Investigators trying to determine why the roof of a Southwest Airlines jet peeled open in flight this month are focusing on the manufacturing process at Boeing.
Government and industry officials say investigators noticed that the stricken jet and five other Southwest planes that had cracks in their metal skins were all built at about the same time in the same Boeing plant.
The officials cautioned Monday that no final determination has been made about why the planes developed cracks in an area of the fuselage many years before Boeing expected to see problems.