Shorted Wire and Insulation Resistance Check of the Power Plant Wire Harness [CFMB]

TASK 71-50-00-280-002-A
Shorted Wire and Insulation Resistance Check of the Power Plant Wire Harness

1. Reason for the Job
Self explanatory
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	AR	ACCESS PLATFORM 1M(3 FT)
No specific	AR	MEGOHMMETER - MODEL 1863
No specific	AR	WARNING NOTICE(S)

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
FOR [1000EM1] (ENGINE-1)
437AL, 438AR, 451AL, 452AR
FOR [1000EM2] (ENGINE-2)
447AL, 448AR, 461AL, 462AR

C. Referenced Information

REFERENCE	DESIGNATION
TASK 71-13-00-010-040-B	Opening of the Fan Cowl Doors
TASK 71-13-00-410-040-B	Closing of the Fan Cowl Doors
TASK 78-30-00-081-041-B	Make the Thrust Reverser Serviceable after Maintenance
TASK 78-30-00-481-041-B	Make the Thrust Reverser Unserviceable for Maintenance
TASK 78-36-00-010-040-B	Opening of the Thrust Reverser Doors
TASK 78-36-00-410-040-B	Closing of the Thrust Reverser Doors
ESPM 205000

3. Job Set-up
Subtask 71-50-00-941-052-A ** ON A/C NOT FOR ALL

A. Safety Precautions
(1) On the center pedestal, on the ENG panel 115VU:
(a) Put a WARNING NOTICE(S) to tell persons not to start the engine.
(2) Make sure that the engine 1(2) shutdown occurred not less than 5 minutes before you do this procedure.
(3) On the overhead maintenance panel 50VU:
(a) Make sure that the ON legend of the ENG/FADEC GND PWR/1(2) pushbutton switch is off.
(b) Put a WARNING NOTICE(S) to tell persons not to energize the FADEC 1(2).

Subtask 71-50-00-010-054-A ** ON A/C NOT FOR ALL

B. Get Access
(1) Open the fan cowl doors (Ref. AMM TASK 71-13-00-010-040):
(2) FOR [1000EM1] (ENGINE-1)
437AL 438AR
(3) FOR [1000EM2] (ENGINE-2)
447AL 448AR
(4) Put the ACCESS PLATFORM 1M(3 FT) in position.

Subtask 71-50-00-040-052-A ** ON A/C NOT FOR ALL

C. Make the thrust reverser unserviceable (Ref. AMM TASK 78-30-00-481-041).

Subtask 71-50-00-010-055-A ** ON A/C NOT FOR ALL

D. Open the thrust reverser doors (Ref. AMM TASK 78-36-00-010-040):
(1) FOR [1000EM1] (ENGINE-1)
451AL 452AR
(2) FOR [1000EM2] (ENGINE-2)
461AL 462AR

4. Procedure
Subtask 71-50-00-280-051-A ** ON A/C NOT FOR ALL

A. Check of the Power Plant Wire Harness

CAUTION: YOU MUST DISCONNECT ALL THE CONNECTORS WHICH HAVE A RELATION TO THE CIRCUITS THAT ARE BEING CHECKED. FAILURE TO DO THIS WILL CAUSE UNSATISFACTORY RESISTANCE INDICATIONS AND POSSIBLE DAMAGE TO THE CIRCUITS.

CAUTION: DO NOT CAUSE DAMAGE TO CONNECTOR PINS WHEN YOU DO CONTINUITY CHECKS. DAMAGED PINS CAN BECOME LOOSE AND CAN THUS INTERMITTENTLY PREVENT CORRECT CONTINUITY.

(1) Shorted Wire Check of the Power Plant Wire Harness:

NOTE: You should do a shorted wire check on wires that could be unsatisfactory with a MEGOHMMETER - MODEL 1863.

(a) Disconnect the connector at each end of the wire harness which contains the unsatisfactory wire.
(b) Set the MEGOHMMETER - MODEL 1863 to the 100VDC scale.
(c) Connect the leads of the megohmmeter to each end of the wire and check for resistance.
(d) The resistance must be infinity.
(e) Defective circuits must be repaired ESPM 205000.
(2) Resistance Check of the Power Plant Wire Harness:

NOTE: You should do a resistance wire check on wires that could to be unsatisfactory with a MEGOHMMETER - MODEL 1863.

(a) Disconnect the connectors at each end of the wire harness which contains the unsatisfactory wire.
(b) Set the MEGOHMMETER - MODEL 1863 to the 500VDC scale.
(c) Connect the lead of the megohmmeter to the backshell body of the connector.
(d) Connect the other lead to the contact pin or the contact socket of the connector.
(e) The resistance must be a minimum of 20 megohms.
(f) If the harness fails the resistance test, replace the harness.

5. Close-up
Subtask 71-50-00-410-054-A ** ON A/C NOT FOR ALL

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Close the thrust reverser doors (Ref. AMM TASK 78-36-00-410-040):
(3) FOR [1000EM1] (ENGINE-1)
451AL 452AR
(4) FOR [1000EM2] (ENGINE-2)
461AL 462AR
(5) Remove the access platform(s).

Subtask 71-50-00-440-052-A ** ON A/C NOT FOR ALL

B. Make the thrust reverser serviceable (Ref. AMM TASK 78-30-00-081-041).

Subtask 71-50-00-410-055-A ** ON A/C NOT FOR ALL

C. Close Access
(1) Close the fan cowl doors (Ref. AMM TASK 71-13-00-410-040):
(2) FOR [1000EM1] (ENGINE-1)
437AL 438AR
(3) FOR [1000EM2] (ENGINE-2)
447AL 448AR
(4) Remove the WARNING NOTICE(S).

[Rev.10 from 2021] 2026.04.02 06:32:23 UTC