Installation of the DC Service Bus Ground Supply Contactor

TASK 24-43-55-400-001-A
Installation of the DC Service Bus Ground Supply Contactor

ZONE: 212
FIN: 3PX

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	WARNING NOTICE(S)
No specific	Torque wrench: range to between 26.55 and 23.9 lbf.in (0.30 and 0.27 m.daN )

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
212	COCKPIT
121AL

C. Referenced Information

REFERENCE	DESIGNATION
TASK 24-42-00-861-001-A	Energize the Ground Service Network from the External Power
TASK 24-42-00-862-001-A	De-energize the Ground Service Network Supplied from the External Power
TASK 25-11-41-000-001-A	Removal of the Third Occupant Seat
TASK 25-11-41-400-001-A	Installation of the Third Occupant Seat
Contactor ** ON A/C NOT FOR ALL
Contactor ** ON A/C NOT FOR ALL

3. Job Set-up
Subtask 24-43-55-860-051-A

A. Aircraft Maintenance Configuration
(1) Make sure that the access platform is in position at the access door 121AL.
(2) Make sure that the access door 121AL is open.
(3) Make sure that the external power connector is not connected to the aircraft receptacle.
(4) Make sure that on the access door 121AL there is a WARNING NOTICE(S) to tell persons not to connect the external power connector.
(5) In the cockpit, on the overhead panel 35VU, make sure that these pushbutton switches are released:

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

(6) Make sure that there is a WARNING NOTICE(S) in the cockpit to tell persons not to operate the pushbutton switches on these overhead panels:

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

(7) In the cockpit, on the APU section of the overhead panel 25VU, make sure that a WARNING NOTICE(S) is in position to tell persons not to start the APU.
(8) In the cockpit, make sure that the third occupant seat is removed (Ref. AMM TASK 25-11-41-000-001).
(9) In the cockpit, make sure that the front panel is removed from the bottom right side of the panel 120VU.

Subtask 24-43-55-865-051-A

B. Make sure that this(these) circuit breaker(s) is(are) open, safetied and tagged:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
122VU	ELEC/DC SVCE/BUS/ON TR2	5PX	U30
124VU	SVCE/601PP/602PP/SPLY	1PX	BB01

4. Procedure
Subtask 24-43-55-420-050-A ** ON A/C NOT FOR ALL

A. Installation of the Contactor

CAUTION: MAKE SURE THAT THE CONTACTOR LOCATING PIN IS CORRECTLY ENGAGED IN ITS RECESS LOCATED IN ONE POWER TERMINAL. THIS PREVENTS DAMAGE TO THE LOCATING PIN WHEN YOU APPLY THE TORQUE.

(1) Put the contactor (3) in position on the two tapped barrels (6) of the contactor base (5).
(2) TORQUE the two captive screws (2) to between 26.55 and 23.9 lbf.in (0.30 and 0.27 m.daN )

.
(3) Remove the CAP-BLANKING from each electrical connector and receptacle.
(4) Make sure that all the electrical connections are clean and in the correct condition.
(5) Connect the connector (4) to the contactor (3).

Subtask 24-43-55-420-050-B ** ON A/C NOT FOR ALL

A. Installation of the Contactor

CAUTION: MAKE SURE THAT THE CONTACTOR LOCATING PIN IS CORRECTLY ENGAGED IN ITS RECESS LOCATED IN ONE POWER TERMINAL. THIS PREVENTS DAMAGE TO THE LOCATING PIN WHEN YOU APPLY THE TORQUE.

(1) Install the contactor (3) on the module 14PN (5).
(2) TORQUE the captive screws (2) to between 26.55 and 23.9 lbf.in (0.30 and 0.27 m.daN )

.
(3) Remove the blanking caps from the electrical connector (4) and the electrical receptacle.
(4) Make sure that all the electrical connections are clean and in the correct condition.
(5) Connect the electrical connector (4) to the contactor (3).

Subtask 24-43-55-865-052-A

B. Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
122VU	ELEC/DC SVCE/BUS/ON TR2	5PX	U30
124VU	SVCE/601PP/602PP/SPLY	1PX	BB01

Subtask 24-43-55-710-050-A

C. Test of the Ground Service Network
(1) Energize the ground service network
(Ref. AMM TASK 24-42-00-861-001).
(2) On the overhead panel 25VU, put the INT LT/DOME switch in the BRT position. On the panel 453VU, the L dome light comes on.

5. Close-up
Subtask 24-43-55-862-050-A

A. De-energize the ground service network
(Ref. AMM TASK 24-42-00-862-001).

Subtask 24-43-55-410-050-A

B. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Install the front panel on the bottom right side of the panel 120VU.
(3) Install the Third Occupant seat (Ref. AMM TASK 25-11-41-400-001).
(4) Remove the WARNING NOTICE(S).
(5) Close the access door 121AL.
(6) Remove the access platform(s).

[Rev.10 from 2021] 2026.04.01 05:53:56 UTC