Narrative:

I was international relief officer for the takeoff. After 80 KTS but before V1; there was a thump felt/heard on the left side of the aircraft. A quick check of the engines and tracking showed no evidence of a problem so the takeoff was continued. Airborne; there was a noticeable unusual vibration. We almost immediately were receiving calls from the cabin about the vibration. We cleaned up and climbed out and the vibration decreased somewhat. We decided to call operations to check with the tower about the possibility of a blown tire. Operations confirmed the tower already had reports of debris on the runway. A check airman was on board administering a line check; so we had him go to the cabin to check on the vibration. He reported that the noise and vibration were higher than normal but not excessive. We called dispatch and they already were aware of the tire debris from us in ZZZ1. The initial decision was that if only a tire had blown; then it would be reasonable to continue to ZZZZ. Dispatch called back later and said that metal with latches and honeycomb had also been found so the decision to continue was being reconsidered. Next there was a conference call with several air carrier departments. It was decided not to continue to ZZZZ. After some discussion; it was decided that the best course of action for all involved was to return to ZZZ1. We had just passed ZZZ3. ATC was informed that we needed to return to ZZZ1 and was immediately cleared left turn direct ZZZ1. ATC was informed that fuel dumping would be required before landing at ZZZ1 and we were cleared to begin fuel dump immediately. Starting abeam ZZZ3; we dumped 50;000 pounds of fuel at FL320. Later; we determined that more fuel dump was necessary to get below maximum landing weight so ATC let us dump another 20;000 pounds at FL330. We had kept the passengers and crew advised through all of this. Captain gave the flight attendants a cabin advisory but telling them to expect a normal approach and landing. We made a normal landing on runway xxr at ZZZ1. We turned left at the end onto the taxiway and stopped. Maintenance came and inspected the condition of our landing gear. They decided to pin the gear and tow the aircraft to the gate. That ended the first segment of our flight to ZZZZ that day. Supplemental information from acn 818578: ultimately; maintenance forwarded that they found parts of one tire; a pack bay door; a wing strut door and many other pieces of honeycomb aluminum with the extent of damage unknown. Maintenance noted color of parts indicated pieces from the bottom of the plane and possibly the flap structure. Maintenance control and dispatch stated they could not determine what the impact would be to continue (fuel burn and effect of unknown damage). It was clearly stated by maintenance that they did not recommend the continued operation to ZZZZ and preferred the plane divert to ZZZ1 as a first choice and as a second option; ZZZ2 was deemed the best option for possible repairs and passenger accommodation. I suggested declaring an emergency but pilot in command did not select that option. Captain did not request emergency equipment to stand by; but did request air carrier personnel to be available to inspect the aircraft immediately after landing. After normal shutdown we all inspected the damage. It appears that the large preconditioned air panel cover was missing. There was a metal support rod/latch hanging down about 3 ft from that area. There was impact damage to the wing gear fixed door. The lower portion of the wing gear fixed door was badly damaged. The #1 tire was destroyed. There were small dents on 2 of the flap 'canoes.' flaps appeared normal. I speculate that if the flight had continued; the rod/latch assembly that was hanging down would have separated from the plane enroute. That was probably the source of much of the vibration (not all). Early analysis by crew favored continuing to destination. ZZZZ should have good maintenance available. A failed tire would present no additional thr

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Original NASA ASRS Text

Title: A B747-400 departing on a transatlantic international flight blew a tire on takeoff. After conferring with Dispatch and Maintenance about the nature of debris found on the runway they decided to dump fuel and return to their departure airport.

Narrative: I was IRO for the takeoff. After 80 KTS but before V1; there was a thump felt/heard on the left side of the aircraft. A quick check of the engines and tracking showed no evidence of a problem so the takeoff was continued. Airborne; there was a noticeable unusual vibration. We almost immediately were receiving calls from the cabin about the vibration. We cleaned up and climbed out and the vibration decreased somewhat. We decided to call OPS to check with the Tower about the possibility of a blown tire. OPS confirmed the Tower already had reports of debris on the runway. A check airman was on board administering a line check; so we had him go to the cabin to check on the vibration. He reported that the noise and vibration were higher than normal but not excessive. We called Dispatch and they already were aware of the tire debris from us in ZZZ1. The initial decision was that if only a tire had blown; then it would be reasonable to continue to ZZZZ. Dispatch called back later and said that metal with latches and honeycomb had also been found so the decision to continue was being reconsidered. Next there was a conference call with several air carrier departments. It was decided not to continue to ZZZZ. After some discussion; it was decided that the best course of action for all involved was to return to ZZZ1. We had just passed ZZZ3. ATC was informed that we needed to return to ZZZ1 and was immediately cleared left turn direct ZZZ1. ATC was informed that fuel dumping would be required before landing at ZZZ1 and we were cleared to begin fuel dump immediately. Starting abeam ZZZ3; we dumped 50;000 LBS of fuel at FL320. Later; we determined that more fuel dump was necessary to get below maximum landing weight so ATC let us dump another 20;000 LBS at FL330. We had kept the passengers and crew advised through all of this. Captain gave the Flight Attendants a cabin advisory but telling them to expect a normal approach and landing. We made a normal landing on Runway XXR at ZZZ1. We turned left at the end onto the taxiway and stopped. Maintenance came and inspected the condition of our landing gear. They decided to pin the gear and tow the aircraft to the gate. That ended the first segment of our flight to ZZZZ that day. Supplemental information from ACN 818578: Ultimately; Maintenance forwarded that they found parts of one tire; a pack bay door; a wing strut door and many other pieces of honeycomb aluminum with the extent of damage unknown. Maintenance noted color of parts indicated pieces from the bottom of the plane and possibly the flap structure. Maintenance Control and Dispatch stated they could not determine what the impact would be to continue (fuel burn and effect of unknown damage). It was clearly stated by maintenance that they did not recommend the continued operation to ZZZZ and preferred the plane divert to ZZZ1 as a first choice and as a second option; ZZZ2 was deemed the best option for possible repairs and passenger accommodation. I suggested declaring an emergency but Pilot in Command did not select that option. Captain did not request emergency equipment to stand by; but did request air carrier personnel to be available to inspect the aircraft immediately after landing. After normal shutdown we all inspected the damage. It appears that the large preconditioned air panel cover was missing. There was a metal support rod/latch hanging down about 3 FT from that area. There was impact damage to the wing gear fixed door. The lower portion of the wing gear fixed door was badly damaged. The #1 tire was destroyed. There were small dents on 2 of the flap 'canoes.' Flaps appeared normal. I speculate that if the flight had continued; the rod/latch assembly that was hanging down would have separated from the plane enroute. That was probably the source of much of the vibration (not all). Early analysis by crew favored continuing to destination. ZZZZ should have good maintenance available. A failed tire would present no additional thr

Data retrieved from NASA's ASRS site as of April 2012 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.