EXPORT CONTROLLED RollsRoyce

250B17F SERIES OPERATION AND MAINTENANCE

POWER AND ACCESSORY GEARBOXMAINTENANCE PRACTICES

1. Replacement
WARNING: FAILURE TO PROPERLY ASSEMBLE COMPONENTS/PARTS OF THE ENGINE
COULD RESULT IN AN ENGINE FAILURE.
CAUTION: CHECK THE 250B17F ILLUSTRATED PARTS CATALOG PUB NO. GTP 52434 FOR
COMPATIBILITY OF THE TURBINE WITH THE GEARBOX BEFORE ORDERING A
REPLACEMENT FOR EITHER PART.
A. Power and Accessory Gearbox Replacement
(1) Remove the coordinator. (Refer to Coordinator Assembly, para 2.A., 732005.)
(2) Remove the fuel controltogovernor Py air tube and propellerpower turbine
governortooverspeed governor oil tube and Py air tubes.
(3) Remove the power turbine governor and propeller governor control cables and mounting
brackets.
(4) Remove the coordinator support forward bracket.
(5) Remove the ignition exciter and start counter. (Refer to Ignition Exciter, para 1.A., 741001.)
(6) Remove the fuel pump and filter assembly. (Refer to Fuel Pump and Filter Removal, para
1.A., 731001.)
(7) Remove the propeller overspeed governor. (Refer to Propeller Overspeed Governor Removal,
para 1.A., 732004.)
(8) Remove the gas producer fuel control. (Refer to Gas Producer Fuel Control Removal, para
2.A., 732002.)
(9) Remove the lubrication system tubing and fittings.
(10) Remove the turbine assembly. (Refer to Replacing the Turbine AssemblyRemoval, para 1.A.,
725000.)
(11) Remove the propeller reduction gearbox. (Refer to Propeller Reduction Gearbox Removal,
para 1.A., 721000.)
(12) Remove the compressor (with Pc filter). (Refer to Compressor Assembly Removal, para 1.A.,
723000.) Remove tubing only as necessary to separate the compressor from the gearbox.
CAUTION: DO NOT USE THE IGNITER PLUG, FUEL NOZZLE OR ANY LINES OR TUBING
AS HANDLES FOR MANEUVERING THE TURBINE AND COMBUSTION
SECTION ASSEMBLY DURING THE INSTALLATION.
(13) Remove the beta valve cover. (Refer to applicable portion of Propeller Beta Control Valve
Removal, para 2.A., 761002.)
(14) Remove the engine identification plate.
(15) Transfer fittings and accessory pad covers from the rejected to the replacement gearbox as
required (See Figure 201).
(16) Reassemble the engine using the replacement gearbox. Assemble in reverse of the order of
removal using the assembly portion of the referenced removal paragraphs.
WARNING: FAILURE TO PROPERLY INSTALL, ALIGN AND TIGHTEN FUEL, OIL, AND AIR
FITTINGS AND TUBES COULD RESULT IN AN ENGINE FAILURE.
(17) Install lubrication system tubing (See Figure 201). Apply a light coating of engine oil to
lubrication system fitting threads and packings to aid installation.
(18) Make appropriate entry relative to gearbox replacement in the Engine Log.

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250B17F SERIES OPERATION AND MAINTENANCE

Lubrication System Tube and Fitting Torques

Figure 201 (Sheet 1 of 2)

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250B17F SERIES OPERATION AND MAINTENANCE

Lubrication System Tube and Fitting Torques

Figure 201 (Sheet 2 of 2)

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Legend for Figure 201

1. Not Used 34. Check ValvetoSupport

2. Front SupporttoAccessory Pressure Oil Tube
Housing Scavenge Tube 35. Screen
3. Sump CantoAccessory 36. Check Valve
Housing Scavenge Tube 37. Not Used
4. Nut (3), Bolt (3), Bracket, Clamp 38. Not Used
5. Nut (2), Bolt (2), Clamp (2) 39. Not Used
6. Fitting, Packing, Bolt (3) 40. Not Used
7. Union 41. Not Used
8. Packing 42. SumptoFireshield Scavenge
9. Union Tube
10. Packing 43. GP SupporttoFireshield
11. Accessory GearboxtoReduction Scavenge Tube
Gearbox Pressure Oil Tube 44. Nut (2)
12. Nut, Bolt, Spacer, Clamp 45. Washer (2)
13. Nut, Bolt, Clamp 46. Spacer
14. Union 47. Elbow (2)
15. Packing 48. FireshieldtoAccessory
16. GearboxtoFront Support Housing Tube
Pressure Oil Tube 49. FireshieldtoAccessory
17. Nut, Bolt, Bracket, Clamp Housing Tube
18. Tee 50. Elbow (2)
19. Nut 51. Nut (2)
20. Packing 52. Packing (2)
21. External Sump 53. Prop GovernortoOverspeed
22. Bolt (2) Governor Tube
23. Nut 54. Nut, Bolt, Spacer, Clamp (2)
24. Bolt 55. Elbow Filter
25. Plug 56. Nut
26. Packing 57. Packing
27. Hose 58. Elbow
28. Union 59. Nut
29. Packing 60. Packing
30. Accessory HousingtoCheck 61. Overspeed Governor
Valve Pressure Oil Tube 62. Nut (3)
31. Elbow 63. Washer (3)
32. Nut 64. Gasket
33. Packing 65. Combined Governor

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250--B17F SERIES OPERATION AND MAINTENANCE

(19) Check run the engine after gearbox replacement. (See Check Run, para 1., 72--00--00, Engine
Adjustment/Test.)
NOTE: When the power and accessory gearbox has been replaced, check the system oil
level before and after the check run.
B. Oil Seals Replacement
Replace leaking power and accessory gearbox seals as follows:
NOTE: Long term use of Aeroshell 555 oil may increase the probability of seal leakage in the
accessory gearbox.
(1) Remove the accessory or drive from the gearbox pad.
CAUTION: DO NOT PRY BETWEEN THE SEAL CAVITY IN THE HOUSING AND THE SEAL.
(2) Use the 6796941 seal replacement kit to remove the seal. Be careful not to contaminate the
shaft bearing or damage the gear shaft. The seal will be damaged during removal,
consequently it will not be salvageable.
CAUTION: DO NOT USE SILICONE LUBRICANTS EXCEPT WHERE SPECIFIED. USE
ONLY THE LUBRICANTS RECOMMENDED IN THE TABLE 301, 72--00--00,
ENGINE--SERVICING.
(3) Apply grease (Shell 6249, Mobil 28, engine oil or equivalent) to the seal lip to aid the
installation, then carefully drive (or press) the replacement seal in place.
(4) Reinstall the accessory or drive on the gearbox pad.
C. Oil Filter Replacement (See Figure 215)
Remove, inspect, clean and install the oil filter as follows: (Refer to Gearbox Housing Lubrication
System Components Disassembly, para 2.D., this section.)
(1) Place a container beneath the gearbox to catch oil which will drain when the cap is removed.
(2) Remove two nuts and washers; then using 6798860 puller, remove the oil filter cap. Remove
the filter element and packing from the housing. Discard the packing.
(3) Inspect filter element and filter cavity for metal particles.
(a) A small amount of metallic debris is acceptable after recent overhaul or repair. If
excessive metal contamination is present, clean filter and perform ground run for 30
minutes at power.
(b) Check filter after ground run for new accumulation of particles. If filter is clean, release
aircraft for flight. If accumulation is present after second ground run, tag engine, noting
cause for rejection.
(4) Reinstall the cap while the oil filter element is being cleaned.
(5) Clean the filter ultrasonically in perchlorethylene. If equipment is not available, clean by
agitating in mineral spirits.
(6) If excessive contamination is present the filter must be ultrasonically cleaned. If excessive
carbon deposits are found, con-- duct the inspection and cleaning of the power turbine support
pressure oil nozzle in accordance with Cleaning the Power Turbine Support Pressure Oil
Nozzle, para 6.F.(3), 72--50--00.
(7) Dry the filter by shaking (air dry), and inspect for any metal particles. If particles are present,
re--clean filter or replace filter element.
(8) Remove the cap and replace packing.
(9) Thoroughly clean the filter cavity of all residual oil and sludge.
(10) Install the cleaned filter element with new packing. Install filter cap with new packing. Tighten
nuts to 30--40 lb in. (3.4--4.5 N.m).

