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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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04/08/21

Message Overview:

Message Name:

FAIL TO OPEN

Message Code:

B3-006333

Associated CAS:

APU FAULT
(Advisory)

Reporting LRU: APU LD CTRL VLV
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 the Load Control Valve (LCV) failed to open.

Possible Causes:

  • Load Control Valve (LCV) (V8)
  • 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 Load Control Valve AMM 49-52-01-000-801
Installation of the Load Control Valve AMM 49-52-01-400-801
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. Dowiring check from APU ECU (A39) to the Load Control Valve (V8) for the following wires:

    From To Result
    Conn. A39AP1-12B Conn. V8BP1-1
    Conn. A39AP1-6D Conn. V8BP1-3

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

  2. Replace the Load Control Valve (V8). Is the fault message still present?

    1. If NO, do close out.
    2. If YES, continue with next step.
      NOTE: The LCV is a spring-loaded, normally closed, torque motor-controlled butterfly-type valve. The LCV switch is open when the valve is not close.

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

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