Narrative:

During takeoff roll; at vr; just as the nose began to rotate; a bang was heard below the first officer's seat. At the same exact instant the bang occurred; the control yoke deflected abruptly to the right approximately 15 degrees. Both left and right main wheels were still on the ground. Both engine indications remained normal throughout the flight. All system; fluid levels; pressures; synoptics and flight characteristics also were normal throughout the flight. Dispatch informed us an aircraft; departing after us; reported some debris on the runway. Dispatch also initially advised an MD80 departed before me and may have had a tire problem. Considering all of our indications remained normal; and fluid levels were stable; I believed the most likely cause of the noise and control deflection was the result of some type of FOD on the runway; possibly from the preceding MD80. I contacted dispatch over satcom; I asked them to keep me updated with the status of the MD80 upon landing. Much later into the flight; dispatch informed me tire tread was found on the runway. Again; all of our indications remained normal and tire pressures were also stable/normal. Upon landing and as a precautionary measure since we still were not certain where the FOD originated from; I asked for the arff equipment to be alerted and standing by during our landing rollout. After parking the aircraft; the crew went outside to observe the exterior of the aircraft. #10 main landing wheel had tread separation. I realize it was likely and possible for some of the tire tread to strike one of the control surfaces displacing the control from its normal position. However; anytime a control moves without crew input it is suspect and something to be very concerned about. Fortunately; the control deflection occurred while both main gear were still firmly on the runway. Had the main gear been slightly off the runway; and the control deflected abruptly as it did; my concern is a wingtip or engine pod contacting/scraping the ground. I have 2 questions: first; I would like to determine what caused the abrupt control deflection; and secondly; is there a simulator scenario that can duplicate tire tread separation just after both main gear lift off? Callback conversation with reporter revealed the following information: reporter stated that the inboard left flap had sustained some damage. This was discovered after the return flight with flaps extended for inspection. It is assumed that the damage was done concurrent with the tread separation. To date there is no explanation for the deflection of the yoke to the right. One could speculate that damage to any flight control surface could cause a corresponding yoke movement; but the #10 tire is located on the left main gear and an impact from the tread would most likely create a roll to the left.

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Original NASA ASRS Text

Title: ON ROTATION; B777 FLT CREW EXPERIENCED A LOUD BANG IN THE COCKPIT ACCOMPANIED BY CONTROL YOKE ROLL DEFLECTION. IT WAS DISCOVERED AFTER LNDG THAT A MAIN GEAR TIRE HAD BLOWN.

Narrative: DURING TKOF ROLL; AT VR; JUST AS THE NOSE BEGAN TO ROTATE; A BANG WAS HEARD BELOW THE FO'S SEAT. AT THE SAME EXACT INSTANT THE BANG OCCURRED; THE CTL YOKE DEFLECTED ABRUPTLY TO THE R APPROX 15 DEGS. BOTH L AND R MAIN WHEELS WERE STILL ON THE GND. BOTH ENG INDICATIONS REMAINED NORMAL THROUGHOUT THE FLT. ALL SYS; FLUID LEVELS; PRESSURES; SYNOPTICS AND FLT CHARACTERISTICS ALSO WERE NORMAL THROUGHOUT THE FLT. DISPATCH INFORMED US AN ACFT; DEPARTING AFTER US; RPTED SOME DEBRIS ON THE RWY. DISPATCH ALSO INITIALLY ADVISED AN MD80 DEPARTED BEFORE ME AND MAY HAVE HAD A TIRE PROB. CONSIDERING ALL OF OUR INDICATIONS REMAINED NORMAL; AND FLUID LEVELS WERE STABLE; I BELIEVED THE MOST LIKELY CAUSE OF THE NOISE AND CTL DEFLECTION WAS THE RESULT OF SOME TYPE OF FOD ON THE RWY; POSSIBLY FROM THE PRECEDING MD80. I CONTACTED DISPATCH OVER SATCOM; I ASKED THEM TO KEEP ME UPDATED WITH THE STATUS OF THE MD80 UPON LNDG. MUCH LATER INTO THE FLT; DISPATCH INFORMED ME TIRE TREAD WAS FOUND ON THE RWY. AGAIN; ALL OF OUR INDICATIONS REMAINED NORMAL AND TIRE PRESSURES WERE ALSO STABLE/NORMAL. UPON LNDG AND AS A PRECAUTIONARY MEASURE SINCE WE STILL WERE NOT CERTAIN WHERE THE FOD ORIGINATED FROM; I ASKED FOR THE ARFF EQUIP TO BE ALERTED AND STANDING BY DURING OUR LNDG ROLLOUT. AFTER PARKING THE ACFT; THE CREW WENT OUTSIDE TO OBSERVE THE EXTERIOR OF THE ACFT. #10 MAIN LNDG WHEEL HAD TREAD SEPARATION. I REALIZE IT WAS LIKELY AND POSSIBLE FOR SOME OF THE TIRE TREAD TO STRIKE ONE OF THE CTL SURFACES DISPLACING THE CTL FROM ITS NORMAL POS. HOWEVER; ANYTIME A CTL MOVES WITHOUT CREW INPUT IT IS SUSPECT AND SOMETHING TO BE VERY CONCERNED ABOUT. FORTUNATELY; THE CTL DEFLECTION OCCURRED WHILE BOTH MAIN GEAR WERE STILL FIRMLY ON THE RWY. HAD THE MAIN GEAR BEEN SLIGHTLY OFF THE RWY; AND THE CTL DEFLECTED ABRUPTLY AS IT DID; MY CONCERN IS A WINGTIP OR ENG POD CONTACTING/SCRAPING THE GND. I HAVE 2 QUESTIONS: FIRST; I WOULD LIKE TO DETERMINE WHAT CAUSED THE ABRUPT CTL DEFLECTION; AND SECONDLY; IS THERE A SIMULATOR SCENARIO THAT CAN DUPLICATE TIRE TREAD SEPARATION JUST AFTER BOTH MAIN GEAR LIFT OFF? CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: REPORTER STATED THAT THE INBOARD LEFT FLAP HAD SUSTAINED SOME DAMAGE. THIS WAS DISCOVERED AFTER THE RETURN FLIGHT WITH FLAPS EXTENDED FOR INSPECTION. IT IS ASSUMED THAT THE DAMAGE WAS DONE CONCURRENT WITH THE TREAD SEPARATION. TO DATE THERE IS NO EXPLANATION FOR THE DEFLECTION OF THE YOKE TO THE RIGHT. ONE COULD SPECULATE THAT DAMAGE TO ANY FLIGHT CONTROL SURFACE COULD CAUSE A CORRESPONDING YOKE MOVEMENT; BUT THE #10 TIRE IS LOCATED ON THE LEFT MAIN GEAR AND AN IMPACT FROM THE TREAD WOULD MOST LIKELY CREATE A ROLL TO THE LEFT.

Data retrieved from NASA's ASRS site as of January 2009 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.