NEW YORK/WASHINGTON Inspections revealed no problems with 737-300 jetliners flown by Southwest Airlines Co following an emergency landing by one of the carrier's planes due to an unexplained hole in its fuselage, the company and U.S. regulators said on Tuesday.
The National Transportation Safety Board (NTSB), which investigates accidents, launched a separate probe of Monday night's incident in which Flight 2294 developed a foot-wide hole and lost cabin pressure about 30 minutes after takeoff from Nashville, airline and federal officials said.
Oxygen masks dropped from overhead before Flight 2294 with 126 passengers and five crew aboard heading to Baltimore landed safely in Charleston, West Virginia. No one aboard was injured, officials said.
The Boeing Co 737-300s represent about a third of Southwest's 500 737s, the only plane it operates. Inspections of the 300-series on Monday night turned up no problems and service was normal on Tuesday, Southwest spokeswoman Marilee McInnis said.
The safety board, the Federal Aviation Administration and Boeing have all sent structural experts to Charleston to investigate, officials from the agencies and Boeing said.
"We're working as quickly as possible to figure out what happened to this plane," FAA Administrator Randy Babbitt said in a statement late on Tuesday.
"We'll be looking closely at all the FAA safety directives that applied to this aircraft, as well as the plane's maintenance history," Babbitt said.
The safety board is responsible for determining what caused the hole in the 15-year-old plane, and government and Boeing officials would not speculate on a reason.
Southwest agreed earlier this year to pay a $7.5 million fine to settle U.S. government allegations that it failed to perform necessary inspections for fuselage cracks in 2006-07.
Southwest has said it meets federal requirements for safety inspections, and officials have not raised any connection between Monday's incident and maintenance practices.
The FAA has issued advisories in the past on the need for 737 structural inspections industrywide, but nothing has been specifically recommended for the region of the fuselage affected in Monday's incident.
Boeing estimates that there are about 1,000 737-300s in worldwide service.
(Reporting by Deepa Seetharaman and John Crawley; Editing by Steve Orlofsky and Carol Bishopric)