04/09/21
Message Overview:
Message Description:
Right engine TT2 heater current sense fault 1B.
[MCID 0804]
TT2 Heat Current Sense 1B.
Detection of a fault in the TT2 current sense wiring between the TT2 current sense relay and the ECU B. The ECU B cannot support full system operation.
Possible Causes:
- TT2 Current Sense Wiring
- Wiring Harness (W1) (RH engine)
- TT2 Current Sense Relay in the Aircraft DC Power Center (DCPC)
- Full Authority Digital Engine Control Unit (FADEC) Electronic Control Unit B (ECU) (A43)
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 72-05-12 SUB TASK 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 72-05-12 SUB TASK 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:
| Component Location | AMM 24-61-00-992-801 |
| Removal of the DC Power Center (DCPC) | AMM 24-61-01-000-801 |
| Installation of the DC Power Center (DCPC) | AMM 24-61-01-400-801 |
| Functional Test of the DC Power Center (DCPC) | AMM 24-61-01-720-801 |
| Operational Test of the Nacelle Anti-Ice System | AMM 30-21-00-710-801 |
| General Visual Inspection of the Engine Wiring Harness | AMM 71-50-00-210-802 |
| Removal of the FADEC Electrical Harness from the Right Engine | AMM 71-50-05-000-803 |
| Installation of the FADEC Electrical Harness on the Right Engine | AMM 71-50-05-400-803 |
| 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 802 fault only is present, troubleshoot using the following steps for aircraft and engine fault isolation with reference to the Honeywell LEMM 72-05-12 TASK 72-00-00-810-110.
- Check & verify the system operation IAW AMM TASK 30-21-00-710-801, look for the system fault by viewing the ANTI-ICE synoptic page looking for the amber T2 fault and verify current faults in the MDC and see if B3-304644 has posted again. If the fault still exists, continue, otherwise closeout.
- If MCID is listing both 801 ECU A fault, and 802 ECU B faults refer to Operator Information Wire AS900-2006-OIW-14. Replace the TT2 connector IAW the LEMM.
- Gain access to the following connectors, inspect for damage, then check the following segments per the table, repair wiring if required per the wiring manual standard practices:
From To Value W6P2 Pin 3 W6P2 Pin 5 50 to 150 Ω W6P7 Pin 1 W6P7 Pin 2 50 to 150 Ω - If no discrepancy is noted, suspect the Electronic Control Unit, remove and replace IAW AMM TASK 76-10-05-000-801, TASK 76-10-05-400-801.
