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CHAPTER 65 - TAIL ROTOR DRIVE SYSTEM

CONTENTS - MAINTENANCE PROCEDURES

ParagraphNumber

Chapter/Section PageTitle Number Number

65-1 Tail rotor drive system ........................... 65-00-00 565-2 Troubleshooting ............................... 65-00-00 5

65-3

TAIL ROTOR DRIVESHAFTS AND HANGERS

Tail rotor driveshafts and hangers ............... 65-00-00 765-4 Tail rotor driveshafts .......................... 65-00-00 765-10 Driveshaft hangers ............................ 65-00-00 1265-16 Alignment - tail rotor drive system ............ 65-00-00 1865-17 Deleted ....................................... 65-00-00 24B

65-18

INTERMEDIATE GEARBOX

Intermediate (42°) gearbox ...................... 65-00-00 2565-19 Maintenance .................................. 65-00-00 2565-29 Sight glass .................................... 65-00-00 3065-33 Chip detector ................................. 65-00-00 3165-37 Oil filler cap ................................... 65-00-00 3265-42 Flexible couplings ............................. 65-00-00 32

65-44

TAIL ROTOR GEARBOX

Tail rotor (90°) gearbox ......................... 65-00-00 3565-45 Removal ....................................... 65-00-00 3565-50 Installation .................................... 65-00-00 3665-52 Sight glass .................................... 65-00-00 4065-56 Chip detector ................................. 65-00-00 4065-61 Oil filler cap ................................... 65-00-00 4165-66 Tail rotor gearbox flexible coupling .............. 65-00-00 4365-67 Lubrication .................................... 65-00-00 43

Figure

FIGURES

PageNumber Title Number

65-1 Tail rotor driveshaft and hangers ...................................... 865-2 Damage limits - tail rotor driveshaft ................................... 1065-3 Tail rotor driveshaft hanger assemblies ............................... 1465-4 Deleted ................................................................ 16A/1 61365-4A Tail rotor driveshaft coupling "TEMP-PLATES" condition and

correction ............................................................. 17

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FIGURES (Cont)

FigureNumber Title

PageNumber

65-5 Tail rotor driveshaft alignment ......................................... 2165-6 Intermediate gearbox .................................................. 2865-7 Intermediate gearbox sight glass ...................................... 3165-8 Chip detector .......................................................... 3365-9 Chip detector damage limits ........................................... 3365-10 Oil filler cap ........................................................... 3465-11 Tail rotor gearbox ..................................................... 3765-12 Tail rotor gearbox pusher T101264-103 tool application .............. 3865-13 Sight glass ............................................................ 4165-14 Tail rotor gearbox electrical chip detector ............................. 4265-15 Tail rotor gearbox electrical chip detector damage limits .............. 4365-16 Tail rotor gearbox oil filler cap ........................................ 44

TABLES

TableNumber Title

PageNumber

65-1 Troubleshooting - tail rotor drive system .............................. 565-2 Troubleshooting - intermediate gearbox ............................... 25

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TAIL ROTOR DRIVE SYSTEM

65-1. TAIL ROTOR DRIVE SYSTEM. 65-2. TROUBLESHOOTING.

This chapter contains maintenanceinformation on tail rotor driveshafts, couplingsand hanger assemblies, intermediate (420)gearbox, and tail rotor (90°) gearbox.

Refer to table 65-1 for troubleshooting tailrotor drive system problems.

Table 65-1. Troubleshooting - tail rotor drive system

INDICATION OF

TROUBLE PROBABLE CAUSE CORRECTIVE ACTION

Vibration believed to be Bolts in V-band couplings Inspect all V-band clamps fororiginating in tail rotor drive loose. loose bolts. Tighten or replacesystem. as required.

Broken hanger or hanger Inspect hangers and supportssupport. for cracks. Replace defective

parts.

Tail rotor driveshaft out of Verify driveshaft balancebalance. weights are secure. The

balance weights are small metalstrips bonded to driveshaft (oneempty bonded space should beopen where a bonded test stripwas removed duringmanufacture). If more than onespace is open, a balance weightis missing. Replace driveshaft.

Visual overheat indicator Shaft hanger bearings rough Check for signs of overheatedstripe(s) on hanger shows or overheating. bearings. If no sign ofdiscoloration (from green to overheating is noted, recheckbrown). after five hours of operation.

Replace bearings if overheatingis evident. Replace bearings, ifrough, after five hours ofoperation, whether or notoverheating.

Excessive loss of grease from Misalignment of bearing in Check and correct alignment ofhanger bearings. hanger. bearings.

65-00-00Page 5

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Table 65-1. Troubleshooting - tail rotor drive system (Cont)

INDICATION OF

TROUBLE PROBABLE CAUSE CORRECTIVE ACTION

Binding or roughness when Dry or faulty hanger bearings. Lubricate bearings.rotor and tail rotor driveshaftis turned by hand.

Faulty tail rotor gearbox. Inspect electric chip detectors inintermediate and tail rotorgearboxes for evidence ofinternal failure. Replacedefective gearbox.

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TAIL ROTOR DRIVESHAFTS AND HANGERS

65-3. TAIL ROTOR DRIVESHAFTS ANDHANGERS.

Five of the six tail rotor driveshafts are of thesame length. Number two shaft, locatedbelow engine tailpipe area, is shorter. Eachshaft is an anodized aluminum alloy tube withface-splined couplings riveted on both ends,and is dynamically balanced by metal stripsbonded on each end of tube. Hinged coverswith cowl-fasteners provide access to shaftsalong tailboom and on the vertical fin.

3. Push shaft (1 or 3) against spring-loadedflexible coupling to disengage opposite end.Remove shaft.

65-6. Cleaning.

MATERIALS REQUIRED

Refer to BHT-ALL-SPM for specification andsource.

NUMBER NOMENCLATURE

Tail rotor driveshaft hanger assemblies aremounted on three supports on the tailboomand one support on the engine deck (figure65-1). Each consists of a flexible and anonflexible coupling attached on a splinedshaft mounted through a sealed single-rowbearing in a ring-shaped hanger. The hangerhas two mounting lugs and is attached tohanger fittings with bolts. Hanger fittings areprealigned with permanent shims on tailboomstructure.

65-4. TAIL ROTOR DRIVESHAFTS.

65-5. Removal.

1. Open hinged covers along top oftailboom and on front of vertical fin. Openengine cowling.

CAUTION

DO NOT DISPLACE EITHER ENDOF SHAFT FROM MATINGCOUPLING UNLESS CLAMP SETIS REMOVED FROM BOTH ENDSOF SHAFT.

DO NOT INTERMIX PARTS OFCLAMP SETS.

2. Remove clamp sets (8, figure 65-1) atboth ends of each shaft (1 or 3). Reassembleclamp set to prevent intermixing of parts.

C-304 Solvent

CAUTION

DO NOT ALLOW SOLVENT TOSATURATE DRIVESHAFT.

1. Clean driveshaft with clean, lint-free clothdampened in solvent (C-304).

2. Dry with filter, compressed air.

65-7. Inspection.

1. Inspect driveshafts in accordance withfigure 65-2.

2. Check two water drain holes are notclogged on contoured surface of curviccoupling.

3. Inspect curvic coupling splines on face ofshaft coupling. There shall be no radial playor backlash between mating couplings whenfully meshed without clamps.

4. Inspect shaft for distortion (figure 65-2).

5. Inspect balance weights for security. Anyweights found debonded may be rebonded. Ifweight is missing, replace driveshaft.

6. Inspect clamp sets for cracks, worn boltholes, and distortion. Damage which can be

65-00-00Rev.5 Page 7

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BHT-212-M M

1. Shaft 8.2. Hanger support fitting (engine deck) 9.3. Short shaft 10.4. Hanger bearing assembly 11.5. Hanger support fitting 12.6. Intermediate gearbox 13.7. Tail rotor gearbox 14.

CLAMP SETTORQUE30 TO 35 IN-LB(3.39 TO 3.96 Nm)ABOVENUT

Clamp set 15.Hanger fitting 16.Nut 17.Nut 18.Nut 19.NutSeal 20.

BearingOuter couplingHanger bolt holeNon-flex couplingVisual OVERTEMPERATUREindicator stripe"TEMP-PLATES"

NOTES

A Location of temperature indicator TEMP-PLATES on outer couplings. (BHT212-CR&O, Chapter 65)

A Torquing sequence is as follows: 10, 12, 13, and 11.

A Clamp halves shall be kept together as a set.

Location of hanger bearing assembly visual overtemperature indicator stripe. (BHT 212-CR&O,Chapter 65)

212-M-65-1

Figure 65-1. Tail rotor driveshaft and hangers

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detected visually requires replacement ofclamp set.

7. Inspect clamp sets for gouges or wearpattern extending into fillet radius at bottom ofinternal groove. Damage which can bedetected visually requires replacement ofclamp set.

8. Inspect clamp sets for mechanicaldamage on spot face, lug fillets, and internalgroove. Damage not exceeding 0.008 in.(0.203 mm) is acceptable without repair.Damage exceeding this limit is not acceptableand shall be repaired or entire clamp setreplaced. Inspect remaining surfaces ofclamp set for mechanical damage. Damagenot exceeding 0.010 in. (0.254 mm) isacceptable without repair. Damageexceeding this limit is not acceptable andshall be repaired or clamp set replaced.

1. Polish out mechanical and corrosiondamage from driveshaft within limits (figure65-2) using 400 to 600 grit abrasive cloth orpaper (C-423).

2. Radius in reworked area shall be 0.50 in.(12.7 mm) or greater. Surface finish shall be32 RMS or better. When surface rework iscomplete, verify damage limits are notexceeded.

