Thirty-six American Airlines planes were evaluated overnight as the airline scrambled to respond to several incidents in which rows of seats have come loose during flight, the airline said.

The incidents happened on flights from Boston to Miami, from Vail., Colo., to Dallas/Forth Worth, and from New York to Miami.

Originally, the airline only planned to evaluate the seats on eight of its Boeing 757 planes, but it later decided that all 47 planes that have the same model seats and common locking mechanism should be inspected, said Andrea Huguely, spokeswoman for American Airlines.

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“The FAA is aware of our internal review and its findings, as well as the steps we are taking to proactively address the issue,” Huguely said.

Huguely said that American’s engineering and maintenance teams have discovered that the cause is a “saddle clamp improperly installed on the foot of the row leg.” These particular clamps were only used in 47 of their 102 Boeing 757 airplanes.

“The issue does not seem to be tied to any one maintenance facility or one workgroup,” Huguely said.

The FAA said in a statement Monday that the seats in the airplanes had recently been removed and reinstalled during maintenance.

An investigation has also been launched by the Transport Workers Union of America, which represents aircraft mechanics and other maintenance workers at American Airlines, after speculation arose linking seat problems to labor issues.

“Problems related to seats are less likely a labor problem, but rather a management issue related to outsourcing work to third-party facilities,” the union said in a statement, saying that work related to seat installation on American’s aircraft has been done by an outside firm.

“Our investigation is ongoing, but we have no reason to believe this was in any way intentional,” the airline said in a statement.

Cancellations were “minimal” and no injuries were reported, the airline said.

The incidents happened Sept. 26 on a flight from Vail to Dallas/Fort Worth, on Saturday on a flight from Boston to Miami, and on Monday on a flight from New York to Miami. One of the planes was used in two of those flights.