Narrative:

During takeoff inbound flap control fault occurred, aborted takeoff. While clear of runway attempted reset of system, in accordance with checklist. Returned to gate. Maintenance reset system and signed off aircraft for flight. System faulted 20 mins later at gate. Replaced control unit next day. System checked good, but later faulted again prior to first landing after repairs. Aircraft ferried flaps up to company maintenance facility. Callback conversation with reporter revealed the following information: the parameters that need to be met for correct flap extension indications compare the flap handle position, jack screws and flap switches, and control box information. All of this is monitored by the computer. The system also checks for dissymetry as well as asymmetry. The aircraft has 3 flap sections on each wing: the outboard, the nacelle flap, and the inboard flap section. Any erratic pressure on a microswitch could set off the fault indication, so a lot can go wrong in the process. In fact, this reporter's company has an incident reporting system which reporter states has 'one huge section' just for flap problems on the E120. The captain was very frustrated by the difficulty in determining what was causing the problem. He assumes that the mechanics at the maintenance base had to run through the entire system to get to the root cause of the problem. In the final analysis, this reporting captain believes that all of the run around might just be from a flap proximity switch that is out of whack.

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Original NASA ASRS Text

Title: AN E120 CAPT ABORTED TKOF AFTER RECEIVING A FLAP CTL FAULT WARNING. WHEN CLR OF THE RWY, HE ATTEMPTED A RESET OF THE SYS BY FOLLOWING THE CHKLIST PROCS. HE THEN RETURNED TO THE GATE AND SUBSEQUENTLY ENCOUNTERED TWO MORE INCIDENTS WITH THE FLAP CTL FAULT BEFORE FERRYING THE ACFT TO THE COMPANY MAINT FACILITY. ACFT EQUIP PROB FLAP CTL FAULT.

Narrative: DURING TKOF INBOUND FLAP CTL FAULT OCCURRED, ABORTED TKOF. WHILE CLR OF RWY ATTEMPTED RESET OF SYS, IN ACCORDANCE WITH CHKLIST. RETURNED TO GATE. MAINT RESET SYS AND SIGNED OFF ACFT FOR FLT. SYS FAULTED 20 MINS LATER AT GATE. REPLACED CTL UNIT NEXT DAY. SYS CHKED GOOD, BUT LATER FAULTED AGAIN PRIOR TO FIRST LNDG AFTER REPAIRS. ACFT FERRIED FLAPS UP TO COMPANY MAINT FACILITY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE PARAMETERS THAT NEED TO BE MET FOR CORRECT FLAP EXTENSION INDICATIONS COMPARE THE FLAP HANDLE POS, JACK SCREWS AND FLAP SWITCHES, AND CTL BOX INFO. ALL OF THIS IS MONITORED BY THE COMPUTER. THE SYS ALSO CHKS FOR DISSYMETRY AS WELL AS ASYMMETRY. THE ACFT HAS 3 FLAP SECTIONS ON EACH WING: THE OUTBOARD, THE NACELLE FLAP, AND THE INBOARD FLAP SECTION. ANY ERRATIC PRESSURE ON A MICROSWITCH COULD SET OFF THE FAULT INDICATION, SO A LOT CAN GO WRONG IN THE PROCESS. IN FACT, THIS RPTR'S COMPANY HAS AN INCIDENT RPTING SYS WHICH RPTR STATES HAS 'ONE HUGE SECTION' JUST FOR FLAP PROBS ON THE E120. THE CAPT WAS VERY FRUSTRATED BY THE DIFFICULTY IN DETERMINING WHAT WAS CAUSING THE PROB. HE ASSUMES THAT THE MECHS AT THE MAINT BASE HAD TO RUN THROUGH THE ENTIRE SYS TO GET TO THE ROOT CAUSE OF THE PROB. IN THE FINAL ANALYSIS, THIS RPTING CAPT BELIEVES THAT ALL OF THE RUN AROUND MIGHT JUST BE FROM A FLAP PROX SWITCH THAT IS OUT OF WHACK.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.