3. Treat repaired areas with chemical filmmaterial (C-100) (BHT-ALL-SPM).

4. Apply one coat of primer (C-202).

5. Touch up paint to match surroundingarea.

6. Rebond loose balance strip as follows:

65-8. Repair.a. Clean balance weight and shaft in area

where weight will be bonded by abradinglightly with 400 grit abrasive cloth or paper

MATERIALS REQUIRED (C-423).

b. Remove sanding residue with a clean,NUMBER NOMENCLATURE lint-free cloth dampened with aliphatic

naphtha (C-305).C-100 Chemical Film Material

C-202 P ic. Mix adhesive (C-317) 33 parts B to 100

r mer parts A. Mix parts thoroughly. (Pot life is 30C-305 Aliphatic Naphtha to 50 minutes after mixing.)

C-317 Adhesive d. Apply a thin coat of adhesive tobalance weight and shaft in area where

C-423 Abrasive Cloth orPaper

weight will be bonded.

e. Place a 6 to 10 mil thread in adhesiveon balance weight to act as a spacer andcontrol bondline thickness.

CAUTION

DO NOT USE GRINDING WHEELTO REMOVE DAMAGE.

DRIVESHAFT SHALL BE CHECKEDAND REBALANCED AS REQUIREDIF REWORKED AREA IS 8.0 SQ.IN. (51.6 SQ. CM) MORE ON ONESIDE THAN THE OTHER.

f. Position weight on shaft. Maintainapproximately 10 psi pressure on weightusing rubber bands or equivalent.

g. Allow adhesive to cure at 70 to 95°F(21 to 350C) for 24 hours. Accelerated curemay be accomplished by heating area to 175to 190°F (79 to 88°C) for 60 minutes.

h. Apply chemical film material (C-100) tobalance weight and appply touch up paint, ifrequired.

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AREA B

DAMAGE LOCATION SYMBOLS0AREA A AREA B

TYPE OF DAMAGE MAX IMUM DEPTHS AND REPAIR AREAS ALLOWEDAFTER POLISHING OUT

CRACKS ALLOWED See Note 6 See Note 6

NICKS AND SCRATCHES 0.008 Inch 0.012 Inch(0.203 mm) (0.304 mm)

SHARP DENTS 0.010 Inch 0.015 Inch(0.254 mm) (0.381 mm)

NONSHARP DENTS 0.020 Inch 0.030 Inch

NOTES

(0.508 mm) (0.762 mm)

1. Damage defined on the chart above is acceptable if repaired as follows:a. Damage is polished out with fine abrasive cloth with minimum radius of 0.5 inch (12.70

millimeters) and with surface finish of 32 RMS or better.b. Maximum depth after rework does not exceed limits shown in chart.c. Reworked area is treated for corrosion prevention.d. If rework area is eight square inches more on one side than the other, shaft balance must

be checked.

2. Loss of one or more balance weights is cause to replace driveshaft. One empty bondingspace should be open where bond test coupon was removed. If more than one empty spaceis observed, replace driveshaft.

3. Damaged curvic coupling splines that result in radial play and/or backlash betweenassembled couplings when fully meshed without clamps are not acceptable.

212-M-65-2-1

Figure 65-2. Damage limits - tail rotor driveshaft (sheet i of 2)

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4. Grooves worn on shaft coupling by clamp to extent that wear prevents proper clamping arecause to replace driveshaft.

5. If tail rotor driveshaft distortion is suspected, support driveshaft on "V" blocks and measurerun out. Maximum acceptable total indicator reading on long shafts is 0.050 inch (1.27millimeters). Maximum acceptable total indicator reading on short shaft is 0.020 inch(0.508 millimeters). Do not attempt to straighten driveshaft.

6. Any crack in a driveshaft is cause to replace the affected driveshaft except cracks in rivetheads are acceptable if they do not exceed the following limits:a. Cracks are approximately radial when viewing top of shop head.b. No crack extends into an area with a diameter less than 1.25 diameters of rivet shank.c. Cracks do not intersect.d. The minimum distance between cracks is less than one shank diameter.e. A maximum of 3 such cracks.f. Crack width does not exceed 0.06 inches (1.52 millimeters) times rivet shank diameter.g. Maximum or ten percent of rivet shop heads may have cracks within above limits.

212-M-65-2-2

Figure 65-2. Damage limit - tail rotor driveshaft (sheet 2)

65-9. Installation.

NOTE

NOTE

All nuts used on a clamp must be ofthe same type and style.

Tail rotor driveshaft clamps (8, figure65-1) are matched sets. Keep insets after removal to maintainbalance. If it is necessary to replaceone clamp half, or if clamp halvesare intermixed, each shall berematched with one of equal weightwithin one gram.

1. Position each shaft (1 or 3, figure 65-1)between mating couplings of hangers (4) andgearboxes.

2. Install matched clamp sets (8) oncouplings, with bolt heads to direction ofrotation and clamp joints indexed 90° to thoseof adjacent clamps for balance in operation.

Adjust clamp set halves to obtainequal gaps at both ends within 0.030in. (0.732 mm).

3. Tighten clamp bolts evenly, torque 30 to35 in.lbs. (3.39 to 3.95 Nm) above nut friction.Driveshaft clamp nuts are self-locking andshall not be reused unless tare torque is aminimum of 3.5 in.lbs. (0.395 Nm). Torquesequence is as follows: 10, 12, 13, and 11(figure 65-1). Tap lightly around outer surfaceto seat clamp, and recheck torque.

4. Close covers and cowling.

65-00-00Page 11

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65-10. DRIVESHAFT HANGERS.

65-11. Removal.

CAUTION i

DO NOT DISPLACE EITHER ENDOF DRIVESHAFT FROM MATINGCOUPLING UNLESS CLAMP SETIS REMOVED FROM BOTH ENDSOF SHAFT. FAILURE TO COMPLYMAY RESULT IN DAMAGE TOHANGER BEARING AND/ORCURVIC COUPLING.

1. Remove tail rotor driveshafts from eachend of hanger to be removed (paragraph 65-5).

2. Remove two bolts (19, figure 65-3),washers (20, 22, 23, and 25), and nuts (26).Remove hanger assembly from support (17).

3. Remove two bolts (27) and washers (28).Remove hanger assembly (5) from fitting (16).

4. Remove hanger assembly (9) same asprevious step.

65-12. Cleaning.

MATERIALS REQUIRED


NUMBER NOMENCLATURE

C-304 Solvent

NOTE

These instructions are applicable toassembled tail rotor driveshafthanger(s) only. Refer to BHT-212-CR&O for instructions to cleandisassembled hanger(s).

CAUTION

DO NOT IMMERSE HANGERASSEMBLY IN SOLVENT.

Clean external surfaces of hanger assemblywith a clean, lint-free cloth dampened withsolvent (C-304). Do not allow solvent tocontact internal surfaces of hangerassemblies.

65-13. Inspection.

MATERIALS REQUIRED


NUMBER NOMENCLATURE

C-454 India Stone

1. Inspect hanger bearing (4, figure 65-1)for cracks, elongated bolt holes, or othervisible damage.

2. Inspect outer coupling (16) temperatureindicator "TEMP-PLATES" (20) as follows:

NOTE

Overtemperature indicator dots on"TEMP-PLATES" are white or lightgray color and turn black whenexposed to an overtemperaturecondition. Chemical contaminationcan also cause indicator DOTS toturn black.

a. Temperature indicator "TEMP-PLATES" must not show evidence ofovertemperature, deterioration, debonding, ordiscoloration of the epoxy coating thatprevents interpretation of the indicatingDOTS. If any of these conditions exist,proceed to step b.

b. If one "TEMP-PLATE" is missing, andno DOT on the other "TEMP-PLATE" (on thesame coupling) is discolored or showsmechanical damage or degradation of the

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epoxy overcoating, the helicopter may bereturned to service.

C. The discrepant "TEMP-PLATE" in stepb. should be replaced as soon as practical. Ifany indicator DOT on "TEMP-PLATE" haschanged color to black, see figure 65-4A forprobable cause and required correctiveaction.

2a. Inspect hanger bearing assembly visualoverheat indicator stripes (19, figure 65-1) fordiscoloration and overheat condition. Achange in color of indicator stripe(s) (fromgreen to brown) indicates a possible overheatcondition and/or component degradation.Cause of discoloration shall be determinedand corrected prior to continued operation(BHT-212-CR&0)

3. Inspect nonflexible couplings for nicks,dents, and cracks. Minor damage which canbe polished out with fine India stone (C-464)is acceptable.

4. Inspect outer coupling (16) for nicks,dents, and cracks. Minor damage which canbe polished out with fine India stone (C-464)is acceptable.

BHT-212-MM

5. Inspect seal (14) for protrusions,leakage, cuts, tears, and deterioration.Replace unserviceable seals (BHT-212-CR&O).

NOTE

Inspect hanger bearing formovement of grease shields,indicated by breakage of witnessmarks. Remove any bearing fromservice whose witness marksindicate that the grease shield hasmoved.

6. Inspect bearing (15) in hanger supportfitting (5) and outer coupling (16) for greaseleakage. Grease leakage of adjacent areas bygrease is cause for replacement with thefollowing exception: A small amount of greaseexpelled from around tip of bearing sealsindicates a slight overlubrication and is notcause for hanger replacement. If leakage isdetected, perform an evaluation of greaseleakage as follows:

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CAUTION'

DO NOT CLEAN OR SPRAYBEARING HANGER ASSEMBLYWITH ANY TYPE OF SOLVENTDURING INSPECTION. USE CLEANCLOTH TO CLEAN EXTERIOR OFHANGER ASSEMBLIES.

a. Wipe grease from outer coupling (16),and bearing (15) in hanger support fitting (5).

b. Record which bearing is leaking andmonitor bearing condition for the next tenflight hours.

