DALLAS — American Airlines said that improperly installed clamps caused seats to pop loose on two planes during flights and an inspection turned up four others with the same problem.
The airline said Tuesday that it inspected and fixed the seats on 36 of its Boeing 757 jets and planned to check 11 other planes.
In the past week, rows of seats have come loose on three separate flights, two of which made emergency landings. Federal officials are looking into the matter, which safety advocates consider to be serious.
David L. Campbell, the airline’s vice president of safety, said in an interview that the clamps might have been installed incorrectly during maintenance work by American crews and an outside contractor, Timco Aviation Services. He could not recall a similar problem with any other American planes.
The first sign of trouble showed up last Wednesday, when crews noticed loose seats on a plane that had flown from Dallas-Fort Worth International Airport to Vail, Colo. The seats were tightened again that day in Boston. The same plane had to make an emergency landing Monday when seats came loose shortly after takeoff on a New York-to-Miami flight.
Another plane flying from Boston to Miami on Saturday diverted to New York after seats loosened in mid-flight.
Separately, an American flight on Tuesday from Chicago to London was diverted to Shannon Airport in Ireland after a report of smoke in the cabin, which the airline attributed to a faulty fan in an entertainment system.
The reports of smoky cabins and seats coming loose during flights raised questions about safety on the nation’s third biggest airline. Aviation industry experts said bad publicity could lead passengers to avoid American.
Matt Ziemkiewicz, president of the safety-advocacy group National Air Disaster Alliance, said passengers could be hurt or killed in an otherwise survivable crash if seats break loose from their moorings.
“What if it’s a little kid or an old person in the row behind them?” he said. “That seat becomes a projectile with people on it.”
The planes in the Saturday and Monday incidents were serviced in the past two months and seats had been removed and reinstalled, American said.
A Timco spokesman declined to comment beyond saying that the company is still investigating.
The Federal Aviation Administration said it is looking into the incidents as well.