72--60--00
.COPYRIGHT 1989, 2008 Rolls--Royce Corporation Page 205
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250B17F SERIES OPERATION AND MAINTENANCE

D. Lube Oil Filter Housing Replacement

Replace the lube oil filter housing as follows:
(1) Place a container beneath the gearbox; then remove the magnetic plug from the filter housing.
(2) Remove the eight nuts and washers. Remove the housing and the gasket.
(3) Replace the packings on the filter housing mating ends of the two transfer tubes.
(4) Replace packings on both ends of the check valve assembly.
(5) Replace the filter housing gasket.
(6) Install the replacement lube oil filter housing. Mate the housing to the two transfer tubes and
to the check valve during the assembly.
(7) Retain the lube oil filter housing with eight nuts and washers. Tighten nuts to 3540 lb in.
(3.94.5 N.m).
(8) Install the magnetic plug with new packing in the replacement housing.
NOTE: 250B17F Series engines incorporates an impending bypass visual (popout)
indicator. Nominal values for this system are:
2129 psid (145200 kPad) Visual indication of impending
bypass. This system has a lock
out below 4966C (120150F).
80130 psid (552896 kPad) Filter bypass valve opens, con
taminated oil is bypassing the filter.
2. Gearbox Disassembly and Assembly
Applicable parts of the following procedure may be used by any knowledgeable and qualified
maintenance facility to perform part replacement in the gearbox. Return the gearbox to an overhaul
facility if repair beyond part replacement is required or if metal particles are detected inside gearbox.
A. Gearbox Disassembly (See Figure 202)
(1) Remove the engine from the aircraft and separate the gearbox from the engine. (Refer to
Power and Accessory Gearbox Replacement, para 1.A., this section.)
(2) Install the gearbox in 6795579 turnover stand (or equivalent) using 6798316 adapter.
(3) Remove the 39 nuts, 4 bolts, and 43 washers at the splitline and separate the cover from the
housing (See Figure 202, 1 of 2).
B. Gearbox Cover Disassembly
Disassemble the gearbox cover as follows:
(1) Remove the two selflocking nuts and take the pinion bearing oil nozzle from the aft side of the
gearbox cover. Discard the packing seal (See Figure 202).
(2) Remove the torquemeter shaft support spanner nut using 6795597 wrench (See Figure 203).
Remove the cup washer. Remove the torquemeter shaft support from the gearbox cover.
(3) Remove the headed pin; then press the bearing inner race from the support using 6796947
drift and 6796950 plate with detail 4 (See Figures 204 and 205).
(4) Simultaneously remove the helical power takeoff gearshaft and the helical torquemeter
gearshaft. Remove the helical torquemeter gearshaft bearing end plate and thrust washer.
Discard packing from the gearbox cover.
(5) Remove the bearing outer race and rollers from the helical torquemeter gearshaft. Remove
the damper ring from the helical torquemeter gearshaft.

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Legend for Figure 202 (Sheet 1 of 2)

1. Not Used 22. Internal Retaining Ring

2. Pinion Bearing Oil Nozzle 23. Roller Bearing
3. Nut (2) 24. Thrust Washer
4. Packing 25. Packing
5. Gearbox Cover 25A. Internal Retaining ring
6. Nut (36) 26. Power Train Drive Helical Gear
7. Bolt 27. Ball Bearing (2)
8. Bolt 28. Internal Retaining Ring
9. Washer (38) 29. Bearing Outer Race and Rollers
10. Nut (3) 30. Fuel Control Spur Gearshaft
11. Washer (3) 31. Internal Retaining Ring
12. Bolt (2) 32. Pin
13. Washer (2) 33. Splined Adapter
14. Spanner Nut 34. Packing
15. Cup Washer 35. Retaining Ring
16. Torquemeter Shaft Support 36. Bearing Retainer
17. Pin 37. Ball Bearing (2)
18. Power Takeoff Helical Gearshaft 38. Spacer
19. Roller Bearing Inner Race 39. Identification Plate
20. Ball Bearing 40. Screw (2)
21. Torquemeter Helical Gearshaft 41. Washer (2)

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250B17F SERIES OPERATION AND MAINTENANCE

Power and Accessory Gearbox Cover Assembly

Figure 202 (Sheet 1 of 2)

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250B17F SERIES OPERATION AND MAINTENANCE

Legend for Figure 202 (Sheet 2 of 2)

1. Accessory Drive Spur 18. Gas Producer Train Idler Spur

Gearshaft Gear (3)
2. Plug 19. Bolt
3. Starter Generator Spur 20. Key Washer
Gearshaft 21. Bearing Retaining Keyway
4. Plug Washer
5. Packing 22. Internal Retaining Ring
6. Fuel Pump Drive Spur 23. Ball Bearing
Gearshaft 24. Idler Gear Support Shaft
7. Internal Retaining Ring (3) 25. Plug
8. Drilled Plug 26. Packing
9. External Retaining Ring (3) 27. Plain Encased Seal (4)
10. Bearing Retainer (3) 28. Plain Encased Seal
11. Ball Bearing (6) 29. Bolt (2)
12. Gearshaft Bearing Sleeve 30. Nut (2)
Spacer (2) 31. Washer (2)
13. Gearshaft Bearing Sleeve Spacer 32. Washer, keyway (2)
14. Gas Producer Train Idler Spur 33. Ring (2)
Gearshaft 34. Ball Bearing (2)
15. Ball Bearing 35. Gas Producer Train Idler Spur
16. Ball Bearing Gear
17. Internal Retaining Ring 36. Packings (2)
37. Idler Gear Support Shaft
38. Packing (2)

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250B17F SERIES OPERATION AND MAINTENANCE

Power and Accessory Gearbox Cover Assembly

Figure 202 (Sheet 2 of 2)

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250B17F SERIES OPERATION AND MAINTENANCE

Removing or Installing Torquemeter Shaft Support Spanner Nut

Figure 203

Torquemeter Shaft Support

Figure 204

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250B17F SERIES OPERATION AND MAINTENANCE

Removing Roller Bearing Inner Race

from the Torquemeter Shaft Support
Figure 205
(6) Remove the ball bearing from the helical power takeoff gearshaft using 6796948 drift and
6796950 plate with detail 11 (See Figure 206). Remove the retaining ring and remove the
roller bearing inner race using 6796948 drift and 6796950 plate with detail 10.
(7) Remove the power train drive helical gear from the gearbox cover.
(8) Remove the two ball bearings (No. 3 and No. 4) from the gear. Bearings which cannot be
removed using detail 23 of puller 6796950 kit with 6796948 drift shall be removed by pulling
at the outer race. Use 6872746 puller with 6796948 drift. Discard any bearings which have
been pulled by the outer race.
(9) Remove the internal retaining ring and roller bearing (No. 2 1/2) from inside the helical drive
gear.
NOTE: Replace the No. 21/2 bearing if it must be pulled or driven from the helical drive
gear.
(10) Remove the fuel control spur gearshaft from the cover by removing the internal retaining ring
with 6796966 retaining ring pliers (See Figure 207). Do not remove the pin or splined adapter
from the gearshaft.
(11) Remove the retaining ring and bearing retainer (See Figure 208). Remove the two bearings
and the bearing spacer from the shaft using 6796946 drift and 6796950 plate with detail 12.
Discard packing.
(12) Remove the accessory drive spur gearshaft (spare) from the gearbox cover by removing the
internal retaining ring with 6796966 pliers (See Figures 202 and 209). Remove the external
retaining ring and bearing retainer. Remove the bearings and spacer from the shaft using
6796946 drift and 6796950 plate with detail 12.
NOTE: Do not remove the plugs from the spur gearshafts unless they are loose. If
replacement is necessary, press out plugs with a 5/8in. (16 mm) OD drift.

