Mixer Controls Installation

and nuts. Torque nut to 30 - 40 inch-

(Ref. Figure 402)

pounds (3.39 - 4.52 Nm) and install

cotter pin.

(1). Position support bracket over forward

lug on mast base.

(12).

Position longitudinal control mixer link

between longitudinal pitch idler and

(2). Install two aft bolts and washers in

longitudinal pitch mixer bellcrank;

support bracket and mast base. Install

check that two slotted bushings are in

two thin washers and nuts; torque nuts

place. Install bolt, three washers (two

to 80 - 100 inch-pounds (9.04 - 11.30

under each nut), nut and cotter pin at

Nm) above drag torque.

each end of link.

(3). Using ball hole gage and standard

(13).

Position longitudinal link between

micrometer, check that misalignment

longitudinal pitch mixer bellcrank

between forward bolt hole bore in

bearings. Install attaching hardware.

Page 403

62-30-00

Revision 31

CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

LONGITUDINAL

BUSHING

PITCH IDLER

CONTROL MIXER LINK

(NOTE 2)

MIXER LINK

*LATERAL MIXER

STATIONARY

BELLCRANK

BUSHING

SWASHPLATE

STATIONARY

(NOTE 2)

SWASHPLATE

BEARING

BUSHING

FLANGED

(NOTE 2)

BUSHING

WASHER

MIXER

BEARING

LINK

MIXER

LONGITUDINAL

SUPPORT

LINK (NOTE 3)

BEARING

ATTACHING

MIXER

BUSHING

SUPPORT

FLANGED

BUSHING

(NOTE 6)

BRACKET

NOTE 1

BUSHING

(NOTE 2)

(NOTE 4)

NOTE 1

BEARING

*COLLECTIVE

PITCH MIXER

BEARING

BELLCRANK

BEARING

NOTE 7

BEARING

SLEEVE

FLANGED

BUSHING

*LONGITUDINAL

NOTE 1

(NOTE 4)

PITCH MIXER

BELLCRANK

PLS

MAST

BASE

NOTES:

DIRECTION OF BOLT OPTIONAL.

EDGE OF BUSHING MUST PROTRUDE MINIMUM OF 0.010 IN. (0.254 MM) TO MAXIMUM OF

0.060 IN. (1.524 MM) ABOVE OUTSIDE OF PART AFTER NUT IS TIGHTENED.

LONGITUDINAL LINK DETAILS ROTATED FOR CLARITY.

MUST BE PULLED OUT FIRST TO REMOVE BELLCRANK.

ASTERISK ( * ) INDICATES PART THAT MAY BE EITHER MAGNESIUM OR ALUMINUM ALLOY.

(FOR ALLOY IDENTIFICATION AND CORROSION CONTROL, REF. SEC. 20-40-00).

INSTALL BUSHING AFTER THE TWO AFT ATTACHING BOLTS WITHOUT EXCESSIVE

G62-3003C

MISALIGNMENT 0 015 IN (0 381 MM)

Figure 402. Mixer Controls − Assembly

Page 404

Revision 31

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MD Helicopters, Inc.

CSP-HMI-2

MAINTENANCE MANUAL

(14). Position mixer links in stationary

Scissors crank must be posi

CAUTION

swashplate and lateral bellcrank; check

tioned (Ref. Figure 401) with de

that slotted bushings are in place.

cal up and proper direction towards lower

Install attaching hardware.

side lugs.

(15). Place collective mixer, lateral mixer

NOTE: Ensure crank-to-hub lower shoe lugs

longitudinal mixer control rods (Ref.

are not preloaded.

Figure 401) in mounting position; check

that slotted bushing in place. Install

(3). Position scissors crank on hub lower

attaching hardware.

shoe lugs; install connecting hardware

(Ref. Figure 401). Torque nuts to 30 -

(16). Install air intake forward fairing.

60 inch-pounds (3.39 - 6.78 Nm);

install cotter pin.

(17). Check rigging of collective and cyclic

controls.

NOTE: Shim washers may be required on

shouldered bushing side of clevis.

5. Scissors

(4). Position elastomer rings and lower end

The scissors provide a movable connection

of pitch control rod in swashplate lug

between the rotating swashplate and main

and install attaching hardware. (Nut is

rotor hub.

to be adjacent to bushing in swash

plate.) Torque nut to 30 - 60 inch-

6. Scissors Replacement

pounds (3.39 - 6.78 Nm).

A. Scissors Removal

7. Scissors Link Replacement

(Ref. Figure 401)

Consumable Materials

Removal of all pitch control rods

CAUTION

(Ref. Section 91−00−00)

is recommended prior to scissors

Item

Nomenclature

removal. Failure to observe this precaution

CM103

Solid film lubricant

could result in damage to pitch control rods,

swashplate and/or hub.