C. If the amount of grease expelled frombearing seal does not decrease after thisperiod of time, replace hanger assembly.

7. Inspect bearing (15) in hanger supportfitting for wear, roughness and binding asfollows:

a. Remove driveshaft from each side ofhanger bearing assembly.

b. Rotate bearing while pressing inaxially on nonflexible coupling and at hangerbearing assembly. Bearing may feel smoothwhen turned with no load, but rough whenloaded by pressing in with hand. Obviousroughness, catching, or binding when turned,by hand, is cause for replacement of hangerbearing assembly.

8. Inspect engine deck hanger, supportfittings and hanger support fitting formechanical and corrosion damage.Mechanical damage in excess of superficialand corrosion damage which can be detectedvisually is not acceptable.

9. Replace driveshaft hanger assemblies forthe following conditions:

a. Bearing is rough, binds when rotated,or shows excessive wear.

B HT-212-M M

b. Hanger bearing assembly (15) isexcessively worn or cracked.

C. Curvic face of couplings areexcessively worn.

d. Couplings show signs of overheating,or being run without lubricant.

e. Hanger support fitting shows signs ofoverheating.

f. Hanger support fitting shows signs ofmetal particles and/or rust colored frettingdebris near bearing.

10. Lubricate hanger bearing assemblies asrequired (paragraph 65-14).

65-14. Lubrication.

1. Remove tail rotor driveshaft sectionsattached to hanger bearings assemblies to belubricated (paragraph 65-5).

2. Remove tail rotor driveshaft hangerassemblies (paragraph 65-11).

3. Clean tail rotor driveshaft hangerassemblies (paragraph 65-12).

4. Disassemble, lubricate, and re-assembletail rotor driveshaft hanger assemblies (BHT-212-CR&O).

5. Install tail rotor driveshaft hangerassemblies (paragraph 65-15).

NOTE

Ground run and leak check must beperformed following installation ofnew, repaired, or relubricatedflexible couplings.

6. Make an entry in helicopter log and inflex couplings lubrication log of datelubricated, date grease manufactured andhelicopter hours (Chapter 12).

65-00-00Rev.5

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BHT-212-MM

1. Drive quill (transmission) 13. Tailboom 25. Steel washer2. Tail rotor driveshaft 14. Fitting 26. Nut3. Hanger assembly 15. Fitting 27. Bolt4. Tail rotor driveshaft 16. Fitting 28. Thin steel washer5. Hanger assembly 17. Support 29. Barrel nut6. Tail rotor driveshaft 18. Flexible coupling 30. Bolt7. Hanger assembly 19. Bolt 31. Thin steel washer8. Tail rotor driveshaft 20. Steel washer 32. Aluminum washer9. Hanger assembly 21. Grease fitting 33. Thin steel washer

10. Tail rotor driveshaft 22. Aluminum washer 34. Nut11. Intermediate gearbox assembly 23. Steel washer12. Tail rotor driveshaft 24. Brace assembly

212-M-65-3-1

Figure 65-3. Tail rotor driveshaft hanger assemblies (sheet 1 of 2)

65-00-00

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DETAIL A

DETAIL B DETAIL C

212-M-65-3-2

Figure 65-3. Tail rotor driveshaft hanger assemblies (sheet 2)

FOR BEST VALUE, BUY GENUINE BELL PARTS 65-00-00Rev.3

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65-15. Installation.

1. Position hanger assembly (3, figure 65-3)on support (17) with flexible coupling (18)forward. Install washers (22 and 23) betweensupport (17) and brace assembly (24) oneach side. Install bolts (19) with washers (20)through hanger assembly (3), support (17),and brace assembly (24). Install washers (25)and nuts (26).

2. Position hanger assembly (5) on fitting(16) with flexible coupling (18) forward.Ensure barrel nuts (29) are aligned on eachside. Install two bolts (27) and washers (28).

NOTE

Use additional washers (33) ifnecessary to obtain proper boltthread engagement.

3. Position hanger assembly (7) on fitting(15) with flexible coupling (18) forward. Installbolts (30) and washers (31) through hangerassembly (7) and fittings (15). Install washer(32) next to fitting (15), washer (33), and nut(34).

4. Install hanger assembly (9) on fitting (14)using procedures in previous step.

5. Install tail rotor driveshafts.

65-00-00 Rev.5

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212-M-65-4

1 Figure 65-4. Deleted

65-00-00Rev. 5 Page 16A/16B

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ONE REDTEMP-PLATE

OTHER REDTEMP-PLATE

PROBLEMCAUSE

SEENOTE

Black Good Defect/Instl 1

Black Black Overtemp 2

Part Black Good Chem Contamination 1

Missing Good Defect/Instl 1

Missing Missing Possible Overtemp 2

NOTES

1. Resume operation. Defective TEMP-PLATE or improper installation, replace defective TEMP-PLATE as soonas practical (BHT 212-CR&O).

2. Coupling overtemp condition is very likely. Remove driveshaft or coupling assembly and perform overtempinspection in accordance with BHT-212-CR&O and the following instructions. Scrap affected male andfemale couplings if any of the conditions listed below exist or if required by BHT-212-CR&O inspectioncriteria.

a. Cadmium plating on outer coupling is discolored (circumferential tan or light brown band) orblistered.

b. Gear teeth of either coupling are discolored (brown or blue) in normally bright contact patterns.

c. Under 5x or 10x magnification, surfaces of gear teeth of either inner or outer coupling exhibit signs ofmetal smearing or tearing in contact patterns.

d. Grease is very viscous (thick) and has a strong pungent order.

NOTE

If NONE of the above conditions exist, coupling may be reassembled in accordancewith BHT 212-CR&O and return to service following replacement of TEMP-PLATES.

212-M-65-4A

Figure 65-4A. Tail rotor driveshaft coupling TEMP-PLATE condition and correction

BUY BELL PARTS - BUY BELL VALUE 65-00-00Rev.3 Page 17

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6. Operate helicopter (BHT-212-FM) for 5minutes at 100% Nr.

7. Shut down engine and inspectcoupling(s) and surrounding structure forevidence of grease leakage. If there isevidence of grease leakage, remove hangerassembly and replace defective parts.

8. Inspect hangers overheat indicatorstripes for discoloration and overheatcondition. A change in color of indicator stripe(from green to brown) indicates a possibleoverheat condition and/or componentdegradation. Cause of indicator stripediscoloration shall be determined andcorrected prior to continued operation (BHT-212-CR&O). Inspect flexible couplingstemperature indicator "TEMP-PLATES". Referto paragraph 65-13.

65-16. ALIGNMENT -TAIL ROTOR DRIVESYSTEM.

MATERIALS REQUIRED


SPECIAL TOOLS REQUIRED (CONT)

NUMBER NOMENCLATURE

412-240-033-101 Hanger simulator (2)

412-240-034-101 Hanger simulator

412-240-035-101 Hanger simulator

1. A tail rotor drive system alignment checkshall be made whenever driveshaftmisalignment is suspected, when damage toairframe structure in area of driveshafthangers requires structural repair or partsreplacement, when major structural repairsare performed in any area of tailboom or in aftsection of forward fuselage, or when originalintermediate gearbox is replaced with agearbox of a different part number. Alignmentof driveshaft hanger supports andintermediate gearbox shall be accomplishedas follows:

a. Open tail rotor driveshaft covers andintermediate gearbox cover.

b. Remove tail rotor driveshafts andNUMBER NOMENCLATURE hangers (paragraphs 65-4 and 65-10).

C-001 GreaseNOTE

C-305 Aliphatic NaphthaDo not remove driveshaft hanger

C-309 Methyl- Ethyl -Ketone(MEK)

support assemblies from tailboom orforward fuselage.

C-317 AdhesiveC. Remove intermediate gearbox

C-508 Lockwire (paragraph 65-28). Ensure any shimsb t be ween gear ox and tailboom remain in theiroriginal locations on tailboom.

SPECIAL TOOLS REQUIRED

NUMBER

T103226-101

T103224-101

T1 03335-1 1 9

T103225-109

NOMENCLATURE

Tail rotor gearboxsimulator

Intermediate gearboxsimulator

Alignment plate

Bushing

d. Remove tail rotor gearbox (paragraph65-54).

e. Remove tailboom from helicopter andplace in suitable support cradle (Chapter 53).

f. Clean surfaces on tailboom and hangersupports where hangers and gearboxes wereremoved of primer and sealant. Use a plasticscraper and a clean cloth moistened withMEK (C-309) or alphatic naphtha (C-305).

65-00-00Page 18 Rev.5

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g. Install alignment plate, T103225-119with T103225-117 bushing for left handposition of plate (looking aft) (figure 65-5,view A, detail A), on forward tailboombulkhead using AN8-31A bolt or equivalentwith AN960-816 washer under bolt head.

h. Install tail rotor/90° gearbox simulatorT103226-101 on top of vertical fin.

safety wire spinner pliers or other positivelocking pliers.

NOTE

Ensure wire is still unkinked and isstill positioned in "V" groove in thepin in intermediate gearboxsimulator T103224-101.

i CAUTION

MAKE SURE THREE LEVELINGSCREWS IN INTERMEDIATEGEARBOX SIMULATOR AREBACKED OFF SO THEY DO NOTPROJECT BELOW THE MOUNTINGSURFACE OF THE SIMULATORBEFORE PROCEEDING.

L Install intermediate gearbox simulatorT103224-101 using AN4-13A bolts andsufficient number of AN960-416 and AN960-416L washers under heads of bolts so boltgrips do not bottom out in mating tailboomnutplates.

