EXPORT CONTROLLED RollsRoyce
250B17F SERIES OPERATION AND MAINTENANCE
PROPELLER REDUCTION GEARBOX MAINTENANCE PRACTICES
1. Propeller Reduction Gearbox Replacement
A. Removal
(1) Remove the beta control valve. (Refer to Beta Control Valve Removal, para 2.A., 761002.)
(2) Remove oil supply and scavenge tubes. Loosen the jam nut and remove the tee from the
reduction gearbox pressure oil port.
(3) Remove the propellerpower turbine governor. (Refer to PropellerPower Turbine Governor
Removal, para 2.A., 732001.)
(4) Remove the start counter and bracket. (Refer to Start Counter Removal, para 1.A.,
742003.)
(5) Remove the compressor pressure and scavenge oil tubes and the antiicing air tube.
(6) Remove the external oil sumptogearbox housing scavenge oil tube. Remove three bolts
and one nut and remove the external oil sump.
CAUTION: DO NOT MOVE THE FRONT SUPPORT AXIALLY AS IT IS BEING ROTATED.
AXIAL MOVEMENT CAN CAUSE DAMAGE TO THE COMPRESSOR ROTOR,
SEAL, AND NO. 1 BEARING.
(7) Remove the remaining compressor casetofront support splitline bolts and nuts. The
compressor identification plate will also be removed. The front supporttocompressor case
pilot diameter is a tight fit. It may be necessary to loosen the compressor case horizontal
splitline bolts and nuts to allow the front support to rotate. Rotate the front support 90
clockwise (as viewed from the front) to allow clearance for removal of the reduction gearbox.
(8) Remove the external retaining ring from the sun gearshaft at the aft side of the PTO gearshaft
in the power and accessory gearbox.
(9) Remove the internal retaining ring and the locating ring from the ID of the PTO gearshaft at the
aft side of the power and accessory gearbox.
(10) Remove the propeller reduction gearbox by removing the remaining 10 bolts, 2 nuts and 12
washers at the splitline.
WARNING: FAILURE TO PROPERLY INSTALL, ALIGN AND TIGHTEN FUEL, OIL AND AIR
FITTINGS AND TUBES COULD RESULT IN AN ENGINE FAILURE.
B. Installation
(1) Apply a light film of Permatex 1372W sealer or equivalent on the mating flange of the propeller
reduction gearbox.
CAUTION: CARE MUST BE USED WHEN INSTALLING GEARBOX. THE SUN GEAR TEETH
MUST NOT DAMAGE PROP SHAFT THROUGH CONTACT AS SPLINES OF THE
SUN GEAR SHAFT ARE ALIGNED IN PTO GEAR SPLINES.
(2) Install the propeller reduction gearbox on the power and accessory gearbox. Attach with 12
bolts, 2 nuts and 10 washers. Do not install washers at the No. 3 and No. 4 bolt positions (as
viewed from the front of the engine). Tighten bolts to 3540 lb in. (3.94.5 N.m). Tighten two
nuts to 7085 lb in. (7.99.6 N.m). Lockwire the bolts in pairs.
(3) Install the locating ring with the internal retaining ring into the PTO gearshaft at the aft side of
the power and accessory gearbox.
(4) Install the external retaining ring onto the sun gearshaft at the aft side of the PTO gearshaft in
the power and accessory gearbox.
CAUTION: DO NOT FORCE THE FRONT SUPPORT FLANGE INTO THE COMPRESSOR
CASE PILOT. LOOSEN THE COMPRESSOR CASE HORIZONTAL SPLITLINE
BOLTS AS NECESSARY FOR EASE OF ASSEMBLY. IF NECESSARY, REMOVE
ONE COMPRESSOR CASE HALF.
(5) Reassemble the front support and compressor identification plate to the compressor case with
seven bolts and nuts. Do not tighten nuts at this time.
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Rolls-Royce Proprietary Data Uncontrolled Printed Copy
EXPORT CONTROLLED RollsRoyce
250B17F SERIES OPERATION AND MAINTENANCE
(6) Install the external oil sump onto the compressor with three bolts and one nut. Tighten the
compressor casetofront support splitline bolts and nuts to 1015 lb in. (1.11.7 N.m) above
locknut drag. Tighten the nut securing the extended leg of the oil sump to 1015 lb in. (1.11.7
N.m) above locknut drag.
(7) Install the start counter and bracket. (Refer to Start Counter Installation, para 1.B.,
742003.)
(8) Install the pressure oil tee with new packing in the reduction gear pressure oil port. Do not
tighten the jam nut.
(9) Install the oil supply and scavenge tubes:
(a) Gearboxtotee pressure oil tube. Tighten coupling nuts to 65100 lb in. (7.311.3 N.m).
(b) Teetofront support pressure oil tube. Tighten coupling nuts to 65100 lb in. (7.311.3
N.m). Tighten the tee jam nut to 5580 lb in. (6.29.0 N.m).
(c) Compressortogearbox scavenge oil tube. Tighten coupling nuts to 150200 lb in.
(1723 N.m).
(d) Reduction gearboxtoexternal oil sump tube. Tighten coupling nuts to 150200 lb in.
(1723 N.m).
(e) Install tube clamps as shown in Figure 201, 723000. Tighten clamp nuts to 3540 lb in.
(3.94.5 N.m).
(f) External oil sumptogearbox housing scavenge oil tube. Tighten coupling nuts to
150200 lb in. (1723 N.m).
(10) Install the antiicing air tube to the front support. Tighten coupling nuts to 150200 lb in.
(1723 N.m).
(11) Install the propellerpower turbine governor. (Refer to PropellerPower Turbine Governor
Installation, para 2.B., 732001.)
(12) Install the beta control valve. (Refer to Beta Control Valve Installation, para 2.B., 761002.)
(13) Check run the engine after propeller reduction gearbox replacement. (Refer to Check Run,
para 1., 720000, EngineAdjustment/Check.)
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