N1 Indication Disagreement between DMC and FWC on Engine 1

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1. Possible Causes
· DMC-1 ( 1WT1 )
· DMC-2 ( 1WT2 )
· DMC-3 ( 1WT3 )
· FWC-1 ( 1WW1 )
· FWC-2 ( 1WW2 )
· EEC ( 4000KS )
2 Job Set-up Information
A. Referenced Information
REFERENCE DESIGNATION
77-00-00-810-801-A Failure of the N1 Sensor on Engine 1
Ref. AMM 31-53-34-000-001 Removal of the Flight Warning Computer (FWC)
Ref. AMM 31-53-34-400-001 Installation of the Flight Warning Computer (FWC)
Ref. AMM 31-63-34-000-001 Removal of the DMC
Ref. AMM 31-63-34-400-001 Installation of the DMC
Ref. AMM 71-00-00-710-012 Test No.3 : Idle Leak Check
Ref. AMM 71-00-00-710-018 Discontinued Start, Restart and Shutdown Procedures
Ref. AMM 71-00-00-710-043 Normal Engine Automatic Start Procedure
Ref. AMM 71-00-00-710-047 Normal Engine Manual Start Procedure
Ref. AMM 73-22-34-000-010 Removal of the Electronic Engine Control (EEC)
Ref. AMM 73-22-34-400-010 Installation of the Electronic Engine Control (EEC)
3. Fault Confirmation
Subtask 77-00-00-710-175-A
A. Test
(1) On the panel 50VU, push the ENG FADEC GND PWR 1 pushbutton switch and release it again.
NOTE: This action resets the FADEC memory.
(2) Adjust the brightness of the MCDU screen.
(3) Push the INIT mode key. The INIT page comes into view.
(4) Enter a new flight number.
(5) Start the engine 1 by the normal engine automatic start procedure Ref. AMM 71-00-00-710-043 or
the normal engine manual start procedure Ref. AMM 71-00-00-710-047 .
NOTE: You must operate the engine for a minimum of three minutes. If not, the LAST LEG REPORT
will not be erased and the fault will not be kept again in the EEC LAST LEG REPORT.
(6) Do a shutdown of the engine 1 by the discontinued start, restart and shutdown procedure Ref.
AMM 71-00-00-710-018 .
(7) Read the LAST LEG REPORT and the scheduled maintenance report of the FADEC (1A and 1B)
menu on the MCDU (Ref. 70-00-00 Page Block 301 Task. Supporting Data)
(a) Make a record of the maintenance message.
(b) Make a record of the channel FADEC 1A or FADEC 1B which found the fault.
(8) Fully decrease the brightness of the MCDU screen (display off).
4. Fault Isolation
Subtask 77-00-00-810-137-A
A. If the fault symptom is identified by the ECAM warning ENG1 N1 DISCREPANCY:
(1) If the test gives the maintenance message N1 SENS/HC/EEC1 or the fault acronyms N1L or N1XCF:
· Do the procedure failure of the N1 sensor on engine 1 (Ref. TSM 77-00-00-810-801) .
(2) If the fault continues:
· Replace the DMC-1 ( 1WT1 ) , Ref. AMM 31-63-34-000-001 and Ref. AMM 31-63-34-400-001 .
(3) If the fault continues:
· Replace the DMC-2 ( 1WT2 ) , Ref. AMM 31-63-34-000-001 and Ref. AMM 31-63-34-400-001 .
(4) If the fault continues:
· Replace the DMC-3 ( 1WT3 ) , Ref. AMM 31-63-34-000-001 and Ref. AMM 31-63-34-400-001 .
(5) If the fault continues:
· Replace the FWC-1 ( 1WW1 ) , Ref. AMM 31-53-34-000-001 and Ref. AMM 31-53-34-400-001 .
(6) If the fault continues:
· replace the FWC-2 ( 1WW2 ) , Ref. AMM 31-53-34-000-001 and Ref. AMM 31-53-34-400-001 .
(7) If the fault continues:
· replace the EEC ( 4000KS ) , Ref. AMM 73-22-34-000-010 and Ref. AMM 73-22-34-400-010 .
Subtask 77-00-00-710-176-A
B. Test
(1) Do a minimum idle check to make sure that all engine instruments give the correct indication Ref.
AMM 71-00-00-710-012 . [Rev.6 from Feb 2017] 2026.04.04 04:37:49 UTC