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

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3-2.

TROUBLESHOOTING

CONTINUED

a. ACCESSORY GEARBOX (AGB) AND

(2) ES-2. AGB GEAR TRAIN TURNS

HIGH PRESSURE COMPRESSOR -

UNEVENLY (BINDS) WHEN TURNED BY

CONTINUED

HAND AND RUBBING OR BINDING IS

FELT WHEN TUBEAXIAL FAN BLADES

OR LEFT COOLING FAN BLADES ARE

TURNED BY HAND.

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

of binding when the AGB gear train is turned by hand, along with rubbing

or binding when the tubeaxial fan blades or left cooling fan blades are

turned by hand. 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 or 4

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 cooling fan blades are turned by hand. 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 or cooling fan blades by hand. Since the AGB

and high pressure compressor assemblies have no mechanical connection

with the power turbine and RGB assemblies, this symptom indicates two

separate failures. The possibility exists of the transmission causing

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

train/high pressure compressor and the power turbine/RGB systems. Refer

to this page along with in-text art while performing troubleshooting.

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