American Airlines canceled about 300 flights, less than 10 percent of the nation's biggest airline's scheduled service, on Wednesday so its crews can inspect some wire bundles aboard its MD-80 aircraft. The cancellations are expected to affect 26,000 passengers.

The need for the new inspections became known during an audit of American by a joint team of inspectors from the Federal Aviation Administration and the Fort Worth-based airline, according to a statement from American.

"We are reinspecting the MD-80s to make sure the wiring is installed and secured exactly according to the directive," American spokesman Tim Wagner said in the statement, which did not describe the function of the wiring.

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

About 50 departures each were canceled at American's hubs at Dallas-Fort Worth and Chicago O'Hare international airports.

"We're just making sure an airworthiness directive was followed," airline spokesman John Hotard told the Chicago Tribune. An airworthiness directive is a legally enforceable rule issued by the FAA to correct an unsafe condition in an aviation product. Air carriers are responsible for complying with all such directives.

The action by American was voluntary and not ordered by the Federal Aviation Administration, FAA spokeswoman Elizabeth Isham Cory told the Tribune.

Shares of American's parent AMR Corp. slipped 13 cents, or 1.4 percent, to $9.50 in premarket trading Wednesday. They have traded in a 52-week range of $8.38 to $34.

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