SECTION III. TROUBLESHOOTING PROCEDURES

TM 9-2835-255-34

SECTION III. TROUBLESHOOTING PROCEDURES

3 - 2 . TROUBLESHOOTING

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ES-1. AGB GEAR TRAIN TURNS

a. ACCESSORY GEARBOX (AGB) AND

HIGH PRESSURE COMPRESSOR

UNEVENLY (BINDS) WHEN TURNED BY

H A N D . AGB INSTALLED ON ENGINE.

NO OTHER ROTATION OR METAL CHIPS

NOTED.

This section contains troubleshooting to correct the cause of binding or

uneven turning when the main hydraullc pump drive gear is turned by

hand. The AGB is coupled to the high pressure compressor in the forward

engine module through a gearshaft. The main oil pump, electro-mechanical

fuel system (EMFS), and starter are mounted on and coupled to the AGB

through splines and gears. During the start cycle, starter rotation

causes the high pressure compressor system, through AGB gears, to turn.

After the start cycle is completed, the drive sequence reverses, and the

high pressure compressor system drives the AGB gear train. A damaged or

broken gearshaft (coupling between AGB and high pressure compressor

system) could cause uneven turning or binding to be felt at the AGB. If

the high pressure compressor is damaged, it could cause binding within

the forward engine module which could be felt when turning the AGB

g e a r s . Damaged AGB gears or contamination in the AGB would also cause

this symptom. The art on this page provides an overview of the AGB gear

train and the high pressure compressor system. Refer to this page along

HP COMPRESSOR SYSTEM

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