TM 1-1520-238-T-4
4–141
4–55.
ECS AIRFLOW PRESENT – WITH ENG START NO 1 SWITCH AT IGN OVRD
4–55
Tools:
Nomenclature
Part Number
Tool Kit, Electrical
SC518099CLA06
Repairer’s
Multimeter, Digital
AN/PSM-45
Personnel Required:
68F
Aircraft Electrician
One person to assist
References:
TM 1-1520-238-T-8
TM 1-1520-238-23
Equipment Conditions:
Ref
Condition
TM 1-1520-238-23
Access provisions –
panel L200 removed
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. Place MASTER IGN switch to ON. Set and hold
ENG START NO 1 switch to IGN OVRD. Check
for 28 VDC at (A402)XK4–7–X1.
Is voltage present?
YES
Go to step 4.
NO
Go to step 2.
2. Check for open between (A402):
TB2–10–G and J20–B10,
XK4–7–X1 and TB2–10–J.
Does open exist?
YES
Repair open wire.
Go to paragraph 4–12.
NO
Go to step 3.
3. Check for open between P433–B10 and
P977–A16.
Does open exist?
YES
Repair open wire.
Go to paragraph 4–12.
NO
Replace start mode relay panel
(TM 1-1520-238-23).
4. Remove (A402)K4–7 (TM 1-1520-238-23),
check for open between (A402)XK4–7–X2 and
ground.
Does open exist?
YES
Repair open wire.
Go to paragraph 4–12.
NO
Go to step 5.
5. Set and hold ENG START NO 1 switch set to
IGN OVRD, check for 28 VDC at
(A402)XK2–9/10–X1.
Is voltage present?
YES
Go to step 6.
NO
Repair open wire between
(A402):
XK4–7–X2 and TB2–10–H.
Go to paragraph 4–12.
6. Check for open between (A402)XK2–9/10–X2
and ground.
Does open exist?
YES
Repair open wire.
Go to paragraph 4–12.
NO
Go to step 7.
7. Attach (A402)K4–7 (TM 1-1520-238-23), detach
wire from (A402)XK4–7–A2. Set and hold ENG
START NO 1 switch to IGN OVRD, check for 28
VDC at (A402)XK4–7–A2.
Is voltage present?
YES
Replace relay (A402)K4–7
(TM 1-1520-238-23).
NO
Go to step 8.
