(AP) - American Airlines canceled about 325flights Wednesday so its crews could inspect some wire bundlesaboard its MD-80 aircraft.

The canceled flights represent about 14 percent of the estimated2,300 flights that the nation's biggest airline had scheduled forthe day. The highest concentrations of the cancellations were inthe airline's hubs at Dallas-Fort Worth and Chicago O'Hareinternational airports.

American initially put the number of cancellations at 200, butspokesman Tim Wagner said the estimate grew as the day progressedbecause the airline prefers to hold off on cancellations as long aspossible. The entire fleet of MD-80s was being inspected, Wagnersaid.

The need for the new inspections became known during an audit ofAmerican by a joint team of inspectors from the Federal AviationAdministration and the Fort Worth-based airline, Wagner said.

The inspection involves proper spacing between two bundles ofwires in the plane's auxiliary hydraulic system, Wagner said. Itmust be installed "exactly according to the directive," he said.

Of the 80 planes that the airline decided needed modification,about 20 have returned to flying, Wagner said. He said no Thursdayflights had been canceled as of Wednesday evening.

"We are in the process of completing the inspections on theremaining airplanes and will return them to service on a rollingbasis throughout the day," Wagner said.

About 85 departures were canceled in Dallas-Fort Worth andanother 68 were grounded in Chicago, Wagner said.

Shares of American's parent AMR Corp. fell $1.02, or 10.6percent, to close at $8.61 Wednesday, approaching the lower end oftheir 52-week range of $8.38 to $34.