When the roof of a Southwest Airlines 737 ripped off in midflight, investigators initially thought it was the result of wear and tear from the plane's 39,000 takeoffs and landings. But now it seems the accident may have been due to a problem in production. Investigators now suspect the part of the fuselage that tore off was not riveted together correctly, and in the years since its manufacture in 1996, the area slowly developed cracks. Immediately after the incident, Boeing ordered inspections of the nearly 600 similar 737s in service worldwide, and so far five of the 190 planes looked at so far have had cracks.