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Removing Ball Bearing from the

Helical Power Takeoff Gearshaft
Figure 206

Removing Fuel Control Spur Gearshaft

Figure 207

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250B17F SERIES OPERATION AND MAINTENANCE

Fuel Control Spur Gearshaft Components

Figure 208
(13) Remove the starter generator spur gearshaft from the gearbox cover by removing the internal
retaining ring with 6796966 pliers (See Figures 202 and 209).
(14) Remove the external retaining ring and bearing retainer. Remove the bearings and spacer
from the shaft using 6796946 drift and 6796950 plate with detail 12. Discard packing.
(15) Remove the fuel pump drive spur gearshaft from the gearbox cover by removing the internal
retaining ring with 6796966 pliers (See Figure 209). Remove the external retaining ring and
bearing retainer. Remove the bearings and spacer from the shaft using 6796946 drift and
6796950 plate with detail 12.
(16) Remove the two external nuts and washers. Remove the through bolts, and washers from the
gas producer gear train idler spur gears. Discard packings. Remove the two gears and
bearings from the idler gear support shafts. Remove the bearings from the idler gears by
removing the internal retaining rings (See Figure 210).
(17) Unlock the key washer of the gas producer gear train idler spur gear beneath the gear train
idler gearshaft. Remove the idler spur gear bolt, washer and key washer as the gear train idler
gearshaft is being lifted out.
(18) Remove the internal retaining ring. Remove the bearing from the cover end of the gearshaft
using 6796946 drift and 6796950 plate with detail 8.

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Removing or Installing Accessory Drive Spur Gearshaft

Figure 209

Removing or Installing Idler Spur Gear Retaining Ring

Figure 210

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250B17F SERIES OPERATION AND MAINTENANCE

Removing or Installing Idler Spur Gear Support Shaft

Figure 211
(19) Remove the bearing from the housing end of the gearshaft using 6796946 drift and 6796950
plate with detail 13. Remove the gear and bearing from the idler gear support shaft. Remove
retaining ring and separate bearing from gear.
(20) Remove the three idler gear support shafts from the gearbox cover using 6795614 puller and
pusher (See Figure 211). Discard two packings.
(21) Remove lockwire and separate the magnetic plug from the gearbox cover. Discard packing.
(22) Use 6796941 seal replacement kit to replace unserviceable gearbox cover seals.
C. Gearbox Housing Disassembly
Disassemble the gearbox housing as follows: (See Figure 212)
(1) Remove the fuel control and oil pump spur gearshaft. Remove the bearings using 6796946
drift and 6796950 plate with details 13 and 14. Rotate bearings during removal to avoid
brinelling the raceways.
(2) Remove the tachometer and governor power train spur gearshaft. Remove the bearings using
6796946 drift and 6796950 plate with details 7 and 12. Do not remove the spring pin.
(3) Unlock the key washer and remove the power train idler spur gear bolt, key washer, and
keyway bearing retaining washer.
(4) Lift the gear and bearing from the idler gear support shaft. Remove two bolts; then pull the
shaft from the gearbox housing using 6795614 puller and pusher.
(5) Remove the bearing from the gear by removing the internal retaining ring.
(6) Lift the helical power takeoff gearshaft roller bearing outer race and rollers from the gearbox
housing.
(7) Remove lockwire; then remove the torquemeter support shaft nut using 6795597 wrench and
6795974 aligning fixture (See Figures 213 and 214). Remove packing and washer. Discard
the packing.

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250B17F SERIES OPERATION AND MAINTENANCE

(8) Remove the shaft.

(9) Remove the torquemeter support shaft bearing end plate and washer from the gearbox
housing. Remove and discard packing from the shaft. Remove piston and bearing from the
shaft.
(10) Remove expander and piston ring. Remove ball bearing from the piston using 6796947 drift
and 6796950 plate with detail 6.
(11) Remove the bearing outer race and rollers from the support shaft. Remove the bearing inner
race from the support shaft using 6796947 drift and 6796950 plate with detail 4.
D. Gearbox Housing Lubrication System Components Disassembly
Disassemble the gearbox housing lubrication system components as follows: (See Figure 215)
(1) Remove the two nuts and washers. Remove the oil filter cap using 6798860 puller. Separate
the oil filter and packings from the filter housing (See Figure 215). Discard the packings.
(2) Remove the eight nuts and washers and lift the lube oil filter housing from the gearbox
housing. Discard the gasket.
NOTE: Do not remove the studs, standpipe or two valve seats in steps 3 and 4.
(3) Remove the lockwire and remove the pressure regulator components from the filter housing.
These components are: (1) poppet guide, (2) packing, (3) spring, and (4) poppet.
(4) Remove the lockwire and separate the magnetic drain plug from the lube oil filter housing.
Discard the packing.
(5) Remove the internal retaining ring and the filter bypass components from the filter housing.
These components are: (1) poppet guide, (2) packing, (3) spring, and (4) poppet.
(6) Remove the screw and separate the oil pressure tube from the gearbox housing. Discard the
packing.
(7) Remove the screw and separate the oil delivery tube from the gearbox housing. Remove the
screen and discard the three packings.
(8) Remove the three oil transfer tubes. Discard two packings from each tube.
(9) Remove the check valve (See Figure 215). Remove and discard the two packings. Do not
disassemble the check valve.

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1. Fuel Control and Oil Pump Spur 14. Bolt (2)

Gearshaft 15. Roller Bearing
2. Ball Bearing (2) 16. Torquemeter Support Shaft Nut
3. Tachometer and Governor Power 17. Internal Flared Washer
Train Spur Gearshaft 18. Packing
4. Pin 19. Torquemeter Support Shaft
5. Ball Bearing 20. Packing
6. Ball Bearing 21. Torquemeter Piston
7. Power Train Idler Spur Gear 22. Ball Bearing
8. Bolt 23. Piston Ring
9. Key Washer 24. Expander Ring
10. Bearing Retaining Keyway Washer 25. Roller Bearing
11. Internal Retaining Ring 26. Washer
12. Ball Bearing 27. Magnetic Plug
13. Idler Gear Support Shaft 28. Packing

Power and Accessory Gearbox Housing Assembly

Figure 212

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Removing or Installing Torquemeter Support Shaft Spanner Nut

Figure 213

Torquemeter Support Shaft Aligning Fixture

Figure 214

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250B17F SERIES OPERATION AND MAINTENANCE

Gearbox Housing Lubrication System Components

Figure 215 (Sheet 1 of 2)
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Legend for Figure 215 (Sheet 1 of 2)

1. Oil Filter Cap 23. Lube Oil Filter Housing

2. Nut (2) 24. Pin (2)
3. Washer (2) 25. Flanged Insert
4. Packing 26. Packing
5. Differential Pressure Indicator 27. Bushing (2)
6. Packing 28. Stud (2)
7. Packing 29. Oil Filter Standpipe
8. Lube Oil Filter 30. Filter Bypass Valve Seat (2)
9. Packing 31. Filter Housing Gasket
10. Lube Oil Filter Housing 32. Magnetic Plug
11. Nut (8) 33. Packing
12. Washer (8) 34. Oil Pressure Tube
13. Poppet Guide 35. Screw
14. Nut Used 36. Packing
15. Packing 37. Oil Delivery Tube
16. Helical Compressor Spring 38. Screw
17. Poppet 39. Packing (3)
18. Internal Retaining Ring 40. Pressure Oil Screen
19. Poppet Guide 41. Oil Transfer Tube (2)
20. Packing 42. Oil Transfer Tube
21. Helical Compression Spring 43. Packing (6)
22. Valve Poppet

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250B17F SERIES OPERATION AND MAINTENANCE

Gearbox Housing Lubrication System Components

Figure 215 (Sheet 2 of 2)

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Legend for Figure 215 (Sheet 2 of 2)

