Inspectors have found small, subsurface cracks in two more Southwest Airlines planes that are similar to the cracks that caused a jetliner to lose pressure and make a harrowing emergency landing in Arizona, the airline said in a statement Sunday.
The two planes will be evaluated further and more repairs will be undertaken before they are returned to service, Southwest said.
Friday's flight carrying 118 people rapidly lost cabin pressure after the Boeing 737-300's fuselage ruptured -- causing a 5-foot-long tear -- just after takeoff from Phoenix.
Passengers recalled tense minutes after the hole ruptured overhead with a blast and they fumbled frantically for oxygen masks. Pilots made a controlled descent from 34,400 feet into a southwestern Arizona military base. No one was seriously injured.
The tear along a riveted "lap joint" shows evidence of extensive cracking that hadn't been discovered during routine maintenance before Friday's flight -- and probably wouldn't have been unless mechanics had specifically looked for it, officials said.
National Transportation Safety Board investigators on Sunday were in Yuma, Ariz., to oversee the removal of the top section of the jetliner's roof around the tear. The structure will be sent to Washington, D.C., for analysis.
Southwest said it cancelled about 300 flights for the second day in a row Sunday as it inspected 79 planes in its fleet similar to the one in Friday's incident.
By Sunday afternoon, 19 planes had undergone the intense inspection with no findings and had been returned to service, the airline said.
Associated Press writers David Koenig contributed from Dallas; Joan Lowy from Washington, D.C.; and Terry Tang, Walter Berry, Mark Evans and Bob Seavey from Phoenix.