04/19/21
Message Overview:
Message Description:
Left engine N1 compensator fault 1A.
[MCID 0505]
N1 Compensator 1A.
Detection of a fault in the N1 compensator harness between the N1 compensator and the electronic control unit (ECU) A. The ECU A cannot support full system operation.
Possible Causes:
- N1 Compensator
- Wiring Harness (W6)
- Full Authority Digital Engine Control (FADEC) Electronic Control Unit A (ECU) (A41)
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
- If the L or R ENGINE MINOR FAULT CAS message is shown with this fault, this is a Short Term dispatch (STD) fault and is subject to correction outlined in the Honeywell LEMM SUBTASK 5-10-00-200-003.
- If a L or R FADEC FAIL CAS message is shown, this is a No Dispatch (ND) fault and is subject to correction outlined in the Honeywell LEMM SUBTASK 5-10-00-200-003.
- Check for the following MDC messages displayed with the fault: X-channel bus 1A (MCID 0905), X-channel bus 1B (MCID 0906), X-channel discrete 1A (MCID 0933), X-channel discrete 1B (MCID 0934). If any of the above MCID codes are posted, correct the cross channel faults first.
Quick Links:
| Removal of the Engine Electronic Control Unit (ECU) | AMM 76-10-05-000-801 |
| Installation of the Engine Electronic Control Unit (ECU) | AMM 76-10-05-400-801 |
| Wiring - Maintenance Practices - ALL | SPM 20-12-00-02 |
| Wire Repair - Maintenance Practices - ALL | SPM 20-12-10-02 |
| Electrical Connectors - Maintenance Practice - ALL | SPM 20-20-00-02 |
Troubleshooting Recommendations:
- MCID 0505 fault only is present, troubleshoot using the following steps for aircraft and engine fault isolation with reference to the Light Engine Maintenance Manual TASK 72-00-00-810-070.
- Reset and reboot the ECU to recheck the MDC MCID for the posted fault.
- Remove the connector on the N1 monopole W6P6, inspect for damaged pins/sockets, then check the following segments per the table, repair wiring if required per the wiring manual standard practices.
From To Value W6P6 Pin A W6P6 Pin B 2.5 to 15 kΩ If good, check at the ECUs W6P2 Pin 25 W6P2 Pin 36 2.5 to 15 kΩ - If the resistance values fail at the N1 compensator, replace IAW Honeywell LEMM TASK 77-10-03-050-801. If the resistance values check good at the sensor and not at the ECU, suspect the W6 or W4 wiring harness, isolate by ringing individual wires and replace per the Honeywell LEMM TASK 76-10-01-050-801.
- If the wiring and compensator check good, consider swapping or replacing the A channel ECUs for the left engine, remove and replace IAW AMM TASK 76-10-05-000-801, TASK 76-10-05-400-801 then recheck the system for the fault.
