Route Ignition Leads to Opposite Ignition Exciters [CFMI]

TASK 74-31-00-040-004-A
Route Ignition Leads to Opposite Ignition Exciters

WARNING: BEFORE YOU START WORK ON THE IGNITION SYSTEM, MAKE SURE THAT THE IGNITION EXCITERS ARE DE-ENERGIZED FOR A MINIMUM OF FIVE MINUTES. ALSO DO NOT TOUCH THE ELECTRICAL CONTACTS. THE IGNITION SYSTEM VOLTAGE IS VERY HIGH, AND THE IGNITION EXCITERS CAN HAVE AN ELECTRICAL CHARGE EVEN WHEN NOT ENERGIZED. IF YOU DO NOT OBEY THESE PRECAUTIONS, INJURY CAN OCCUR.

CAUTION: BE CAREFUL WITH THE IGNITION LEAD TO PREVENT DAMAGE TO THE CONDUIT AND THE INTERNAL WIRES.

FIN: 1000EM1 ** ON A/C NOT FOR ALL
FIN: 1000EM2 ** ON A/C NOT FOR ALL

1. Reason for the Job
MMEL 74-31-01A
IGNITION SYSTEM A (FAA ONLY)
left ignition lead on aircraft battery bus. MMEL743101
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	AR	ACCESS PLATFORM 1M(3 FT)
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
No specific	AR	WARNING NOTICE(S)
No specific	Torque wrench: range to between 160 and 140 lbf.in (1.81 and 1.58 m.daN )

B. 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

C. Referenced Information

REFERENCE	DESIGNATION
TASK 71-13-00-010-040-A	Opening of the Fan Cowl Doors
TASK 71-13-00-410-040-A	Closing of the Fan Cowl Doors
TASK 74-00-00-710-040-A	Operational Test of the Ignition System
TASK 74-00-00-710-040-A-01	Operational Test of the Ignition System without CFDS
TASK 78-30-00-081-041-A	Make the Thrust Reverser Serviceable after Maintenance
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
TASK 78-36-00-410-040-A	Closing of the Thrust Reverser Doors
Ignition Lead Routing
Ignition Lead Routing

3. Job Set-up
Subtask 74-31-00-941-053-A ** ON A/C NOT FOR ALL

A. Safety Precautions
(1) On the center pedestal, on the ENG panel 115VU:
(a) 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 74-31-00-865-057-A ** ON A/C NOT FOR ALL

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
49VU	ENGINE/1 AND 2/IGN/SYS A	1JH	A03
FOR FIN: 1000EM1 (ENGINE1)
121VU	ENGINE/IGN/ENG1/SYS B	3JH1	P41
121VU	ENGINE/IGN/ENG1/SYS A BAT	2JH1	P39
FOR FIN: 1000EM2 (ENGINE2)
121VU	ENGINE/IGN/ENG2/SYS B	3JH2	P42
121VU	ENGINE/IGN/ENG2/SYS A BAT	2JH2	P40

Subtask 74-31-00-010-050-A ** ON A/C NOT FOR ALL

C. 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 74-31-00-040-050-A ** ON A/C NOT FOR ALL

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

Subtask 74-31-00-010-051-A ** ON A/C NOT FOR ALL

E. 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 74-31-00-020-050-A ** ON A/C NOT FOR ALL

A. Disconnection of the Ignition Leads
(1) Disconnect the ignition leads from the aft side of the ignition exciters on the fan inlet case.
(2) Remove the ignition leads from the clamps between the ignition exciters and junction box bundle.
(3) Install the leads in opposite clamps and connect to ignition exciters.
(4) Make sure the left lead is not under tension at the ignition exciter. Adjust the lead routing to prevent tension.
(5) TORQUE the ignition lead connectors to between 160 and 140 lbf.in (1.81 and 1.58 m.daN )

Subtask 74-31-00-865-058-A ** ON A/C NOT FOR ALL

B. Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
49VU	ENGINE/1 AND 2/IGN/SYS A	1JH	A03
FOR FIN: 1000EM1 (ENGINE1)
121VU	ENGINE/IGN/ENG1/SYS B	3JH1	P41
121VU	ENGINE/IGN/ENG1/SYS A BAT	2JH1	P39
FOR FIN: 1000EM2 (ENGINE2)
121VU	ENGINE/IGN/ENG2/SYS B	3JH2	P42
121VU	ENGINE/IGN/ENG2/SYS A BAT	2JH2	P40

Subtask 74-31-00-710-053-A ** ON A/C NOT FOR ALL

C. Do an operational test of the ignition system (Ref. AMM TASK 74-00-00-710-040).

5. Close-up
Subtask 74-31-00-410-050-A ** ON A/C NOT FOR ALL

A. Close access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Close the thrust reverser doors: (Ref. AMM TASK 78-36-00-410-040)
(a) FOR [1000EM1] (ENGINE-1)
451AL 452AR
(b) FOR [1000EM2] (ENGINE-2)
461AL 462AR

Subtask 74-31-00-440-053-A ** ON A/C NOT FOR ALL

B. Make the thrust reverser serviceable (Ref. AMM TASK 78-30-00-081-041).

Subtask 74-31-00-410-051-A ** ON A/C NOT FOR ALL

C. Close Access
(1) Close the fan cowl doors: (Ref. AMM TASK 71-13-00-410-040)
(a) FOR [1000EM1] (ENGINE-1)
437AL 438AR
(b) FOR [1000EM2] (ENGINE-2)
447AL 448AR
(2) Remove the access platform(s).
(3) Remove the WARNING NOTICE(S).
(4) Make an entry in the logbook.
(5) Put a WARNING NOTICE(S) to tell persons that the ignition leads are routed to opposite ignition exciters to allow dispatch with the left ignition lead on aircraft battery bus.

[Rev.10 from 2021] 2026.04.01 03:07:17 UTC