Records show holed jet had history of cracks in fuselage

Records show that cracks were found and repaired a year ago in the frame of the Southwest Airlines Boeing 737-300 that made an emergency landing at an Arizona military base after a hole was torn in the passenger cabin, it emerged yesterday.

No-one was seriously injured as the aircraft carrying 118 people lost cabin pressure and made a controlled descent from 34,500 feet, landing safely near Yuma, Arizona, on Friday.

Investigators in Yuma said they were cutting a piece from the fuselage of the stricken plane to determine how the rupture occurred.

Southwest grounded 80 similar planes to carry out inspections and said it expected to cancel 300 flights to do so.

A review of Federal Aviation Administration (FAA) records of maintenance problems for the 15-year-old plane showed that in March 2010 at least eight instances were found of cracking in the frame, which is part of the fuselage. The records showed that those cracks were repaired.

It is not uncommon for fuselage cracks to be found during inspections of planes that age, especially during scheduled heavy maintenance checks in which they are taken apart so that inspectors can see into areas not usually visible.

The National Transportation Safety Board (NTSB) worked to determine what caused part of the fuselage to rupture.

NTSB member Robert Sumwalt said investigators will study the cut-out fuselage piece for fracture patterns and examine the plane's black box and flight recorders.

Southwest officials said the Arizona plane had undergone all inspections required by the FAA. They said the plane was given a routine inspection last Tuesday and underwent its last so-called heavy check, a more costly and extensive overhaul, in March 2010.

Southwest operates about 170 of the 737-300s in its fleet of about 540 planes, but it replaced the aluminum skin on many of the 300s in recent years, spokeswoman Linda Rutherford said.

The planes that were grounded on Saturday have not had their skin replaced, she added.

"Obviously we're dealing with a skin issue, and we believe that these 80 airplanes are covered by a set of (federal safety rules] that make them candidates to do this additional inspection that Boeing is devising for us," Ms Rutherford said.

A similar incident happened in July 2009, when a football-sized hole opened up in-flight in the fuselage of another of Southwest's Boeing 737s, depressurising the cabin.

The plane made an emergency landing in Charleston, West Virginia.It was later determined that the hole was caused by metal fatigue.

In response to that incident, the airline changed its maintenance plan to include additional inspections, which FAA reviewed and accepted, said John Goglia, a former NTSB member and an expert on airline maintenance. The details of the plan are considered proprietary and are not made public, he said.

Four months before that emergency landing, Southwest had agreed to pay $7.5 million to settle charges that it operated planes that had missed required safety inspections for cracks in the fuselage. The airline inspected nearly 200 of its planes then, found no cracks and put them back in the sky.