Replacement of the APU Start Fuse

TASK 49-42-00-960-003-A
Replacement of the APU Start Fuse

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.

FIN: 6KA ** 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	AR	ACCESS PLATFORM 1M (3 FT)-ADJUSTABLE
No specific	AR	WARNING NOTICE(S)
No specific	Torque wrench: range to between 1.0 and 0.8 m.daN (88.50 and 70.80 lbf.in )

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
121AL

C. Expendable Parts

FIG.ITEM	DESIGNATION	IPC-CSN
4	WASHER	AIPC 49-42-08-01-040
6	WASHER	AIPC 49-42-08-01-132
4	WASHER	AIPC 49-42-08-01-133
3	FUSE	AIPC 49-42-08-01-140
7	FUSE	AIPC 49-42-08-01-140
4	WASHER	AIPC 49-42-88-01-090
3	FUSE	AIPC 49-42-88-01-100

D. 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 25-11-41-000-001-A	Removal of the Third Occupant Seat
TASK 25-11-41-400-001-A	Installation of the Third Occupant Seat
TASK 49-00-00-860-008-A	APU Start by External Power
TASK 49-00-00-860-008-A-01	APU Start by Batteries
TASK 49-00-00-860-009-A	APU Shutdown by External Power (131-9(A))
TASK 49-00-00-860-009-A-01	APU Shutdown by Batteries (131-9(A))
APU Start Fuse (6KA) - 120VU ** ON A/C NOT FOR ALL
APU Start Fuse (6KA) - 120VU ** ON A/C NOT FOR ALL

3. Job Set-up
Subtask 49-42-00-010-052-A ** ON A/C NOT FOR ALL

A. Get Access

APU Start Fuse (6KA) - 120VU ** ON A/C NOT FOR ALL

(1) Remove the third occupant seat (Ref. AMM TASK 25-11-41-000-001).
(2) In the cockpit, on the left lower side of the panel 120VU:

Release the quick release fasteners (1) and remove the panel (2).

(3) Put the ACCESS PLATFORM 1M (3 FT)-ADJUSTABLE at the access door 121AL.
(4) Open the access door 121AL.

Subtask 49-42-00-860-054-A ** ON A/C NOT FOR ALL

B. Safety precautions
(1) Make sure that the external power connector is not connected to the aircraft EXT PWR receptacle.
(2) Put a warning notice on the access door 121AL to tell persons not to connect the external power connector.
(3) In the cockpit, on the overhead panel 35VU, make sure these pushbutton switches are released:

APU GEN,
BAT1, BAT2,
GEN1, GEN2,
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),
25VU (APU),
35VU (ELEC).

4. Procedure
Subtask 49-42-00-960-052-A ** ON A/C NOT FOR ALL

A. Replacement of the Fuse

NOTE: Installation of a new fuse (7) requires one new flat washer (4) and one new locking washer (6) for each stud. Remove and discard one washer (4) and one locking washer (6) from each stud before you install the new fuse (7).

(1) Remove the nuts (5).
(2) Remove and discard the locking washers (6).
(3) Remove and discard the flat washers (4).
(4) Remove and discard the fuse (7).
(5) Install the new AIPC 49-42-08-01-140 FUSE (7) on the terminals of the mount (3) as shown on the view C.
(6) Install the new AIPC 49-42-08-01-133 WASHER (4).
(7) Install the new AIPC 49-42-08-01-132 WASHER (6).
(8) Install the nuts (5).
(9) TORQUE the nuts (5) to between 1.0 and 0.8 m.daN (88.50 and 70.80 lbf.in )

Subtask 49-42-00-960-052-B ** ON A/C NOT FOR ALL

A. Replacement of the Fuse

NOTE: A new fuse (3) has one locking washer (4) for each screw. Remove and discard locking washers (4) from screws (5) before you install the new fuse (3).

(1) Remove the screws (5).
(2) Remove and discard the locking washers (4).
(3) Remove and discard the fuse (3) from the terminal.
(4) Install the new AIPC 49-42-88-01-100 FUSE (3) or the new AIPC 49-42-08-01-140 FUSE (3) on the terminal.
(5) Put the new AIPC 49-42-88-01-090 WASHER (4) or the new AIPC 49-42-08-01-040 WASHER (4) on the screws (5).
(6) Tighten the screws (5).

Subtask 49-42-00-861-052-A ** ON A/C NOT FOR ALL

B. Energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-861-002).

Subtask 49-42-00-710-052-A ** ON A/C NOT FOR ALL

C. Test
(1) Start the APU (Ref. AMM TASK 49-00-00-860-008).
(2) Shutdown the APU (Ref. AMM TASK 49-00-00-860-009).

5. Close-up
Subtask 49-42-00-862-052-A ** ON A/C NOT FOR ALL

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

Subtask 49-42-00-410-052-A ** ON A/C NOT FOR ALL

B. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) In the cockpit, in the left lower side of the panel 120VU:

Put the panel (2) in position and tighten the quick release fasteners (1).

(3) Istall the third occupant seat (Ref. AMM TASK 25-11-41-400-001).
(4) Remove the WARNING NOTICE(S).
(5) Close the access door 121AL.
(6) Remove the access platform(s).

[Rev.10 from 2021] 2026.04.01 01:30:25 UTC