? CAUTION

VERIFY TAIL ROTOR GEARBOXSIMULATOR, T103226-101 ANDBULKHEAD ALIGNMENT PLATE,T103225-119 ARE SECUREDBEFORE PROCEEDING.

j. Install unkinked 0.020 inch lockwire (C-508) in hole of tail rotor gearbox simulator,T103226-101. Secure end of wire on upperside of plate.

k. Pass other end of wire through hole intop of plate of intermediate gearbox simulator,T103224-101, around "V" groove in pin andout through hole of forward (vertical) endplate (figure 65-5, view E).

1. Pass wire through hole in tailboombulkhead alignment plate, T103225-119 andtighten wire until all slack is removed andsecure end of wire. Secure end of wire with

M. Check for alignment of intermediategearbox by confirming wire clears the edgesof holes in top and forward end plates by atleast 0.005 inch (0.127 mm). See view B. Ifalignment is not acceptable, proceed directlyto step m(1). Pluck wire and check to see ifthe wire continues to vibrate. If vibrationcontinues, wire clearance is sufficient toproceed.

If alignment is acceptable loosen 0.020diameter alignment wire and removeintermediate gearbox simulator T103224-101.Install the P/N 212-040-003 intermediategearbox and then verify that a minimum of0.030 inch (0.762 mm) clearance existsbetween lower surfaces of gearbox (otherthan four mounting pads) and underlyingsurfaces of tailboom. If sufficient clearanceexists, proceed directly to step n. If sufficientclearance does not exist, add shims (equalamounts at all four mounting pads) asrequired to achieve clearance required, thenproceed directly to step m (2).

(1) Loosen 0.020 inch diameteralignment wire and remove intermediategearbox simulator T103224-101.

(2) Remove all shims on tailboom atintermediate gearbox location, note thicknessof shim-stacks removed. Using a plasticscraper and a cloth moistened with MEK (C-309) remove any adhesive or sealant residuearound gearbox mounting hole locations ontailboom.

(3) Adjust three leveling screws onintermediate gearbox simulator T103224-101so they project below mounting surface anamount approximately equal to thickness ofshim-stack established in step m(2) atcorresponding mounting bolt location.

65-00-00Rev. 5 Page 19

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WHEN GEARBOX SIMULATORT103224-101 IS SUPPORTED ONITS THREE LEVELING SCREWS.TIGHTEN 4 SIMULATORMOUNTING BOLTS TO 20 TO 30INCH- LB. (2.26 TO 3.39 Nm).

(4) Install intermediate gearboxsimulator T103224-101 on tailboom inaccordance with step i. and reinstallalignment wire in accordance with steps k.and I. Ensure alignment wire is positioned in"V" groove in simulator pin.

(5) Loosen or tighten each of foursimulator mounting bolts while adjusting eachof three levelling bolts until an acceptablesimulator position is obtained. See step m.

(6) Ensure simulator mounting bolts aretorqued to only 20 to 30 inch-lb. (2.26 to 3.39Nm); then using a thickness gage, measureand record gaps between lower surface ofsimulator and tailboom at each of themounting bolt locations.

(7) Size thickness of shim-stacks foreach simulator mounting bolt location equal tothe respective gaps measured in step m(6).

(8) Loosen alignment wire and removeintermediate gearbox simulator T103224-101.Retract each of three leveling bolts so it doesnot project below lower surface of simulator.Install tail rotor gearbox using shim-stacksmanufactured in step m(7), then verify that aminimum of 0.030 inch (0.762 mm) clearanceexists between lower surfaces of gearbox(other than the four mounting pads). Ifsufficient clearance exists, proceed directly tonext step. If sufficient clearance does notexist, add equal amounts of shims at all fourmounting bolt locations as required to achieveclearance required and repeat steps m(2) thruthis step except in step m(3) adjust simulatorleveling screws such that they project belowmounting surface equal to total shimthickness established above in this step.

(9) Reinstall simulator in accordancewith step i using shim-stacks manufactured in

step m(7) and reinstall alignment wire inaccordance with steps k and I. Tightensimulator mounting bolts 50 to 70 inch-lb.(5.65 to 7.91 Nm) and confirm satisfactorywire positions in holes in top and forward endplates of simulator in accordance with step m.If wire placement is satisfactory proceed tostep (10) otherwise repeat steps m(1) throughm(9) until satisfactory alignment is obtained.

(10) Loosen alignment wire and removeintermediate gearbox simulator T103224-101.Measure and record final thickness of shimsat each of four mounting bolt locations.

(11) Clean shim contact areas ontailboom using alphatic naphtha (C-305).Apply a light coat of adhesive (C-317) tobottom surface of each of four shim-stacks.Avoid placing adhesive within 0.25 inch (6.35mm) of bolt holes.

(12) Install shim-stacks, adhesive sidedown, in their original locations on tailboom.

NOTE

Coat bottom surface of intermediategearbox simulator T103224-101 andthe threads and shank of eachsimulator mounting bolt with a verylight coat of petroleum jelly orgrease (C-001) prior to installation.

(13) Reinstall intermediate gearboxsimulator and tighten four mounting bolts 50to 70 inch-lb. ( 5.65 to 7.91 Nm). Do notremove simulator until shim adhesive has set.

(14) Reinstall alignment wire inaccordance with steps k and I and confirmsatisfactory wire positions in holes in top andforward end plates of simulator in accordancewith step m.

n. Remove alignment wire from alignmentplate T103225-119 and thread wire throughforward and aft holes of a hanger simulator412-240-033-101.

0. Install hanger simulator 412-240-033-101 at number four location on tailboom usingtwo AN4-10A bolts, two MS35650-3252 nutsand sufficient number of AN960-416L

65-00-00Page 20 Rev.5

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212-M-65-5-1

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65-00-00Page 21

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/` 412-240-035-101(LARGE HOLE)(USE ONLY AS WIREANCHOR IN THISOPERATION)

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412.240-034-1010.020 WIRE

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ESTABLISHING PROPERTAILBOOM POSITION

POSITION #3412-240-035-101(LARGE HOLE) i

ADJUSTABLESUPPORT

VIEW D

ALIGNMENT OF NO. 1HANGER BEARING ASSEMBLY

T103226-101

T103225-119

VIEW EINTERMEDIATE GEARBOX

ALIGNMENT

Figure 65-5. Tail rotor driveshaft alignment (sheet 2)

0.020 WIRE

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washers under nut to keep nut from bottomingout in bolt grip, see detail B. Leave fastenersslightly loose at this point.

p. Using uniform hand pressure onextreme aft end of simulator, push hangersimulator forward and hold in this positionwhile tightening the two bolts.

q. Tighten alignment wire in accordancewith steps k and I. Ensure alignment wire ispositioned in "V" groove in the intermediategearbox simulator T103224-101 pin.

r. Verify acceptable alignment of hangersimulator 412-240-033-101 by confirmingalignment wire clears edges of holes inforward and aft end plates of simulator by atleast 0.005 inch (0.127 mm), see view B.Pluck wire and watch wire closely to see if thewire continues to vibrate. If vibrationcontinues, wire clearance in holes is sufficientto proceed. Also verify alignment wire is inacceptable positions in holes in forward andtop end plates of intermediate gearboxsimulator T103224-101. If alignment ofhanger simulator is acceptable proceeddirectly to step s; otherwise proceed asfollows:

2 CAUTION

DO NOT LOOSEN HANGERSUPPORT TO AIRFRAME BOLTSONCE "YAW" ADJUSTMENTSHAVE BEEN MADE.

both forward mounting pads. Do the oppositeto adjust hanger simulator "pitch" aft. Installfour mounting bolts and verify acceptablealignment in accordance with step r. It willlikely be necessary to perform step r(1) toachieve acceptable "yaw" alignment.

(3) If a "lateral position" error exists atany hanger simulator (not simply a "yaw"error) remove alignment wire and hangersimulator. Remove four bolts securing hangersupport to tail boom and remove support.Rework only the problem support inaccordance with figure 65-5. Followingrework, reinstall support. Reinstall hangersimulator and alignment wire in accordancewith steps n thru q. Loosen four bolts slightlyand adjust lateral position of support so as toobtain satisfactory lateral alignment ofsimulator. Verify acceptable alignment inaccordance with step r. It will likely benecessary to perform step r (1) to restoreacceptable "yaw" alignment.

(4) If hanger simulator position error isin "elevation" (vertical position), remove fourbolts securing hanger support to tailboom andadd or remove same thickness of shims undereach of four support mounting pads. Installfour mounting bolts and verify acceptablehanger simulator alignment in accordancewith step r. It will likely be necessary toperform step r(1) and (3) to achieveacceptable "yaw" and "lateral position"alignment. If lateral position is acceptableproceed to step s.

NOTE

(1) If hanger simulator 412-240-033-101position error is in "yaw", loosen four boltssecuring hanger support to tailboom and shiftsupport to obtain acceptable alignment.Retighten bolts and verify acceptablealignment in accordance with step r.

(2) If hanger simulator error is in "pitch"direction, remove four bolts securing hangersupport to tailboom. To adjust hangersimulator "pitch" forward, add equal shimsunder both aft support mounting pads andremove same thickness of shims from under

Ensure alignment wire remains freeof kinks and is seated in "V" groovein intermediate gearbox simulatorpin in the following operations.

S. Remove hanger simulator 412-240-033-101 from number four hanger locationand install at location three. Perform steps othru r.

(1) Loosen the alignment wire andremove hanger simulator 412-240-033 fromhanger location three.

65-00-00Rev. 5 Page 23

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Hanger simulators 412-240-035 and412-240-034 are very similar inappearance. Confirm the correctsimulator is installed in the followingoperation.

