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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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06/21/19

Message Overview:

Fault Message:

APUGCU APU RDY/SENSE/SIGNAL FAULT

Fault Code:

2420250LPS

Associated CAS:

None

Reporting LRU: Auxiliary Power Unit Generator Control Unit (APU GCU)
System Description: 24-22-00
Schematic Diagram: 24-22-00 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Wiring Diagram: 24-22-01 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Fault Description:

Auxiliary Power Unit Generator Control Unit (APU GCU) has detected a problem with the FADEC connection between the APU GCU and the Full-Authority Digital Engine-Controller (FADEC), consequently resulting in the APU Generator tripped off-line or not come on-line.

Possible Causes:

  • Auxiliary Power Unit Generator Control Unit (APU GCU) (A109)
  • Auxiliary Power Unit (APU) Full-Authority Digital Engine-Controller (FADEC) (A108)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

A GCU patch cable (GSE REF # 24X-24-02) can be used to swap GCU 1, GCU 2, GCU 3, GCU 4 and the APU GCU into a different position (for troubleshooting only). You can monitor the GCU faults in CAIMS via the active faults page.

Quick Links:

Removal of the Generator Control Units (GCU) AMM 24-24-01-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Generator Control Units (GCU) AMM 24-24-01-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Removal of the Full-Authority Digital Engine-Controller (FADEC) AMM 49-61-01-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Full-Authority Digital Engine-Controller (FADEC) AMM 49-61-01-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Troubleshooting Recommendations:

  1. Disconnect APU GCU connector A109P2 and APU FADEC connector A108BP1. Do a continuity check (refer to SSM 24-22-00-101) as follows:

    From To Result
    A109P2-38 Ground

    1. If there is continuity, repair defective wiring as required and do close out.
    2. If there is no continuity, continue with next step.

  2. Do a continuity check as follows:

    From To Result
    A109P2-38 A108BP1-A4

    1. If there is no continuity, repair defective wiring as required and do close out.
    2. If there is continuity, continue with next step.

  3. Swap APU GCU with GCU 2 (physically or using the GCU patch cable). Is the fault still present?

    1. If NO, replace defective APU GCU and do close out.
    2. If YES, continue with next step.

  4. Replace APU FADEC.
  5. Do close out.

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