02/16/21
Message Overview:
Message Description:
No L-AHC-1 data received at L-IOC but is not reported failed by the TTR-A channel or SVC.
Possible Causes:
- Left Input/Output Concentrator Unit (IOC 1) (A4-IOC)
- Junction Box 1 (JB 1)
- Integrated-Avionics Processor System (IAPS) Card Cage (ICC) (A4)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
Quick Links:
| Removal of the Junction Boxes | AMM 24-63-01-000-802 |
| Installation of the Junction Boxes | AMM 24-63-01-400-802 |
| Removal of the Integrated Avionics Processor System (IAPS) Card Cage (ICC) | AMM 31-45-01-000-801 |
| Installation of the Integrated Avionics Processor System (IAPS) Card Cage (ICC) | AMM 31-45-01-400-801 |
| Removal of the Input/Output Concentrator Unit (IOC) | AMM 31-45-05-000-801 |
| Installation of the Input/Output Concentrator Unit (IOC) | AMM 31-45-05-400-801 |
| Removal of the Attitude Heading Computer (AHC) | AMM 34-21-01-000-801 |
| Installation of the Attitude Heading Computer (AHC) | AMM 34-21-01-400-801 |
| Standard Practices - Replace Wiring | SPM 20-12-00-02 |
| Standard Practices - Wire Repair | SPM 20-12-10-02 |
Troubleshooting Recommendations:
- Reset L IAPS (CB1-B6) circuit breaker.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Swap IOCs.
- If system check passes, do close out.
- If fault remains, continue with next step.
- Do a wiring check of the ARINC 429 data bus L-AHC-1 from IAPS connector A4P1, through Junction Box 1, to AHC 1 connector A11P1. Repair/replace as required.
- If system check passes, do close out.
- If fault remains, continue with next step.
- Replace ICC.
- Do close out.