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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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For AOG assistance contact:

CRC Montreal (YUL)
Quick Links

04/08/21

Message Overview:

Message Name:

UNDERSPEED

Message Code:

B3-006359

Associated CAS:

None

Reporting LRU: APU
System Description: 49-00-00
Schematic Diagram: 49-61-00
Wiring Diagram: 49-61-01 Sh 1
49-61-01 Sh 2

Message Description:

APU operating and speed less than 80%. For ground operation, this failure triggers a protective shutdown. For flight operation, the shutdown is inhibited.

Possible Causes:

  • Auxiliary Power Unit (APU)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Fault Confirmation Procedure:

  1. Message# = 14
  2. {Term Definitions}

    1. APU-46 XX 353 01 EXCT XXXX-XXXX XXXX-XXXX XXXX-TXXX 353: 12; APU S/D UNDERSPEED

Quick Links:

Removal of the Auxiliary Power Unit (APU) Electronic Control Unit (ECU) AMM 49-61-01-000-801
Installation of the Auxiliary Power Unit (APU) Electronic Control Unit (ECU) AMM 49-61-01-400-801
Wiring - Maintenance Practices - ALL SPM 20-12-00-02
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02

Troubleshooting Recommendations:

  1. None

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