Message Name:

FLAP ASYMMETRY

Message Code:

B3-006687

Associated CAS:

FLAPS FAIL
(Caution)

Flap Control Unit (FCU) detected an Asymmetry in the Flap System. Check mechanical driveline (If OB Actuator is disconnected or replaced, Flaps must be rigged).

• Mechanical driveline
• Flap Position Sensor (LH) (MPE77)
• Flap Position Sensor (RH) (MPE78)
• Flap Power Unit (FPU) (A123)
• Associated Wiring

Advisory Wire/Service Bulletin:

• AW300-27-0058 - Flap Control Unit - CAS Messages Reset procedure (20501 to 20999)

Forum Articles/Infoservice/Newsletter: None

In the MDC system parameters, an FPU PRESS XDCR SIGNAL showing 3740 PSI indicates the FCU have detected a malfunction in the system and do not send the excitation signal to the FPU pressure transducer.

MDC REPORT: SYSTEM PARAMETERS
FILENAME:
DATE:
...
FLAP SURFACE ANGLE - 3.74 DEG
FPU PRESS XDCR SIGNAL - 3740 PSI
APU HOURS - 1116.75 HRS
…

Source of the problem still has to be found.

1. Reset the following circuit breakers.

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

   FLAP R IND	CB2-B12
   FLAP L IND	CB1-B13
   FLAP CTRL	CB1-B14

2. Perform a General Visual Inspection of the Flap system per AMM (Verify integrity of driveline by pulling and pushing on the flap panel and by attempting to rotate the driveline by hand, verify integrity of AGB, and actuators to ensure that they are not loose or do not have stripped gears.).

   1. Replace any defective component per AMM.
   2. Continue with next step.

3. Reset the FCU by pressing the FCU reset button on the MAINTENANCE TEST control-panel. If unable to reset, engage the Alternate Flaps button with the left hydraulic system pressurized, and attempt another reset using the Flap Reset switch on the left galley.

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

4. Verify wiring to the position sensors. Check for any shorts or opens in the wiring/shielding. Where accessible, shake the wiring and ensure no fluctuation in supply voltage of 7 volts. Check the flap position sensor for possible internal failures.

   LH Channel A			LH Channel B
   A124AP1	MPE77P1	Value	A124BP1	MPE77P2	Value
   8F, 8E	1, 2	110Ω	14K, 15K	1, 2	110Ω
   10F, 10E	3, 4	75Ω	14H, 15H	3, 4	75Ω
   9F, 9E	5, 6	75Ω	14J, 15J	5, 6	75Ω

   RH Channel A			RH Channel B
   A124BP1	MPE78P1	Value	A124AP1	MPE78P2	Value
   9F, 9E	1, 2	110Ω	14K, 15K	1, 2	110Ω
   11F, 11E	3, 4	75Ω	14H, 15H	3, 4	75Ω
   10F, 10E	5, 6	75Ω	14J, 15J	5, 6	75Ω

5. Carry out mechanical rigging of the flap system per AMM.

   1. Continue with next step.

6. Carry out electrical rigging of the flap system per AMM.

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

7. Replaced FCU per AMM.

   1. If system checks are good, do close out.