By DAVID KOENIG

Associated Press

American Airlines says passenger seats on a third flight came loose as the plane was airborne, and it’s continuing to inspect other jets with similar seating.

The airline acknowledged Tuesday that seats came loose on a flight last week from Dallas-Fort Worth International Airport to Vail, Colo. The same thing happened aboard the same plane Monday and a second plane Saturday, according to the airline.

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. An airline spokesman said it turned out to be a faulty cooling fan in an entertainment system, and the plane was expected to continue on to London Tuesday night.

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 publicity about the problem could make passengers stay away from American and fly on other airlines instead.

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 spate of loose-seat reports prompted American to inspect eight of its Boeing 757s that share similar seat assemblies.

Airline spokeswoman Andrea Huguely said an initial review indicated that there could be a problem with the way the seats fit into tracks on the floor of the Boeing 757, but technical teams from the airline “are looking at everything.”

Asked if seats had ever come loose on an American flight before last week, Huguely replied, “Not that I’m aware of.”

Huguely was adamant, however, in saying that the incidents were not the result of sabotage by workers. American’s union employees are unhappy about pending layoffs and cuts in pay and benefits that American has imposed since filing for bankruptcy protection in November. American accuses some pilots of conducting an illegal work slowdown that has caused a jump in canceled and delayed flights.

The problem planes were worked on by several crews in different cities. After seats came loose the first time, a crew in Vail tightened them and the plane made a return flight to Dallas. It flew to Boston later that day, where the seats were tightened again, according to American.

No further problems were noticed until a flight Monday from New York to Miami, which returned to Kennedy Airport. Another plane making a Boston-to-Miami trip on Saturday made an emergency landing in New York after a row of seats came loose in flight.

The seats on both planes had been removed and reinstalled during recent maintenance at an American Airlines maintenance base in Tulsa, Okla., and a Timco Aviation Services facility in North Carolina. In both cases American employees were the last to touch the seats, Huguely said.

A Timco spokesman declined to comment beyond saying that the company is still investigating.