Narrative:

During recurrent training last month, the ground school system training instructor presented a scenario involving electrical bus failure which the crew misdiagnosed as asymmetrical flaps, among other things. In the course of the discussion after the presentation, the instructor pointed out that the S80 hadn't a procedure for asymmetrical flaps 'because it cannot happen.' well, I mentioned that it happened twice to me and he (as a member of the ack team) encouraged me to write it up in the safety format, even though it's way out of date, for the benefit of considering a change to the operating manual. The most recent occurrence for myself was on the night of sat/xa/97. From ZZZ1-ZZZ it was my leg. We were late departing due to a maintenance problem and a subsequent spare. On approach into ZZZ as I called for flaps 11 degrees, the aircraft began a sudden roll to the left. I looked at the flap/slat indicator and the right flap indicated several degrees further extension than the left. I called for 'flaps up' and we ended up landing slats only at ZZZ. I was familiar with the problem because it happened to me on a previous flight (perhaps a yr or so earlier). I was flying a maintenance check flight at ZZZ2 predawn. The previous crew complained of a very strong roll input during flap extension and maintenance spent the night adjusting flap rig. Well, when we took off from ZZZ2, there was no problem, but when we extended the flaps to 11 degrees, there was a strong roll with the exact same flap gauge indications. We called ZZZ3 maintenance who asked us to fly the jet there so they could go over it carefully. We diverted from the ZZZ2 radar pattern to ZZZ3 and gave them the jet. Perhaps a procedure might be considered, as experimenting with a full load of passenger seemed a bad idea that night in ZZZ (whether to stop moving the flaps, attempting to land with massive rudder, etc, versus retracting and landing slat only).

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Original NASA ASRS Text

Title: AN MD80 CAPT WHO EXPERIENCED 2 TRAILING EDGE FLAP FAILURE SUGGESTS THE COMPANY UPDATE THE OPERATING MANUAL WITH A FLAP FAILURE PROC.

Narrative: DURING RECURRENT TRAINING LAST MONTH, THE GND SCHOOL SYS TRAINING INSTRUCTOR PRESENTED A SCENARIO INVOLVING ELECTRICAL BUS FAILURE WHICH THE CREW MISDIAGNOSED AS ASYMMETRICAL FLAPS, AMONG OTHER THINGS. IN THE COURSE OF THE DISCUSSION AFTER THE PRESENTATION, THE INSTRUCTOR POINTED OUT THAT THE S80 HADN'T A PROC FOR ASYMMETRICAL FLAPS 'BECAUSE IT CANNOT HAPPEN.' WELL, I MENTIONED THAT IT HAPPENED TWICE TO ME AND HE (AS A MEMBER OF THE ACK TEAM) ENCOURAGED ME TO WRITE IT UP IN THE SAFETY FORMAT, EVEN THOUGH IT'S WAY OUT OF DATE, FOR THE BENEFIT OF CONSIDERING A CHANGE TO THE OPERATING MANUAL. THE MOST RECENT OCCURRENCE FOR MYSELF WAS ON THE NIGHT OF SAT/XA/97. FROM ZZZ1-ZZZ IT WAS MY LEG. WE WERE LATE DEPARTING DUE TO A MAINT PROB AND A SUBSEQUENT SPARE. ON APCH INTO ZZZ AS I CALLED FOR FLAPS 11 DEGS, THE ACFT BEGAN A SUDDEN ROLL TO THE L. I LOOKED AT THE FLAP/SLAT INDICATOR AND THE R FLAP INDICATED SEVERAL DEGS FURTHER EXTENSION THAN THE L. I CALLED FOR 'FLAPS UP' AND WE ENDED UP LNDG SLATS ONLY AT ZZZ. I WAS FAMILIAR WITH THE PROB BECAUSE IT HAPPENED TO ME ON A PREVIOUS FLT (PERHAPS A YR OR SO EARLIER). I WAS FLYING A MAINT CHK FLT AT ZZZ2 PREDAWN. THE PREVIOUS CREW COMPLAINED OF A VERY STRONG ROLL INPUT DURING FLAP EXTENSION AND MAINT SPENT THE NIGHT ADJUSTING FLAP RIG. WELL, WHEN WE TOOK OFF FROM ZZZ2, THERE WAS NO PROB, BUT WHEN WE EXTENDED THE FLAPS TO 11 DEGS, THERE WAS A STRONG ROLL WITH THE EXACT SAME FLAP GAUGE INDICATIONS. WE CALLED ZZZ3 MAINT WHO ASKED US TO FLY THE JET THERE SO THEY COULD GO OVER IT CAREFULLY. WE DIVERTED FROM THE ZZZ2 RADAR PATTERN TO ZZZ3 AND GAVE THEM THE JET. PERHAPS A PROC MIGHT BE CONSIDERED, AS EXPERIMENTING WITH A FULL LOAD OF PAX SEEMED A BAD IDEA THAT NIGHT IN ZZZ (WHETHER TO STOP MOVING THE FLAPS, ATTEMPTING TO LAND WITH MASSIVE RUDDER, ETC, VERSUS RETRACTING AND LNDG SLAT ONLY).

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.