Removal of the Ground Auxiliary Power Control Unit (GAPCU)

TASK 24-41-34-000-001-B
Removal of the Ground Auxiliary Power Control Unit (GAPCU)

CAUTION: MAKE SURE THAT NO AC OR DC POWER IS CONNECTED TO THE AIRCRAFT ELECTRICAL CIRCUITS. THERE IS A RISK OF DAMAGE TO EQUIPMENT DURING ITS REMOVAL/ INSTALLATION IF THE AC OR DC POWER STAYS CONNECTED.

ZONE: 122
FIN: 24XG ** 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	1	ACCESS PLATFORM 1M (3 FT)-ADJUSTABLE
No specific	1	ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE
No specific	AR	CAP - BLANKING
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
No specific	AR	WARNING NOTICE(S)

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
122	AVIONICS COMPARTMENT
121AL, 811

C. Referenced Information

REFERENCE	DESIGNATION
Ground Auxiliary Power Control Unit (GAPCU) ** ON A/C NOT FOR ALL
Ground Auxiliary Power Control Unit (GAPCU) ** ON A/C NOT FOR ALL

3. Job Set-up
Subtask 24-41-34-010-051-A ** ON A/C NOT FOR ALL

A. Get Access
(1) Put an ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE in position at the access door 811.
(2) Open the access door 811.
(3) Put an ACCESS PLATFORM 1M (3 FT)-ADJUSTABLE in position at the access door 121AL.
(4) Open the access door 121AL.

Subtask 24-41-34-941-053-A ** ON A/C NOT FOR ALL

B. Safety Precautions
(1) Make sure that the external power connector is not connected to the aircraft external power 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.

Subtask 24-41-34-865-059-A ** ON A/C NOT FOR ALL

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
122VU	ELEC/GAPCU	17XG	W24
122VU	ELEC/EXT PWR/CTL	11XG	X29
123VU	GND/PWR/PROT	2XG	AB07

4. Procedure
Subtask 24-41-34-020-051-A ** ON A/C NOT FOR ALL

A. Removal of the GAPCU
(1) Loosen the nuts (1).
(2) Lower the nuts (1).
(3) Pull the GAPCU (4) on its rack (6) to disconnect the electrical connectors (5).
(4) Remove the GAPCU from its rack (6).
(5) Put the CAP-BLANKING on each disconnected electrical connector and receptacle.

[Rev.10 from 2021] 2026.03.31 23:24:18 UTC