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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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Quick Links

09/13/19

Message Overview:

Fault Message:

VOLTS TO START MOTOR OUT LOW

Fault Code:

4960114APU

Associated CAS:

None

Reporting LRU: Full-Authority Digital Engine-Controller (FADEC)
System Description: 49-40-00
Schematic Diagram: 49-61-00 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Wiring Diagram: 49-61-01 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Fault Description:

The start relay feedback voltage is less than 10 volts when the Starter relay is commanded on.

Possible Causes:

  • Auxiliary Power Unit (APU) Full-Authority Digital Engine-Controller (FADEC) (A108)
  • Auxiliary Power Unit (APU) Starter Motor (B55)
  • Auxiliary Power Unit (APU) Starter Contactor Assembly (ASCA) (A48)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Quick Links:

Removal of the APU Starter-Contactor Assembly AMM 24-62-05-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the APU Starter-Contactor Assembly AMM 24-62-05-400-801 [ 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 Starter Motor AMM 49-42-01-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Starter Motor AMM 49-42-01-400-801 [ 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. Verify engine branched wiring-harness for bare wiring, kinks, worn areas and other damage.

    1. If engine branched wiring-harness is damaged, go to step 9.
    2. If engine branched wiring-harness is not damaged, continue with next step.

  2. Perform wiring checks between APU Starter Motor "-" negative and "+" positive terminals (MPE3) as follows:

    From To Expected Result Result
    MPE3-NEG MPE3-POS Continuity < one ohm

    1. If the continuity is good, go to step 4.
    2. If the continuity check fails, continue with next step.

  3. Replace the APU Starter Motor (B55). Is the fault still present?

    1. If NO, do close out.
    2. If YES, continue with next step.

  4. Perform wiring checks between aircraft wiring harness (J802) and FADEC (A108BP1), make sure there is no short between each pin 4 and 5, and the connector shell of J802.

    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.

  5. Perform wiring checks between APU starter-contactor assembly (A48P2) and FADEC (A108BP1).

    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.

  6. Perform wiring checks between APU Starter Motor B55 (MPE3) and APU Start Contactor Assembly (ASCA).

    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.

  7. This step requires two people. While one person is close to the ASCA, listening carefully, the other person is in the cockpit setting the APU switch to "RUN". Can the person close to the ASCA hear the Starter-Contactor relay K2 click?

    1. If NO, go to step 11.
    2. If YES, continue with next step.

  8. This step requires two people. While one person has a DC Voltmeter between the positive terminal of the APU Starter motor, the other person is in the cockpit setting the APU switch to "RUN".

    1. If there is no voltage or voltage value is less than 10 VDC, go to step 11.
    2. If there is 28 VDC present, continue with next step.

  9. Replace the engine branched wiring-harness. Is the fault still present?

    1. If NO, do close out.
    2. If YES, continue with next step.

  10. Replace FADEC.

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

  11. Replace APU Starter-Contactor Assembly (ASCA).
  12. Do close out.

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