Removal of the 115/26VAC Autotransformer

TASK 24-51-51-000-001-A
Removal of the 115/26VAC Autotransformer

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: 15XN1
FIN: 15XN2

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
Autotransformers

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

A. Get Access
(1) In the cockpit, remove the panel (6) which gives access to the panel 122VU. The panel 122VU is at the top of the panel 120VU.
(2) Put the ACCESS PLATFORM 1M (3 FT)-ADJUSTABLE in position at the access door 121AL.
(3) Open the access door 121AL.

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

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

BAT 1, BAT 2,
APU GEN,
GEN 1(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 24-51-51-865-050-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
FOR FIN: 15XN1 (A/XFMR115/26VAC, 1)
123VU	BUS 1/131XP-A/SPLY	5XN1	AB12
FOR FIN: 15XN2 (A/XFMR115/26VAC, 2)
123VU	BUS 2/231XP-A/SPLY	5XN2	AB01

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

A. Removal of the Autotransformer
(1) Disconnect the electrical connector (1).
(2) Put blanking caps on the disconnected electrical connectors (1) and (5).
(3) Loosen the 4 screws (4).
(4) Hold the transformer (2).
(5) Remove the screws (4) and the washers (3).
(6) Remove the transformer (2).

[Rev.10 from 2021] 2026.03.31 23:24:49 UTC