(2) Install hanger simulator 412-240-035-101 at hanger location two using twoAN4H7A bolts and a sufficient number ofAN960-416L washers to keep the bolts frombottoming out in the bolt grip. Leave fastenersslightly loose at this point. Perform steps pthru r, except, in step r the hanger simulatorwill be the 412-240-035-101.

t. Tail rotor driveshaft hanger assemblyalignment on tailboom is now complete.Remove tailboom bulkhead alignment plateT103225-119, alignment wire, and hangersimulator 412-240-035-101.

U. Install tailboom on helicopter (Chapter53).

CAUTION

THE FOLLOWING PROCEDURESFOR ALIGNMENT OF HANGERBEARING ASSEMBLY AT HANGERPOSITION NUMBER ONE MUST BEPERFORMED USING A TAILBOOMKNOWN TO HAVE ACCEPTABLETAIL ROTOR DRIVE SYSTEMALIGNMENT.

V. Install hanger simulators as follows:

(1) Install hanger simulator 412-240-034-101 at number two hanger location inaccordance with step s(2) for the 412-240-035-101 hanger simulator except perform onlyreferenced step p. See view C.

(2) Install hanger simulator 412-340-033-101 at number three and number fourhanger locations in accordance with steps o &p. See view C.

(3) Install hanger simulator 412-340-035-101 at number one hanger position in

accordance with instructions given for 412-340-033-101 hanger simulator in step o & p.See view C.

NOTE

In steps w, x, and y, the 412-240-035-101 hanger simulator at hangernumber one location is used as awire anchor. Alignment of thenumber one hanger support isaccomplished per steps z thru ab.

...................

CAUTION

DO NOT LOOSEN BOLTSSECURING ANY HANGERSUPPORT TO TAILBOOM IN ANE F F O R T TO A C H I E V ESATISFACTORY ALIGNMENT INSTEPS W THROUGH AB.

W. Install a length of unkinked 0.020 inchdiameter wire in accordance with steps j andk. Route wire through each of three hangersimulators. Tighten wire until all slack isremoved. Secure wire at forward end ofhanger simulator 421-240-034-101 at numberone hanger location. Secure end of wire withsafety-wire spinner pliers or other positive-locking pliers.

NOTE

A stable cushion such as shot bagsor a sand bag should be placedbetween tailboom skin and supportso as to distribute the load andprevent damage to tailboomstructure. Tension on alignment wiremay require adjustment duringtailboom positioning operation toprevent wire sag.

X. Position an adjustable support undertailboom. This support should be located at apoint approximately 12 inches (30.48 cm)forward of intermediate gearbox locationwhere extension of canted vertical fin sparapproaches adjacent tailboom bulkhead atlower surface of tailboom, see view C. Slowly

65-00-00Page 24 Rev.5

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adjust elevation of support as required toposition alignment wire within acceptablelimits in each of three hanger simulators, seeview B. Once this position is obtained do notreposition helicopter or readjust tailboomsupport until tail rotor drive system alignmentis complete.

y. Remove alignment wire and hangersimulator 412-240-035-101 from the numberone hanger location. Reposition hangersimulator 412-240-034-101 from number twohanger location to number one location onforward fuselage. Install hanger simulator421-240-034-101 in accordance with steps oand p, except use AN4-7A bolts. See view D.

Z. Remove hanger simulator 412-240-033-101 from number four hanger location.Install hanger simulator 412-240-035-101 atnumber two hanger location in accordancewith step s(2).

aa. Install a new length of unkinked 0.020inch diameter wire in accordance with steps jand k. Route wire through hanger simulatorsat number three, two and one hangerlocations. Tighten wire until all slack isremoved and secure wire at the forward endof hanger simulator 412-240-034-101 atnumber one hanger location. Secure end ofwire with safety-wire spinner pliers or otherpositive-locking pliers. Ensure alignment wireis seated in "V" groove in intermediategearbox simulator T103224-101 pin.

NOTE

As an alternate procedure thealignment wire may be anchored atforward face of hanger simulator412-240-034-101 and tension/clamped at top end plate ofintermediate gearbox simulatorT103224-101.

bb. Verify acceptable alignment ofhanger simulator by confirming alignment wireclears edges of holes in forward and aft endplates of hanger simulators on tailboom, in aftend plate of hanger simulator at number onehanger location and in forward and top endplates of intermediate gearbox simulator. Seeview B. If alignment of hanger simulator 412-

BHT-212-MM

240-034-101 is acceptable proceed directly tostep ac; otherwise proceed as follows:

NOTE

Elongation of the four mountingholes in the No. 1 hanger support isnot permitted.

(1) If hanger simulator error is in "yaw"direction, loosen four bolts securing hangersupport to airframe and shift support to obtainacceptable alignment. Tighten four bolts andverify acceptable alignment in accordancewith step ab.

(2) If hanger simulator error is in "pitch"position, relax tension on alignment wire andremove four bolts securing hanger support toairframe. To "pitch" hanger simulator forwardadd equal shims under both aft supportmounting pads and remove same thickness ofshims from under both forward mountingpads. Do just the opposite to "pitch" supportaft. Install four support mounting bolts, tightenalignment wire and verify acceptable hangersimulator alignment in accordance with stepab. It may be necessary to perform step ab(1)to achieve acceptable "yaw" alignment.

(3) If hanger simulator error is in"elevation" position (alignment wire hits top orbottom of holes in hanger simulator at numbertwo hanger location), relax tension onalignment wire and remove four bolts securinghanger support to airframe. Add or removeequal shim thickness under each of foursupport mounting pads to obtain requiredelevation. Install four mounting bolts andverify acceptable hanger simulator alignmentin accordance with step ab. It may benecessary to repeat step ab(1) to achieveacceptable "yaw" alignment.

CC. Tail rotor drive system alignment iscomplete. Remove all alignment tools andtailboom support. Verify bolts securing hangersupports to forward fuselage and to tailboomare properly torqued. Remove any greaseremaining on uppermost shim at intermediategearbox location.

2. Install tail rotor gearbox (paragraph 65-58).

65-00-00Rev. 5 Page 24A

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3. Install intermediate gearbox (paragraph 5. Close and secure tail rotor driveshaft65-33). covers.

4. Install tail rotor hangers and tail rotor 65-17. DELETED.driveshafts (paragraphs 65-14 and 65-8).

65-00-00Page 24B Rev. 5

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INTERMEDIATE GEARBOX

65-18. INTERMEDIATE (42°) GEARBOX.

The intermediate gearbox is installed on thetailboom forward of the vertical fin. Thegearbox is aligned by use of shims betweengearbox and tailboom (paragraph 65-16). Anelectrical chip detector and an oil level sightgage are located on the right side. A ventedfiller plug is installed on top of the case. Boththe input and output quills have flexible,crown-toothed couplings for attachment ofdriveshafts. A cover with cowl fastenersprovides access to the gearbox.

65-19. MAINTENANCE.

The following maintenance proceduresconsists of troubleshooting, inspection (whilestill installed), removal, cleaning, limitedrepair, and installation.

NOTE

When any doubt exists as to theserviceability of a gearbox, performserviceability checks defined inChapter 63.

65-20. Troubleshooting.

Table 65-2. Troubleshooting - intermediate gearbox

INDICATION OFTROUBLE PROBABLE CAUSE CORRECTIVE ACTION

CHIP 42/90 BOX caution M e t a I c h i p s h a v e Remove and inspect electricsegment illuminated. accumulated on chip chip detector. If chips are found,

detector. retain in a clean container forsubsequent investigation.

Faulty wiring or faulty chip Inspect wiring to chip detectordetector. for continuity and grounding

(Chapter 98). Repair wiring orreplace defective chip detectoras required.

Oil leakage from intermediate Faulty seals, packings, or Clean gearbox and recheck forgearbox. wear sleeves. oil leak both static and dynamic

(engine operating). Measureand record rate of leakage.Maximum allowable static ordynamic leakage at any singlesource is two drops per minute.Total allowable leakage from allsources on gearbox is six dropsper minute.

FOR BEST VALUE, BUY GENUINE BELL PARTS 65-00-00Rev.3 Page 25

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INDICATION OFTROUBLE PROBABLE CAUSE

Cracked gearbox housing.

65-21. Inspection (installed).

1. Open tail rotor driveshaft covers andremove intermediate gearbox cover.

2. Shake gearbox (9, figure 65-6) and checkfor looseness on tailboom. No looseness isacceptable.

3. Check for evidence of fretting corrosion atmating surface between gearbox and tailboomwhich could be caused by movement ofgearbox on tailboom. A gray residue is anindication of fretting corrosion. If residue ispresent, remove and inspect gearbox (BHT-212-CR&O).

NOTE

Inspection steps 4. through 10. arenot applicable if gearbox is removedat step 3.

4. Inspect four bolts (2) for correct torqueand correct thread engagement.

5. Inspect couplings (8 and 10) for greaseleakage and for overheating evidenced bydiscoloration of temperature indicator TEMP-PLATES (11) from white or light gray to black.A change in color indicates a possibleoverheat and /or component degradation.

CORRECTIVE ACTION

Replace gearbox seals,packings, or wear sleeves ifmaximum allowable leakagerate is exceeded (BHT-212-CR&O).

Inspect gearbox for cracks inhousing. Replace gearbox ifcracks are found.

Cause of TEMP-PLATE discoloration shall bedetermined and corrected prior to continuedoperation. Refer to paragraph 65-13 forcoupling TEMP-PLATE inspection.

6. Deleted.

7. Inspect oil filler cap (paragraph 65-39).

8. Inspect oil sight glass for correct oil level.Inspect sight glass and indicator for stainingand/or cracks and crazing. Damage whichcould cause oil leakage or make oil leveldifficult to determine is not acceptable.

