Removal of the Main Junction Box [CFMB]

TASK 77-21-10-000-025-A
Removal of the Main Junction Box

FIN: 1000EM1 ** ON A/C NOT FOR ALL
FIN: 1000EM2 ** ON A/C NOT FOR ALL

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	CAP - BLANKING
No specific	AR	PLUG - BLANKING
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 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
Main Junction Box

3. Job Set-up
Subtask 77-21-10-941-061-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 77-21-10-010-074-A ** ON A/C NOT FOR ALL

B. Open the fan cowl doors: (Ref. AMM TASK 71-13-00-010-040)
(1) FOR [1000EM1] (ENGINE-1)
437AL 438AR
(2) FOR [1000EM2] (ENGINE-2)
447AL 448AR

Subtask 77-21-10-040-068-A ** ON A/C NOT FOR ALL

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

Subtask 77-21-10-010-084-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 77-21-10-020-063-A ** ON A/C NOT FOR ALL

A. Removal of the Main Junction Box
(1) Cut and remove the lockwires.
(2) Disconnect the upper extension lead (10) and the lower extension lead (40) from the main junction box (20).
(3) Disconnect the CJ13 harness connector (60) from the main junction box (20).
(4) Disconnect the main junction box leads (20) from the upper left T495 sector junction box (100) and lower left T495 sector junction box (140).
(5) Remove the parts which attach the upper extension lead (10) as follows:
(a) Remove the bolt (80) from the braket (70) on flange S, at the 10:15 o'clock position (Detail C).
(b) Remove the clamp (90).
(c) Remove the bolt (120) from the braket (110) on flange S, at the 8:30 o'clock position (Detail E).
(d) Remove the clamp (130).
(e) Remove the nuts (30) from the flange S, at the 9:15 o'clock position (Detail B).
(f) Remove the clamp (50).
(6) Remove the main junction box (20) from the engine.
(7) Install the PLUG - BLANKING and CAP - BLANKING on the connectors and receptacles.

[Rev.10 from 2021] 2026.04.01 03:17:28 UTC