Date: 17 Dec 97 03:41:24 From: Patrick McConnell <firstname.lastname@example.org> Organization: Sprynet News Service References: 1 Followups: 1
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Wayne Dohnal wrote: > During the Monday night TWA 800 NTSB hearings, the "sequencing team" > reported that both wingtips separated from the inner portions of the > wings fairly early in the breakup sequence. The man giving the report > tried to explain the logic of this, and the panelists shook their heads > like they understood what he was saying, but I still can't understand! > > Can anyone explain how it make any sense for the wingtips to separate > when they weren't anywhere close to the explosion or structural breakup > area? After watching the load test and breakup of the 777 wing on TV, > I concluded that there was no possible way for a wing to break up in > flight. (I realize these are different aircraft, but I'm assuming > Boeing would have similar wing strength across the product lines). My guess would be that, after the nose separated from the aircraft, the aft section pitched up violently because the center of gravity move way, way aft. The pitch-up caused the wings to reach an angle of attack far beyond that which could be achieve by the intact aircraft at the airspeed they were travelling. The resulting lift loads could quite conceivably have failed the wings. The wing will fail at it's weakest point, which could well be just outboard of the fuel tanks. Fuel in the wings relieves the wing bending moment (at least compared to an equivalent weight carried in the fuselage), so the fuel tank termination could be the failure point. Or, the outboard engine attachment point, where the engine point load is introduced, could be it. Certainly the failure point is known to the investigators from the full scale static test.