1. Check Valve 21. Packing

2. Retaining Ring 22. Packing (6)
3. Poppet Guide 23. Packing
4. Helical Spring 24. Oil Transfer Tube
5. Poppet Assembly 25. Oil Pump Supply Connector
6. Poppet 26. Packing (2)
7. Poppet Stem 27. Oil Transfer Tube
8. Body 28. Oil Transfer Tube
9. Packing 29. Packing (4)
10. Packing 30. Magnetic Plug
11. Fuel Control and Oil Pump 31. Packing
Flex Shaft Coupling 32. Low Pressure Scavenge Oil
12. Scavenge Oil Tube Check Valve
13. Oil Filter Inlet Tube 33. Cap
14. Oil Filter Bypass Tube 34. Housing
15. Lube Oil Pump 35. Piston
16. Screw (5) 36. Spring
17. Screw 37. Packing
18. Screw (2) 38. Packing
19. Washer (6) 39. Packing
20. Lube Oil Pump Gasket 40. Plain Encased Seal (2)
41. Power and Accessory Gearbox
Housing

(10) Remove the fuel control and oil pump flex shaft coupling.
(11) Remove the eight pump attaching screws and six washers. Remove the oil filter inlet and
bypass tubes, the transfer tube to the filter housing, and the scavenge oil tube. Discard the
seven packings. Remove pump. Discard the gasket and packing beneath the pump.
(12) Remove the two oil transfer tubes and connector beneath the oil pump. Discard two packings
from each.
(13) Remove the lockwire and separate the magnetic plug from the gearbox housing. Discard
packing.
(14) Remove the low pressure scavenge check valve from the gearbox housing. Discard packing.
(15) Remove gearbox housing accessory pad seals using 6796941 seal replacement kit only if the
seals are defective.
E. Oil Filter Inlet Tube Assembly Drop Dimension Inspection
(1) Engines that exhibit low or fluctuating oil pressure may have been assembled with an
incorrectly manufactured tube assembly, P/N 6876925A. If the gearbox modification log card
does not show compliance with 250B17F TP CEB 722041, proceed to the next step.
(2) Remove the Lube Oil Filter Housing Assembly from the gearbox. Refer to para 2.D., this
section.
(3) Make sure that all gasket material is removed from the gearbox. Do not let gasket material or
other foreign material fall into the gearbox.

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(4) Using a 23 inch depth micrometer, measure the distance from the gearbox/filter housing
splitline to the top of the oil filter inlet tube assembly, P/N 6876925A (See Figure 216).
(5) If this dimension exceeds 2.843 in. (72.21 mm), then the oil inlet tube assembly and the oil
filter housing assembly may not be correctly engaged. Reject the gearbox for compliance of
250B17F TP CEB 722041 or replace P/N 6876925A, Oil Filter Inlet Tube Assembly with P/N
6876925B (or later) Oil Filter Inlet Tube Assembly.
F. Oil Pump Disassembly, Inspection and Assembly
Disassemble and inspect the oil pump when it is the suspected cause of oil pressure and/or oil
scavenging discrepancies. Remove pump in accordance with the Gearbox Housing Lubrication
System Components Disassembly para 2.D., this section. Install pump in accordance with the
Gearbox Housing Assembly and Check, para 2.I., this section.
CAUTION: BE CAREFUL NOT TO PRY ON, OR DAMAGE, ANY LAPPED SURFACES.
(1) Disassemble the oil pump as follows: (See Figure 217)
(a) Remove two screws and separate the pressure oil pump body from the balance of the
pump.
(b) Remove the oil pump idler spur gear. Remove and discard the packing in the pump body.
Do not remove the pinned bushing cage or flanged bushings unless replacement is
required.
(c) Remove the oil pump and gas producer tachometer spur gearshaft. Do not remove the
oil seal plug unless it is loose. If replacement is necessary, press out the plug using
1/4in. (6 mm) OD drift.
(d) Remove the pressure and scavenge oil pump separator body using a prying tool. Do not
pry on lapped surfaces. Remove the oil pump drive spur gear and three oil pump idler
spur gears. Discard five packings.
(e) Remove the scavenge oil pump cover from the scavenge oil pump body using a prying
tool. Do not pry on lapped surfaces. Remove the oil pump drive spur gear and three oil
pump idler spur gears. Discard three packings.
(f) Do not remove the four dowel pins from the pump body unless replacement is necessary.
Do not remove the three pinned oil pump gearshafts or the pinned bushing from the
scavenge oil pump cover unless replacement is necessary.
(2) Inspect the components of the oil pump in accordance with Table 201.
(3) Replace or secure loose oil pump gearshafts as follows:
(a) Immediately prior to installing gearshafts, clean the bores and the gearshaft using
cleaning agent recommended by Loctite Corporation. Apply Loctite 290, in accordance
with Loctite Corporation recommendations, to the mating surfaces of the gearshaft OD
only.
(b) Install gearshaft with the slot aligned with the antirotation pin and ensure that it bottoms
in the cover assembly bore.
(c) Immediately after gearshaft installation, clean off any Loctite on the shaft OD and cover
assembly.

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Oil Filter Inlet Tube Assembly Drop Dimension Inspection

Figure 216
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Oil Pump Assembly

Figure 217

1. Not Used 16. Studding Scavenge Oil Pump

2. Pressure Oil Pump Body Cover
3. Screw 17. Scavenge Oil Pump Cover
4. Pin 18. Pin (3)
5. Sleeve Bushing 19. Oil Pump Gear Shaft
6. Pin 20. Oil Pump Gear Shaft (2)
7. Plain Bearing Cage 21. Pin
8. Flanged Bushings (2) 22. Bushing
9. Oil Pump Idler Spur Gear 23. Scavenge Oil Pump Body
10. Packing 24. Pin (2)
11. Oil Pump and Gas Producer 25. Pin (2)
Tachometer Spur Gearshaft 26. Oil Pump Drive Spur Gear
12. Oil Seal Plug 27. Oil Pump Idler Spur Gear (3)
13. Pressure and Scavenge Oil Pump, 28. Oil Pump Drive Spur Gear
Separator Body 29. Oil Pump Idler Spur Gear (3)
14. Packing 30. Packing (3)
15. Packing 31. Packing

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Table 201

Oil Pump Inspection Limits

Item Condition Serviceable Repairable Disposition

Limit Limit
Oil Pump Body, Separator, and Cover (fig. 217)

1 Cracks (FPI) None Replace pump.

2 Fretting of housing Max. of 0.010 in. (0.25 Repair or replace.
bores mm)
3 Wear of gear pockets Max. of 0.005 in. (0.13 Replace pump.
mm)
4 Gear end clearance 0.00050.0015 in. Select gears or lap
(0.0130.038 mm) parts. (Refer to
para 2.F. for de-
tails.) or replace
pump.

Oil Pump Gears

5 Cracks in radii root cor- None Replace pump.

ners of spline teeth or in
line or parallel in close
proximity on involute of
a gear tooth side (visual
with magnification)
6 Nonmetallic inclusion on Light scattered inclu- Replace pump.
small gears and gear- sions parallel to materi-
shafts al flow lines
Open inclusion on shaft Replace pump.
3/8in. (10 mm) max.
length and not extend-
ing into a radius hole or
spline root
7 Nicks and dents Max. of 0.010 in. (0.25 Max. of 0.060 in. Remove sharp
mm) length, width or dia (1.52 mm) length, edges by stoning.
and without sharp cor- width or dia after
ners sharp corners are re-
moved
8 Tooth damage which in- None. Replace pump.
volves metal displace-
ment to a degree where
subsurface damage is
detected by magnetic
inspection
9 Scuffing Scuffing when accom- Scuffing evidenced by Remove sharp
panied by wearoff of pickup. edges by stoning.
metal pickup if gear as-
sembly is still matched
with mating gears.

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Table 201 (cont)

Item Condition Serviceable Repairable Disposition

Limit Limit

Oil Pump and Gas Producer Tachometer Spur Gearshaft (fig. 217)

10 Seal journal wear Max. of 0.0015 in. Replace pump.

(0.038 mm) radial wear
on dia.
11 Spline wear Max. of 0.002 in. (0.05 Replace pump.
mm) wear measured
from adjacent unworn
area.
12 Scoring, grooves, nicks, Evenly polished surface Replace pump.
gouges, scuffing or min- in seal contact without
ute flats on shaft seal lead or axial marking.
journal surfaces.

