Narrative:

I recently had a major difference of opinion with maintenance and management personnel about the airworthiness of an large transport we were assigned to fly. The previous crew had written up an airframe vibration they felt on the previous flight at 315 KTS. The company had contract maintenance inspect the aircraft but found nothing. Company maintenance officials declared that the problem was spoiler float (spoiler float is when the spoiler will not lock down flush with the upper surface of the wing. It will vibrate in the air stream at cruise speeds. I noticed in the log book that the aircraft had been written up 2 previous times for airframe buffet in the same month. I protested flying the aircraft but was eventually convinced to do so. The captain flew the aircraft with passenger to chicago at 250 KTS to avoid the vibration which was said to occur between 280-315 KTS. I have since discussed the problem with more experienced large transport pilots who say that spoiler float can cause problems in maintaining a desired flight path at approach speeds flap configns. The FAA approved operating manual is not clear on this situation. The company says it is ok to fly an aircraft with suspected spoiler float problems. I think the aircraft mfr should provide clear guidance to flight crews for determining airworthiness when spoiler float causes airframe vibration.

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Original NASA ASRS Text

Title: FO QUESTIONS CORRECTNESS OF DECISION TO DISPATCH ACR LGT WITH DIAGNOSED SPOILER FLOAT.

Narrative: I RECENTLY HAD A MAJOR DIFFERENCE OF OPINION WITH MAINT AND MGMNT PERSONNEL ABOUT THE AIRWORTHINESS OF AN LGT WE WERE ASSIGNED TO FLY. THE PREVIOUS CREW HAD WRITTEN UP AN AIRFRAME VIBRATION THEY FELT ON THE PREVIOUS FLT AT 315 KTS. THE COMPANY HAD CONTRACT MAINT INSPECT THE ACFT BUT FOUND NOTHING. COMPANY MAINT OFFICIALS DECLARED THAT THE PROB WAS SPOILER FLOAT (SPOILER FLOAT IS WHEN THE SPOILER WILL NOT LOCK DOWN FLUSH WITH THE UPPER SURFACE OF THE WING. IT WILL VIBRATE IN THE AIR STREAM AT CRUISE SPDS. I NOTICED IN THE LOG BOOK THAT THE ACFT HAD BEEN WRITTEN UP 2 PREVIOUS TIMES FOR AIRFRAME BUFFET IN THE SAME MONTH. I PROTESTED FLYING THE ACFT BUT WAS EVENTUALLY CONVINCED TO DO SO. THE CAPT FLEW THE ACFT WITH PAX TO CHICAGO AT 250 KTS TO AVOID THE VIBRATION WHICH WAS SAID TO OCCUR BTWN 280-315 KTS. I HAVE SINCE DISCUSSED THE PROB WITH MORE EXPERIENCED LGT PLTS WHO SAY THAT SPOILER FLOAT CAN CAUSE PROBS IN MAINTAINING A DESIRED FLT PATH AT APCH SPDS FLAP CONFIGNS. THE FAA APPROVED OPERATING MANUAL IS NOT CLR ON THIS SITUATION. THE COMPANY SAYS IT IS OK TO FLY AN ACFT WITH SUSPECTED SPOILER FLOAT PROBS. I THINK THE ACFT MFR SHOULD PROVIDE CLR GUIDANCE TO FLT CREWS FOR DETERMINING AIRWORTHINESS WHEN SPOILER FLOAT CAUSES AIRFRAME VIBRATION.

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.