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(WARNING)
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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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09/16/20

Message Overview:

Fault Message:

ACPC RS422 RECEIVE (APUGCU) FAULT

Fault Code:

2420176LPS

Associated CAS:

ELEC SYS FAULT
(Advisory)

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) senses a RS422 communication failure from the AC Power Center (ACPC).

Possible Causes:

  • AC Power Center (ACPC) (A54)
  • A/D Converter Card
  • Auxiliary Power Unit (APU) Generator Control Unit (GCU) (A109)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

NOTE: This fault will always have an associated CAIMS fault "APU EXT A/D CONVERTER-A9 RS422" reported by ACPC.

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 AC Power Center (ACPC) AMM 24-51-00-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the AC Power Center (ACPC) AMM 24-51-00-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Removal of the AC Power Center (ACPC) External AC-to-DC Converter AMM 24-51-17-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the AC Power Center (ACPC) External AC-to-DC Converter AMM 24-51-17-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02 [ Global Express ]  [ G5000 ]  [ Global XRS ]
AC Power Center Component Maintenance Manual CMM 24-51-02 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Troubleshooting Recommendations:

  1. Swap APU GCU with GCU#2.

    1. If system checks are good, replace APU GCU and do close out.
    2. If fault remains, continue with next step.

  2. Replace AD converter card.

    1. If system checks are good, do close out.
    2. If fault remains, continue with next step.

  3. Perform wiring checks between APU GCU, ACPC and P501.

    1. If wiring checks are not good, repair the defective associated wiring and do close out.
    2. If fault remains, continue with next step.
      NOTE: Disconnect APU GCU connector and remove ACPC AD converter card to measure for short/open circuit.

  4. Replace ACPC.
  5. Do close out.

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