Removal of the AC Service Bus Normal Supply Contactor

TASK 24-51-55-000-001-A
Removal of the AC Service Bus Normal Supply Contactor

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: 12XN

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	SAFETY CLIP - CIRCUIT BREAKER
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 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

3. Job Set-up
Subtask 24-51-55-010-050-A

A. Get Access
(1) Remove the Third Occupant seat (Ref. AMM TASK 25-11-41-000-001).
(2) Remove the front panel (8) of the panel 123VU.
(3) Put the ACCESS PLATFORM 1M (3 FT)-ADJUSTABLE in position at the access door 121AL.
(4) Open the access door 121AL.

Subtask 24-51-55-860-050-A

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

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

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

21VU (EMER ELEC PWR section),
25VU (APU section),
35VU (ELEC).

Subtask 24-51-55-865-050-A

C. Open, safety and tag this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
122VU	ELEC/AC PWR/SVCE/CTL	3XX	V29

4. Procedure
Subtask 24-51-55-020-050-A

A. Removal of the Contactor

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 blanking caps on the disconnected electrical connector (1) and electrical receptacle (7).
(3) Loosen the captive screws (2).

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

(4) Remove the contactor (3).

[Rev.10 from 2021] 2026.03.31 23:24:52 UTC