Message Name:

LGECU NLG DOWNLOCK/ WIRING

Message Code:

3250018DWY

Associated CAS:

NOSE STEER FAIL
(Caution)

The Nose Gear Downlock Proximity Switch signal from the Landing Gear Electronic Control Unit (LGECU) Channel A is not communicating properly with the Steering Control Unit (SCU).

• Left Nose Gear Down Lock Proximity Sensor (MT23)
• Landing Gear Electronic Control Unit (LG ECU) (A52)
• Steering Control Unit (SCU) (A36)
• Associated Wiring

Advisory Wire/Service Bulletin:

• AW700-32-0280 - Nose Wheel Steering - Troubleshooting SCU GW415-8100-3

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

Flight Operation Notifications Manual (FONM): None

NOTES:

• Although this fault code indicates an issue with the Downlock sensors, please note that the WOW input signal to the SCU can also cause this CAIMS message to generate.

1. In CAIMS selected "SYSTEM DIAG/32-00 LANDING GEAR/STEERING CONTROL UNIT/LRU TEST/SCU-3 DATA PAGES".
   
   

   1. If one of the WOW signals shows a wrong status, go to step 3.
   2. If the NLG DOWNLOCK status is not correct, go to step 7.
   3. if WOW 1, WOW 2 and NLG DOWNLOCK status are correct per current aircraft configuration, continue with next step.

2. Use targets and anti-targets to simulate Weight on wheels and weight off wheels and monitor the data page sensor status.

   1. If all sensor status indicated the correct status, go to step 7.
   2. If one of the WOW inputs shows a wrong status at one point, continue with next step.

3. In CAIMS selected “SYSTEM DIAG / 32-00 LANDING GEAR / LDG ELEC CTRL UNIT A / LRU TEST / LGECU A / WOW SENSOR DATA. Make sure all WOW signals are good per aircraft configuration.

   1. If one or more of the sensors shows a wrong status, go to step 6.
   2. If all sensors are working properly, continue with next step.

4. Remove the LGECU and inspect the condition of all the connectors and pins.

   1. If defects are found, rectify as required and do close out.
   2. If no defects are found, continue with next step.

5. Remove the SCU. Perform a wiring check of the WOW signals wiring between the LGECU and the SCU.

   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. Perform a wiring check of the interface wiring between the LGECU and the affected WOW sensor.

   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.

7. In CAIMS selected “SYSTEM DIAG / 32-00 LANDING GEAR / LDG ELEC CTRL UNIT A / LRU TEST / LGECU A LDG GR DOWNLOCK SENSOR DATA “.
8. Using an anti target, set the Left Nose Downlock sensor to a not down and lock state. CAIMS should show the Nose Gear Downlock sensors as follows:

   SENSOR VARIABLE NAME	STATUS
   NLG DOWNLOCK SENSOR A STATE	NOT DOWNLOCKED
   NLG DOWNLOCK SENSOR A AGREE	AGREE
   NLG DOWNLOCK SENSOR A FAULT	NO FAULT

   1. If the sensor status is not as per above, replace the proximity sensor.
   2. If the sensor status is as per above, continue with next step.

9. Remove the anti target to set the Left Nose Downlock sensor to a down and lock state. CAIMS should shows the Nose Gear Downlock sensors as follows:

   SENSOR VARIABLE NAME	STATUS
   NLG DOWNLOCK SENSOR A STATE	DOWNLOCKED
   NLG DOWNLOCK SENSOR A AGREE	AGREE
   NLG DOWNLOCK SENSOR A FAULT	NO FAULT

   1. If the sensor status is not as per above, replace the proximity sensor.
   2. If the Proximity sensor status is good, continue with next step.

10. perform a wiring check between the following pins:

    From	To	Result
    A36P1-13	A52BP1-J15

    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.

11. Replace LGECU.
12. Do close out.