9. Inspect electrical chip detector for metalparticles. Refer to Chapter 63, ServiceabilityChecks if metal particles are found.

65-22. Removal.


NUMBER NOMENCLATURE

DB3703-30 Drain line

1. When intermediate gearbox is to bereplaced, unless conditions prevent operation,perform a ten minute ground runup and drain

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operation oil using drain line DB3703-30. Ifrunup is not practical, remove intermediate(42°) gearbox and flush with new lubricatingoil (Chapter 12) of same type being used ingearbox. Attach tag to intermediate gearboxstating: "PRESERVED WITH OPERATINGLUBRICANT."

2. Open tail rotor driveshaft covers andremove intermediate gearbox cover.

3. Remove tail rotor driveshafts (1 and 7,figure 65-6) (paragraph 65-5).

4. Remove chip detector (paragraph 65-34).

5. Remove four bolts (3).

6. Remove gearbox (9). Inspect shims (6)for secure installation on tailboom. If shims(6) are not bonded to tailboom, index theshims for installation in same location.

65-23. Cleaning.

MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-304 Solvent

1. Clean gearbox with clean, lint-free clothdampened with solvent (C-304).

CAUTION.................

DO NOT FORCE SOLVENT AND/OR DIRT INTO FLEXIBLECOUPLING WHEN USINGCOMPRESSED AIR.

2. Dry with filtered, compressed air.

65-24. Inspection (removed fromhelicopter).

Refer to BHT-212-CR&O manual.

65-25. Inspection (special/conditional).

NOTE

Special/conditional inspections ofintermediate gearbox are requiredafter tail rotor drive systemovertorque, sudden stoppage,compressor stall, etc. (Chapter 5).

65-26. Repair.

1. Repair intermediate gearbox (BHT-212-CR&O).

2. Repair faulty filler cap by same procedureoutlined for tail rotor gearbox filler cap(paragraph 65-64).

3. Replace sight glass (3, figure 65-7) and/orindicator (4) that fails to pass inspection(paragraph 65-31).

4. Replace chip detector and/or self-closingvalve that fails to pass inspection (paragraph65-35).

5. Deleted.


MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-201 Primer

C-204 Primer

C-405 Lockwi re

GENUINE BELL PARTS ARE YOUR BEST VALUE 65-00-00Rev.3 Page 27

BHT-212-MM

1. Driveshaft2. Bolt3. Steel washer4. Aluminum washer5. Tailboom6. Shim7. Driveshaft8. Coupling9. Gearbox

10. Coupling11. Temperature indicator

TEMP-PLATES

NOTE

Refer to BHT 212-CR&0 for TEMP-PLATES installation procedure.

212-M-65-6

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PRIOR TO INSTALLATION OFINTERMEDIATE (42) GEARBOX,ACCOMPLISH THE FOLLOWING:

ENSURE FLEXIBLE COUPLINGSON INPUT AND OUTPUT QUILLSARE PROPERLY LUBRICATED(PARAGRAPH 65-42).

ROTATE FLEXIBLE COUPLING ONINPUT QUILL AND CHECK FORBINDING AND FOR EXISTENCE OFBACKLASH BETWEEN PINION ONINPUT QUILL AND GEAR ONOUTPUT QUILL.

DRAIN OIL FROM GEARBOX ANDSERVICE WITH GEARBOX OIL(CHAPTER 12).

SHIMS (6, FIGURE 65-6) SHOULDBE BONDED TO TAILBOOM. IFSHIMS ARE NOT BONDED TOTAILBOOM, ENSURE SAME SHIMSWHICH WERE REMOVED, ORS H I M S OF I D E N T I C A LTHICKNESS, ARE INSTALLED.FAILURE TO COMPLY COULDCAUSE MISALIGNMENT ANDFAILURE OF TAIL ROTOR DRIVECOMPONENTS.

1. Clean mating surfaces of gearbox (9,figure 65-6) and tailboom (5).

2. Position gearbox on tailboom.

3. Check gearbox for contact with shim (6)at four points where bolts (2) are to beinstalled. Maximum acceptable gap at any ofthe four points is 0.001 inch (0.025 mm).

4. Remove gearbox and coat all fayingsurfaces, bolts, and bolt holes with unreducedprimer (C-201) or primer (C-204).

BHT-212-MM

NOTE

Complete driveshaft alignment andgearbox shimming (paragraph 65-16) before proceeding with this step.

5. Position gearbox on tailboom and installfour bolts (2) with steel washers (3) next tobolt head and aluminum washer (4) next togearbox. Bottoming of bolt grip is to bedetermined as follows:

NOTE

One aluminum washer and one steelwasher is normally required at eachbolt location, however, additionalwashers may be required at eachlocation if bolt grip bottoms inairframe prior to securing gearbox.

a. Torque each bolt 30 to 40 inch-Ibs andcheck the washers under bolt heads forlooseness. If any of the washers are looseadd washers, as required at each boltlocation, to ensure no looseness is apparentwhen above stated procedure is repeated.

b. After completion of bolt -grip-bottomingtest, retorque bolts 50 to 70 inch-Ibs. (5.7 to5.9 Nm). Secure bolts in pairs at each sidewith lockwire (C-405). Additional washers (3)may be required if bolt grip bottoms out onnut plate.

6. Install driveshafts (1 and 7) (paragraph65-15).

7. Verify actual presence of oil in sight gageand check oil level to full mark on indicator.

8. Install chip detector (paragraph 65-36).Connect wiring.

9. If gearbox has not previously beenqualified on run-in test stand, accomplishalternate run-in and test (paragraph 65-28).

10. Install intermediate gearbox cover andclose tail rotor driveshaft covers.

11. Perform alternate run-in test (paragraph65-28).

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NOTE

It is desirable that intermediategearbox, after overhaul, be test runand inspected in accordance withpublication(s) furnished with run-instand for qualification for flight. Inthe event a run-in stand is notavailable, the following functionaltest may be accomplished as aminimum acceptable alternate test.

1. Install sufficient ballast in cabin to obtainmaximum allowable gross weight (BHT-212-FM).

2. Verify helicopter is properly serviced andlubricated.

3. Start power sections (BHT-212-FM) andoperate at 60% rpm for five minutes.

4. Gradually increase rpm to 88% a rate of7% each six minutes.

5. Hold at 88% for two minutes withcollective pitch applied to maximum which canbe maintained without becoming airborne, orexceeding 100% torque.

6. Shut down engine (BHT-212-FM) andcheck electrical chip detector for foreignmaterial or chips.

7. Clean and install chip detector.

8. Start engine (BHT-212-FM) and graduallyincrease to 88%. Run at 88% for six minutes.

9. Apply collective pitch to maximumposition which can be maintained withoutbecoming airborne or exceeding 100% torque.

10. At a rate of 3% each six minutes,gradually increase rpm to 100% withoutbecoming airborne or exceeding 100% torque.

11. Run at 100% rpm for 30 minutes withcollective pitch in maximum up position whichcan be maintained without becoming airborneor exceeding 100% torque.

12. Shut down engine (BHT-212-FM) anddrain oil from gearbox. Check gearbox oil andchip detector for an excessive amount ofmetal particles indicating internal failure.

13. Inspect input and output quill couplingsand surrounding area for evidence of greaseleakage. If there is evidence of grease

leakage, remove couplings and replacedefective parts. Repeat test run.

14. Check temperature indicator "TEMP-PLATES" (1 1 , figure 65-6) for discolorationand overheat condition. A change in color of"TEMP-PLATES" from white or light gray toblack indicates a possible overheat conditionand/or component degradation. Cause ofdiscoloration shall be determined andcorrected prior to continued operation. Referto paragraph 65-13 for inspection procedure.

15. Install chip detector and fill gearbox tospecified level with approved lubricating oil(Chapter 12).

65-29. SIGHT GLASS.

65-30. Removal.


NUMBER NOMENCLATURE


1. Remove chip detector (paragraph 65-34).

2. Insert one end of DB3703-30 drain lineinto container. Insert other end in hole wheredetector was installed. Oil will automaticallydrain.

3. Remove ring (1, figure 65-7).

4. Remove glass (3) and packing (2).

5. Remove indicator (4).

6. Remove DB3703-30 drain line.

7. Install chip detector (paragraph 65-36).

65-31. Inspection and repair.

Inspect sight glass for cracking and crazing.Replace glass if cracked or if crazed ordiscolored to the extent that accurateindication of oil level cannot be determined.


1. Install indicator (4, figure 65-7).

2. Install packing (2) on glass (3). Coatpacking (3) with oil used in gearbox (Chapter12). Install glass (3) in gearbox port.

3. Install ring (1).

65-00-00Page 30 Rev. 5

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212-M-65-7

Figure 65-7. Intermediate gearbox sight glass

65-33. CHIP DETECTOR.

65-34. Removal.

disengage locking detent and withdrawelectrical chip detector (3) from self-closingvalve (5). Inspect chip detector (3) forpresence of metal particles. If any metalparticles are detected, refer to Chapter 63.

SPECIAL TOOLS REQUIREDNOTE

NUMBER NOMENCLATURE

DB3703-30 Drain lineIf self-closing valve (5) is to beremoved, install DB3703-30 oildraining line in self-closing valve (5)and allow oil to drain from gearbox.

NOTE

Electrical chip detector element (3,figure 65-8) may be removed forinspection without draining gearboxoil.