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

(1). Disconnect lower end of pitch control

that join link and crank.

rod that is in line with scissors link in

rotating swashplate.

(2). Remove two bushings from link only if

replacement is necessary.

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

bolt from each leg of scissors crank.

(3). Do not remove bearing from link,

Disconnect crank from hub lower shoe.

replace complete link if bearing is

defective.

(3). Remove cotter pin, nut, washer, and

bolt connecting scissors link to swash

NOTE: Install new bushings using solid film lu

plate; remove scissors.

bricant (CM103); do not use zinc chro

mate.

B. Scissors Installation

(Ref. Figure 401)

(4). If bushings were removed at disassem

bly, install new bushings. After installa

(1). Place scissors link in mounting posi

tion, dimension between outer faces of

tion, chamfered edge of link must face

bushings should be 1.579-1.586 inches

outboard.

(4.0107-4.0284 cm).

(2). Check that slotted bushing is in

(5). Align bore of link with bore of crank;

swashplate web and install attaching

install bolt, washer and nut. Torque nut

hardware. Torque nut to 15 - 20

to 30 - 40 inch-pounds (3.39 - 4.52

inch-pounds (1.69 - 2.26 Nm).

Nm), install cotter pin.

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CSP-HMI-2

MD Helicopters, Inc.

MAINTENANCE MANUAL

8. Pitch Control Rods

NOTE: Bushing must project 0.010-0.060 inch

(0.254-1.524 mm) after nut is torqued.

Five pitch control rods transfer pitch control

(4). Torque lower nut to 30 - 60 inch-

from the rotating swashplate to the main rotor

pounds (3.39 - 6.78 Nm).

blades.

(5). Secure nuts with cotter pins.

9. Pitch Control Rod Replacement

(6). Rotate pitch change rod assembly fore

A. Pitch Control Rod Removal

and aft to ensure clearance exists

between rod end bearing and pitch

(Ref. Figure 401)

housing clevis at both ends.

NOTE:

(7). If installation is final and tracking is

not required, safetywire rod ends to rod;

D If rod is not to be reinstalled, but is to be

ensure rod ends are centered.

replaced, measure and record length of

removed rod. Optimum length may have

(8). As necessary, repeat above procedures

been changed at previous rigging; pre-ad

for remaining pitch control rods.

just replacement rod to length of rod re

moved.

10. Counterweight and Interrupter Installation

D Rods are color coded for reinstallation at

correct locations. If more than one rod is

Consumable Materials

being removed and color coding is not vis

(Ref. Section 91−00−00)

ible, identify each by color or similar

Item

Nomenclature

means to points of connection to simplify

CM111

Grease, aircraft

reinstallation.

CM409

Adhesive, epoxy

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

from each end of pitch control rod.

NOTE: If counterweights are to be added, one

thick and one thin (any position) is recom

(2). Remove pitch control rod and O-ring.

mended for ease of balancing; Hub must be

re-balanced.

B. Pitch Control Rod Installation

(1). Apply coat of adhesive (CM409) to

(Ref. Figure 401)

counterweight OD. Reinstall weight

with smaller hole outboard, using

At installation, install rod at

dummy bolt to align weight to rotating

CAUTION

correct color code location. Cen

swashplate. Remove bolt and allow

ter bearing rodends between attach clevis. If

adhesive to cure according to container

rod length is changed, blades must be

instructions.

tracked.

NOTE: Ensure interrupters are installed with

(1). If actual rod length is incorrect or

same type and number of washers removed

either actual or required rod length is

at disassembly, and that correct part num

unknown, preset rod length to optimum

ber interrupter is installed in each swash

length of 6.25 inches (15.875 cm).

plate arm. (Ref. CSP-IPC-4 for correct part

numbers and corresponding locations).

NOTE: Install both pitch change rod bolts in

direction of rotation.

(2). Install interrupters, beveled edges

inboard, with bolts, washers, nuts and

(2). Install rod with elastomeric rings on

new cotter pins. Coat bolts with grease

both sides of lower bearing.

(CM111) prior to installation. Torque

nuts to 30 - 60 inch-pounds (3.39 -

NOTE: Add washers as required to align nut

6.79 Nm).

with cotter pin hole.

(3). Install interrupters using bolts,

(3). Torque upper nut to 100 - 130 inch-

washers and nuts; torque nuts to 15 -

pounds (11.30 - 14.69 Nm).

20 inch-pounds (1.69 - 2.26 Nm).

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HANDBOOK OF MAINTENANCE INSTRUCTIONS FOR MDHI 369D/E/FF-500/600N HELICOPTERS (ISSUED: 1990) - page 18