ators said they believe the force of the explosion in the Center Wing Fuel Tank (CWT) pushed the No.3 spanwise beam, which forms the front wall of the tank, into the front spar ahead of it (see figure 1). The front spar broke free of the wing’s upper skin and rotated down into the forward cargo bay.Cracks propagated from the sides of the spar into the pressure bulkhead below it, then into the aircraft’s belly skin. The skin cracked forward longitudinally for about 200in, then each crack turned in toward the aircraft centerline until they intersected.Figure 1 The Center Wing Fuel Tank Area (source: Dornheim, 1997, p56)The 747’s wing rear spar forms the aft wall of the center tank. Three span-wise beams pass laterally through the tank. The No. 1 of these span-wise beams is between the rear spar and the wing’s mid-spar. Ahead of the mid-spar are the No. 2 and No. 3 sspan-wise beams, the latter forming the front wall of the tank. Between the No. 3 span-wise beam and the front spar is the dry spar, which contains no fuel.With the skin and some stringers and frames fractured, this belly skin was pushed down into the slipstream by cabin pressurisation and perhaps the overpressure from the center tank blast. It then tore free, taking with it a 13.5-ft long section of the aircraft’s keel beam. The skin to the right and left of the belly section then peeled back and free of the aircraft. About four seconds after the blast, a 70-ft section of the aircraft, from just in front of the tank to the nose, rotated to the right and down, then tore free.The rear fuselage, wings attached, are likely rolled about 50 degrees to the left and continued climbing, then rolled right until it was inverted and in a dive.Compression-buckling on the upper skin of the center wing tank and tension failures on the bottom skin indicate the wings failed upward, with the left wing breaking free and the right remaining attached to a larg...
