Page:CAB Accident Report, American Airlines Flight 1.pdf/12



During the investigation of the accident the question necessarily arises as to whether any abnormal functioning by the airplane or its equipment had contributed to the accident, or if a collision occurred while in flight with some external object. A thorough inspection was made of the wreckage of aircraft NC 25663 and a substantial amount of testimony was received at the hearing as the result of this examination.

The position and appearance of the wreckage indicated that the aircraft had struck the ground at an angle of approximately 70 degrees with the horizontal. First contact was made by the nose of the fuselage and leading edges of the wings with the left wing slightly ahead of the right. The airplane was subsequently damaged by fire. The engines had penetrated the earth at the point of impact, remaining in the same positions with relation to each other that they occupied on the wing. The fuselage had telescoped forward and to the left as had the center section and wings. The empennage, nearly intact, had shifted forward approximately 30 feet, relative to the engines, and slightly to the left, and was resting on the left stabilizer tip. The left wing tip was broken just outboard of the wing tip attachment rib. The appearance of the collapsed structure of the broken portion definitely indicated that the breakage was caused by the inertia forces and whipping action at impact. The internal structure in both wings had collapsed until the rear and front spars of the wing panels were nearly together. The position of the center section and wings indicated that a slight shift to the left had occurred. The leading edges of the wings remained in line with each other. The general center line of the aft section of the fuselage was offset from its normal line of symmetry with the wings and formed an acute angle with the left wing. Both engines were buried in the earth until only the rear parts of their starters were visible at the ground level. A number of clay clods were found distributed over a fanshaped pattern to the rear of the engines and extending about 115 feet behind the empennage. The aircraft wreckage was well confined to the immediate area surrounding the single point of impact. There was no indication of ice on the wings or other surfaces of the airplane.

It appears that all major parts of the airplane were accounted for except for a central portion of the fuselage, side and top structure, along with their supporting members which were partially destroyed by fire, however, the appearance and relative positions of various parts of the structure, along with adjacent attachments remaining, definitely indicated that the missing portions were present prior to the impact and fire. Furthermore, no parts were found along the flight path, thus leading to the conclusion that no parts of the airplane failed and broke off in flight.

The engine controls, gauges, flight instruments and related equipment in the cockpit section were so damaged by impact and fire that their original condition and position could not be determined, however, they were all found whole or in part and were identified. There was no evidence to indicate that a control failure had occurred, for while the control surfaces were damaged, it was clearly indicated that the damage resulted from the impact and fire, and while some of both the main and auxiliary control cables were broken, the characteristics of the breaks definitely indicated that they were broken under an impact tension load.

The right down elevator cable was found off the pulley and jammed between the pulley hub and the right fork of the mounting bracket, located just forward of the tail wheel spindle mounting bulkhead, which apparently had been torn from its mounting gusset by impact. Furthermore, a portion of the outboard flange of the micarta pulley had broken off with that portion of the cable forward of the pulley bracket under tension and that portion to