(Bloomberg) -- Southwest Airlines Co. is stepping up inspections on its jet fleet after investigators said they discovered evidence of metal fatigue on an engine that exploded Tuesday, sending shrapnel into the plane and killing a passenger seated near a window.
The woman was partly sucked out of the plane carrying 149 people as it flew about 32,500 feet above Pennsylvania, according to passenger accounts and the National Transportation Safety Board. The death was the first fatality on a U.S.-registered airline in more than nine years.
The plane, a Boeing Co. 737-700 bound for Dallas from New York’s LaGuardia airport, made an emergency landing at Philadelphia International Airport shortly after 11 a.m. on Tuesday.
Safety Board investigators found indications of metal fatigue, an area of weakness caused by repeated bending, where a fan blade on the engine was missing, NTSB Chairman Robert Sumwalt said in a briefing on Tuesday night. Sumwalt cautioned that the information was preliminary.
Southwest Chief Executive Officer Gary Kelly told the NTSB that the company would begin additional inspections of its engines, Sumwalt said.
Sumwalt said Wednesday on CNN that he’d been told by the executive that the company planned "aggressive" ultrasound testing to detect potential fatigue in its fleet. The pilots brought the plane down promptly, landing at a higher speed than usual to ensure they could control the plane, he added.
"I did listen to the aircraft control communications, and it certainly sounded to me like they did an excellent job,” Sumwalt said. “From a fellow airline pilot, my hat’s certainly off to them." Sumwalt flew the 737 and other aircraft during a career as a pilot.
The plane was powered by CFM56-7B engines, which are made by CFM International Inc., a joint venture between General Electric Co. and France’s Safran SA. CFM, the sole supplier of engines for 737-700 planes, said it has sent technical representatives to examine the plane.
The Associated Press identified the woman who was killed as Jennifer Riordan, a vice president of community relations for Wells Fargo & Co. in Albuquerque, New Mexico. Seven people suffered minor injuries.
She was nearly sucked out of the cabin as it decompressed at high altitude and other passengers had to pull her back into the plane as it flew at hundreds of miles an hour, according to passenger accounts.
A man in a cowboy hat rushed forward a few rows "to grab that lady to pull her back in,” Alfred Tumlinson, of Corpus Christi, Texas, told the AP. “She was out of the plane. He couldn’t do it by himself, so another gentleman came over and helped to get her back in the plane, and they got her.”
One of the Southwest pilots radioed to air-traffic control during the emergency that "someone went out," according to a recording on the LiveATC.net website.
“This is a sad day,” Southwest’s Kelly said on a video released by the company. “On behalf of the whole Southwest family, I want to extend our deepest sympathies to the family and loved ones of our deceased customer.”
As the cabin suddenly lost pressure, flight attendants began crying, one passenger, Marty Martinez, founder and CEO of Social Revolt digital marketing in Dallas, said in an interview.
“When we saw that they started crying, of course we thought we were in a really bad place. We were going down,” Martinez said. The woman who was injured “made no noise at all,” he said.
In a LinkedIn profile, Riordan said she managed volunteer service by almost 1,700 employees at non-profits in New Mexico and helped represent the company in the community.
The death shattered an unprecedented string of more than nine years without an accident-related fatality on a U.S. passenger airline.
The last fatal accident involving a U.S.-registered carrier occurred near Buffalo, New York, on Feb. 12, 2009, when a commuter carrier operated by Colgan Air crashed, killing 49 people on board and a man on the ground.
The NTSB shipped the Southwest plane’s two black boxes, crash-proof recorders to its lab in Washington, where investigators did an initial download of the cockpit voice recorder on Tuesday night, Sumwalt said.
Television feeds and photos posted on Twitter show the front of the aircraft’s left engine had been ripped open. A metal piece that covers the exterior of the engine was found in Bernville, Pennsylvania, about 60 miles north of Philadelphia, Sumwalt said.
The plane had been aloft for about 30 minutes when an explosion shattered the routine and oxygen masks descended from the ceiling, Martinez said. He and others took to social media, using the plane’s Wi-Fi connection, trying to leave final messages in case the plane crashed.
“I kind of just felt like it was over,” he said. “We’re flying at 30,000 feet going 500 miles an hour.”
Reports of shrapnel shattering a window suggest that the engine broke apart in what is known as an “uncontained” failure. U.S. regulations require engines to be covered in tough casings designed to prevent metal from flying into fuel tanks and passenger areas if an engine breaks apart.
Sumwalt said the NTSB did not have enough information yet to call the failure uncontained.
The CFM engines are among the most widely used in the world, powering more than 6,700 aircraft for more than 350 million flight hours, CFM said in a statement.
The NTSB investigates the most serious engine failures and conducted a probe of a similar Southwest episode in 2016 involving the same type of engine.
While engine failures haven’t caused a major crash in the U.S. in decades, incidents that threaten safety continue to occur.
On Oct. 28, 2016, an engine on an American Airlines plane exploded on a Chicago runway as the aircraft was preparing to take off, triggering a massive blaze that melted one wing. A disk within the GE CF6-80 engine was later found to have a manufacturing defect, the NTSB said. Pieces of the spinning disk flew as far as 2,920 feet (890 meters), striking a warehouse. The plane was a Boeing 767.
The 737-700 that made the emergency landing on Tuesday was delivered in August 2000 and only flown by Southwest, FAA records show. The model is the smallest jetliner currently manufactured by Boeing and is the heart of the airline’s all-737 fleet. The Texas carrier has hunted for used -700s in recent years as it parked an earlier version known as the 737 Classics.
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