LOS ANGELES – Southwest Airlines grounded 79 of its Boeing 737-300 aircraft Saturday after a harrowing incident in which a hole tore open in the fuselage of a 15-year-old plane and depressurized the cabin.
Southwest spokeswoman Brandy King said the company canceled 300 flights across the country so Boeing engineers could help conduct emergency inspections on planes of that model. Investigators from the National Transportation Safety Board and the Federal Aviation Administration were still trying to determine what caused the fuselage to rupture on Flight 812 from Phoenix to Sacramento, Calif., on Friday afternoon. The aircraft, which carried 118 passengers, safely made an emergency landing in Yuma, Ariz.
Passengers described a terrifying and chaotic scene. Some reported hearing a noise like a small explosion or gunshot before the cabin lost pressure.
Passenger Shawna Malvini Redden covered her ears, then felt a brisk wind rush by. Oxygen masks fell, the cabin lost pressure, and Redden, suddenly lightheaded, fumbled to maneuver the mask in place.
Then she prayed. And, instinctively, reached out to the stranger seated next to her in Row 8 as the pilot of the damaged aircraft began a rapid descent from about 34,400 feet in the sky.
“I don’t know this dude, but I was like, ‘I’m going to just hold your hand,’ ” Redden, a 28-year-old doctoral student at Arizona State University, recalled Saturday.
While the aircraft’s breathing masks were deployed, some occupants lost consciousness. One flight attendant and one passenger were treated for minor injuries, according to the airline.
At an altitude above 34,000 feet, the Southwest pilots would have had only 10 to 20 seconds of “useful consciousness” to get their oxygen masks on or pass out, said John Gadzinski, an airline pilot and aviation safety consultant.
“The higher you are the less useful consciousness time you have,” said Gadzinski, president of Four Winds Consulting in Virginia Beach, Va. “It’s a credit to the pilots that they responded so quickly.”
Saturday’s cancellations were felt throughout the airline’s network, and it was unclear when the grounded planes would be returned to service.
Officials said the inspections could last for several days and that they were looking for any indications that other planes were suffering from “aircraft skin fatigue.”
“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,” airline spokeswoman Linda Rutherford said.
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, Rutherford said. The planes that were grounded Saturday have not had their skin replaced, she said.
NTSB board member Robert Sumwalt said investigators were going to cut a piece out of the fuselage of the aircraft in Friday’s depressurization incident, which would be studied for fracture patterns. Data from the plane’s flight recorders and black boxes also will be examined, he said.
Southwest officials said the Arizona plane had undergone all inspections required by the FAA. They said the plane was given a routine inspection Tuesday and underwent its last so-called heavy check, a more costly and extensive overhaul, in March 2010.
An Associated Press review of FAA records of maintenance problems for the plane shows that in March 2010 at least eight instances were found of cracking in the aircraft frame, which is part of the fuselage. Those cracks were repaired, the records indicated.
It’s 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 normally visible.
The 737-300 is the oldest plane in Southwest’s fleet, and the Dallas-based company is retiring 300s as it takes deliveries of new models. But the process of replacing all the 300s could take years.
A total of 288 Boeing 737-300s currently operate in the U.S. fleet, and 931 operate worldwide, according to the Federal Aviation Administration.
Southwest has had problems with fuselages tearing in the past. In 2009, a foot-long hole opened in the top of a jet while it was cruising at 30,000 feet, forcing an emergency landing in West Virginia.
That same year, the airline was fined $7.5 million by the FAA for nearly 60,000 flights in which the planes had not undergone required inspections for fuselage cracks.
“Given Southwest’s history, this raises a real concern,” said Jim Hall, a transportation consultant. “Everyone knows they pound those airplanes hard.”
The FAA earlier this year implemented new rules requiring additional structural inspections of Boeing 757 and 737 aircraft. The agency rejected Southwest’s request for more time to complete inspections.
As for Friday’s flight, there was obvious relief when it touched down safely. When the pilot emerged after the landing, passengers “clapped and cheered,” Redden said.
“If overhead bins weren’t in the way, I’m pretty sure we would’ve given him a standing ovation,” she said.
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