03/23/21
Message Overview:
Message Description:
Left MFD data bus (L-MFD-3) is reported failed by 2 of the following: right MFD, right PFD, left PFD and right RIU.
Possible Causes:
- Adaptive Flight-Display Unit 'A429 output' (L MFD) (A29)
- Adaptive Flight-Display Unit 'A429 input' (R PFD) (A26)
- Adaptive Flight-Display Unit 'A429 input' (R MFD) (A28)
- Adaptive Flight-Display Unit 'A429 input' (L PFD) (A27)
- Right Radio Interface Unit (RIU 2) (A18)
- Junction Box 1 (JB 1)
- 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 JB1 | AMM 24-63-01-000-802 |
| Installation of the Junction Box JB1 | AMM 24-63-01-400-802 |
| Removal of the Adaptive Flight-Display Unit | AMM 31-61-01-000-801 |
| Installation of the Adaptive Flight-Display Unit | AMM 31-61-01-400-801 |
| 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:
- Reset L PFD Circuit Breaker CB1-C3, L MFD Circuit Breaker CB1-C5, R PFD Circuit Breaker CB2-C3, R MFD Circuit Breaker CB2-C5, RIU 2A Circuit Breaker CB2-B4 and RIU 2B/AURAL Circuit Breaker CB2-B5. Is the fault message still present?
- If NO, do close out.
- If YES, continue with next step.
- Swap L MFD (A29) with R MFD (A28). Is the fault message still present?
- If NO, do close out.
- If YES, continue with next step.
- Do wiring check between L MFD, through JB1, and the 3 others Adaptive Flight-Display Units and the RIU 2 for the following wires:
From To Results Conn A29P2 - 94 Conn A27P2 - 26 Conn A29P2 - 95 Conn A27P2 - 27 Conn A29P2 - 94 Conn. A26P1 - 70 Conn A29P2 - 95 Conn. A26P1 - 71 Conn A29P2 - 94 Conn. A28P1 - 70 Conn A29P2 - 95 Conn. A28P1 - 71 Conn A29P2 - 94 Conn. A18P2 - 59 Conn A29P2 - 95 Conn. A18P2 - 60 - If the check is not satisfactory, repair defective wiring or replace defective JB1.
- If the check if satisfactory, continue with next step.
- Disconnect R PFD (A26). Is the fault message still present?
- If NO, replace defective R PFD (A26).
- If YES, reconnect R PFD and continue with next step.
- Disconnect R MFD (A28). Is the fault message still present?
- If NO, replace defective R MFD (A28).
- If YES, reconnect R MFD and continue with next step.
- Disconnect L PFD (A27). Is the fault message still present?
- If NO, replace defective L PFD (A27).
- If YES, reconnect L MFD and continue with next step.
- Disconnect RIU 2 (A18). Is the fault message still present?
- If NO, replace defective RIU 2 (A18).
- If YES, reconnect RIU 2 and continue with next step.
- Do close out.