FORT WORTH (CBSDFW.COM) — There are new developments centered around American Airlines and the problems they’ve had after loose seats were found on three flights, including one headed to Dallas/Fort Worth International Airport.

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CBS 11 News has learned that American is now voluntarily conducting a second round of inspections on 48 separate 757s, and will have to cancel over 40 flights Friday due to the inspections.

Since the first incident American has blamed the problem on a malfunctioning seat locking mechanism.

American Airlines Seat Lock Connector (Jason Allen)

In a press release statement airline spokeswoman Andrea Huguely said, “Working with the FAA, American Airlines is taking additional steps to prevent seats from becoming dislodged on some of our Boeing 757 aircraft. After further analysis by our engineering team, the company is taking additional  preventative steps to enhance the locking mechanism features used to secure the seats to the aircraft floor.”

Last week, a row of seats came loose on a 757 during a flight from Colorado to DFW Airport. That same plane had an identical problem on a flight Saturday.

One other 757 also had a row of seats come loose during flight.

Mechanics were told to pay particular attention to the “seat lock plunger” that secures the seat to the floor.  The airline is “going through the fleet and we’re adding an additional locking feature on top of this that we believe prevent this from happening again,” said American’s Vice President for Safety David Campbell.

The seat lock plunger from an American Airlines airplane. (Jason Allen)

The tiny pin at the top of this connector is what the airline says can get gummed up, stick and prevent seats from locking .

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Seat Lock Plunger Mechanism (American Airlines handout photo)

Earlier this week, the airline conducted inspections on their 757 fleet and found four other planes had the same potential loose seat problem.

Lynn Lunsford with the Federal Aviation administration (FAA) released the following statement on the inspection. “The FAA is aware of American’s decision to conduct further inspections on certain Boeing 757s and concurs with this step.  Our safety investigation continues and we’ll take additional action as appropriate.”

The airline will be placing a secondary lock on each of the seats on the planes, a move that has taken between 4 to 6 hours per plane.

The airline canceled 50 flights Thursday, and has already canceled 44 flights for Friday as of Thursday night.  “Some select flights may be delayed or canceled in order to complete this work. We expect this work will be completed by Saturday, Oct 6,” Huguely said.

CBS 11 obtained a copy of the inspection instructions for the seats. It is two lines – grab the seat back and move it. Make sure it doesn’t move at the floor.

When asked if maintenance crews did all the inspections required when seats were moved to create more legroom, the airline said it didn’t see anything to believe it was due to human failure.

The work will be done on each plane as it lands at its next destination.  American says years of soda and coffee spills can gum up the lock.

American says it has found records that show the particular seats on 757s have a history of being loose, but never dislodge.  Campbell says two incidents with the planes within days was completely random.

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