Pump Bushings and Dowel Pins

13 Loose or bent dowel None. Replace pump.

pins.
14 Wear on ID of pump None. Replace pump.
bushings.
Gearshafts

15 Loose in scavenge oil No looseness allowed Replace or secure

pump cover loose gearshafts
with Loctite 290.
(Refer to para 2.F.
for details.)

(4) Assemble the lube oil pump as follows: (See Figure 217)
CAUTION: USE SPECIFIED LUBRICANTS DURING PUMP ASSEMBLY; DO NOT USE
SILICONE LUBRICANTS.
(a) Lubricate and install the three packings in the scavenge body assembly. Install the oil
pump drive gear and three oil pump idler gears.
1 Measure the gear end clearance in the pressure and scavenge elements between
the splitline and gear end with a dial indicator. The gear end clearance must be
0.0005 0.0015 in. (0.0130.038 mm).
2 If the end clearance limit is exceeded, select gears or lap scavenge oil pump body,
pressure and scavenge oil pump separator body or pressure oil pump body as
necessary to obtain required gear end clearance. Make sure that lapping is done on
a flat lap surface and that the whole face of the item being lapped is smooth and
square. Surface finish after lapping must be 32 microinches (0.80 micrometers) or
better.
(b) Place cover assembly on the scavenge body assembly. Install oil pump drive gear with
lubricated packings and oil pump idler gears. Lubricate and install four packings in the
separator body. Place separator body on the scavenge body assembly.
(c) Install oil seal plug in oil pump and gas producer tachometer spur gearshaft if it has been
removed. Install oil pump idler spur gear and oil pump and gas producer tachometer spur
gearshaft on the separator body.

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(d) Lubricate and install packing in pressure oil pump body. Place pressure oil pump body on
scavenge body assembly. Install two screws; tighten to 1822 lb in. (2.02.5 N.m).
NOTE: The pump must turn freely by hand after assembly.
G. Gearbox Assembly and Test
Assemble the gearbox as follows:
(1) Lube Oil Filter Housing Assembly and Test (See Figure 215).
(a) Assemble and test the lube oil filter housing as follows:
CAUTION: INSPECT THE RETAINING RING BEFORE INSTALLATION TO BE SURE
IT HAS NO DEFECTS AND AFTER INSTALLATION TO BE SURE IT IS
PROPERLY SEATED.
1 Install the poppet, spring, lubricated packing, and guide in the filter housing. Retain
with an internal retaining ring. Use 6798807 compressor to aid in installation of
retaining ring.
2 Lubricate and install the packing on the pressure regulator guide. Insert poppet,
spring, and guide into the filter housing. Make an approximate adjustment of the
regulator by bottoming the adjusting screw and backing out 51/2 turns.
3 Test the lube oil filter housing as follows:
a Plug the standpipe and install the cap on the filter housing.
b Connect a supply of calibration fluid at 2429C (7585F) or engine oil at
2738C (80100F) to the filter housing inlet port.
c Slowly apply increasing pressure until the bypass valve opens. Pressure must
be 80130 psig (552896 kPag).
d Decrease pressure to 30 psig (207 kPag). Leakage through the bypass valve
must not exceed 63 cc per minute.
e Connect the fluid supply to the outlet port and plug the inlet port.
f Adjust the fluid supply to obtain a flow of 720 pph (327 kg/hr) across the filter.
g Adjust the guide assembly until 130 5 psig (896 34.5 kPag) is obtained with
720 pph (327 kg/hr) flow.
h Decrease flow to 15 pph (6.8 kg/hr). Pressure must not be less than 125 psig
(862 kPag). If pressure is not within limits, repeat steps f and g, adjusting the
guide assembly for a higher pressure within the 130 5 psig (896 34.5 kPag)
range. If pressure is less than 125 psig (862 kPag) at 15 pph (6.8 kg/hr)
replace the pressure regulating poppet valve and repeat the entire test.
i Remove the cap and remove the plug from the stand pipe. Remove the plug
from the inlet port.
4 Install the filter assembly with new lubricated packing in the filter housing. Install cap
with lubricated packing in the filter housing. Secure the cap with two nuts and
washers. Tighten nuts to 3540 lb in. (3.94.5 N.m).
H. Gearbox Housing Assembly and Check (Refer to Figure 212)
Assemble and check gearbox housing as follows:
(1) Install gearbox housing seals as necessary at the following locations using 6796941 seal
installation kit with details 16 or 19 (See Figures 218 and 219). Apply grease to the seal lip
to aid in installation.
(a) Power turbine tachometer generator pad (use detail 16).
(b) Gas producer tachometer generator pad (use detail 16).

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(2) Lubricate and install the packings on the two oil transfer tubes and the connector which go
beneath the oil pump. Install the transfer tubes and connector in the gearbox housing (See
Figure 220).

(3) Lubricate and install the two packings on oil transfer tube and insert tube in the pump (See
Figure 215).

(4) Lubricate and install the packing on the underside of the lube pump (See Figure 215). Position
the pump mounting gasket and install the pump in the gearbox housing using 6796941 seal
guide with detail 13 (See Figure 221). Install the filter inlet and filter bypass tubes with
lubricated packings.

(5) Insert eight pump attaching screws and six washers. Washers are used at positions 1, 3, 4, 5,
6, and 7 counting clockwise with 1 at the point nearest the filter housing. The five 1032 X 2
in. screws go at positions 1, 2, 3, 7, and 8; the two 1032 X 2.750 in. screws go at positions 4
and 6; the 1032 X 2.375 in. screw goes at position 5. Do not tighten screws at positions 2
and 8 at this time, tighten others finger tight.

(6) Lubricate packing and install it on the scavenge oil tube. Install the scavenge oil tube in the oil
pump. Retain the scavenge oil tube with a screw at the oil pressure tube and with a screw at
the oil delivery tube.

(7) Lubricate and install the two packings on the check valve; install the valve in the gearbox
housing (See Figure 222).

(8) Position the gasket and install the filter housing assembly in the gearbox housing (See Figure
215). Mate the filter inlet and filter bypass transfer tubes and check valve to the filter housing
during the assembly (See Figure 222).

(9) Retain the housing with eight nuts and washers. Tighten nuts to 3540 lb in. (3.94.5 N.m).
Align the two tubes; then tighten the pump attaching screws to 3540 lb in. (3.94.5 N.m).
Loosen and retorque to 2226 lb in. (2.52.9 N.m). Secure with lockwire.

(10) Lubricate and install two packings on each of the three oil scavenge transfer tubes; install the
two short tubes in the pump and the long tube in the gearbox housing.

(11) Lubricate and install two packings on the oil delivery tube and one packing on the oil pressure
tube. Install the oil pressure tube (nozzle) and the oil delivery tube with screen in the gearbox
housing. Retain each with a screw; tighten screws to 2226 lb in. (2.52.9 N.m) and secure
with lockwire.

(12) Make a static leak check of the oil filter housing and lube oil pump assembly.

(a) Equipment. A six foot length of oneinch (25.4 mm) ID copper tubing having a length of
hose with a shutoff valve near the outlet end; a four foot (1.2 m) head of oil in the
standpipe; and a fitting for connecting the hose to the oilin port of the gearbox.

(b) Attach the fitting to the gearbox and the standpipe hose to the fitting. Keep the hose
coupling loose until the system can be bled. Open the shutoff valve and bleed the air
from the system, then tighten the hose coupling nut.

(c) Place the gearbox housing in a vertical position with the oil pump at the top.

(d) Visually check the partial assembly for ten minutes for oil leakage.

NOTE: Leakage will be evident if a problem exists. Slight moistness or seepage should
not be interpreted as leakage.

(e) Correct the condition causing leakage before proceeding with the assembly of the
gearbox.

