Narrative:

After selection of full landing flaps (30 degrees), the large transport rolled to left requiring full aileron deflection to right, right rudder inputs to maintain level flight. Immediately, we retracted the flaps to their next position of 25 degrees. Some control was regained. Our company procedures call for evaluation of flaps jammed/asymmetry and leading edge device problems. None of these problems were apparent. The engineer made a visual inspection from the cabin and no abnormal spoiler float or aileron problem could be found or determined. Since control was adequate for a safe landing, we decided not to pursue the problem any further. An uneventful landing was made. Fire and crash equipment were standing by. One other procedure that was discussed was a procedure in which 5 degree flaps are used in landing if there could be a spoiler float problem. However, our near maximum landing weight and high airport elevation considered, we decided to land the aircraft in the confign it was in and eliminate the risk of compromising control instead of increasing it. Upon maintenance inspection, a broken #2 spoiler actuator was determined to be the cause. We were informed by maintenance that had we retracted the flaps, it would have caused substantial damage to the #1 flap and #1, 2, 3 spoilers. Upon landing, the spoilers were deployed and jammed in the full up position. In-flight, had we pulled the spoiler handle slightly to determine a spoiler float (as is common practice) we might have bit off more than the large transport could chew. Callback conversation with reporter revealed the following: when the flaps were retracted to 25 degrees, the spoiler float was not noticeable. The flaps were never re-extended to 30 degrees. The captain decided that things were well under control with the flaps at 25 degrees and he decided not to do any more experimenting for fear of damage. This proved to be a wise decision. The aircraft flew a large 360 degree turn during the troubleshooting.

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Original NASA ASRS Text

Title: ACFT ROLLED SHARPLY TO THE LEFT ON FINAL APCH TO COS.

Narrative: AFTER SELECTION OF FULL LNDG FLAPS (30 DEGS), THE LGT ROLLED TO LEFT REQUIRING FULL AILERON DEFLECTION TO RIGHT, RIGHT RUDDER INPUTS TO MAINTAIN LEVEL FLT. IMMEDIATELY, WE RETRACTED THE FLAPS TO THEIR NEXT POS OF 25 DEGS. SOME CTL WAS REGAINED. OUR COMPANY PROCS CALL FOR EVALUATION OF FLAPS JAMMED/ASYMMETRY AND LEADING EDGE DEVICE PROBS. NONE OF THESE PROBS WERE APPARENT. THE ENGINEER MADE A VISUAL INSPECTION FROM THE CABIN AND NO ABNORMAL SPOILER FLOAT OR AILERON PROB COULD BE FOUND OR DETERMINED. SINCE CONTROL WAS ADEQUATE FOR A SAFE LNDG, WE DECIDED NOT TO PURSUE THE PROB ANY FURTHER. AN UNEVENTFUL LNDG WAS MADE. FIRE AND CRASH EQUIP WERE STANDING BY. ONE OTHER PROC THAT WAS DISCUSSED WAS A PROC IN WHICH 5 DEG FLAPS ARE USED IN LNDG IF THERE COULD BE A SPOILER FLOAT PROB. HOWEVER, OUR NEAR MAX LNDG WT AND HIGH ARPT ELEVATION CONSIDERED, WE DECIDED TO LAND THE ACFT IN THE CONFIGN IT WAS IN AND ELIMINATE THE RISK OF COMPROMISING CTL INSTEAD OF INCREASING IT. UPON MAINT INSPECTION, A BROKEN #2 SPOILER ACTUATOR WAS DETERMINED TO BE THE CAUSE. WE WERE INFORMED BY MAINT THAT HAD WE RETRACTED THE FLAPS, IT WOULD HAVE CAUSED SUBSTANTIAL DAMAGE TO THE #1 FLAP AND #1, 2, 3 SPOILERS. UPON LNDG, THE SPOILERS WERE DEPLOYED AND JAMMED IN THE FULL UP POS. INFLT, HAD WE PULLED THE SPOILER HANDLE SLIGHTLY TO DETERMINE A SPOILER FLOAT (AS IS COMMON PRACTICE) WE MIGHT HAVE BIT OFF MORE THAN THE LGT COULD CHEW. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: WHEN THE FLAPS WERE RETRACTED TO 25 DEGS, THE SPOILER FLOAT WAS NOT NOTICEABLE. THE FLAPS WERE NEVER RE-EXTENDED TO 30 DEGS. THE CAPT DECIDED THAT THINGS WERE WELL UNDER CONTROL WITH THE FLAPS AT 25 DEGS AND HE DECIDED NOT TO DO ANY MORE EXPERIMENTING FOR FEAR OF DAMAGE. THIS PROVED TO BE A WISE DECISION. THE ACFT FLEW A LARGE 360 DEG TURN DURING THE TROUBLESHOOTING.

Data retrieved from NASA's ASRS site as of August 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.