03/11/21
Message Overview:
Message Description:
PSEU detects an internal SHORT circuit in the proximity sensor PX08 Right Main Landing Gear Downlock1 or the wiring to the proximity sensor is shorted to the aircraft.
Possible Causes:
- Proximity-Sensor Electronic Unit (PSEU) (A9)
- Main Landing-Gear Downlock 1 Proximity-Sensor (RH) (PX08)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
Forum Articles/Infoservice/Newsletter: None
Quick Links:
| Removal of the Main Landing-Gear (MLG) Proximity-Sensors | AMM 32-61-01-000-801 |
| Installation of the Main Landing-Gear (MLG) Proximity-Sensors | AMM 32-61-01-400-801 |
| 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 |
| Standard Practices - Replace Wiring | SPM 20-12-00-02 |
| Standard Practices - Wire Repair | SPM 20-12-10-02 |
Troubleshooting Recommendations:
- Pull and reset the PSEU gear system breakers (CB1-C13, CB1-C14, CB2-C13, CB2-C14).
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Remove the PSEU from its rack and disconnect the connector PX08P1.
- Do wiring checks (shorted to ground = failure) between PX08J1 (pins1, 2) and ground. Repair as required.
- If system checks are good, do close out.
- If fault remains, continue with next step.
- Replace PX08.
NOTE: Sensor resistance should be made with a meter using a < 10 mA supply of current. Never apply voltage through a sensor! Current will magnetize the sensor rendering it unreliable. Sensor resistance is typically 11 to 13Ω.- If system checks are good, do close out.
- If fault remains, continue with next step.
- Replace PSEU.
- Do close out.


