As airlines cut costs by outsourcing their maintenance, federal safety inspectors need to keep a closer eye on the outside repair work, the Transportation Department's inspector general told Congress.

Airlines contracted out 54 percent of their repair work last year, half again as much as they did in 1996, Kenneth Mead told the Senate Transportation aviation subcommittee.

"The transition to increased use of outside repair facilities is not the issue," Mead said. "It is that maintenance, wherever it is done, requires oversight."

Mead also told the subcommittee he worries about FAA oversight of non-U.S. repair stations.

He said his investigators found that 138 repair stations in France, Germany and Ireland were not inspected by the FAA at all because the civil aviation authorities in these countries reviewed them instead.

But FAA was not monitoring their surveillance adequately, he said. Foreign inspectors didn't give FAA enough information on results of their inspections, in many cases because they weren't written in English, he said.

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