Federal investigators say the crash of an Air Midwest Express commuter plane, which killed 21 people in Charlotte six months ago, was the result of shoddy maintenance done by outside contractors.
Now the Inspector General of the Department of Transportation is warning more safety problems could follow unless the FAA tightens inspections of outside maintenance shops.
Since 1996 major airlines have increasingly farmed out maintenance, going from 37 percent in 1996 to 47 percent in 2002. Now almost half is done by outside contractors.
The process -- called "outsourcing" -- saves airlines money. In-house airline mechanics make about $80 an hour, outside mechanics about $45.
Yet, the IG's investigation says the FAA is paying little attention to the outside work.
Investigators say they found serious problems undetected by the FAA at 18 of 21 maintenance repair stations checked -- everything from improper parts and tools to outdated maintenance manuals.
The FAA says it's working to tighten controls but also suggests the IG's investigation was too narrow to produce accurate results.