Two separate incidents in which passenger seats came loose midflight on two Boeing 757 jets are being examined by US aviation authorities.
An American Airlines (AA) flight from Boston to Miami was forced to make an emergency landing in New York on Saturday.
On Monday a second AA flight from New York to Miami returned to John F Kennedy International Airport after loose seats were discovered.
No injuries were reported in either incident.
AA said both planes underwent maintenance work that required seats to be removed and reinstalled. A spokeswoman for the carrier, Andrea Huguely, said an initial review found that there could be a problem with the way the seats fit into tracks on the floor.
"Out of an abundance of caution, American has decided to proactively reinspect eight 757s that could possibly have this same issue," Ms Huguely said.
The Federal Aviation Administration (FAA) confirmed it was also looking into the incidents, which involved separate repair facilities. Boeing declined to comment other than to say it had nothing to do with the recent maintenance work.
Airline and government officials played down speculation the incidents could be related to tensions between unions and AA, which is cutting labour costs and laying off maintenance workers since it filed for bankruptcy last November.
A recent spate of delays and cancellations have annoyed passengers, but aviation experts have warned just the hint of mechanical issues could frighten customers away and even threaten the airline's existence.
"These things can kill an airline," according to George Hobica, founder of travel website airfarewatchdog.com. "With a delay or cancellation, you're sitting on the ground. [With loose seats] if the plane hits turbulence, people go flying."
AA operates 124 Boeing 757s. The eight being inspected use a similar seat assembly, with 22 first-class places and 166 in economy.
