Removal of the Core Fire Detectors

TASK 26-12-17-000-040-A
Removal of the Core Fire Detectors

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.

WARNING: BE CAREFUL WHEN YOU USE CONSUMABLE MATERIALS. OBEY THE MATERIAL MANUFACTURER'S INSTRUCTIONS AND YOUR LOCAL REGULATIONS.

FIN: 4001WD1 ** ON A/C NOT FOR ALL
FIN: 4001WD2 ** 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 1M(3 FT)
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
No specific	AR	SCREWDRIVER - PHILLIPS HEAD
No specific	AR	WARNING NOTICE(S)

B. Consumable Materials

REFERENCE	DESIGNATION
(Material No.CP2244)	primer 1200
(Material No.CP2541)	sealant RTV 88
(Material No.14SBA1)	Textile-Lint free Cotton -
No specific	MEK
No specific	MIBK

C. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
FOR [1000EM1] (ENGINE-1)
437AL, 438AR, 451AL, 452AR
FOR [1000EM2] (ENGINE-2)
447AL, 448AR, 461AL, 462AR

D. Referenced Information

REFERENCE	DESIGNATION
TASK 24-42-00-861-001-A	Energize the Ground Service Network from the External Power
TASK 71-13-00-010-040-A	Opening of the Fan Cowl Doors
TASK 78-30-00-481-041-A	Make the Thrust Reverser Unserviceable for Maintenance
TASK 78-36-00-010-040-A	Opening of the Thrust Reverser Doors
Core Fire Detector (4001WD1) - Left Side
Core Fire Detector (4001WD2) - Right Side

3. Job Set-up
Subtask 26-12-17-861-051-A ** ON A/C NOT FOR ALL

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

Subtask 26-12-17-941-052-A ** ON A/C NOT FOR ALL

B. Safety Precautions
(1) On the center pedestal, on the ENG panel 115VU:
(a) Make sure that the ENG/MODE/CRANK/NORM/IGN/START selector switch is in the NORM position.
(b) Put a WARNING NOTICE(S) to tell persons not to start the engine.
(2) Make sure that the engine 1(2) shutdown occurred not less than 5 minutes before you do this procedure.
(3) On the overhead maintenance panel 50VU:
(a) Make sure that the ON legend of the ENG/FADEC GND PWR/1(2) pushbutton switch is off.
(b) Put a WARNING NOTICE(S) to tell persons not to energize the FADEC 1(2).

Subtask 26-12-17-865-053-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
49VU	ENGINE/2/FIRE DET/LOOP B	8WD2	A07
49VU	ENGINE/1/FIRE DET/LOOP A	7WD1	A06
121VU	ENGINE/ENG2/FIRE DET/LOOP A	7WD2	Q39
121VU	ENGINE/ENG1/FIRE DET/LOOP B	8WD1	Q38

Subtask 26-12-17-010-054-A ** ON A/C NOT FOR ALL

D. Get Access
(1) Open the fan cowl doors (Ref. AMM TASK 71-13-00-010-040):
(a) FOR [1000EM1] (ENGINE-1)
437AL 438AR
(b) FOR [1000EM2] (ENGINE-2)
447AL 448AR
(2) Put the ACCESS PLATFORM 1M(3 FT) in position.

Subtask 26-12-17-040-052-A ** ON A/C NOT FOR ALL

E. Make the thrust reverser unserviceable (Ref. AMM TASK 78-30-00-481-041).

Subtask 26-12-17-010-055-A ** ON A/C NOT FOR ALL

F. Open the thrust reverser doors (Ref. AMM TASK 78-36-00-010-040):
(1) FOR [1000EM1] (ENGINE-1)
451AL 452AR
(2) FOR [1000EM2] (ENGINE-2)
461AL 462AR

4. Procedure
Subtask 26-12-17-020-052-A ** ON A/C NOT FOR ALL

CAUTION: REMOVE THE FIRE DETECTORS AND THE RAIL AS ONE ASSSEMBLY. THE FIRE DETECTOR SENSOR ELEMENTS CAN BE DAMAGED IF NOT SUPPORTED BY THE RAIL.

A. Removal of the Core Fire Detectors

NOTE: If it is necessary to replace a clamp (70), refer to steps 4.B.

