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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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02/24/21

Message Overview:

Message Name:

NO L-IOC-4 BUS INPUT

Message Code:

B3-339599

Associated CAS:

None

Reporting LRU: RIU 1 DATALINK
System Description: 23-00-00
23-51-00
Schematic Diagram: 23-23-00
23-51-00
Wiring Diagram: 23-51-21
31-45-11

Message Description:

L-IOC 4 (FMC) Input to DATALINK inactive and FMS is active to IOC and SVC.

Possible Causes:

  • Left Radio Interface Unit (RIU) 1 (A17)
  • Junction Box 4 (JB4)
  • 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
Standard Practices - Replace Wiring SPM 20-12-00-02
Standard Practices - Wire Repair SPM 20-12-10-02

Troubleshooting Recommendations:

  1. Reset RIU 1A (CB1-B5) and RIU 1B (CB1-B4) circuit breakers.

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

  2. Do wiring check of ARINC 429 data bus L-IOC-4 from RIU1 connector A17P2, through Junction Box 4 to IAPS connector A4P1. Repair/replace as required.

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

  3. Replace RIU 1.
  4. Do close out.

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