Removal of the Loop-B Fire Harness

TASK 26-12-62-000-802-A
Removal of the Loop-B Fire Harness

WARNING: BE CAREFUL WHEN YOU DO WORK ON THE ENGINE AFTER SHUTDOWN. THE ENGINE CAN STAY HOT FOR A LONG TIME. IF YOU DO NOT OBEY THIS INSTRUCTION, INJURY CAN OCCUR.

WARNING: WEAR APPLICABLE PERSONAL PROTECTIVE EQUIPMENT (PPE) WHEN YOU DO THIS TASK. BEFORE YOU USE PPE, READ, UNDERSTAND AND OBEY ALL INSTRUCTIONS FOR ITS USE. THESE INSTRUCTIONS INCLUDE INSTRUCTIONS FROM THE MANUFACTURER, YOUR EMPLOYER AND GOVERNMENT REGULATIONS. YOU CAN GET INJURED IF YOU DO NOT USE PPE. GET INSTRUCTIONS FROM YOUR EMPLOYER ON WHICH PPE IS NECESSARY.

ZONE: 450
ZONE: 460
FIN: 4166KS ** 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 2M (6 FT) - ADJUSTABLE
No specific	AR	CAP - PROTECTION
No specific	AR	COVER - PROTECTION
No specific	1	PLIERS - CONNECTOR, JAW, SOFT
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
450	ENG 1 THRUST REVERSER & EXHAUST SECTION
460	ENG 2 THRUST REVERSER & EXHAUST SECTION
FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1)
437AL, 438AR, 451AL, 452AR
FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
447AL, 448AR, 461AL, 462AR

C. Referenced Information

REFERENCE	DESIGNATION
TASK 24-42-00-861-001-A	Energize the Ground Service Network from the External Power
TASK 71-00-00-860-833-A	Procedure to Prevent Engine Motoring
TASK 71-13-00-010-802-A	Opening of the Fan Cowl Doors
TASK 78-30-00-040-805-A	Deactivation of the Thrust Reverser System for Ground Maintenance
TASK 78-36-00-010-802-A	Opening of the Thrust Reverser Cowl-Doors
Loop-B Fire Harness

3. Job Set-up
Subtask 26-12-62-861-050-A ** ON A/C NOT FOR ALL

A. Energize the ground service network (Ref. AMM TASK 24-42-00-861-001).

Subtask 26-12-62-941-052-A ** ON A/C NOT FOR ALL

B. Safety Precautions
(1) Do the procedure to prevent engine motoring
(Ref. AMM TASK 71-00-00-860-833).

Subtask 26-12-62-865-053-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
FOR FIN: 4020KM1 (POWER PLANTDEMOUNTABLE, ENG 1)
49VU	ENGINE/1/FIRE DET/LOOP A	7WD1	A06
121VU	ENGINE/ENG1/FIRE DET/LOOP B	8WD1	Q38
FOR FIN: 4020KM2 (POWER PLANTDEMOUNTABLE, ENG 2)
49VU	ENGINE/2/FIRE DET/LOOP B	8WD2	A07
121VU	ENGINE/ENG2/FIRE DET/LOOP A	7WD2	Q39

Subtask 26-12-62-010-054-A ** ON A/C NOT FOR ALL

D. Get Access
(1) Open the fan cowl doors (Ref. AMM TASK 71-13-00-010-802):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1)
437AL 438AR
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
447AL 448AR

Subtask 26-12-62-040-052-A ** ON A/C NOT FOR ALL

E. Deactivation of the Thrust Reverser for Ground Maintenance

WARNING: YOU MUST DEACTIVATE THE THRUST REVERSER BEFORE YOU DO WORK ON OR AROUND IT. IF YOU DO NOT, THE THRUST REVERSER CAN OPERATE ACCIDENTALLY AND CAUSE AN INJURY AND/OR DAMAGE.

(1) Do the deactivation of the thrust reverser system for ground maintenance (Ref. AMM TASK 78-30-00-040-805).

