The Transportation Department's inspector general said the outsourcing, which has more than doubled in four years, was of concern because the Federal Aviation Administration has failed to closely track how much maintenance is farmed out and where it is performed.
Although the FAA has taken steps to improve, "the agency still faces challenges in determining where the most critical maintenance occurs and ensuring sufficient oversight," investigators said in the report issued this week.
In their effort to lower costs, the report said, airlines continue to shift their heavy airframe maintenance from their own in-house mechanics and engineers to hundreds of repair companies in the United States, Canada, Mexico and countries in Central America and Asia.
Nine major airlines examined by the inspector general outsourced 71 percent of their heavy air frame maintenance
- repairs and servicing to an aircraft's body, wings and tail - in 2007, up from 34 percent in 2003. More than a quarter of that maintenance
- 27 percent - was performed at foreign repair facilities.
The airlines examined in the report were AirTran Airways, Alaska Airlines, America West Airlines, Continental Airlines, Delta Air Lines, JetBlue Airways, Northwest Airlines, Southwest Airlines, and United Airlines. American Airlines, the nation's largest domestic carrier, was not included, the inspector general said, because it handles most maintenance in-house.
The FAA relies heavily on the airlines - and the repair facilities themselves
- to make sure outsourced repairs meet the air safety standards and requirements of the individual airlines.
FAA requires each repair station to undergo a government inspection at least once a year, FAA spokesman Les Dorr said. The report says those inspections often are not being conducted by agency inspectors most familiar with standards and requirements of the airline whose planes are being repaired.
As much as five years lapsed between visits to some major maintenance facilities by inspectors assigned to individual airlines. Inspectors not assigned to a specific airline may not be familiar with the special maintenance requirements of that airline's planes, which are often customized.