Message Name:

FPU INTERNAL FAULT

Message Code:

B3-006787

Associated CAS:

FLAPS FAULT
(Advisory)

Flap Power Unit (FPU) or wiring fault.

• Flap Power Unit (FPU) (A123) solenoid leakage monitor fault
• Flap Power Unit (FPU) (A123) alternate supply test fault
• Associated Wiring

Advisory Wire/Service Bulletin: None

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. Do a visual General Inspection of the FPU per AMM.

   1. If leakage is detected, replace FPU.
   2. If system checks are good, continue with next step.

2. Reset the following circuit breakers.

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

   1. If system checks are good, do close out.
   2. If fault remains, 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. Replace FPU.

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