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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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03/10/25

Message Overview:

Message Name:

OPEN CKT- APU FEED SOV RELAY/WIRING

Message Code:

4960209APU

Associated CAS:

None

Reporting LRU: Full-Authority Digital Engine-Controller (FADEC)
System Description: 49-60-00 - Engine Controls
Schematic Diagram: [ Global Express ]  [ G5000 ]  [ Global XRS ] - 49-62-01-1_001 Sheet 1 - APU Emergency Shutdown System - [ALL]
Wiring Diagram: [ Global Express ]  [ G5000 ]  [ Global XRS ] - 49-62-00-1_001 Sheet 1 - APU Compartment Shutdown Switch - [9002-9129]
[ Global Express ]  [ G5000 ]  [ Global XRS ] - 49-62-00-2_001 Sheet 1 - APU Compartment Shutdown Switch - [9130-9158]
[ Global Express ]  [ G5000 ]  [ Global XRS ] - 49-62-01-1_001 Sheet 1 - APU Emergency Shutdown System - [9127 TO 9129]
[ Global Express ]  [ G5000 ]  [ Global XRS ] - 49-62-01-2_001 Sheet 1 - APU Emergency Shutdown System - [9130-9431, 9998]
[ Global Express ]  [ G5000 ]  [ Global XRS ] - 49-62-01-1_001 Sheet 1 - APU Emergency Shutdown System - [ALL]

Message Description:

The signals from the Auxiliary Power Unit (APU) Feed Shut-Off Valve (SOV) Relay to the Full-Authority Digital Engine-Controller (FADEC) are not within the expected range. This shows a possible open in the APU feed SOV relay, the aircraft wiring harness or the APU Fire-Detection-and-Extinguishing (FIREX) Handle.

Possible Causes:

  • Auxiliary Power Unit (APU) Fire Extinguisher Container (FIREX) Handle (A211)
  • JB4/PCB3/APU Fuel Feed Shut-Off Valve (SOV) Relay (K29 (K2)) 
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Full Throttle Blog/Forum Articles/Infoservice/Newsletter: None

Flight Operation Notifications Manual (FONM): None

Quick Links:

Standard Aircraft Configuration for Maintenance [ G5000 ]  [ Global Express ]  [ Global XRS ] AMM12-00-00-867-801
Electrical/Electronic Safety Precautions [ G5000 ]  [ Global Express ]  [ Global XRS ] AMM24-00-00-910-801
Electrostatic Discharge Safety Precautions [ G5000 ]  [ Global Express ]  [ Global XRS ] AMM24-00-00-910-802
Removal of the Junction Box JB4 Circuit-Cards [ G5000 ]  [ Global Express ]  [ Global XRS ] AMM24-00-06-000-801
Installation of the Junction Box JB4 Circuit-Cards [ G5000 ]  [ Global Express ]  [ Global XRS ] AMM24-00-06-400-801
Operational Test of Junction Box JB4 Circuit-Card 3 [ G5000 ]  [ Global Express ]  [ Global XRS ] AMM24-00-06-710-803
Removal of the Fire Handles [ G5000 ]  [ Global Express ]  [ Global XRS ] AMM26-21-13-000-801
Installation of the Fire Handles [ G5000 ]  [ Global Express ]  [ Global XRS ] AMM26-21-13-400-801
Operational Test of the APU Fire-Handle Circuit, Related Circuits and Relays [ G5000 ]  [ Global Express ]  [ Global XRS ] AMM26-21-13-710-812
CAIMS PMAT General Instructions [ G5000 ]  [ Global Express ]  [ Global XRS ] AMM45-45-00-970-801
Access to Active Faults [ G5000 ]  [ Global Express ]  [ Global XRS ] AMM45-45-00-970-802
Access to Stored Faults [ G5000 ]  [ Global Express ]  [ Global XRS ] AMM45-45-00-970-803

Troubleshooting Recommendations:

  1. Make sure there is no short between A108BP1-A2 and the connector shell of A108BP1 (WM 49-62).

    1. If there is a short, repair defective wiring as required and do close out.
    2. If there is no short, continue with next step.

  2. If OPEN CKT - APU FEED SOV RELAY/WRG shows on the CAIMS PMAT as active faults, perform a continuity check between the pins of FADEC (A108BP1) as follows:

    From To Expected Result Result
    A108BP1-A2 A108BP1-B2 200-2000 ohms

    1. the resistance is as mentioned above, repair defective wiring as required and do close out.
    2. If the resistance value is not as mentioned above, continue with next step.

  3. Perform a wiring check between FADEC (A108BP1) and APU FIREX handle (A211P1).

    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. Make sure there is no short between A211P1-14 and the connector shell of A211P1.

    1. If there is a short, repair defective wiring as required and do close out.
    2. If there is no short, continue with next step.

  5. Perform a wiring check of APU FIREX handle (receptacle) as follows:

    From To Result
    A211P1-14 A211P1-31

    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. Make sure there is no short between A211P1-14 and the connector shell of APU FIREX handle (receptacle).

    1. If there is a short, repair defective wiring as required and do close out.
    2. If there is no short, continue with next step.

  7. Perform a wiring check between APU FIREX handle (A211P1) and junction box 4 (JB4AP1).

    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.

  8. Make sure there is no short between A211P1-31 and the connector shell of A211P1.

    1. If there is a short, repair defective wiring as required and do close out.
    2. If there is no short, continue with next step.

  9. Perform a continuity check between the pins of junction box 4 (JB4) as follows:

    From To Expected Result Result
    JB4AP1-2K JB4AP1-2H 200-2000 ohms

    1. If the resistance is as mentioned above, repair defective wiring as required and do close out.
    2. If the resistance value is not as mentioned above, continue with next step.

  10. Make sure there is no short between JB4AP1-2H and the connector shell of junction box 4 (JB4) (receptacle).

    1. If there is a short, repair defective wiring as required and do close out.
    2. If there is no short, continue with next step.

  11. Perform a wiring check between FADEC (A108BP1) and junction box 4 (JB4AP1).

    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.

  12. Make sure there is no short between JB4AP1-2K and the connector shell of JB4AP1.

    1. If there is a short, repair defective wiring as required and do close out.
    2. If there is no short, continue with next step.

  13. Interchange JB4/PCB3/APU Fuel Feed SOV Relay (K29 (K2)) with Relay (K11 (K3)) located in JB4-PCB3.
  14. Does the fault remain posted? 

    1. If YES, continue with the next step.
    2. If NO, replace the Relay K29 (K2) and do the close out.

  15. Replace APU FIREX Handle (A211).
  16. Do close out.

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