Subtask 26-12-62-010-055-A ** ON A/C NOT FOR ALL

F. Get Access
(1) Open the thrust reverser cowl-doors (Ref. AMM TASK 78-36-00-010-802):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1)
451AL 452AR
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
461AL 462AR
(2) Put an ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE in position.

4. Procedure
Subtask 26-12-62-020-051-A ** ON A/C NOT FOR ALL

A. Removal of the Loop-B Fire Harness

CAUTION: MAKE SURE THAT THE ELECTRICAL CONNECTORS ARE CLEAN BEFORE YOU DISCONNECT OR CONNECT THEM. CONTAMINATION ON THE ELECTRICAL CONNECTORS CAN CAUSE DAMAGE TO EQUIPMENT.

CAUTION: USE TEFLON-JAWED PLIERS TO CONNECT ELECTRICAL CONNECTORS. DO NOT USE METAL-JAWED PLIERS. DAMAGE TO THE ELECTRICAL CONNECTORS COULD OCCUR.

CAUTION: WIPE CLEAN ALL PARTS AND TOOLS AS NECESSARY TO REMOVE UNWANTED DEBRIS AND PREVENT DAMAGE TO THE ENGINE.

CAUTION: REMOVE THE PROTECTION COVERS FROM THE OPENINGS AS NECESSARY TO PREVENT ENGINE DAMAGE.

(1) Removal of the electrical connector
(a) Use PLIERS - CONNECTOR, JAW, SOFT to disconnect the Loop-B fire harness (1) connector (454VC-A) from the pylon interface.
(b) Put CAP - PROTECTION on the Loop-B fire harness (1) connector and the pylon interface.
(2) Remove the nuts (2) and (5) from the aft overheat fire detector element.
(3) Disconnect the Loop-B fire harness (1) STUD C lug (4001WD2C) and the STUD A lug (4001WD2A) from the aft overheat fire detector element.
(4) Remove the screw (3) and washer (4) that attach the ground lug of the Loop-B fire harness (1) to the aft overheat fire detector element.
(5) Remove the nuts (23) and (24) from the forward fire/overheat detector element.
(6) Disconnect the Loop-B fire harness (1) STUD A lug (4002WD2A) and the STUD C lug (4002WD2C) (1) from the forward fire/overheat detector element.
(7) Remove the screw (21) and washer (22) that attach the ground lug of the Loop-B fire harness (1) to the forward fire/overheat detector element.
(8) Remove the bolt (6) and washer (7) that attach the clamp (8) and the Loop-B fire harness (1) to the heatshield electrical bracket and the aft overheat fire detector bracket.
(a) Remove the clamp (8) from the Loop-B fire harness (1).
(9) Remove the bolt (25), two washers (26) and nut (29) that attach together the clamps (28) and (27) on the Loop-B fire harness (1) and the IDG-EDP-MON harness.
(10) Remove the clamps (28) and (27) from the harnesses.
(11) Remove the bolts (9) and (12) and washers (10) and (13) that attach the clamps (11) and (14) and the Loop-B fire harness (1) to the heatshield electrical bracket assembly.
(a) Remove the clamps (11) and (14) from the Loop-B fire harness (1).
(12) Remove the three bolts (15) and washers (16) that attach the three clamps (17) and the Loop-B fire harness (1) to the fuel return support bracket assemblies.
(a) Remove the clamps (17) from the Loop-B fire harness (1).
(13) Remove the bolt (18) and washer (19) that attach the clamp (20) and the Loop-B fire harness (1) to the PW support bracket.
(a) Remove the clamp (20) from the Loop-B fire harness (1).
(14) Remove the Loop-B fire harness (1) from the spring clip on the heatshield electrical bracket assembly.
(15) Remove the Loop-B fire harness (1) from the spring clip on the PW support bracket.
(16) Remove the Loop-B fire harness (1) from the engine.
(17) Installation of protection covers

CAUTION: INSTALL PROTECTION COVERS ON ALL THE OPENINGS IMMEDIATELY TO PREVENT DAMAGE TO THE ENGINE.

(a) Make sure that you install COVER - PROTECTION as necessary to prevent damage to the engine.

[Rev.10 from 2021] 2026.04.01 06:39:08 UTC