Narrative:

Climbing through FL280 at .82 mach, we felt a high frequency flutter through the air frame. Suspecting possible spoiler float, the flight engineer did a visual inspection of the flight controls. Spoilers were tight, but the right outboard aileron balance tab was fluttering 1-2' up and down. The flutter stopped some time during deceleration to .74 mach and was stable on a second inspection. A company mechanic was aboard and also performed a visual inspection. He also indicated no signs of delamination or structural failure. After consultation with flight control and the maintenance coordinator, and with their assurance that sep of the tab was not a concern, the decision was made to continue to atl. While the controller characteristics of the aircraft were somewhat unusual, the reduced mach/airspeed (.72/250 KIAS) cruise provided a stabilized situation, and an approach had to be conducted to 'somewhere,' I felt continuing was the best course available, especially since we were level at FL350. On approach to atl, I had the company mechanic in a position where he could observe the tab during the approach phase, and instructed him to advise if confign changed and caused an extreme flutter of the tab. This was done so as to establish a safe landing confign. No such condition developed, and landing was uneventful. Maintenance found a separated inboard hinge on the tab.

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Original NASA ASRS Text

Title: ACR MLG FLT CREW ENCOUNTERS LIMITED STRUCTURAL FAILURE OF AILERON TRIM TAB.

Narrative: CLBING THROUGH FL280 AT .82 MACH, WE FELT A HIGH FREQ FLUTTER THROUGH THE AIR FRAME. SUSPECTING POSSIBLE SPOILER FLOAT, THE FE DID A VISUAL INSPECTION OF THE FLT CTLS. SPOILERS WERE TIGHT, BUT THE R OUTBOARD AILERON BALANCE TAB WAS FLUTTERING 1-2' UP AND DOWN. THE FLUTTER STOPPED SOME TIME DURING DECELERATION TO .74 MACH AND WAS STABLE ON A SECOND INSPECTION. A COMPANY MECH WAS ABOARD AND ALSO PERFORMED A VISUAL INSPECTION. HE ALSO INDICATED NO SIGNS OF DELAMINATION OR STRUCTURAL FAILURE. AFTER CONSULTATION WITH FLT CTL AND THE MAINT COORDINATOR, AND WITH THEIR ASSURANCE THAT SEP OF THE TAB WAS NOT A CONCERN, THE DECISION WAS MADE TO CONTINUE TO ATL. WHILE THE CTLR CHARACTERISTICS OF THE ACFT WERE SOMEWHAT UNUSUAL, THE REDUCED MACH/AIRSPD (.72/250 KIAS) CRUISE PROVIDED A STABILIZED SITUATION, AND AN APCH HAD TO BE CONDUCTED TO 'SOMEWHERE,' I FELT CONTINUING WAS THE BEST COURSE AVAILABLE, ESPECIALLY SINCE WE WERE LEVEL AT FL350. ON APCH TO ATL, I HAD THE COMPANY MECH IN A POS WHERE HE COULD OBSERVE THE TAB DURING THE APCH PHASE, AND INSTRUCTED HIM TO ADVISE IF CONFIGN CHANGED AND CAUSED AN EXTREME FLUTTER OF THE TAB. THIS WAS DONE SO AS TO ESTABLISH A SAFE LNDG CONFIGN. NO SUCH CONDITION DEVELOPED, AND LNDG WAS UNEVENTFUL. MAINT FOUND A SEPARATED INBOARD HINGE ON THE TAB.

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.