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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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02/16/21

Message Overview:

Message Name:

NO L-IOC-4 BUS OUTPUT

Message Code:

B3-645785

Associated CAS:

None

Reporting LRU: IOC 1
System Description: 31-45-00
Schematic Diagram: 31-45-00
Wiring Diagram: 31-45-01
31-45-09
31-45-11

Message Description:

L-IOC-4 data absent at L-FMC and 1 of [L-RIU and SVC].

Possible Causes:

  • Left Input/ Output Concentrator Unit 1 (IOC 1) (A4-IOC1)
  • Junction Box 3 (JB3)
  • Left Flight Management Computer 1 (FMC 1) (A4-FMC1)
  • Synthetic Vision Computer (SVC) (A230)
  • Left Radio Interface Unit (RIU 1) (A17)
  • 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 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 Boxes AMM 24-63-01-000-802
Installation of the Junction Boxes AMM 24-63-01-400-802
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 Synthetic Vision Computer (SVC) AMM 34-34-01-000-801
Installation of the Synthetic Vision Computer (SVC) AMM 34-34-01-400-801
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
Standard Practices - Replace Wiring SPM 20-12-00-02
Standard Practices - Wire Repair SPM 20-12-10-02

Troubleshooting Recommendations:

  1. Reset L IAPS (CB1-B6) circuit breaker.

    1. If system checks are good, do close out.
    2. If fault remains, continue with next step.

  2. Swap IOCs.

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

  3. Do a wiring check of the ARINC 429 data bus L-IOC-4 from IAPS connector A4P3, through Junction Box 4, to RIU 1 connector A17P2 and to SVC connector A230AP1. 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 FMCs.

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

  5. Replace SVC.

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

  6. Replace RUI 1.

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

  7. Replace IAPS Card Cage (ICC).
  8. Do close out.

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