Installation of the Contactor

TASK 24-51-55-400-002-A
Installation of the 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: 27XN

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	WARNING NOTICE(S)
No specific	Torque wrench: range to between 0.18 and 0.15 m.daN (15.93 and 13.27 lbf.in )

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
212	COCKPIT
121AL

C. Referenced Information

REFERENCE	DESIGNATION
TASK 24-41-00-861-002-A	Energize the Aircraft Electrical Circuits from the External Power
TASK 24-41-00-861-002-A-01	Energize the Aircraft Electrical Circuits from the APU
TASK 24-41-00-861-002-A-02	Energize the Aircraft Electrical Circuits from Engine 1(2)
TASK 24-41-00-862-002-A	De-energize the Aircraft Electrical Circuits Supplied from the External Power
TASK 24-41-00-862-002-A-01	De-energize the Aircraft Electrical Circuits Supplied from the APU
TASK 24-41-00-862-002-A-02	De-energize the Aircraft Electrical Circuits Supplied from the Engine 1(2)
Contactor ** ON A/C NOT FOR ALL
Contactor ** ON A/C NOT FOR ALL

3. Job Set-up
Subtask 24-51-55-860-053-A

A. Aircraft Maintenance Configuration
(1) Make sure that the ACCESS PLATFORM 1M (3 FT)-ADJUSTABLE 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, a WARNING NOTICE(S) is in position to tell persons not to connect the external power connector.
(5) 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.

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

21VU (EMER ELEC PWR section).
25VU (APU section).
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 panel (6) which gives access to the panel 122VU is removed.

Subtask 24-51-55-865-054-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/AC SHED BUS/CNTOR	26XN	U25
123VU	SHED BUS/218XP/220XP SPLY	28XN	AC02

4. Procedure
Subtask 24-51-55-420-052-A ** ON A/C NOT FOR ALL

A. Installation of the Contactor
(1) Remove blanking caps from the electrical receptacle (5).
(2) Install the contactor (3) on the contactor base (1).
(3) TORQUE the six captive screws (2) to between 0.18 and 0.15 m.daN (15.93 and 13.27 lbf.in )

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

Subtask 24-51-55-420-052-B ** ON A/C NOT FOR ALL

A. Installation of the Contactor
(1) Remove blanking caps from the electrical receptacle (5).
(2) Install the contactor (3) on the module (1).
(3) TORQUE the six captive screws (2) to between 0.18 and 0.15 m.daN (15.93 and 13.27 lbf.in )

Subtask 24-51-55-865-055-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/AC SHED BUS/CNTOR	26XN	U25
123VU	SHED BUS/218XP/220XP SPLY	28XN	AC02

Subtask 24-51-55-710-051-A ** ON A/C NOT FOR ALL

C. Test
(1) Energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-861-002).
(2) On the overhead ELEC panel 35VU, push the GALY & CAB pushbutton switch (2XA) (the white indication light goes off).
(3) On the rear panel 120VU, make sure that there is 115VAC on busbars 218XP and 220XP.
(4) On the overhead ELEC panel 35VU, release the GALLEY pushbutton switch (2XA) (the white indication light goes on).

Subtask 24-51-55-710-051-B ** ON A/C NOT FOR ALL

C. Test
(1) Energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-861-002).
(2) On the overhead ELEC panel 35VU, push the ELEC/COMMERCIAL pushbutton switch (22XN) (the white indication light goes off).
(3) On the overhead ELEC panel 35VU, push the GALY & CAB pushbutton switch (2XA) (the white indication light goes off).
(4) On the rear panel 120VU, make sure that there is 115VAC on busbars 218XP and 220XP.
(5) On the overhead ELEC panel 35VU, release the GALY & CAB pushbutton switch (2XA) (the white indication light goes on).
(6) On the overhead ELEC panel 35VU, release the ELEC/COMMERCIAL pushbutton switch (22XN) (the white indication light goes on).

5. Close-up
Subtask 24-51-55-410-051-A

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Install the panel (6) of the panel 122VU.
(3) Remove the WARNING NOTICE(S).
(4) Close the access door 121AL.
(5) Remove the access platform(s).

Subtask 24-51-55-862-051-A

B. De-energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-862-002).

[Rev.10 from 2021] 2026.03.31 23:24:55 UTC