Narrative:

It is an older boeing 737-200 model pwred with prattt and whitney JT8D-9 engines. We departed phx runway 08 left and flew the buckeye 2 departure to buckeye VOR. Captain was flying the aircraft. At 4100 ft MSL captain called for the after takeoff checklist and accelerated the plane from 210 KTS to normal climb speed of 250 KTS. I performed the checklist, part of which is verifying that the flaps are up, the flap handle is in the zero position and the leading edge flaps lights are out. At about 10000 ft I felt something. I looked up and saw the amber leading edge transit light was on and the flap gauge needles at 1. I looked down to the flap handle. I definitely saw it in the zero position. Captain reached for it to jiggle it in its zero detent. It was definitely in the zero detent. I looked back up to the front panel in time to see the amber light go out and the green leading edge flaps extension light come on. We had apparently experienced an uncommanded extension of the flaps (both leading edge and trailing edge) to the flaps 1 position. Captain brought the power back to idle, and we slowed to below 230 KTS, the flaps 1 placard speed. We tried moving the flap handle to the flaps 1 position and then back to the flaps up position. The flaps would not recycle to the up position. We called maintenance control. We had to repeat our problem to them 3 times before they understood or believed us. Maintenance control had us move the flaps to 2. The flaps followed to the 2 position. We then cycled them to the up position and they followed right on up to zero. Maintenance control wanted us to continue to ont, so we did. Both of us were certain that the leading edge flaps lights had been out and the flap gauge at zero after takeoff, but there is always that little bit of uncertainty in the back of your mind. The flight attendants knew something was up and rang the cockpit chime to come to the flight deck to discuss the situation. They stated that they had felt the flaps too. They all said it felt like the speed brakes had come out, and then 5-10 seconds later the power came back. This made me feel much better because the ride was smooth and not vibrating before the extension. All 5 of us had felt the same thing -- the flaps coming out at 250 KTS. The flight was then normal until we approached ont. As we slowed for the visual/ILS to runway 26L at ont, the flaps would not go past the 1 position on approach. We leveled off and assessed what we had. Flaps at 1, no flap asymmetry and a green leading edge flaps ext light. We tried a recycle after checking the circuit breaker's, but nothing worked. We went around, and used the alternate flap extension system to get the flaps to 15 and landed normally. We left the flaps down taxiing in and called for maintenance after shutdown. Now we sort of felt vindicated, because we did have a flap problem. Maintenance sent a mechanic to ont on the next flight. He found that the flaps were tripping at 1 for asymmetry protection several times for him. He said that this plane had similar trips about 1 week prior in den. Maintenance had swapped out the faulty flap gauge for 1 of theirs and the plane had flown since then with no problems. Just before we flew to ont, maintenance replaced the loaner gauge, sent it back to den and put a gauge in it's place. The mechanic could find nothing else wrong, so we were telexed a ferry permit and ferried back to phx with the flaps at 1. As we extended the flaps beyond 1 for landing at phx, they again would not go to the 5 position. The mechanic, riding the jumpseat reached up and rapped (pretty hard) on the panel next to the gauge and they then went to 5. We continued the flaps on schedule to 10 and 15. He said what we had was an asymmetry problem, although I would defy anyone to see any split in the needles. The needles appeared to be right on top of each other as per normal operations. When he rapped on the gauge it 'reset the asymmetry protection' (or something like that), so the flaps would continue in their normal sequence. Upon arrival at the gate in phx, maintenance said they planned to replace the flap gauge and the trailing edge flap positioning valve. Is there any record or history of uncommanded flap extensionsin the 737 or any transport aircraft? In our case, it appears that the trailing edge flaps came out and the leading edge flaps just did their normal duty when the trailing edge flaps reached 1, they came out too, just like they are supposed to do. Why isn't there some back up in the flap handle? If there had been, in our case at least, the leading edge flaps would have stayed up, thereby reducing the potential for damage to the leading edge flaps. I shudder to think what might have happened had this happened later at 280 or 300 KTS. Callback conversation with reporter revealed the following information: reporter stated that the only information heard back causing the unwarranted flap extension was a faulty electrical control unit for the hydraulic flap system. He has not heard any further problems with that aircraft. He was advised that there have been other aircraft, of various make and models, over the yrs experiencing similar problems. However, there were no common causal factors.

