Federal investigators say the entire length of a 5-foot-long tear in the skin of a Southwest Airlines Boeing 737 shows evidence of pre-existing fatigue cracking.
National Transportation Safety Board member Robert Sumwalt says the rip in the jet that made an emergency landing in Yuma, Ariz., Friday was a foot wide. It started along a lap joint where two sections of the Boeing 737-300's skin are riveted together.
Southwest mechanics will be cutting the entire ripped section out of the plane on Sunday. Sumwalt says he expects a 9-foot by 3-foot section will be removed and sent to Washington D.C., for analysis.
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The jet had leveled off at 36,000 feet after taking off from Phoenix when the skin ruptured. The pilots rapidly descended. One flight attendant was hurt.
Flight 812 Makes Emergency Landing in Yuma
A Southwest Airlines flight made an emergency landing Friday because of a hole in the aircraft's roof.
Dallas-based Southwest said the plane suddenly lost cabin pressure. Passengers said they could see daylight in the cabin and that the plane began to drop fast.
The flight crew discovered a hole in the top of the Boeing 737 after it landed safely in Yuma, Ariz., Southwest said. Passengers said the hole was about 6 feet wide.
"It's at the top of the plane, right up above where you store your luggage," passenger Brenda Reese told The Associated Press in a telephone interview. "The panel's not completely off. It's like ripped down, but you can see completely outside... When you look up through the panel, you can see the sky."
Reese said the plane had just left the airport when she awoke after hearing a "gunshot-like sound."
Flight 812 left Phoenix at 3:25 p.m. PST for Sacramento, Calif. It landed at Yuma Marine Corps Air Station/International Airport at 4:07 p.m. PST.
The 118 passengers were expected to arrive in Sacramento later Friday night, Southwest said in a statement.
A flight attendant had minor injuries after the descent.
A passenger told KCRA-TV that a few passengers apparently passed out after the oxygen masks dropped. The airline said no passengers were injured.
It was not immediately clear what caused the hole.
Julie O'Donnell, an aviation safety spokeswoman for Seattle-based Boeing Commercial Airplanes, confirmed there was "a hole in the fuselage and a depressurization event" but declined to speculate on what caused the incident.
The Federal Aviation Administration and the National Transportation Safety Board will investigate the incident.
The FAA said Friday that an inspector from Phoenix was headed to Yuma. The NTSB said an inspection team would leave for Yuma on Saturday.
Terrorism was not suspected because "it appears to be a mechanical issue," said Steve Dupre, an FBI spokesman in Sacramento.
Holes in aircrafts can be caused by metal fatigue or lightning. The National Weather Service said the weather was clear from the Phoenix area to the California border on Friday afternoon.
A hole about the size of a football opened up in the roof a Southwest Airlines Boeing 737 in July 2009. Federal investigators blamed the incident on metal fatigue.
Southwest Airlines Flights Canceled
Dallas-based Southwest Airlines grounded 79 of the airline's Boeing 737s to be inspected.
Southwest expected to cancel approximately 300 flights Saturday to accommodate the inspections, which caused flight delays and cancellations across the country.
The airline will work with Boeing to inspect for aircraft skin fatigue.
"The safety of our Customers and Employees is our primary concern," said Mike Van de Ven, Southwest's executive vice president and chief operating officer in a news release. "We are working closely with Boeing to conduct these proactive inspections and support the investigation. We also are working aggressively to attempt to minimize the impact to our Customers' travel schedules today."
The 118 passengers on board Flight 812 have received a full refund along with an apology and two complimentary round trip passes on Southwest for future flights.
NBCDFW's Elvira Sakmari contributed to this report.