AGB GEAR TRAIN TURNS UNEVENLY (BINDS) WHEN TURNED BY HAND, RUBBING OR BINDING IS FELT WHEN TUBEAXIAL FAN BLADES OR LEFT COOLING FAN BLADES ARE TURNED BY HAND

TM 9-2835-255-34

3-2. TROUBLESHOOTING - CONTINUED

E S - 1 0 . AGB GEAR TRAIN TURNS

(l0)

ACCESSORY GEARBOX (AGB) AND

U N E V E N L Y (BINDS) WHEN TURNED BY

HIGH PRESSURE COMPRESSOR -

H A N D , RUBBING OR BINDING IS

CONTINUED

F E L T WHEN TUBEAXIAL FAN

B L A D E S OR LEFT COOLING FAN

BLADES ARE TURNED BY HAND AND

T H E R E ARE METAL CHIPS IN THE

O I L PUMP TO OIL COOLER FLUID

FILTER.

This section contains troubleshooting to locate and correct cause(s) of

binding in the AGB gear train when turned by hand, rubbing and binding

when the tubeaxial fan blades or left cooling fan blades are turned by

hand, and metal chips in the oil pump to oil cooler fluid filter. The

AGB is coupled to the high pressure compressor in the forward engine

module through a gearshaft. If there is damage to the high pressure

compressor, forward engine module position No. 3, 4, 11 or 12 bearing,

or AGB gears and/or bearings, binding will be felt when the AGB gear

train is turned by hand. The power turbine and reduction gearbox (RGB)

are coupled mechanically through the power shaft. If there is damage to

the power turbine, rear engine subassembly position No. 6A or 6B

bearing, or RGB bearings and/or gears, binding will be felt when the

tubeaxial fan blades or left coolinq fan blades are turned by hand. The

RGB oil return line feeds directly into the oil pump passage that houses

the magnetic plug. The only possible source of metal chips on the oil

pump magnetic plug is the RGB. The transmission is mechanically coupled

to the RGB through a splined shaft. If there is internal transmission

damage, binding will be felt when turning the tubeaxial fan blades or

cooler fan blades by hand. The lubrication system delivers hot oil,

scavenged from bearing packages throughout the engine, through a fluid

filter, to the engine 0il cooler. Cooled oil is then returned to the oil

tank. Whenever metal chips are generated, the fluid filter will catch

and retain most of the chips. Based on the above described symptoms, two

separate failures may have occurred. The art on the following pages

provides an overview-of the related systems. Refer to these pages along

with in-text art while performing troubleshooting.

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