CBS News reports that cracks were found in the structure that holds the engine to three 767s, according to the Federal Aviation Administration. The airline, however, insists cracks were only found on two of its aircraft.
"It was only those three airplanes that exhibited cracking," FAA spokesman Les Dorr told CBS News. "We and Boeing and American are evaluating the situation, trying to see what the root cause of the cracking is because you need to know the cause to develop the fix for it."
American spokesman Tim Wagner said Tuesday the cracks were discovered in the pylons that attach the engines to the wings on one plane during normal maintenance, and that prompted the general inspection of all planes with the same type of part.
American, which is based in Fort Worth, Texas, has 73 Boeing 767s in its fleet of 620 aircraft.
Wagner says 54 planes had been inspected by Monday. The other two were to be inspected Monday night, but Wagner didn't have confirmation that those inspections had been completed. He said the airline has sent one of the cracked pylons to an outside company for testing.
"Right now, we're in evaluation mode," Dorr, the FAA spokesman, told CBS News. "Depending on what that evaluation shows, it's conceivable that we might take some further action. That would cover more than just American airplanes; it would cover the model."
Wagner said the inspections have not caused any major disruption to American's schedule. Two of the planes found to have cracks were repaired overnight and put back into service.
FAA spokesman Les Dorr said the cause of the cracks has not yet been determined. Once the cause is found, Dorr said, "some broader action" by the FAA is possible. That includes inspections of pylons at other airlines.
Shares of American Airlines' parent company AMR Corp. dropped 33 cents, or 4.1 percent, to $7.91 in afternoon trading.