American Airlines aircraft seats that dislodged in flight, temporarily grounding 48 Boeing Co. 757s, had already had been under scrutiny by the carrier for becoming loose more often than on other aircraft.
The airline initially blamed incorrectly installed saddle clamps before determining that a buildup of residue from spilled sodas, coffee and juice kept locking pins from remaining in place, David Campbell, American's vice president for safety, security and environmental, said Friday.
"We look every month because we have seen they were coming loose a little more than the average fleet we have," he said. "We have a very aggressive maintenance program. There were just generally problems with the seat in terms of how it's designed compared to later designs out there."
The seat issues developed as the Fort Worth-based airline, which is operating in bankruptcy, struggled with delayed flights and tried to fend off a takeover attempt by US Airways Group Inc. American, a unit of AMR Corp., canceled 94 flights Thursday and Friday while it carried out the inspections.
The seats, which have been used for years, differ from others because two locks are torque-tightened and two are tightened by hand instead of all being torque-tightened. The manufacturer recommends inspections every 18 months, Campbell said.
The seats were designed and made specifically for American by Zodiac Aerospace's Weber Aircraft Inc. unit in Gainesville, Texas. Robert Funk, vice president of sales and marketing for Weber, said he couldn't immediately comment.
The 757 inspections began after seat rows in coach sections worked free on three flights from Sept. 26 through Monday. Seat rows were tightened multiple times on at least one of two planes involved, and one set of seats was so loose it shifted backward toward the next row. The seats never came completely loose from the floor, Campbell said.