American Airlines, the world's largest carrier, canceled 300 flights yesterday to reinspect wiring in Boeing Co. MD-80s after federal regulators raised questions during a maintenance audit.

The cancellations represent about 13 percent of yesterday's flights. American is checking whether a sleeve covering a bundle of wires was installed according to a Federal Aviation Administration directive, American spokesman Tim Wagner said.

It's the second time in a week that American parent AMR Corp. has had to scrub flights amid industrywide FAA maintenance audits. Carriers have come under increased scrutiny since the FAA proposed a $10.2 million fine against Southwest Airlines Co. this month for flying 46 jets without required fuselage checks.

The FAA is "going through things with a fine-toothed comb," James M. Higgins, a Soleil Securities Corp. analyst in Solebury, Pa., said in an interview. "I don't suggest there's a real safety issue here. Much of this is paperwork."

The FAA, based on its experience at American, advised other MD-80 operators to check their compliance with the wiring-sleeve requirement, agency spokesman Les Dorr said. The FAA didn't require the carriers, including Delta Air Lines Inc., to pull their jets from service to inspect them, he said.

American has 300 MD-80s, which make up about 46 percent of the main jet fleet at the Fort Worth, Texas-based carrier. All 300 have been or are being inspected, Wagner said.

"Many inspections have already been completed and the aircraft are currently in service," Wagner said. "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."

American initially canceled 200 flights yesterday. Additional flights had to be dropped to accommodate the reinspections, Wagner said. About 80 flights were canceled at the carrier's Dallas-Fort Worth hub, and about 68 more in Chicago. The rest were scattered across the United States.

The inspections are intended to verify that a sleeve covering a wire bundle to the auxiliary hydraulic pump is attached to the wheel-well wall at one-inch intervals, as directed by the FAA, Wagner said.

"We have found that some of the attachments were slightly more than one inch," he said. "We are going back to make sure we have precisely attached the sleeve every single inch. This is an abundance of caution on our part."

AMR's American Eagle regional airline grounded 25 jets and canceled 15 flights March 21 to review inspection paperwork on the planes' rudders and hydraulic systems.