SECTION V: TROUBLESHOOTlNG
TM 9-2350-256-20
J
K
L
M
N
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P
Q
R
Check PREHEAT switch on APU control box for
malfunction by troubleshooting APU starter circuit,
Check for clogged fuel lines. Clean or replace lines
(see paragraph 13-5).
Check for dirty fuel filters. Clean or replace filters as
necessary (see paragraph 13-5).
Remove APU access cover (see paragraph 9-49).
Check that all air intake tubes and passages are free
of obstructions. Remove obstructions from air
intake tubes and passages.
Check high engine temperature sending unit.
Troubleshoot APU high air temperature circuit (see
paragraph 2-19, APU HIGH AIR TEMP lamp does
not light when air temperature is high). If defective,
notify Direct Support Maintenance.
Check for air in fuel supply system. Bleed fuel lines
at fuel filters (see paragraph 13-5).
Remove APU access cover (see paragraph 9-39).
Check fuel for contamination. If contaminated fuel
i s f o u n d , d r a i n f u e l t a n k s a n d f i l l w i t h
uncontaminated fuel (refer to TM 9-2350-256-10).
Check air intake tubes for restrictions. If restrictions
are found, clean or replace tubes (see paragraph
13-2).
Notify Direct Support Maintenance.
MAIN HYDRAULIC PUMP
SYMPTOMS
Main hydraulic pump fails to
operate.
Do steps A through E.
Main hydraulic pump fails to
Main hydraulic pump is noisy
develop sufficient pressure.
during operation.
Do steps C through F.
Do steps C through F.
A
Ensure system selector control lever is in the MAIN
position. If problem persists, go to step B.
B
Test for defective power control valve or restricted
hose.
Remove hose No. 66 from mechanical
transmission (see paragraph 12-1). With mechanical
transmission drive shaft rotating, and power control
valve lever placed in ON position, oil should flow
from hose.
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