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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 SATCOM BUS TO CDU

Message Code:

B3-398068

Associated CAS:

None

Reporting LRU: SAT 2X00
System Description: 23-00-00
Schematic Diagram: 23-15-00 (POST SB 350−23−012)
23-15-00 (POST SB 350−23−013)
Wiring Diagram: 23-15-01

Message Description:

SDU-2 data bus is being reported as failed by both CDUs.

Possible Causes:

  • SATCOM Satellite Data Unit (SDU) (A82)
  • Junction Box 3 (JB3)
  • Left Control Display Unit (CDU) (A69)
  • Right Control Display Unit (CDU) (A68)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Quick Links:

Removal of the SATCOM Satellite Data Unit (SDU) AMM 23-15-01-000-801
Installation of the SATCOM Satellite Data Unit (SDU) AMM 23-15-01-400-801
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 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 - Wire Repair SPM 20-12-10-02

Troubleshooting Recommendations:

  1. Reset SATCOM (CB4-D2) circuit breaker.

    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 SDU-2 from SDU connector A82BP1, through Junction Box 3, to CDU 1 connector A69P1 and CDU2 connector A68P1. Repair/replace as required.

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

  3. Replace SDU.

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

  4. Replace CDU 1.

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

  5. Replace CDU 2.
  6. Do close out.

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