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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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09/18/19

Message Overview:

Fault Message:

APU GEARBOX LOW OIL LEVEL

Fault Code:

4960226APU

Associated CAS:

APU OIL LO QTY
(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:

Aircraft is on ground and the Auxiliary Power Unit (APU) Oil Quantity Probe is sensing less than 3.5 qt (3.3 L) as reported by the APU Full-Authority Digital Engine-Controller (FADEC).

Possible Causes:

  • Oil Level Sensor (MT2)
  • Oil Quantity Probe
  • 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

For Info Only: APU oil level is measured using a capacity probe sensor (ac excitation). The characteristics of the sensor are listed below. This information was extracted from the Interface Control Document RAE-A700-105 (31-12515B).

Sensor Type Capacity probes
Measurement Probe 28.7 +/- 1.5 pF
Compensation Probe 18.3 +/- 1 pF
Measurement Probe 27.4 +/- 0.6 pF
(dielectric=1)
Measuring Probe 27.4 +/- 0.6 pF
Compensation Probe 16.4 pF
Sensor Accuracy +/- 1 percent of full scale
Number of Wires 3

Quick Links:

Quantity Check of the Oil Supply in the APU AMM 12-14-09-610-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Servicing of the APU Oil Supply AMM 12-14-09-612-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Access to Active Faults AMM 45-45-00-970-802 [ 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 Oil Level Sensor AMM 49-90-05-000-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Installation of the Oil Level Sensor AMM 49-90-05-400-801 [ Global Express ]  [ G5000 ]  [ Global XRS ]
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02 [ Global Express ]  [ G5000 ]  [ Global XRS ]

Troubleshooting Recommendations:

  1. Check oil quantity at APU.

    1. If oil quantity is low, check for leaks, investigate low quantity and do close out.
    2. If oil quantity is good, continue with next step.

  2. Check CAIMS for any additional APU messages.

    1. If additional messages are found, troubleshoot accordingly and do close out.
    2. If no additional messages are found, continue with next step.

  3. Perform a wiring check between APU FADEC and the oil quantity probe (MT2P1).

    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. Replace oil quantity probe.

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

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

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