1. Move nipple (8) back on electrical wire (2)to expose nut (1). Remove nut (1) andelectrical wire (2).

2. Press in on knurled body of electrical chipdetector (3), turn counterclockwise to

3. Remove self-closing valve (5) fromgearbox (7). Remove gasket (6) from self-closing valve (5). Discard gasket.


1. Inspect chip detector for damage (figure65-9).

2. Repair of the electrical chip detector isrestricted to replacement of defective parts.


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MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-405 Lockwire

1. Lubricate new gasket (6, figure 65-8) withlubricating oil used in gearbox and installgasket on valve (5).

2. Install self-closing valve (5) on gearboxcase (7). Torque valve (5) 120 to 150 in.lbs.(14 to 17 Nm). Secure valve (5) to gearboxcase (7) with lockwire (C-405).

CAUTION% '

ENSURE PROPER PACKING (4) ISINSTALLED ON CHIP DETECTOR(3). THE WRONG PACKING MAYNOT ALLOW CAUTION SEGMENTTO ILLUMINATE AND MAYRESTRICT OPERATION OF SELF-CLOSING VALVE.

3. Lubricate new packing (4) with lubricatingoil used in gearbox and install packing onchip detector (3). Insert chip detector (3) intovalve (5). Push and twist clockwise toengage locking detents.

4. Position electrical wire (2) on chipdetector (3) and install nut (1). Do notexceed 4 in.lbs. (0.45 Nm) torque on nut.Position nipple (8) over nut (1).

65-37. OIL FILLER CAP.

65-38. Removal.

1. Push down on cap (6, figure 65-10) andtwist to disengage pin (7) from gearbox (4).

2. Unsnap pin (1) from gearbox (4).

65-39. Inspection.

1. Inspect filler cap for distortion of pin (7,figure 65-10) or other damage which wouldaffect function.

NOTE

Some cap assemblies have astainless steel mesh plug installedinstead of aluminum wool. Thespring-back check is not required forthese cap assemblies.

2. For cap assemblies with aluminum woolinstalled, invert filler cap to expose washer(11). Press washer in to cap approximately0.06 in. (1.5 mm) and release. Washershould spring back against ring (12). Ifwasher does not immediately spring back intoposition aluminum wool packing (10) is dirtyor an insufficient amount is installed.

65-40. Repair.

1. Repair intermediate gearbox filler capassembly by same procedure outlined for tailrotor gearbox filler cap (paragraph 65-64).


NOTE

Ensure replacement cap is abreather type.

1. Position cap assembly on gearbox (4,figure 65-10). Push down on cap (6) andtwist clockwise to engage pin (7) in slots ingearbox adapter.

2. Secure chain (3) to gearbox (4) withsafety pin (1).

65-42. FLEXIBLE COUPLINGS.

65-43. Lubrication.

For lubrication of input and output flexiblecouplings, refer to paragraph 65-14.

65-00-00Page 32

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AREA

All No cracks allowed.

Figure 65-8. Chip detector

AREAB

LIMITS

A Maximum depth of pitting is 0.030 inch (0.762 millimeter) with no more than40 percent of any 1.0 inch (25.4 millimeters) square or 20 percent of total areaof any surface to be pitted.

B Maximum depth of pitting is 0.020 inch (0.508 millimeter) with no more than40 percent of any 1.0 inch (25.4 millimeters )square or 20 percent of total areaof any surface to be pitted. Thread damage is not permitted.

212-M-65-9

Figure 65-9. Chip detector damage limits

BHT-212-MM

DETAIL A

212-M-65-8

GENUINE BELL PARTS ARE YOUR BEST VALUE 65-00-00Rev.3 Page 33

B HT-212-M M

1. Safety pin2. Packing3. Chain4. Gearbox5. Ring6. Cap7. Pin8. Spring assembly9. Plug

10. Packing (aluminum wool)11. Washer12. Ring (spiralox)

65-00-00Page 34 Rev.3

DETAIL A

Figure 65-10. Oil filler cap

FOR BEST VALUE, BUY GENUINE BELL PARTS

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TAIL ROTOR GEARBOX

65-44. TAIL ROTOR (90°) GEARBOX. 6. Remove driveshaft (13) (paragraph 65-5).

7. Remove six nuts (11) with steel washers65-45. REMOVAL. (10).


NUMBER NOMENCLATURE


T101264-103 Pusher set

1. When tail rotor (90°) gearbox is to bereplaced, unless conditions prevent operation,perform a ten minute ground run. Drainoperating oil using DB3703-30 drain line. Ifrun up is not practical, remove tail rotorgearbox and flush with new lubricating oil ofsame type being used in gearbox. Attach tagto tail rotor gearbox stating: "PRESERVEDWITH OPERATING LUBRICANT".

2. Remove tail rotor hub and bladeassembly (Chapter 64).

3. Remove bolt (7, figure 65-11) anddisconnect link (8) from lever (3).

4. Disconnect electrical wire and removechip detector (paragraph 65-57).

5. Open vertical fin cover (12) and removeintermediate gearbox fairing.

CAUTION.................

REMOVE CLAMP SET FROM BOTHENDS OF DRIVES HAFT (13)BEFORE REMOVING EITHER ENDOF SHAFT FROM CURVICCOUPLINGS OR SUPPORTUNATTACHED END OF SHAFT TOHOLD SHAFT ALIGNED INNORMAL OPERATING POSITIONWHILE GEARBOX IS REMOVED.

8. Remove gearbox (1) from support fitting(14) using T101264-103 tailrotor gearboxpusher (figure 65-12).

NOTE

Install two spacers (15, figure 65-11), nut (11) with steel washer (10)on gearbox studs (17) to hold inputquill in gearbox (1) while gearbox isremoved from helicopter.

65-46. Cleaning.

MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-304 Solvent

1. Clean gearbox with clean cloth dampenedin solvent (C-304).

CAUTION

DO NOT FORCE SOLVENT AND/OR DIRT INTO FLEXIBLECOUPLING WHEN USINGCOMPRESSED AIR.

DO NOT IMMERSE GEARBOX INSOLVENT.

2. Dry with filtered, compressed air.

65-47. Inspection (installed).

1. Open vertical fin cover (12, figure 65-11).

65-00-00Page 35

BHT-212-MM-7

65-00-00Page 36 Rev. 10 18 SEP 2009 ECCN EAR99

2. Shake gearbox (1) and check for looseness ontail rotor gearbox support fitting (14).

3. Inspect for evidence of fretting corrosion atmating surface between gearbox (1) and tail rotorgearbox support fitting (14), which could be caused bymovement of gearbox on support. A gray residue is anindication of fretting-corrosion. If residue is present,remove gearbox and inspect in accordance withBHT-212-CR&O and inspect tail rotor gearbox supportfitting in accordance with Chapter 53.

NOTE

Step 4 through step 9 are not applicable ifgearbox is removed at step 3.

Oil leaks shall not exceed two drops perminute from any single source and shall notexceed a total of six drops per minute fromall sources on gearbox.

4. Inspect gearbox for cracks and external damage,oil leaks, and unserviceable fittings.

5. Inspect six nuts (11) for correct torque and correctthread engagement (paragraph 65-50).

6. Inspect link assembly (8) and lever (3) for secureinstallation.

7. Inspect coupling (16) for grease leakage andouter coupling temperature indicator TEMP-PLATESfor discoloration and overheat condition. A change incolor of TEMP-PLATES (from white or light gray toblack) will indicate a possible overheat condition and/or component degradation. The cause of discolorationshall be determined prior to continued operation. Referto paragraph 65-13 for inspection procedure.

8. Inspect oil sight glass for correct oil level. Inspectsight glass and indicator for damage and discoloration(paragraph 65-54).

9. Inspect electrical chip detector for metal particlesand damage (paragraph 65-58). Refer to Chapter 63for metal particle identification and requiredmaintenance actions.

65-48. Inspection (Off Helicopter)

Inspect gearbox and historical records for evidencegearbox has been involved in an accident or incident

requiring special or conditional inspection (Chapter 5and BHT-212-CR&O).

65-49. Repair

1. Polish out mechanical and corrosion damagewithin limits (BHT-212-CR&O).

2. Repair faulty oil filler cap (paragraph 65-61).

3. Replace faulty sight glass (paragraph 65-52).

4. Replace chip detector and/or self-closing valvethat fails to pass inspection (paragraph 65-56).

5. Replace temperature indicator TEMP-PLATES(Figure 65-11). Refer to BHT-212-CR&O forinstallation procedures.

65-50. INSTALLATION

CAUTION

PRIOR TO INSTALLATION OF TAILROTOR GEARBOX, ACCOMPLISH THEFOLLOWING:

ENSURE GEARBOX FLEXIBLECOUPLING IS PROPERLY LUBRICATED(PARAGRAPH 65-42).

ROTATE FLEXIBLE COUPLINGAND CHECK FOR BINDING ANDFOR EXISTENCE OF BACKLASHBETWEEN PINION ON INPUTQUILL AND GEAR ON OUTPUT

Refer to BHT-ALL-SPM for specifications.

MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-204 Epoxy Polyamide Primer

C-309 MEK

BHT-212-MM

NOTES

Q1 Shipping spacer isremoved from gearbox prior toinstallation.

Q2 Refer to BHT-212-CR&0for TEMP-PLATEinstallation procedure.

1. Tail rotor gearbox2. Cap assembly3. Lever4. Nut5. Washer6. Washer7. Bolt8. Link assembly9. Cotter pin

10. Thin steel washer11. Nut12. Vertical fin cover13. Driveshaft14. Support fitting15. Spacer (NAS43DD6-49) (2)A,16. Coupling17. Stud18. Temperature indicator

TEMP-PLATE212-M-65-11

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NOTES

1. If not previously accomplished, thread screw assembly (6) into clamp assembly (5). Allowsufficient clearance for positioning on support (4) and adapter assembly (2).

