Message Name:

WOW DISC MISMATCH

Message Code:

B3-006678

Associated CAS:

FLAPS FAULT
(Advisory)

Flap Control Unit (FCU) detected a mis-match between control and monitor channel Weight on Wheel (WOW) discrete inputs. Check WOW wiring and Proximity Sensor Electronic Unit (PSEU) outputs.

• Proximity Sensor Electronic Unit (PSEU) (A9)
• Flap Control Unit (FCU) (A124)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

FLAP RESET Procedure:

1. With flaps stuck at 0 and handle at 0, turn left and right DCMP to On.
2. Select 'Altn Flaps' button on the Hydraulic Control Panel.
3. Select Flap Handle to 10.
4. Engage the flap critical reset switch on the PMAT panel by the entry door.
5. Move the handle back to 0 degrees. If it works the flaps on the synoptic page should turn green.
6. Move the handle back to 10 and allow the flaps to move and stop at 10.
7. Move the handle back to 0 and allow the flaps to move and stop at 0.
8. If no further issues, push the 'Altn Flaps' button to switch back to normal mode and run the flaps to verify fault is still cleared.

1. Pull and reset the PSEU gear system breakers (CB1-C13, CB1-C14, CB2-C13, CB2-C14).

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

2. Check the MDC for PSEU faults related to WOW.

   1. If a PSEU fault is logged, troubleshoot this fault first per SmartFix Plus.
   2. If fault remains, continue with next step.

3. Check continuity of the aircraft wiring between the FCU A124P1 PIN 6K to PSEU A9AP1 PIN 4H, the wire should be open to ground. With the PSEU installed, the FCU A124P1 PIN 6K should be open for WOW.

   1. Repair as necessary per SPM. If system checks are good, do close out.
   2. If fault remains, continue with next step.

4. Check continuity of the aircraft wiring between the Flap Control Unit A1247P1 PIN 3K to PSEU A9CP1 PIN 6D, the wire should be open to ground. With the PSEU installed, the Flap Control Unit PIN 6D should be open for WOW.

   1. Repair as necessary per SPM. If system checks are good, do close out.
   2. If fault remains, continue with next step.

5. If possible, download and have field service review the PSEU NVM. Further troubleshooting will depend on results of the PSEU NVM.
6. If the failure still exists with the wiring good, and the NVM download does not identify external inputs as the fault, replace the PSEU.
7. Functional check the proximity sensor electronic unit.