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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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09/19/19

Message Overview:

Fault Message:

SPEED SENSOR [CKT 1 XREF FAILURE]

Fault Code:

4960268APU

Associated CAS:

APU FAULT
(Advisory)

Reporting LRU: Full-Authority Digital Engine-Controller (FADEC)
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:

The output of Speed Sensor circuit 1 is 2% less than output of Speed Sensor circuit 2. The Full-Authority Digital Engine-Controller (FADEC) has detected an internal failure to its overspeed protection circuitry.

Possible Causes:

  • Auxiliary Power Unit (APU) Full-Authority Digital Engine-Controller (FADEC) (A108)
  • Speed Sensor (MT4)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

If CAS message is not active, verify stored faults on CAIMS.

Quick Links:

Access to Stored Faults AMM 45-45-00-970-803 [ 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 Speed Sensor AMM 49-61-17-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Speed Sensor AMM 49-61-17-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Troubleshooting Recommendations:

  1. Monitor APU speed sensor speed in CAIMS: (CAIMS PATH: SYSTEM DIAG/49-00 APU/CONTROLLER FADEC/LRU TEST/APU DATA STATUS - 1/ APU DATA STATUS - 2). Compare the 2 readings to see if they are different.

    1. If the readings are not different, go to step 4.
    2. If the readings are different, continue with next step.

  2. Swap the Speed Sensors.

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

  3. Perform wiring checks (continuity, ground and shielding) between APU FADEC connector A108AP1 and the speed sensor 1 connector MT4P1 as follow:

    From To Result
    A108AP1-G11 MT4P1-A
    A108AP1-H11 MT4P1-B

    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.

  4. Re-rack FADEC and verify both the tray and FADEC connectors for damage or FOD, verify if fault is still present.

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

  5. Replace FADEC.
  6. Do close out.

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