background
x
loader
Troubleshooting
arrow By ATA By Message Color By Observed Faults by MDCBy Tips

Select color for CAS message that you wish to troubleshoot

(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.

This page includes :

For AOG assistance contact:

CRC Montreal (YUL)
Quick Links

04/08/21

Message Overview:

Message Name:

LOW AMPLITUDE
(Service Message)

Message Code:

B3-006339

Associated CAS:

APU FAULT
(Advisory)

Reporting LRU: APU SPEED SNSR
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) Electronic Control Unit (ECU) is reporting an open or short circuit of the APU Speed Sensor.

Possible Causes:

  • Speed Sensor (MT116)
  • Auxiliary Power Unit (APU) Electronic Control Unit (ECU) (A39)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

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
Removal of the Speed Sensor AMM 49-61-13-000-801
Installation of the Inlet Temperature Sensor AMM 49-61-13-400-801
Wiring - Maintenance Practices - ALL SPM 20-12-00-02
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02

Troubleshooting Recommendations:

  1. Do wiring check between the APU ECU (A39) and the Speed Sensor (MT116) for the following wires:

    From To Result
    Conn. A39AP1-15A Conn. MT116P1-A
    Conn. A39AP1-15C Conn. MT116P1-A
    Conn. A39AP1-14A Conn. MT116P1-C
    Conn. A39AP1-14C Conn. MT116P1-C

    1. If the check is satisfactory, continue with next step.
    2. If the check is not satisfactory, repair defective wiring.

  2. Replace the Speed Sensor (MT116). Is the fault message still present\?

    1. If NO, do close out.
    2. If YES, continue with next step.
      NOTE: The internal resistance (A - C) of the Speed Sensor can be measure. It is approximately 135 ohms maximum. However, a satisfactory check is NOT a confirmation of a good Speed Sensor.

  3. Replace APU ECU (A39).
  4. Do close out.

Registered and/or unregistered trademarks of Bombardier Inc. or its subsidiaries. © 2015 Bombardier Inc. All rights reserved.