Removal of the External Power Contactor (EPC)

TASK 24-41-55-000-001-A
Removal of the External Power Contactor (EPC)

WARNING: MAKE SURE THAT NO AC OR DC POWER IS CONNECTED TO THE AIRCRAFT ELECTRICAL CIRCUITS. THERE IS A RISK OF ELECTROCUTION IF THE AC OR DC POWER STAYS CONNECTED.

ZONE: 212
FIN: 3XG

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

REFERENCE	QTY	DESIGNATION
No specific	1	ACCESS PLATFORM 1M (3 FT)-ADJUSTABLE
No specific	AR	CAP - BLANKING
No specific	AR	WARNING NOTICE(S)

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
212	COCKPIT
121AL

C. Referenced Information

REFERENCE	DESIGNATION
TASK 24-23-55-000-001-A	Removal of the APU GLC
TASK 25-11-41-000-001-A	Removal of the Third Occupant Seat
Contactor ** ON A/C NOT FOR ALL
Contactor ** ON A/C NOT FOR ALL
Contactor Base ** ON A/C NOT FOR ALL
APU/EXT Power-Contactor Module ** ON A/C NOT FOR ALL

3. Job Set-up
Subtask 24-41-55-010-050-A

A. Get Access
(1) Remove the Third Occupant seat (Ref. AMM TASK 25-11-41-000-001).
(2) On the left lower side of panel 120VU, remove the access panel (4).
(3) Put the ACCESS PLATFORM 1M (3 FT)-ADJUSTABLE in position at access door 121AL.
(4) Open access door 121AL.

Subtask 24-41-55-941-050-A

B. Safety Precautions
(1) Make sure that the external power connector is not connected to the aircraft receptacle.
(2) Put WARNING NOTICE(S) on the access door 121AL to tell persons not to use the external power receptacle.
(3) In the cockpit, on the overhead ELEC panel 35VU, release these pushbutton switches:

BAT 1, BAT 2,
APU GEN,
GEN 1, GEN 2,
EXT PWR.

(4) In the cockpit, put WARNING NOTICE(S) to tell persons not to operate the pushbutton switches on these overhead panels:

21VU (EMER ELEC PWR),
35VU (ELEC).

(5) In the cockpit, on the APU section of the overhead panel 25VU, put WARNING NOTICE(S) to tell persons not to start the APU.

4. Procedure
Subtask 24-41-55-020-050-A ** ON A/C NOT FOR ALL

A. Removal of the Contactor

Contactor ** ON A/C NOT FOR ALL

CAUTION: REMOVE THE CONTACTOR ONLY AND NOT THE BASE OR THE MODULE WHERE THE WIRES ARE CONNECTED.

(1) Disconnect the electrical connector (1).
(2) Put CAP - BLANKING on the disconnected electrical connector (1) and the electrical receptacle (6).
(3) Loosen the six captive screws (3).

NOTE: Do not remove the captive screws (3) from the contactor (2).

(4) Remove the contactor (2) from the contactor base (5).

Subtask 24-41-55-020-051-A ** ON A/C NOT FOR ALL

CAUTION: MAKE MATCH MARKS ON ALL THE ELECTRICAL WIRES BEFORE YOU DISCONNECT THEM. INCORRECT CONNECTION OF WIRES WILL CAUSE DAMAGE TO EQUIPMENT.

B. Removal of the Contactor Base

Contactor Base ** ON A/C NOT FOR ALL

NOTE: The removal of the base is necessary only if the base is damaged.

(1) Remove the six nuts (1) and washers (2).
(a) Remove the three jumpers (3) from the contactor base and the adjacent base.
(2) Remove the three nuts (9) and washers (8).
(a) Disconnect the three electrical cables (7) from the contactor base.
(3) Remove the three nuts (12) and washers (11).
(a) Disconnect the six electrical cables (10) from the contactor base.
(4) Remove the four screws (6) and washers (5).
(5) Remove the contactor base.

Subtask 24-41-55-020-050-B ** ON A/C NOT FOR ALL

C. Removal of the Contactor

Contactor ** ON A/C NOT FOR ALL

CAUTION: REMOVE THE CONTACTOR ONLY AND NOT THE BASE OR THE MODULE WHERE THE WIRES ARE CONNECTED.

(1) Disconnect the electrical connector (1).
(2) Put CAP - BLANKING on the disconnected electrical connector (1) and the electrical receptacle (6).
(3) Loosen the six captive screws (3).

NOTE: Do not remove the captive screws (3) from the contactor (2).

(4) Remove the contactor (2) from the APU/EXT power-contactor module (5).

Subtask 24-41-55-020-051-B ** ON A/C NOT FOR ALL

CAUTION: MAKE MATCH MARKS ON ALL THE ELECTRICAL WIRES BEFORE YOU DISCONNECT THEM. INCORRECT CONNECTION OF WIRES WILL CAUSE DAMAGE TO EQUIPMENT.

D. Removal of the APU/EXT Power-Contactor Module

APU/EXT Power-Contactor Module ** ON A/C NOT FOR ALL

NOTE: The removal of the APU/EXT power-contactor module is necessary only if the APU/EXT power-contactor module is damaged.

(1) Remove the APU GLC (Ref. AMM TASK 24-23-55-000-001).
(2) Remove the three screws (14) and washers (15).
(a) Disconnect the three electrical wires (16).
(3) Remove the six nuts (1) and washers (2).
(a) Disconnect the six cables (3) from the APU/EXT power-contactor module (5).
(4) Remove the twelve screws (8) and washers (7) from the APU/EXT power-contactor module (5) and from the adjacent module.
(a) Remove the six jumpers (6) from the APU/EXT power-contactor module (5) and from the adjacent modules.
(5) Remove the three screws (11) and washers (12).
(a) Disconnect the three cables (13) from the APU/EXT power-contactor module (5).
(6) Remove the eight screws (10) and washers (9).
(7) Remove the APU/EXT power-contactor module (5).

[Rev.10 from 2021] 2026.03.31 23:24:26 UTC