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Typical Power and Accessory Gearbox Housing Oil Seal Location

Figure 218

Typical Seal Installation

Figure 219

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Oil Transfer Tubes in Gearbox Housing

Figure 220

Lube Oil Pump and Seal Guide

Figure 221

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Removing or Installing Lube Oil Pump and Filter Housing

Figure 222
(13) Install the helical power takeoff bearing outer race and rollers in the gearbox housing. DO
NOT apply petrolatum or grease to these rollers. Lubricate using engine oil only.
(14) Install the idler gear support shaft in the gearbox housing using 6795614 pusher and puller.
Attach with two bolts. Secure with lockwire (See Figure 211).
(15) Lubricate and install the bearing in the power train idler spur gear. Retain with an internal
retaining ring. Install the gear and bearing on the shaft. Apply Locktite No. 242 lightly to the
bolt threads; then retain the gear assembly on the shaft with the bolt, a keywasher and a
keyway bearing retaining washer. Tighten bolt to 3540 lb in. (3.94.5 N.m) and bend locktab.
(16) Install the bearing inner race on the torquemeter support shaft. Install with the thrust flange
toward the torquemeter piston using 6796930 plate, location D, and 6796947 drift (See Figure
223).
(17) Apply a thin coat of petrolatum to the bearing and assemble the bearing outer race and rollers
on the shaft. Install the bearing end plate and washer on the shaft.
(18) Lubricate and install the expander ring and piston ring in the torquemeter support shaft piston
ring groove. The gap of the ring shall be 180 removed from the gap of the expander ring.
(19) Lubricate and install the ball bearing on the torquemeter piston using 6796930 plate, location J
and 6796947 drift. Install with the wide portion of the outer race away from the torquemeter
piston. Install the piston on the torquemeter support shaft. Lubricate the packing and place it
on the shaft.
(20) Install the torquemeter support shaft in the gearbox housing (See Figure 212). Install 6795974
aligning fixture (See Figure 215). Install the internal flared washer and lubricated packing on
the shaft. Tighten the nut to 275300 lb in. (3134 N.m) using 6795597 wrench (See Figure
213). Secure with lockwire.
(21) Lubricate and install the bearings on the tachometer and governor power train spur gearshaft
using 6796930 plate, locations C and G and 6796946 drift.

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(22) Apply lubricant lightly to the splines then install the tachometer and governor spur gearshaft in
the gearbox housing using 6796941 seal guide with detail 13.
(23) Lubricate and install the bearings on the fuel control and oil pump spur gearshaft using
6796930 plate, location H and 6796946 drift. The small ball bearing that was pulled by the
outer race must be replaced with a new bearing at this step if there is any apparent indication
of raceway brinelling. Install the gearshaft in the oil pump bearing cage.
(24) Apply lubricant lightly to the splines then install the fuel control and oil pump flex shaft coupling
on the oil pump drive shaft (See Figure 215).
(25) Lubricate packing and install with magnetic plug in the gearbox housing. Tighten plug to 6080
lb in. (6.89.0 N.m) and secure with lockwire.
(26) Lubricate packing and install with low pressure scavenge oil check valve on outside of gearbox
housing. Install check valve with arrow pointing away from gearbox housing.
I. Gearbox Cover Assembly (See Figure 202)
Assemble the gearbox cover as follows:
(1) Install gearbox cover seals as necessary at the following locations using 6796941 seal
installation kit with details 16, 17, and 20 (See Figures 219 and 224). Apply grease to the
seal lip to aid in installation.
(a) Accessory drive pad (use detail 17).
(b) Gas producer fuel control pad (use detail 17).
(c) Fuel pump pad (use detail 17).
(d) Starter generator pad (use detail 18).
(e) Gas producer idler spur gearshaft (internal installation held by a retaining ring) (use detail
20).
(2) Lubricate and install packings on two of the three idler gear support shafts. Install the three
idler gear support shafts in the gearbox cover using 6795614 pusher and puller (See Figure
211).
(3) Lubricate and install the bearings in the three gas producer gear train idler spur gears; retain
with internal retaining rings (See Figure 210).
(4) Install one idler spur gear and bearing on the idler shaft adjacent to the accessory drive spur
gearshaft. Retain gear assembly with keyway washer, key washer, and bolt which has been
lightly coated with Loctite No. 242. Tighten the bolt to 3540 lb in. (3.94.5 N.m) and bend
locktab of the key washer.
(5) Install one idler spur gear and bearing on the idler shaft adjacent to the fuel pump drive spur
gearshaft. Retain gear assembly with through bolt, lubricated packing, keyway washer, and
external washer and locknut. Tighten locknut to 3540 lb in. (3.94.5 N.m).
(6) Lubricate and install the ball bearings on the gas producer gear train idler spur gearshaft using
6796946 drift and 6796930 plate, locations F and H.
(7) Install the remaining idler spur gear, keyway washer, lubricated packing, through bolt, external
washer and locknut at the same time the gas producer gear train idler spur gearshaft is
installed. Tighten the locknut that retains the idler gear to 3540 lb in. (3.94.5 N.m).
(8) Install the internal retaining ring; then lubricate and install the two ball bearings, one at a time,
and the bearing sleeve spacer on the accessory drive spur gearshaft using 6796949 drift and
6796930 plate, location C. A 0.0000.0007 in. (0.0000.018 mm) T fit between the inner race
ID and the shaft OD must be maintained.
(9) Install the bearing retainer and secure it with an external retaining ring.
(10) Apply lubricant to the splines of the gearshaft and using 6796941 seal guide with detail 14,
install the gearshaft in the gearbox cover. Secure with an internal retaining ring using 6796966
pliers.

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Torquemeter Support Shaft Bearing Installation

Figure 223

Power and Accessory Gearbox Cover

Figure 224

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(11) Install the fuel pump drive spur gearshaft in the same manner that the accessory drive spur
gearshaft was installed [steps (8) through (10)].
(12) Lubricate packing and install it on the startergenerator spur gearshaft. Assemble the
startergenerator spur gearshaft in the same manner that the accessory drive spur gearshaft
was installed [steps (8) through (10)].
(13) Lubricate packing and install with the plug at the top of the gearbox cover. Tighten plug to
6080 lb in. (6.89.0 N.m) and secure with lockwire.
(14) Lubricate packing and install it on the fuel control spur gearshaft. Assemble the fuel control
spur gearshaft in the same manner that the accessory drive spur gearshaft was installed
[steps (8) through (10)] (See Figure 202).
CAUTION: FAILURE TO INSTALL THE INTERNAL RETAINING RING IN THE HELICAL
POWER TRAIN DRIVE GEAR CAN ALLOW DISENGAGEMENT OF THE TURBINE
SHAFTTOPINION GEAR COUPLING CAUSING POWER TURBINE
OVERSPEED.
(15) Install the roller bearing in the helical power train drive gear. Secure with internal retaining
ring.
(16) Install the two ball bearings on the drive gear using 6796948 drift and 6796930 plate, location
A. The bearings shall be selected to obtain an internal clearance of not less than 0.0003 in.
(0.008 mm) after assembly on the gear. Check clearance using 6872165 gage. Chill the gear,
60C (76F) max., and heat the bearings, 121C (250F) max., to aid the installation. When
bearings have cooled, lubricate bearings and install the gear in the gearbox cover.
(17) Lubricate and install the ball bearing on the helical power takeoff gearshaft using 6796948
drift and 6796930 plate, location A (See Figure 225).
(18) Uniformly heat to 177204C (350400F), and install the roller bearing inner race on the
gearshaft using 6796948 drift and 6796930 plate, location B. Hold the heated bearing race in
position against the gear shoulder until heat distribution has normalized. Install the retaining
ring.
(19) Apply lubricant to the splines of the gearshaft and using 6796941 seal guide with detail 15,
install the gearshaft in the gearbox cover.
(20) Lubricate and install the packing in the groove at the torquemeter shaft opening of the gearbox
cover. Lubricate and position the thrust washer and bearing end plate in the gearbox cover.
(21) Use petrolatum to retain the bearing outer race and rollers of the torquemeter bearing in the
torquemeter gearshaft. Install the damper ring in the retaining groove of the helical
torquemeter gearshaft.
(22) Place the gearshaft in position in the cover, meshing the gear teeth with the teeth of the helical
power train drive gear and the helical power takeoff gearshaft.
(23) Lubricate and install the roller bearing inner race on the torquemeter shaft support using
6796930 plate, location E and 6796947 drift.
(24) Install the headed pin in the shaft support.
(25) Install the shaft support in the cover through the gear using 6795969 holder (See Figure 226).
Secure the support with a cup washer and spanner nut lightly coated with antiseize
compound. Tighten spanner nut to 390400 lb in. (4445 N.m) using 6795597 wrench (See
Figure 203). Crimp cup washer securely into locknut slot.
(26) Apply antiseize compound to the oil nozzle mounting studs; in stall oil nozzle with lubricated
packing. Secure with two washers and nuts. Tighten nuts to 3540 lb in. (3.94.5 N.m).

