02/24/21
Message Overview:
Message Description:
L-RIU-11 bus absent at L-IOC and L-CDU and L-FMC 6200. L-RIU-12 bus is present at R-IOC.
Possible Causes:
- Left Radio Interface Unit (RIU 1) (A17)
- Junction Box (JB1)
- Connector Plug 2000
- Left Control Display Unit (CDU)
- Left Input/Output Concentrator Unit (IOC) (A4-IOC1)
- Left Flight Management Computer (FMC) (A4-FMC1)
- Left File Server Unit (FSU) (A221)
- 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 Radio Interface Unit (RIU) | AMM 23-51-21-000-801 |
| Installation of the Radio Interface Unit (RIU) | AMM 23-51-21-400-801 |
| Removal of the Junction Box 1 | AMM 24-63-01-000-802 |
| Installation of the Junction Box 1 | 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 Flight Management Computer (FMC) | AMM 34-61-01-000-801 |
| Installation of the Flight Management Computer (FMC) | AMM 34-61-01-400-801 |
| Removal of the Control Display Unit (CDU) | AMM 34-61-05-000-801 |
| Installation of the Control Display Unit (CDU) | AMM 34-61-05-400-801 |
| Removal of the File Server Unit (FSU) | AMM 46-21-01-000-801 |
| Installation of the File Server Unit (FSU) | AMM 46-21-01-400-801 |
| Standard Practices - Replace Wiring | SPM 20-12-00-02 |
| Standard Practices - Wire Repair | SPM 20-12-10-02 |
Troubleshooting Recommendations:
- Reset RIU 1A (CB1-B5) and RIU 1B/AURAL (CB1-B4) circuit breaker.
- If system check passes, do close out.
- If fault remains, continue with next step.
- Do the wiring check of the ARINC 429 data bus L-RIU-11 between RIU 1 connector A17P2, through Junction Box 1, to the left CDU connector A69P1, left FSU connector A221P1 and to the IAPS connectors A4P3 (L FMC input) & A4P1 (L-IOC input). Repair/replace as required.
- If system check passes, do close out.
- If fault remains, continue with next step.
NOTE: An internal short of any LRUs connected to this data bus might cause this failure.
- Swap FMCs.
- If system check passes, 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.
- Swap CDUs.
- If system check passes, do close out.
- If fault remains, continue with next step.
- Swap FSUs.
- If system check passes, do close out.
- If fault remains, continue with next step.
- Replace the left RIU.
- If system check passes, do close out.
- If fault remains, continue with next step.
- Replace ICC.
- Do close out.