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(WARNING)
RED MESSAGE (CAUTION)
AMBER MESSAGE (ADVISORY)
CYAN MESSAGE (STATUS)
WHITE MESSAGE Require immediate crew attention. These messages are accompanied by flashing master warning, triple chime attenson with or without voice message or dedicated tone. Require immediate crew awareness and future crew action may be required in the form of alternate system selection or performance limitation. These message are accompanied by flashing master caution and a single chime. Indicate safe or normal system operation which require crew awareness, over and above the dark cockpit philosophy. Indicate minor failures or reduction in systems capability, which require no crew action.

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03/24/21

Message Overview:

Message Name:

NO L-CDU-6 BUS INPUT

Message Code:

B3-007255

Associated CAS:

None

Reporting LRU: NAV 1
System Description: 34-51-00
Schematic Diagram: 34-51-00
Wiring Diagram: 34-51-01
34-61-05

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:

  • L NAV-4000 VOR/LOC/GS/MB/ADF Receiver 1 (VHF NAV) (A047)
  • 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:

  1. Reset NAV 1 Circuit Breaker CB1-A1. Is the fault message still present\?

    1. If YES, continue with next step.
    2. If NO, do close out.

  2. Swap the Left VHF NAV (A47) with the Right VHF NAV (A48). Is the fault message present\?

    1. If YES, continue with next step.
    2. If NO, replace defective VHF NAV.

  3. 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

    1. If wiring check is satisfactory, continue with next step.
    2. If wiring check is not satisfactory, repair the defective wire.

  4. Replace Junction Box No. 3 (JB3).
  5. Do close out.

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