Installation of the Essential 115/26VAC Autotransformer

TASK 24-52-51-400-001-A
Installation of the Essential 115/26VAC Autotransformer

ZONE: 125
FIN: 5XH

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 2M (6 FT) - ADJUSTABLE

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
125	LATERAL AVIONIC COMPARTMENT
812

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)
TASK 24-42-00-861-001-A	Energize the Ground Service Network from the External Power
AutoTransformer

3. Job Set-up
Subtask 24-52-51-860-050-A

A. Aircraft Maintenance Configuration
(1) Make sure that the ground service network is energized
(Ref. AMM TASK 24-42-00-861-001).
(2) Make sure that the ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE is in position at the access door 812.
(3) Make sure that the access door 812 is open.
(4) Make sure that the access panel of the AC/DC emergency power center 106VU is open.

Subtask 24-52-51-865-051-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
106VU	26VAC/ESS BUS/SPLY	4XH	B06

4. Procedure
Subtask 24-52-51-420-050-A

A. Installation of the Autotransformer
(1) Put the transformer (1) in position.
(2) Install the washers (5) and the screws (4), then tighten the screws.
(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 electrical connector (3).

Subtask 24-52-51-865-052-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
106VU	26VAC/ESS BUS/SPLY	4XH	B06

Subtask 24-52-51-710-050-A ** ON A/C NOT FOR ALL

C. Test of the Essential 115/26 VAC Autotransformer
(1) Energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-861-002).
(2) On the ADIRS CDU, put the OFF/NAV/ATT selector switch of the ADIRU 1 and ADIRU 3 in NAV position.
(3) Make sure that the FAULT legend on the ADR 1 and ADR 3 pushbutton switches does not stay on.
(4) De-energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-862-002).

Subtask 24-52-51-710-050-B ** ON A/C NOT FOR ALL

C. Test of the Essential 115/26 VAC Autotransformer
(1) Energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-861-002).
(2) On the ADIRS MSU panel 41VU, set the OFF/NAV/ATT selector switch of the ADIRU 1 and ADIRU 3 to the NAV position.
(3) On the ADR 1 and ADR 3 pushbutton switches, makes sure that the FAULT legend does not stay on.
(4) De-energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-862-002).

5. Close-up
Subtask 24-52-51-410-050-A

A. Close Access
(1) In the avionics compartment, close the access panel of the AC/DC emergency power center 106VU.
(2) Close the access door 812.
(3) Remove the access platform(s).

[Rev.10 from 2021] 2026.03.31 23:24:59 UTC