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J. Gearbox Cover--to--Housing Assembly

Assemble the power and accessory gearbox cover to the housing as follows:
(1) Apply a thin film of sealing compound (Scot Clad 776 or equivalent) to the gearbox housing splitline.
NOTE: A strand of silk thread, gently pressed into the sealing compound around the splitline,
will give added assurance against oil leaks (See Figure 226). Do not use dental floss
or nylon thread.
(2) Install the 6886201 power takeoff roller bearing guide in the helical power takeoff gearshaft
(See Figure 228). Install 6796941 seal guide, detail --14 in the tachometer and governor
power train spur gearshaft (See Figure 229). Install 6895957 alignment tool over the oil tubes
at the oil pump.
(3) With the gearbox housing mounted in 6795579 stand, carefully assemble the gearbox cover to the
gearbox housing, aligning the oil transfer tubes and the fuel control and oil pump flex shaft coupling.
(4) Insert 6799790 adapter in the tachometer and governor power train spur gearshaft. This may
be used to turn the gear train to assist in assembly.
(5) Rotate the fuel control and oil pump spur idler gearshaft by hand to assure proper engagement
with the fuel control spur gearshaft. Remove 6895957 alignment tool.
(6) Apply antiseize compound lightly to the threads of studs and bolts used to attach the gearbox
cover to the gearbox housing. The cover is secured by 39 nuts, 4 bolts, and 43 washers (See
Figure 202).
(a) Tighten the two 10--32 bolts to 20--25 lb in. (2.3--2.8 N.m).
(b) Tighten the 10--32 nuts to 35--40 lb in. (3.9--4.5 N.m).
(c) Tighten the 1/4--28 nuts to 70--85 lb in. (7.9--9.6 N.m).
(d) Tighten the 5/16--24 bolts to 120--150 lb in. (14--17 N.m) and secure with lockwire.

(7) Check the operation of the power and control gear trains to make sure no binding is present
between the meshing teeth.

(a) Turn the power train counterclockwise through the power turbine fuel governor pad (See
Figure 224). Use 6799790 engine turning adapter. No binding is acceptable.

(b) Turn the control gear train counterclockwise through the gas producer fuel control pad
(See Figure 224). Use 6799790 engine turning adapter. No binding is acceptable.

(8) Remove the 6886201 power takeoff roller bearing guide from the helical power takeoff
gearshaft. Install the gearbox housing seal in the power output pad (use detail --19). Lubricate
the seal with engine oil prior to installation.

K. Turbine Pressure Oil System Check Valve

(1) Disassemble, clean, inspect and assemble the check valve as follows: (See Figure 230)
NOTE: Check Valve P/N 23074872 and subsequent part numbers are not applicable to this
inspection (these valves are considered ON CONDITION.)
(a) Remove the fitting from the check valve housing.
(b) Separate the packing, spring and poppet from the housing. Discard packing.
(c) Wash parts in mineral spirits.
(d) Inspect valve parts in accordance with Table 202.
(e) Insert poppet and spring into valve housing.
(f) Install fitting with new packing on housing.

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Power Takeoff Gearshaft Bearing Installation

Figure 225

Installing Torquemeter Shaft Support

Figure 226
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Installing Silk Thread on Gearbox Cover Splitline

Figure 227

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Seal Guide Location (Cover)

Figure 228

Seal Guide Location (Housing)

Figure 229

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1. Fitting 3. Spring 5. Housing

2. Packing 4. Poppet

Turbine Pressure Oil System Check Valve

Figure 230

Table 202

Turbine Pressure Oil System Check Valve Inspection

Item Condition Serviceable Repairable Disposition

Limit Limit
1 Stripped or crossed None. Max. of one damaged Chase threads.
threads on fitting or thread.
housing.
2 Nicks or scratches on None. Repair or replace
flared tube sealing sur- part.
face of fitting or hous-
ing.
3 Nicks or scratches on None. Repair or replace
poppet seating surface part.
or housing valve seat.
4. Fretting wear in bore of None. Replace part.
housing.

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CAUTION: BE SURE THE CHECK VALVE IS INSTALLED WITH THE ARROW POINTING
TOWARD THE REAR OF THE ENGINE.
(g) Inspect check valve for external leakage at first engine operation after valve installation on
the engine. No leakage permitted.
L. Test the Turbine Pressure Oil System Check Valves. (See Figure 230)
NOTE: Valves with part numbers 23074872 and subsequent are not field repairable.
WARNING: DO NOT BREATHE THE FUMES FROM SYNTHETIC LUBRICATING OIL. IT CAN
CONTAIN TRICRESYL PHOSPHATE. USE IN AN AREA WITH CONTINUOUS
AIRFLOW. KEEP AWAY FROM HEAT, SPARKS, AND OPEN FLAMES. DO NOT
GET IT ON YOUR SKIN OR IN YOUR EYES. WEAR GOGGLES,
CHEMICAL--RESISTANT GLOVES, AND SAFETY CLOTHING. IF YOU GET IT ON
YOUR SKIN, CLEAN WITH SOAP AND WATER. IF YOU GET IT IN YOUR EYES,
FLUSH WITH WATER. GET MEDICAL AID.
(1) Test the check valve using engine oil (MIL--L--23699 Series at 225F (107C) or MIL--L--7808
Series at 180F (82C)) as follows:
(a) Install the valve on the test stand with the large end down.
(b) Apply the test pressure to the small end of the valve.
(c) Cycle the valve open and closed at least once before taking pressure readings.
(d) Slowly increase the pressure and observe the opening pressure. Opening pressure must
not exceed 5.0 psig (34.5 kPag).
(e) As the test pressure is reduced, the valve must be fully closed (with no leaks) at 3.0 psig
(20.7 kPag).
3. Adjustment/Test
A. Oil Pressure Regulating Valve (See Figure 215)
CAUTION: EXCEPT FOR INITIAL ADJUSTMENTS ON NEWLY INSTALLED ENGINES, DO
NOT ADJUST THE PRESSURE REGULATING VALVE TO CORRECT FOR HIGH
OIL PRESSURE. DO NOT MAKE A PRESSURE REGULATING VALVE
ADJUSTMENT TO CORRECT FOR A SUDDEN INCREASE OR RAPID CHANGE
IN OIL PRESSURE. THESE CONDITIONS ARE CAUSE TO SUSPECT OTHER
OIL SYSTEM PROBLEMS HAVE DEVELOPED.
(1) Make necessary changes in the engine oil pressure by adjusting the pressure regulating valve.
(Refer to Gearbox Housing Lubrication System Components Disassembly, para 2.D., this section.)
NOTE: During the initial check run of a newly installed engine the pressure regulating valve
may be adjusted to increase or decrease oil pressure as per specified limits. A direct
reading gage is to be utilized anytime an adjustment to the pressure regulating valve
is required.
(a) Remove the lockwire.
(b) Using a wrench, turn the regulating valve clockwise to increase and counterclockwise to
decrease the oil pressure. An approximate adjustment may be made by bottoming the
valve and then backing it out 5--1/2 turns. One turn of the adjustment will change the oil
pressure approximately 13 psig (90 kPag). Oil pressure is 120--130 psig (827--896 kPag)
at 82C (180F) oil temperature.
4. Inspection/Check/Repair
A. Oil Leakage Inspection
Inspect the power and accessory gearbox for oil leaks. Replace the seal assembly if excessive oil
leakage is detected at the accessory pad locations (See Figure 231).
B. Magnetic Plug Inspection (Refer to para 11.I., 72--00--00, Engine--Servicing for inspection procedure.)
(1) Operational Check.