(1) Disconnect the rail assembly (50) from the engine brackets as follows:

NOTE: Remove the clamps (55) from the mounting brackets (60) before you disconnect the fire detector sensors.

(a) Turn the screw (65) on the center mount clamp (55), then move the clamps out of the brackets (60) (10 locations). Use a SCREWDRIVER - PHILLIPS HEAD.
(2) Remove the wire harness from the LH core loop A fire detector sensor (4001WD1):
(a) Remove the nut (15) from terminal A of the sensor. Remove wire (45) from terminal A.
(b) Remove the nut (20) from terminal B of the sensor. Remove wire (25) from terminal B.

NOTE: After the harness wires are removed, install the nuts on the fire detector terminals. Tighten the nuts with your hand.

(c) Cut the lockwire and remove the screws (5) that attach the harness clamp (10) to the fire detector sensor (40).
(d) Remove the loop A wire harness from the fire detector sensor (40).
(e) Put the harness clamp (10) on the fire detector sensor (40) and attach it with the screws (5).
(3) Remove the LH core loop A fire detector sensor 4001WD1 (40) and the rail assembly (50) from the engine bracket:
(a) Remove the screws (30) and washers (35), 2 locations, that attach the fire detector sensor (40) and rail assembly (50) to the engine bracket.
(b) Remove the fire detector sensor (40) and rail assembly (50) from the engine bracket.
(4) Remove the wire harness from the RH core loop B fire detector sensor (4001WD2):
(a) Remove the nut (15) from terminal A of the sensor. Remove wire (45) from terminal A.
(b) Remove the nut (20) from terminal B of the sensor. Remove wire (25) from terminal B.

NOTE: After the harness wires are removed, install the nuts on the fire detector terminals. Tighten the nuts with your hand.

(c) Cut the lockwire and remove the screws (5) that attach the harness clamp (10) to the fire detector sensor (40).
(d) Remove the loop B wire harness from the fire detector sensor (40).
(e) Put the harness clamp (10) on the fire detector sensor (40) and attach it with the screws (5).
(5) Remove the RH core fire detector sensor 4001WD2 (40) and rail assembly (50) from the engine bracket:
(a) Remove the screws (30) and washers (35), three locations, that attach the fire detector sensor (40) and rail assembly (50) to the engine bracket.
(b) Remove the fire detector sensor (40) and rail assembly (50) from the engine bracket.
(6) Remove the rail assembly and fire detectors from the engine.

Subtask 26-12-17-920-050-A ** ON A/C NOT FOR ALL

B. Replacement of Right or Left Side Core Fire Detector Clamp Assembly
(1) Open the clamp (70) on the two core fire detector elements (75).

CAUTION: MAKE SURE NOT TO BEND OR KINK THE FIRE DETECTOR ELEMENTS (75). DAMAGE TO THE ELEMENTS CAN MAKE THE FIRE DETECTION SYSTEM NOT WORK.

(2) Remove the clamp (70) from the two core fire detector elements (75) and from the core fire detector rail assembly (50).

NOTE: Steps 4.B(3) through 4.B (7) will prevent the clamp(s) (70) from turning on the rail assembly (50).

(3) Lightly abrade the rail assembly (50) and clamp (70) in the area where the clamp attaches to the rail assembly with 400-grit abrasive paper or cloth.

WARNING: BE CAREFUL WHEN YOU USE CONSUMABLE MATERIALS. OBEY THE MATERIAL MANUFACTURER'S INSTRUCTIONS AND YOUR LOCAL REGULATIONS.

(4) Wipe clean the rail assembly (50) and clamp (70) in the area where the clamp attaches to the rail assembly with a cloth made moist with MEK/MIBK blend (40 percent MEK, 60 percent MIBK).
(5) Dry the surfaces with a clean Textile-Lint free Cotton - (Material No.14SBA1) before the solvent becomes gas.
(6) Apply one coat of primer 1200 (Material No.CP2244) to the cleaned area of the rail assembly (50) and let dry.
(7) Prepare and apply one coat of sealant RTV 88 (Material No.CP2541) over the dry coat of DC1200 primer per the manufacturers instructions.
(8) Put clamp (70) on the two core fire detector elements (75) and the rail assembly (50) and close the clamp (70).

[Rev.10 from 2021] 2026.03.31 23:42:58 UTC