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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:

S/D-SPEED ROLLBACK

Message Code:

B3-006354

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:

Auxiliary Power Unit (APU) protective shutdown - engine speed dropped below 25% after starter cutout.

Possible Causes:

  • Mechanical Engine
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Fault Confirmation Procedure:

  1. Message# = 9
  2. {Term Definitions}

    1. APU-41 XX 352 01 EXCT XXXX-XXXX TXXX-XXXX XXXX-XXXX 352: 24; APU S/D SPEED FALLBACK

Quick Links:

Removal of the Battery AMM 24-32-01-000-801
Installation of the Battery AMM 24-32-01-400-801
Removal of the Fuel Control Unit AMM 49-31-01-000-801
Installation of the Fuel Control Unit AMM 49-31-01-400-801
Removal of the Fuel Solenoid Valve AMM 49-31-09-000-801
Installation of the Fuel Solenoid Valve AMM 49-31-09-400-801
Removal of the Ignition Unit AMM 49-41-01-000-801
Installation of the Ignition Unit AMM 49-41-01-400-801
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. This condition could be due to restricted fuel flow, or mechanical engine failure.

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