Removal of the GCU-APU

TASK 24-23-34-000-001-A
Removal of the GCU-APU

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: 121
FIN: 1XS ** 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 18M (59 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
121	AVIONICS COMPARTMENT
811

C. Referenced Information

REFERENCE	DESIGNATION
APU Generator Control Unit (GCU)

3. Job Set-up
Subtask 24-23-34-860-051-A ** ON A/C NOT FOR ALL

A. Safety Precautions
(1) In the cockpit, on the overhead panel 25VU and 35VU, make sure these pushbutton switches are released:

START,
APU GEN.

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

25VU (APU),
35VU (ELEC).

Subtask 24-23-34-865-050-A ** ON A/C NOT FOR ALL

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
122VU	ELEC/GEN1/OFF/BTC1 SPLY	5XU	T28
122VU	ELEC/APU/GCU	6XS	Y25

Subtask 24-23-34-010-050-A ** ON A/C NOT FOR ALL

C. Get Access
(1) Put an ACCESS PLATFORM 18M (59 FT) - ADJUSTABLE at the access door 811 of the avionics compartment.
(2) Open the access door 811.

4. Procedure
Subtask 24-23-34-020-050-A ** ON A/C NOT FOR ALL

A. Removal of the GCU
(1) Loosen the 2 knurled nuts (1).
(2) Lower the 2 knurled nuts (1) to disengage the 2 studs (2).
(3) Carefully pull the handle (3) of the GCU (4) until the GCU is disconnected from the rack receptacle (5).
(4) Remove the GCU from the rack (6).
(5) Put CAP - BLANKING on the rack receptacle (5) and the GCU connector.

[Rev.10 from 2021] 2026.03.31 23:22:26 UTC