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FRONT REAR
1. Power Turbine Tachometer-- 5. Starter Generator Pad
Generator Pad 6. Power Takeoff Pad
2. Power Output Pad 7. Fuel Pump Pad
3. Gas Producer Tachometer-- 8. Vacuum--Hydraulic Pad
Generator Pad 9. Power Turbine Fuel Governor Pad
4. Torquemeter Spanner Nut 10. Gas Producer Fuel Control Pad

Power and Accessory Gearbox

Figure 231

(a) If magnetic plugs are removed for scheduled maintenance, perform an operational check
prior to reinstallation. Connect harness lead and bridge plug with a suitable conductor.
Check each plug separately for proper cockpit indication.
(b) Reinstall magnetic plug, tighten to 60--80 lb in. (6--8--9.0 N.m).
C. Starter--generator Gearshaft Female Spline Inspection
(1) Remove the starter--generator.
(2) Clean the female splines of the starter--generator gearshaft and the male splines of the
starter--generator driveshaft with mineral spirits and a soft brush.
(3) Using a bright light, inspect the splines in accordance with the criteria depicted in Figure 232.
NOTE: A sharp pointed scribe, 0.020 in. (0.51 mm) radius, should be used to detect a wear
step. A 0.010 in. (0.25 mm) feeler gage can be helpful in visually comparing the
depth of the wear step.
(4) Lubricate acceptable splines with engine oil.
(5) Before reinstallation of the starter--generator, make sure the torsional damper members of the
driveshaft in the starter--generator are in hard contact with each other.
D. Opened Gearbox Inspection
Whenever the gearbox is opened for any reason, and at an Authorized Maintenance Facility make
a general inspection of the assembly, paying particular attention to the following:
(1) Check condition of accessory gearshaft drive splines. If excessive wear is believed present,
replace the gearshaft.
(2) Check condition of gears. Replace gears having spalled or chipped teeth.
(3) Check mounting and attachment security of all internal parts including tab lockwashers and
safety wire. Secure as required.
(4) Check integrity of oil pump attaching screws and oil tube packings.

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(5) Check condition of the accessory pad seal for the gas producer gear train idler spur gearshaft
(inside the gearbox cover). Replace seal if it shows apparent damage or if the engine is prone
to blow oil out the gearbox vent.
(6) Check the filter housing for excessive wear at the opening for the filter inlet and filter bypass
tubes. Replace packings on the filter inlet and bypass tubes at each disassembly. Replace
the filter housing if necessary to prevent air/oil leakage.
(7) If the records indicate that more than 3500 hours have elapsed since the gears were new or
were last magnafluxed at overhaul or repair, all gears are to be magnetically inspected. (Refer
to the Engine Overhaul Manual, publication No. GTP 5243--3, for inspection criteria.)
NOTE: If any doubt exists concerning the serviceability of any part, repair or replace the part
before closing the gearbox.
E. Insert Inspection
Any time the compressor is removed or when insert looseness is known or suspected, check for
space between each of the five inserts and the gearbox housing. If a piece of 0.0015 in. (0.038
mm) shim stock can be inserted anywhere under the insert, it must be reworked.
F. Repair of Compressor Mounting Inserts
CAUTION: THE GEARBOX HOUSING MUST HAVE AT LEAST THREE GOOD
COMPRESSOR MOUNTING INSERTS BEFORE REWORK CAN BE
ACCOMPLISHED ON A LOOSE INSERT.
Repair loose compressor mounting inserts in the gearbox housing as follows:
NOTE: The rework shall be made with the engine removed from the air--frame and with the
turbine and compressor assembly removed from the gearbox. (Refer to Compressor
Assembly Replacement, para 1., 72--30--00.)
(1) Clean the area of the loose insert on the gearbox housing with methylethylketone.
(2) If the insert is pinned, use a No. 53 drill to drill out the insert locking pin. Remove the insert
using wrench 6872881 (EX 97154) or 6872927 as applicable.
(3) File off the burrs and clean the threads and surrounding area of the housing using a brush and
methylethylketone.
(4) Check the threads of the gearbox housing for wear by reinstalling the removed insert in the
threaded opening of the housing. The threads should be snug when the bottom side of the
insert flange is 1/8--in. (3 mm) above the surface of the gearbox. If any side movement or
wobble is present, use an oversized insert for the replacement. Select the oversized insert to
obtain the best fit.
(5) Install the selected insert. Tighten to 125--150 lb in. (14--17 N.m) plus running torque. Do not
exceed 180 lb in. (20 N.m).
(6) Install checking fixture 6872880 (EX 92634) over the five compressor mounting inserts (See
Figure 233). Be sure the fixture does not touch any of the four bosses around the insert at the
one oclock position. Determine the one oclock position by viewing the gearbox from the front
(compressor) side.
(7) Use shim stock to feel for clearance between each insert flange and the bottom of the fixture.
Rework insert flange using spotfacing kit 6872879 (EX 97156) until there is no clearance at
any of the five locations (See Figure 232).
NOTE: When properly installed and reworked, the five compressor mounting inserts are the
same height. In this condition the checking fixture rests on all five points and each
insert--to--fixture fit will be closed to the passage of the shim stock feeler gage.
(8) Mark the gearbox boss at the location of the insert pin slot. Remove the insert using wrench
6872881 (EX 97154) or 6872927 as applicable. Clean the threads of the insert and the
gearbox using methylethylketone.
(9) Apply Resiweld FE 186, or equivalent, sealer to the threads of the replacement insert. Thread
the insert into the gearbox. The insert will apply sealer to the threads in the gearbox. Repeat
the application of sealer to the insert as necessary to cover all threads of both parts. Also, at
the one oclock insert position, do not install the packing; however, be sure the packing groove
is filled with sealer.

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Startergenerator Gearshaft Spline Inspection

Figure 232

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CAUTION: WIPE EXCESS SEALER FROM THE END OF THE INSERT TO MAKE SURE
THAT NONE OF THE SEALER ENTERS THE GEARBOX AT THE ONE OCLOCK
INSERT POSITION THROUGHHOLE. ON BOTTOM HOLED INSERT
LOCATIONS, MAKE SURE THE HOLE DOES NOT ACCUMULATE EXCESS
SEALER WHICH CAN PUSH UP THROUGH THE INSIDE THREAD OF THE
INSERT. CLEAN SEALER FROM INSERT INSIDE THREADS BEFORE IT
HARDENS USING METHYLETHYLKETONE AND A 1/428 BOLT. RETAP (1/428)
THE INSIDE THREAD IF HARDENED SEALER IS ENCOUNTERED.
(10) Install the new insert. Tighten to 125150 lb in. (1417 N.m) plus running torque to a position
where the pin slot aligns with the mark on the gearbox boss. (See step (8).) Do not exceed
180 lb in. (20 N.m).
(11) Wipe any excess sealer from the insert or gearbox. Recheck insert height. (See steps (6) and
(7).) Cure sealer for 2535 minutes at 177C (350F), or as an option, at 149C (300F) for
two hours (to combine cure cycle with paint bake cycle).
(12) Install compressor and turbine assemblies on the gearbox. (Refer to Replacing the
Compressor Assembly, para 1.B., 723000.)
(13) Return the engine to service. Inspect the insert at the one oclock position for any sign of oil
leakage after the Check Run. Repair the insert if any leakage is detected.
G. Power Train Pinion Helical Gear Spline Inspection
Inspect the power train pinion helical gear spline whenever the engine has been subjected to a
sudden stoppage as defined in para 1.C.(4)., 720000, EngineInspection/Check. Replace the
gear (See Figure 202) if any of the following conditions exist:
(1) Chipped, damaged, pitted or worn spline teeth.
NOTE: Use a sharp pointed scribe, 0.020 in. (0.51 mm) radius, to detect a wear step.
(2) Evidence of spline deformation or twisting.

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Checking Insert Setting Height

Figure 233

Machining New Insert

Figure 234

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