07/14/23
Message Overview:
Message Description:
Fuel Quantity Gauging Computer has detected a discrepancy between the Proximity Sensing Electronic Unit (PSEU) and the Input/Output Concentrator Units (IOC) weight-off-wheels inputs to the FQGC, or, the PSEU signal is invalid or has failed.
Possible Causes:
- Fuel Quantity Gauging Computer (FQGC) (A57)
- Proximity-Sensor Electronic Unit (PSEU) (A9)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/ Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
Quick Links:
| Pressure Refueling | AMM 12-11-01-650-801 |
| Suction Defueling | AMM 12-11-09-650-801 |
| Drain Water from the Fuel Tank | AMM 28-10-00-680-801 |
| Built-In Test of the Fuel-Quantity Gauging System | AMM 28-41-00-740-801 |
| Removal of the Fuel Quantity Computer | AMM 28-41-01-000-801 |
| Installation of the Fuel Quantity Computer | AMM 28-41-01-400-801 |
| Removal of the Input/Output Concentrator Unit (IOC) | AMM 31-45-05-000-801 |
| Installation of the Input/Output Concentrator Unit (IOC) | AMM 31-45-05-400-801 |
| Operational Test of the Input/Output Concentrator Unit (IOC) | AMM 31-45-05-710-801 |
| Put the Aircraft in a Weight-Off-Wheel Configuration with the Aircraft on the Ground | AMM 32-61-00-867-801 |
| Remove the Aircraft from a Weight-Off-Wheel Configuration with the Aircraft on the Ground | AMM 32-61-00-867-802 |
| Operational Test of the Proximity Sensors | AMM 32-61-00-710-801 |
| Functional Test of the Proximity Sensors | AMM 32-61-00-720-801 |
| Adjustment of the Proximity Sensors | AMM 32-61-00-820-801 |
| Removal of the Proximity-Sensor Electronic Unit (PSEU) | AMM 32-61-09-000-801 |
| Installation of the Proximity-Sensor Electronic Unit (PSEU) | AMM 32-61-09-400-801 |
| Functional Test of the Proximity-Sensor Electronic Unit (PSEU) | AMM 32-61-09-720-801 |
| Wiring - Maintenance Practices - ALL | SPM 20-12-00-02 |
| Wire Repair - Maintenance Practices - ALL | SPM 20-12-10-02 |
| Electrical Connectors - Maintenance Practice - ALL | SPM 20-20-00-02 |
Troubleshooting Recommendations:
- Make sure the Refuel/Defuel Panel is set to OFF and reset the Fuel Quantity system breakers (CB3-C3, CB4-C3), waiting 10 seconds before pushing the breakers back.
- If fault continues, go to next step.
- Interrogate the MDC and verify for any "PROX SYSTEM FAULT" OR "PROX SYSTEM FAIL" message and troubleshoot the associated B3 code first.
- If no PSEU fault messages/codes are found, verify wiring per the following table.
PSEU (A9) FCGC (A57) Expected Result Connector Pin + Connector Pin - A9AP1 2H A57BP1 88 Continuity A9AP1 2H Ground Open - If wiring is found serviceable, go to next step.
- Re-rack the Fuel Quantity Gauging Computer (FQGC). Is the fault message still present?
- If YES, go to next step.
- If NO, do close out.
- Replace FQGC.
- Do close out.
