Removal of the Core Engine Fire Detection Elements with the Rail

TASK 26-12-17-000-805-A
Removal of the Core Engine Fire Detection Elements with the Rail

WARNING: BE CAREFUL WHEN YOU DO WORK ON THE ENGINE PARTS AFTER THE ENGINE SHUTDOWN. USE APPLICABLE THERMAL GLOVES. THE ENGINE PARTS CAN STAY HOT FOR ONE HOUR AFTER SHUTDOWN AND CAN BURN YOU.

ZONE: 450
ZONE: 460
FIN: 4001WD1
FIN: 4001WD2

1. Reason for the Job
Two persons are necessary to do this task
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
450	ENG 1 THRUST REVERSER & EXHAUST SECTION
460	ENG 2 THRUST REVERSER & EXHAUST SECTION
FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
437AL, 438AR, 451AL, 452AR
FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 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 71-13-00-010-803-A	Opening of the Fan Cowl Doors
TASK 78-30-00-040-807-A	Deactivation of the Thrust Reverser System for Nacelle Maintenance (ICU)
TASK 78-36-00-010-806-A	Opening of the Thrust Reverser Cowl Doors
Core Engine Fire Detection Elements with the Rail

3. Job Set-up
Subtask 26-12-17-861-069-A

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

Subtask 26-12-17-941-065-A

B. Safety Precautions
(1) On the center pedestal, on ENG panel 115VU:
(a) Make sure that the ENG/MODE selector switch is in the NORM position.
(b) Make sure that the ENG/MASTER 1(2) control switch was in the OFF position not less than five minutes before you do this procedure.
(c) Put WARNING NOTICE(S) in position to tell persons not to operate the ENG/MODE selector switch and the ENG/MASTER 1(2) control switch.
(2) On the ENG section of maintenance panel 50VU:
(a) Make sure that the ON legend of the FADEC GND PWR/1(2) pushbutton switch is off.
(b) Put a WARNING NOTICE(S) in position to tell persons not to energize FADEC 1(2).

Subtask 26-12-17-865-078-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
FOR FIN: 4020KM1 (POWER PLANTDEMOUNTABLE, ENGINE 1)
49VU	ENGINE/1/FIRE DET/LOOP A	7WD1	A06
121VU	ENGINE/ENG1/FIRE DET/LOOP B	8WD1	Q38
FOR FIN: 4020KM2 (POWER PLANTDEMOUNTABLE, ENGINE 2)
49VU	ENGINE/2/FIRE DET/LOOP B	8WD2	A07
121VU	ENGINE/ENG2/FIRE DET/LOOP A	7WD2	Q39

Subtask 26-12-17-010-090-A

D. Get Access
(1) Open the fan cowl doors (Ref. AMM TASK 71-13-00-010-803):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
437AL 438AR
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
447AL 448AR

Subtask 26-12-17-040-070-A

E. Deactivation of the Thrust Reverser System for 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 maintenance (Ref. AMM TASK 78-30-00-040-807).

Subtask 26-12-17-010-091-A

F. Open the thrust reverser cowl-doors (Ref. AMM TASK 78-36-00-010-806):
(1) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
451AL 452AR
(2) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
461AL 462AR
(3) Put an ACCESS PLATFORM 1M (3 FT)-ADJUSTABLE in position.

4. Procedure
Subtask 26-12-17-020-066-A

A. Removal of the Core Engine Fire Detection Elements with the Rail
(1) On the left side of the engine, disconnect the harness (1) from the left fire detection element rail (3) as follows:
(a) Remove the screw (27) and retainer (26) that attach the harness (1) to the responder (2).
(b) Remove the two nuts (24) and (25) that attach the ring connectors on the harness (1) to the studs on the responder (2).
(c) Lift the harness (1) away from the left fire detection element rail (3).
(2) On the right side of the engine, disconnect the harness (1) from the right fire detection element rail (22) as follows:
(a) Remove the screw (27) and retainer (26) that attach the harness (1) to the responder (2).
(b) Remove the two nuts (24) and (25) that attach the ring connectors on the harness (1) to the studs on the responder (2).
(c) Lift the harness (1) away from the right fire detection element rail (22).
(3) Loosen (but do not remove) the nut (18) and bolt (17) that connect the left and right fire detection element rails (3) and (22).

NOTE: This connection is a joint that moves to permit removal of the left and right halves from the engine.

(4) Remove the 15 bolts (6) from the loop clamps (5) that attach the left and right rails (3) and (22) to the engine brackets (4), (7), (8), (9), (10), (11), (12), (13), (14), (15), (16), (19), (20), (21) and (23) as follows:
(a) Remove the lower 13 bolts (6) but keep the highest bolt (6) installed on the right side and the left side of the engine.
(b) While one mechanic holds the right fire detection element rail (22), remove the upper bolt (6) on the right side of the engine.
(c) While a second mechanic holds the left fire detection element rail (3), remove the upper bolt (6) on the left side of the engine.
(5) Very carefully pull the two upper ends of the fire detection element rails (3) and (22) away from the engine. The joint between the left and right fire detection element rails (3) and (22) moves to permit removal of the assembly.
(6) Carefully remove the left and right fire detection element rails (3) and (22) from the engine.

NOTE: During removal of the left fire detection element rail, a potential clash exists between the rail and an EBU duct. It may be necessary for a mechanic to clamp the duct by hand to prevent the clash.

(7) Make a record of the position of the 15 loop clamps (5) on the left and right fire detection element rails (3) and (22). This record will help to put the loop clamps in the correct position during the installation.

[Rev.10 from 2021] 2026.03.31 23:43:19 UTC