Map Aircraft Repair & Maintenance Facilities

Source: FAA records, as of Nov. 19, 2010

A decade ago, aircraft repair and maintenance work was mostly done by the airlines flying the planes. Today, most major airlines outsource the bulk of heavy maintenance to lower-cost independent operations in the U.S. and abroad. And generally, most of the mechanics at these independent facilities aren't FAA-licensed.

Federal Aviation Regulations allow U.S.-based repair stations to hire unlicensed mechanics as long as they're properly supervised by licensed mechanics. In these U.S.-based facilities, 46 percent of mechanics hold some FAA license.

But increasingly, contract maintenance is being done overseas in FAA-certified facilities spread across 64 countries. In these facilities, less than 4 percent of the mechanics hold a FAA license of any kind -- although their mechanics may substitute sufficient training or expertise for an FAA license.

Should we worry? Watch the full investigation online and read about what went into reporting the story.

Learn more about how mechanics are licensed from veteran FAA inspector Linda Goodrich. According to Goodrich, the license, known as Airframe and Powerplant [A&P], requires "a significant amount of training, usually about two and a half years of training exclusive on working through every single detail of how to work on an airplane." In addition, read more about what FAA head of aviation safety Peggy Gilligan says about overseeing these foreign stations.

Map Credits: Jacob Fenton, Lisa Hill and Catherine Rentz