03/30/21
Message Overview:
Message Description:
R-FMC-3 data bus is not received at R-CDU.
Possible Causes:
- Right Flight Management Computer 2 (FMC) (A4-FMC)
- Right Control Display Unit 2 (CDU) (A68)
- 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 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 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 |
| Standard Practices - Replace Wiring | SPM 20-12-00-02 |
| Standard Practices - Repair Wiring | SPM 20-12-10-02 |
Troubleshooting Recommendations:
- Reset R IAPS circuit breaker CB2-B6 and CDU 2 circuit breaker CB2-A4. Is the fault message still present?
- If YES, continue with next step.
- If NO, do close out.
- Do wiring check between IAPS (A4) and CDU 2 (A68) for the following wires:
From To Result Conn. A4P101 - 29 Conn. A68P1 - 61 Conn. A4P101 - 28 Conn. A68P1 - 62 - If the check is satisfactory, continue with next step.
- If the check is not satisfactory, repair defective wire.
- Swap FMC 2 with FMC 1. Is the fault message still present\?
- If YES, continue with next step.
- If NO, replace defective FMC.
- Swap CDU 2 (A68) with CDU 1 (A69). Is the fault message still present\?
- If YES, continue with next step.
- If NO, replace defective CDU.
- Replace IAPS Card Cage (A4).
- Do close out.