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Original NASA ASRS Text

Title: B737-200 UNWARRANTED WING FLAP SLAT EXTENSION DURING NORMAL CLB AFTER FLAP RETRACTION AND SUBSEQUENTLY COULD NOT BE NORMALLY EXTENDED DURING APCH. ALTERNATE EXTENSION SYS USED FOR A NORMAL LNDG.

Narrative: IT IS AN OLDER BOEING 737-200 MODEL PWRED WITH PRATTT AND WHITNEY JT8D-9 ENGS. WE DEPARTED PHX RWY 08 L AND FLEW THE BUCKEYE 2 DEP TO BUCKEYE VOR. CAPT WAS FLYING THE ACFT. AT 4100 FT MSL CAPT CALLED FOR THE AFTER TKOF CHKLIST AND ACCELERATED THE PLANE FROM 210 KTS TO NORMAL CLB SPD OF 250 KTS. I PERFORMED THE CHKLIST, PART OF WHICH IS VERIFYING THAT THE FLAPS ARE UP, THE FLAP HANDLE IS IN THE ZERO POS AND THE LEADING EDGE FLAPS LIGHTS ARE OUT. AT ABOUT 10000 FT I FELT SOMETHING. I LOOKED UP AND SAW THE AMBER LEADING EDGE TRANSIT LIGHT WAS ON AND THE FLAP GAUGE NEEDLES AT 1. I LOOKED DOWN TO THE FLAP HANDLE. I DEFINITELY SAW IT IN THE ZERO POS. CAPT REACHED FOR IT TO JIGGLE IT IN ITS ZERO DETENT. IT WAS DEFINITELY IN THE ZERO DETENT. I LOOKED BACK UP TO THE FRONT PANEL IN TIME TO SEE THE AMBER LIGHT GO OUT AND THE GREEN LEADING EDGE FLAPS EXTENSION LIGHT COME ON. WE HAD APPARENTLY EXPERIENCED AN UNCOMMANDED EXTENSION OF THE FLAPS (BOTH LEADING EDGE AND TRAILING EDGE) TO THE FLAPS 1 POS. CAPT BROUGHT THE PWR BACK TO IDLE, AND WE SLOWED TO BELOW 230 KTS, THE FLAPS 1 PLACARD SPD. WE TRIED MOVING THE FLAP HANDLE TO THE FLAPS 1 POS AND THEN BACK TO THE FLAPS UP POS. THE FLAPS WOULD NOT RECYCLE TO THE UP POS. WE CALLED MAINT CTL. WE HAD TO REPEAT OUR PROB TO THEM 3 TIMES BEFORE THEY UNDERSTOOD OR BELIEVED US. MAINT CTL HAD US MOVE THE FLAPS TO 2. THE FLAPS FOLLOWED TO THE 2 POS. WE THEN CYCLED THEM TO THE UP POS AND THEY FOLLOWED R ON UP TO ZERO. MAINT CTL WANTED US TO CONTINUE TO ONT, SO WE DID. BOTH OF US WERE CERTAIN THAT THE LEADING EDGE FLAPS LIGHTS HAD BEEN OUT AND THE FLAP GAUGE AT ZERO AFTER TKOF, BUT THERE IS ALWAYS THAT LITTLE BIT OF UNCERTAINTY IN THE BACK OF YOUR MIND. THE FLT ATTENDANTS KNEW SOMETHING WAS UP AND RANG THE COCKPIT CHIME TO COME TO THE FLT DECK TO DISCUSS THE SIT. THEY STATED THAT THEY HAD FELT THE FLAPS TOO. THEY ALL SAID IT FELT LIKE THE SPD BRAKES HAD COME OUT, AND THEN 5-10 SECONDS LATER THE PWR CAME BACK. THIS MADE ME FEEL MUCH BETTER BECAUSE THE RIDE WAS SMOOTH AND NOT VIBRATING BEFORE THE EXTENSION. ALL 5 OF US HAD FELT THE SAME THING -- THE FLAPS COMING OUT AT 250 KTS. THE FLT WAS THEN NORMAL UNTIL WE APCHED ONT. AS WE SLOWED FOR THE VISUAL/ILS TO RWY 26L AT ONT, THE FLAPS WOULD NOT GO PAST THE 1 POS ON APCH. WE LEVELED OFF AND ASSESSED WHAT WE HAD. FLAPS AT 1, NO FLAP