04/02/21
Message Overview:
Message Description:
L-CDU-6 data absent at L-NAV(ADF/VIR) while 2 of the following LRUs receives it: L-IOC, L-DME, L-VHF.
Possible Causes:
- Left VHF NAV (NAV 1) (A47)
- Junction Box (JB3)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
Quick Links:
| Removal of the Junction Box JB3 | AMM 24-63-09-000-802 |
| Installation of the Junction Box JB3 | AMM 24-63-09-400-802 |
| Removal of the VHF Navigation Receiver | AMM 34-51-01-000-801 |
| Installation of the VHF Navigation Receiver | AMM 34-51-01-400-801 |
| Standard Practices - Replace Wiring | SPM 20-12-00-02 |
| Standard Practices - Repair Wiring | SPM 20-12-10-02 |
Troubleshooting Recommendations:
- Reset NAV 1 Circuit Breaker CB1-A1. Is the fault message still present?
- If YES, continue with next step.
- If NO, do close out.
- Swap the Left VHF NAV (A47) with the Right VHF NAV (A48). Is the fault message present?
- If YES, continue with next step.
- If NO, replace defective VHF NAV.
- Do wiring check between Left VHF NAV (A47) and Junction Box No.3 (JB3) for the following wires:
From To Results A47P1 - 15 JB3DP1 - 4F A47P1 - 16 JB3DP1 - 4G - If wiring check is satisfactory, continue with next step.
- If wiring check is not satisfactory, repair the defective wire.
- Replace Junction Box No. 3 (JB3).
- Do close out.