National Transportation Safety Board RePort 219

those specified by the manufacturer if its engineering-and mainte-

nance Personnel believe that the task can be accomplished more effi. ciently by using an alternate method.

Thus, in what they perceived to be in the interest of efficiency, safety, and economy, three major carriers developed procedures to comply with the changes required in service bulletins 54-48 and 5459 by removing the engine and pylon assembl as a single unit. One carrier apparently developed an alternate procyedure which was used without incident. However, both American Airlines and Continental Airlines employed a procedure which damaged a critical structural member of the aircraft. The procedure, developed by American Airlines and issued under ECO R-2693, was within American Airlines' authority, and approval or review was neither sought nor required from the manufacturer or the FAA.

The evidence indicated that American Airlines' engineering and maintenance personnel implemented the procedure without a thorough evaluation to insure that it could be conducted without difficulty and without the risk of damaging the pylon structure. The safety board believes that a close examination of the procedure might have disclosed difficulties that would have concerned the engineering staff In order to remove the load from the forward and aft bulkhead's spherical joints simultaneously, the lifting forks had to be placed precisely to insure that the load distribution on each fork was such that the resultant forklift load was exactly beneath the center of gravity of the engine and pylon assembly. To accomplish this, the forklift operator had to control the horizontal, vertical, and tilt movements with extreme precision. The failure of the ECO to emphasize the precision this operation required indicates that engineering personnel did not consider either the degree of difficulty involved or the consequences of placing the lift improperly. Forklift operators apparently did not receive instruction on the necessity for Precision, and the maintenance and engineering staff apparently did not conduct an adequate evaluation of the forklift to ascertain that it was capable of providing the required precision.

The safety board, therefore, concludes that there were other deficiencies within the American Airlines maintenance program, some of which contributed to this accident. Among these was the failure of the engineering department to ascertain the damage-inducmg potential of a procedure which deviated from the manufacturers recommended procedure, their failure to adequatel evaluate the performance and condition of the forklift to assure its capability for the task, the absence of communications between maintenance per-