Page:NTSB Aircraft Accident Report, United Airlines Flight 389.pdf/30

 degrees magnetic, and the slight right-wing—down attitude caused the wing to dig in and rotate the aircraft to the right as it broke up. Damage to the right wing was more extensive than to the left and the leading edge devices received considerable damage, much more so than the leading edge devices on the left wing. The fractures on the horizontal stabilizers had a downward component indicating forces which overloaded the spars, resulting in a complete failure. All the fractures examined were caused by gross overloads and there was no evidence of pre—impact damage or fatigue.

The aircraft‘s mass, the rate of descent of the aircraft, and the hydraulic action of the water caused the destruction of the lower portion of the fuselage and started the failure of the No. 2 engine mounts. Immediately after the initial impact the forward lower section of the airframe and the lower wing surfaces struck the water. The amount of destruction to the air-frame indicated a high rate of speed. The distortion of the engine tubing attached to the No. 3 engine strut attests to the fact that the engine separated from the strut in a forward and downward direction. The location of the recovered components of this engine indicates separation of the engine at the time of initial impact or immediately thereafter. The separation of the engine this early in the accident sequence explains its severe disintegration

The separation of the No. 1 engine was in an outward and rearward direction based on fracture examination and the engine's location in the wreckage area. It did not separate at initial impact but rather after the aircraft started to rotate to the right.

Portions of all the control surfaces and trim tabs were in the recovered wreckage. There was no evidence of unusual wear, distress, or pre-impact malfunction in any of the control system components recovered.