2. Position both halves of adapter assembly (2) on tail rotor gearbox (3) against input quill asshown.

3. Position tail rotor gearbox pusher (1) on gearbox and support with hooks of clamp assembly(5) centered securely over shoulders of support (4) and adapter retainer (7) over both halvesof adapter assembly (2).

4. Tighten screw assembly (6) clockwise with a suitable wrench until tail rotor gearbox (3)separates from support (4). Remove tools and lift gearbox from support.

212-M-65-12

Figure 65-12. Tail rotor gearbox pusher T101264-103 tool application

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DRAIN PRESERVATIVE OIL (IFANY) FROM GEARBOX ANDSERVICE WITH GEARBOX OIL(CHAPTER 12).

1. Check mounting flange of gearbox (1,figure 65-11) for sealant protruding from thethree jackscrew holes. Trim off sealant flush(using a sharp, non-metallic scraper) to allowproper seating of tail rotor gearbox (1) flangeon support fitting (14).

2. Remove nuts (11), spacers (15), andwashers (10) from studs (17) around inputdrive quill.

3. Using MEK (C-309) and a non-metallicscraper, clean mating surfaces of gearboxand tailboom support fitting.

4. Coat all faying surfaces of gearbox, studs,tailboom mount fitting, holes for studs inmount and washers with primer (C-204).Install gearbox while primer is wet.

CAUTION.................

ENSURE A MINIMUM OF TWOTHREAD PITCHES, INCLUDINGCHAMFER, EXTEND THROUGHNUTS (11). ENSURE NUTS DONOT BOTTOM ON GRIP PORTIONOF STUDS. USE ADDITIONALTHIN STEEL WASHERS (10) IFREQUIRED.

SHIPPING SPACERS (15) AREFOR SHIPMENT OF GEARBOXONLY, DO NOT INSTALLSPACERS.

6. Install six thin steel washers (10) and nuts(11).

7. Torque nuts evenly in a star pattern 200to 235 in.lbs. (22.6 to 26.5 Nm). Repeattorque pattern until all nuts retain torqueinitially applied to first nut in pattern. Torquevalue of first nut will decrease as other nutsare torqued.

8. Use a 0.005 in. (0.127 mm) feeler gage toensure no gap exists between gearbox inputquill and gearbox shim.

9. Install driveshaft (13) (paragraph 65-8).

NOTE

Additional washers (5) may be usedto align nut (4) for cotter pininstallation.

10. Connect link (8) to lever (3). Install bolt(7) with one steel washer (6) under boltheadand one steel washer (5) under nut (4).Install cotter pin (9).


12. Verify actual presence of oil in sightgage and check oil level to full mark onindicator.

13. Close vertical fin cover (12) and installintermediate gearbox fairing.

14. Install and rig tail rotor hub and bladeassembly and controls (Chapter 64 and 67).

15. If gearbox has not previously beenqualified on run-in test stand, accomplishalternate run-in and test (paragraph 65-51).

65-51. Alternate run-in test.

NOTE

Perform special inspection (Chapter5) after installation of tail rotorgearbox.

5. Position tail rotor gearbox (1) on supportfitting (14) with coupling (16) and studs (17)through holes in support fitting (14).

NOTE

It is desirable that tail rotor gearbox,after overhaul, be test run andinspected in accordance withpublication(s) furnished with run-instand for qualification for flight. Inthe event a run-in stand is not

65-00-00Page 39

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Perform alternate run-in test for tail rotorgearbox per paragraph 65-28.

(Chapter 12).

65-56. CHIP DETECTOR.

65-52. SIGHT GLASS.65-57. Removal.

65-53. Removal.SPECIAL TOOLS REQUIRED

SPECIAL TOOLS REQUIREDNUMBER NOMENCLATURE

NUMBER NOMENCLATURE DB3703-30 Drain lineDB3703-30 Drain line

1. Remove chip detector (6,figure 65-13)(paragraph 65-57).

2. Insert one end of DB3703-30 drain lineinto container. Insert other end in hole wheredetector was installed. Oil will automaticallydrain.

3. Remove ring (5).

NOTE

Electrical chip detector element (5,figure 65-14) may be removed forinspection without draining gearboxoil.

1. Move nipple (8) back on electrical wire (6)to expose nut (7). Remove nut (7) and wire(6).

4. Remove glass (4) and packing (3).Discard packing.

5. Remove indicator (2).

6. Remove DB3703-30 drain line.



Inspect sight glass for crazing anddiscoloration. Inspect indicator fordiscoloration or any markings which wouldimpair determination of oil level. Replacedefective parts.


1. Install indicator (2, figure 65-13)

2. Install new packing (3) on glass (4). Coatpacking (3) with oil used in gearbox (Chapter12). Install glass (4) in gearbox port.

2. Press in on knurled body of chip detector(5), turn counterclockwise to disengagelocking mechanism, and withdraw element (5)from self-closing valve (3).

NOTE

If self-closing valve (3) is to beremoved, drain gearbox oil intocontainer with DB3703-30 drain lineinstalled in valve (3).

3. Remove valve (3). Remove packing (2)from valve (3). Discard packing.

65-58. Inspection.

1. Inspect electrical chip detector element(5, figure 65-14) for metal particles. Refer toChapter 63 for metal particle determinationand maintenance action required.

2. Inspect electrical chip detectorcomponents for damage (figure 65-15).

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212-M-65-13

Figure 65-13. Sight glass

65-59. Repair.

Repair of the electrical chip detector isrestricted to replacement of defective parts.


chip detector element (5). Insert element (5)into self-closing valve (3). Push down andtwist element until locking detents engage.

4. Position electrical wire (6) on element (5)and install nut (7). Do not exceed 4 in.lbs.(0.45 Nm) torque on nut. Position nipple (8)over nut (7).

MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-405 Lockwire

1. Lubricate new packing (2, figure 65-14)with lubricating oil used in gearbox and installpacking on self-closing valve (3).

2. Install self-closing valve (3) on gearbox(1). Torque valve (3) 120 to 150 in.lbs. (14 to17 Nm). Secure valve (3) to gearbox (1) withlockwire (C-405).

3. Lubricate new packing (4) with lubricatingoil used in gearbox and install packing on

5. Service gearbox to specified level withapproved lubricating oil if self-closing valve(3) was removed (Chapter 12).

65-61. OIL FILLER CAP.

65-62. Removal.

1. Push down on cap assembly (6, figure 65-16) and twist to disengage pin (7) fromgearbox (1).

2. Unsnap safety pin (4) from gearbox (1). 1

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Figure 65-14. Tail rotor gearbox electrical chip detector

65-63. Inspection.

1. Inspect filler cap for distortion of pin (7,figure 65-16) or other damage which wouldaffect function.

NOTE

Some cap assemblies have astainless steel mesh plug installed inlieu of aluminum wool. The spring-back check is not required whenstainless steel mesh plug isinstalled.

2. Invert the filler cap to expose washer (9).

3. Press washer approximately 0.06 in, (1.5mm) and release. The washer should springback against ring (8). If washer does notspring back, aluminum wool packing (10) isdirty or an insufficient amount is installed.

65-64. Repair.

212-M-65-14

MATERIALS REQUIRED

NUMBER NOMENCLATURE

C-304

C-422

Solvent

Aluminum Wool

1. Repair is restricted to replacement ofaluminum wool packing (10, figure 65-16) asoutlined in steps 2. through 10.

2. Remove pin (7).

3. Remove ring (5), cap (6), and springassembly (12) from plug (11).

4. Remove ring (8) and washer (9).

5. If installed, remove aluminum woolpacking (10) and discard.

6. Clean parts with solvent (C-304).

65-00-00 GENUINE BELL PARTS ARE YOUR BEST VALUEPage 42 Rev.3

-'O^CQ

((D

D

((D

D

BHT-212-MM

AREA

A

AREA

All No cracks allowed.

AREAB ARFA

A B

LIMITS

A Maximum depth of pitting is 0.030 inch (0.762 millimeter) with no more than40 percent of any 1.0 inch (25.4 millimeters) square or 20 percent of total areaof any pitted surface.

B Maximum depth of pitting is 0.020 inch (0.508 millimeter) with no more than40 percent of any 1.0 inch (25.5 millimeters) square or 20 percent of total areaof any pitted surface. Thread damage is not permitted.

212-M-65-15

Figure 65-15. Tail rotor gearbox electrical chip detector damage limits

7. For filler caps which are filled withaluminum wool, fill plug (11) with newaluminum wool (C-422) until washer (9) willspring back to original position after beingpressed in 0.06 in. (1.5 millimeters). Add orremove aluminum wool as required.

8. Install washer (9) and ring (8).

9. Ensure packing (3) is in place and installspring assembly (12), cap (6), and ring (5) onplug (11).

10. Insert pin (7) through cap (6). Bend endof pin to secure.


1. Position cap assembly on gearbox (1,figure 65-16). Push down on cap (6) and

twist clockwise to engage pin (7) in gearboxadapter.

2. Secure chain (2) to gearbox (1) withsafety pin (4).

65-66. TAIL ROTOR GEARBOX FLEXIBLECOUPLING.

65-67. LUBRICATION.

For lubrication of input flexible coupling, referto paragraph 65-14.

65-00-00Page 43

BHT-212-MM

1. Gearbox2. Chain3. Packing4. Safety pin5. Ring6. Cap7. Pin8. Ring (spiralox)9. Washer

10. Packing (aluminum wool)11. Plug12. Spring assembly

Figure 65-16. Tail rotor gearbox oil filler cap

DETAIL A

212-M-65-16

65-00-00 BUY BELL PARTS - BUY BELL VALUEPage 44 Rev.3

b ht-212-m m - unlpaero.ing.unlp.edu.ar/catedras/archivos/212-mm-ch65.pdfb ht-212-m m chapter 65 -...

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