ASYMMETRY AND A GREEN LEADING EDGE FLAPS EXT LIGHT. WE TRIED A RECYCLE AFTER CHKING THE CB'S, BUT NOTHING WORKED. WE WENT AROUND, AND USED THE ALTERNATE FLAP EXTENSION SYS TO GET THE FLAPS TO 15 AND LANDED NORMALLY. WE LEFT THE FLAPS DOWN TAXIING IN AND CALLED FOR MAINT AFTER SHUTDOWN. NOW WE SORT OF FELT VINDICATED, BECAUSE WE DID HAVE A FLAP PROB. MAINT SENT A MECH TO ONT ON THE NEXT FLT. HE FOUND THAT THE FLAPS WERE TRIPPING AT 1 FOR ASYMMETRY PROTECTION SEVERAL TIMES FOR HIM. HE SAID THAT THIS PLANE HAD SIMILAR TRIPS ABOUT 1 WK PRIOR IN DEN. MAINT HAD SWAPPED OUT THE FAULTY FLAP GAUGE FOR 1 OF THEIRS AND THE PLANE HAD FLOWN SINCE THEN WITH NO PROBS. JUST BEFORE WE FLEW TO ONT, MAINT REPLACED THE LOANER GAUGE, SENT IT BACK TO DEN AND PUT A GAUGE IN IT'S PLACE. THE MECH COULD FIND NOTHING ELSE WRONG, SO WE WERE TELEXED A FERRY PERMIT AND FERRIED BACK TO PHX WITH THE FLAPS AT 1. AS WE EXTENDED THE FLAPS BEYOND 1 FOR LNDG AT PHX, THEY AGAIN WOULD NOT GO TO THE 5 POS. THE MECH, RIDING THE JUMPSEAT REACHED UP AND RAPPED (PRETTY HARD) ON THE PANEL NEXT TO THE GAUGE AND THEY THEN WENT TO 5. WE CONTINUED THE FLAPS ON SCHEDULE TO 10 AND 15. HE SAID WHAT WE HAD WAS AN ASYMMETRY PROB, ALTHOUGH I WOULD DEFY ANYONE TO SEE ANY SPLIT IN THE NEEDLES. THE NEEDLES APPEARED TO BE RIGHT ON TOP OF EACH OTHER AS PER NORMAL OPS. WHEN HE RAPPED ON THE GAUGE IT 'RESET THE ASYMMETRY PROTECTION' (OR SOMETHING LIKE THAT), SO THE FLAPS WOULD CONTINUE IN THEIR NORMAL SEQUENCE. UPON ARR AT THE GATE IN PHX, MAINT SAID THEY PLANNED TO REPLACE THE FLAP GAUGE AND THE TRAILING EDGE FLAP POSITIONING VALVE. IS THERE ANY RECORD OR HISTORY OF UNCOMMANDED FLAP EXTENSIONSIN THE 737 OR ANY TRANSPORT ACFT? IN OUR CASE, IT APPEARS THAT THE TRAILING EDGE FLAPS CAME OUT AND THE LEADING EDGE FLAPS JUST DID THEIR NORMAL DUTY WHEN THE TRAILING EDGE FLAPS REACHED 1, THEY CAME OUT TOO, JUST LIKE THEY ARE SUPPOSED TO DO. WHY ISN'T THERE SOME BACK UP IN THE FLAP HANDLE? IF THERE HAD BEEN, IN OUR CASE AT LEAST, THE LEADING EDGE FLAPS WOULD HAVE STAYED UP, THEREBY REDUCING THE POTENTIAL FOR DAMAGE TO THE LEADING EDGE FLAPS. I SHUDDER TO THINK WHAT MIGHT HAVE HAPPENED HAD THIS HAPPENED LATER AT 280 OR 300 KTS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THE ONLY INFO HEARD BACK CAUSING THE UNWARRANTED FLAP EXTENSION WAS A FAULTY ELECTRICAL CTL UNIT FOR THE HYD FLAP SYS. HE HAS NOT HEARD ANY FURTHER PROBS WITH THAT ACFT. HE WAS ADVISED THAT THERE HAVE BEEN OTHER ACFT, OF VARIOUS MAKE AND MODELS, OVER THE YRS EXPERIENCING SIMILAR PROBS. HOWEVER, THERE WERE NO COMMON CAUSAL FACTORS.

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.