TM 1-1520-238-T-5
7–141
7–48.
SHAFT DRIVEN COMP INDICATOR – IS NOT LIGHTED DURING APU START CYCLE
7–48
Tools:
Nomenclature
Part Number
Tool Kit, Aircraft
SC518099CLA01
Mechanic’s
Tool Kit, Electrical
SC518099CLA06
Repairer’s
Multimeter, Digital
AN/PSM-45
Extractor, Relay
CTJ-RO6
Personnel Required:
67R
Attack Helicopter Repairer
68X
Armament/Electrical Systems Repairer
References:
TM 1-1520-238-T-7
TM 1-1520-238-T-8
TM 1-1520-238-23
WARNING
Turn off power before detaching or
attaching wires and connectors. High
current 28 VDC or 115 VAC is present.
Failure to do so could result in death or
serious injury.
1. Check FUEL BST circuit breaker.
Does circuit breaker stay closed?
YES
Go to step 2.
NO
Refer to TM 1-1520-238-T-7 to
troubleshoot fuel
crossfeed/boost system.
2. Detach P1323. Check for open between
P442–B1 and wire end at GS541–K.
Does open exist?
YES
Replace SDC outlet pressure
switch (S14)
(TM 1-1520-238-23).
NO
Go to step 3.
3. Check for open between P18–38 and S14–SP1.
Does open exist?
YES
Repair open wire between:
P18–38 and P440–B15,
S14–SP1 and P442–B1.
(A402):
J16–B15 and TB2–12–R,
J5–B1 and TB2–12–S.
Go to paragraph 7–45.
NO
Go to step 4.
4. During APU start, check SDC throttle inlet valve
indicator position.
Is indicator at open position?
YES
Go to step 5.
NO
Refer to TM 1-1520-238-T-8 to
troubleshoot ECS.
5. During APU start sequence check for 28 VDC
between P217–1 and P217–2.
Is voltage present?
YES
Go to step 6.
NO
Replace SDC inlet throttle valve
(TM 1-1520-238-23).
6. Remove SDC time delay relay. Check for open
between (A402):
XK2–1/2–X1 and TB2–6–F,
XK2–1/2–X2 and GS4–C.
Does open exist?
YES
Repair open wire.
Go to paragraph 7–45.
NO
Go to step 7.
7. Refer to TM 1-1520-238-T-8 to locate and
detach P51 and P941. Set and hold APU
START/RUN switch to START. Check for
28 VDC at (A402)XK2–1/2–C1.
Is voltage present?
YES
Replace relay (A402)K2–1/2
(TM 1-1520-238-23).
NO
Refer to TM 1-1520-238-T-8 to
troubleshoot APU.
END OF TASK
