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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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09/13/19

Message Overview:

Fault Message:

OPEN CKT-LOW OIL PRESS SWITCH/WRG

Fault Code:

4960128APU

Associated CAS:

APU FAULT
(Advisory)

APU SHUTDOWN
(Advisory)

Reporting LRU: Full-Authority Digital Engine-Controller (FADEC) System
System Description: 49-60-00
Schematic Diagram: 49-61-00 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Wiring Diagram: 49-12-01 [ Global Express ]  [ G5000 ]  [ Global XRS ]
49-61-01 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Fault Description:

During an Auxiliary Power Unit (APU) start, the Low Oil Pressure Switch does not transmit a low oil pressure condition when the APU switch goes back to the RUN position.

Possible Causes:

  • Auxiliary Power Unit (APU) Full-Authority Digital Engine-Controller (FADEC) (A108)
  • Low Oil Pressure Switch (S1)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Quick Links:

APU Safety Precautions AMM 49-00-00-910-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Removal of the Engine Branched Wiring-Harness AMM 49-12-01-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Engine Branched Wiring-Harness AMM 49-12-01-400-801 [ 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 ]
Removal of the Low Oil-Pressure Switch AMM 49-90-41-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Low Oil-Pressure Switch AMM 49-90-41-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Troubleshooting Recommendations:

  1. Check for fault message FADEC CONTROLLER shows on the CAIMS PMAT.

    1. If fault message shows, replace FADEC and do close out.
    2. If fault message not shows, continue with next step.

  2. Check for OPEN CKT-LOW OIL PRESS SWITCH/WRG still shows on the CAIMS PMAT.

    1. If fault message shows, repair as required and do close out.
    2. If fault message not shows, continue with next step.

  3. Examine the engine branched wiring-harness for bare wiring, kinks, worn areas and other damage (WM 49-12).

    1. If there is bare wiring, kinks, worn areas or other damage, go to step 9.
    2. If damages are not found, continue with next step.

  4. Check for message OPEN CKT-LOW OIL PRESS SWITCH/WRG still shows on the CAIMS PMAT.

    1. If fault message shows, repair as required and do close out.
    2. If fault message not shows, continue with next step.

  5. Examine the low oil-pressure switch (S1) receptacle for contamination and damage.

    1. If there is contamination or damage, go to step 10.
    2. If there is no contamination or damage, continue with next step.

  6. Perform a continuity check within the low oil-pressure switch (S1) receptacle (WM 49-12). The resistance should measure as follows:

    From To Expected Result Result
    S1P1-A S1P1-B <50 ohms

    1. If measurement is not less than 50 ohms, go to step 10.
    2. If it is within the range, continue with next step.

  7. Perform wiring checks between P1 (APU) and S1P1 (low oil-pressure switch).

    1. If wiring checks are not good, go to step 9.
    2. If wiring checks are good, continue with next step.

  8. Perform wiring checks between J802 (aircraft wiring harness) and A108AP1 (FADEC).

    1. If wiring checks are not good, repair defective wiring as required and do close out.
    2. If wiring checks are good, continue with next step.

  9. Replace engine branched wiring-harness.

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

  10. Replace Low Oil Pressure Switch (S1).
  11. Do close out.

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