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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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04/02/21

Message Overview:

Message Name:

NO L-CDU-6 BUS OUTPUT

Message Code:

B3-648577

Associated CAS:

None

Reporting LRU: CDU 1
System Description: 34-00-00
Schematic Diagram: 34-61-00
Wiring Diagram: 34-61-05

Message Description:

No L-CDU-6 data received at 3-of (L-IOC, L-NAV, L-DME, L-VHF, TSS).

Possible Causes:

  • Left Control Display Unit (CDU 1) (A69)
  • Junction Box (JB3)
  • Left Input/Output Concentrator Unit (IOC 1) (A4-IOC1)
  • Left VHF Communication Unit (VHF COM 1) (A7)
  • Third VHF Communication Unit (VHF COM 3) (A10)
  • Left HF Transceiver (HF 1) (A61)
  • Left Distance Measuring Equipment (DME 1) Transceiver (A49)
  • Left VHF Navigation Receiver (A47)
  • Traffic/Collision Avoidance System (TCAS) and Traffic Surveillance System (TSS) Transponder Unit (A5)
  • 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 VHF Communication Unit AMM 23-11-01-000-801
Installation of the VHF Communication Unit AMM 23-11-01-400-801
Removal of the HF Transceiver AMM 23-12-01-000-801
Installation of the HF Transceiver AMM 23-12-01-400-801
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 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 Traffic/Collision Avoidance System (TCAS) and Traffic Surveillance System (TSS) Transponder Unit AMM 34-43-03-000-801
Installation of the Traffic/Collision Avoidance System (TCAS) and Traffic Surveillance System (TSS) Transponder Unit AMM 34-43-03-400-801
Removal of the VHF Navigation Receiver AMM 34-51-01-000-801
Installation of the VHF Navigation Receiver AMM 34-51-01-400-801
Removal of the Distance Measuring Equipment (DME) Transceiver AMM 34-53-01-000-801
Installation of the Distance Measuring Equipment (DME) Transceiver AMM 34-53-01-400-801
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:

  1. Reset CDU 1 (CB1-A4) circuit breaker.

    1. If system check passes, do close out.
    2. If fault remains, continue with next step.

  2. Swap CDUs.

    1. If system check passes, do close out.
    2. If fault remains, continue with next step.

  3. Do a complete wiring check of the ARINC 429 data bus L-CDU-6 from CDU 1 connector A69P1, through Junction Box 3, to the VHF COM 3 connector A10P1, the TSS connector A238EP1, the DME 1 connector A49P1, the VHF NAV 1 connector A47P1, the VHF COM 1 connector A7P1, the IAPS connector A4P1 and the HF 1 connector A61P1. Repair/replace as required.

    1. If system check passes, do close out.
    2. If fault remains, continue with next step.
      NOTE: An internal short of any LRUs connected to this data bus might cause this failure.

  4. Swap IOCs.

    1. If system check passes, do close out.
    2. If fault remains, continue with next step.

  5. Swap VHF COMs (1 & 2 are interchangeable).

    1. If system check passes, do close out.
    2. If fault remains, continue with next step.

  6. Swap DMEs (or replace, if dual DME option is not installed).

    1. If system check passes, do close out.
    2. If fault remains, continue with next step.

  7. Swap VHF NAVs (or replace, if dual ADF option is not installed).

    1. If system check passes, do close out.
    2. If fault remains, continue with next step.

  8. Swap HFs (or replace, if dual HF option is not installed).

    1. If system check passes, do close out.
    2. If fault remains, continue with next step.

  9. Replace TSS.

    1. If system check passes, do close out.
    2. If fault remains, continue with next step.

  10. Replace VHF COM 3.

    1. If system check passes, do close out.
    2. If fault remains, continue with next step.

  11. Replace ICC.
  12. Do close out.

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