NEW YORK (CBSNewYork) -- The federal government has announced that inspections on Boeing 737s should be expanded beyond Southwest Airlines.
On Monday, Southwest revealed that inspectors found cracks in three more of its planes -- similar to the ones suspected in the fuselage tear on one of its jets on Friday.
The hole opened up in one Southwest's jets 35,000 feet over Arizona, a terrifying mid-flight fracture, created an intense noise and a wild wind that sent 118 passengers scrambling for their oxygen masks.
"People looked up and said 'Oh my God, you can see the sky'," said passenger David Mathias.
"All of a sudden a loud bang, masks dropped, it was windy, we put on masks," recalled passenger Shawna Malvini Redden.
The plane set down in Yuma, remarkably with no serious injuries onboard.
Mechanics sawed out a section of the plane's aluminum skin and was expected to sent it to the National Transportation Safety Board in Washington Monday morning.
FAA records show at least eight instances of cracks in the same plane a year ago, but they were all repaired.
Investigators said this crack would not have been visible to the naked eye. An examination showed extensive pre-existing damage along the tear and more cracks in areas that had not torn open.
"We did find evidence of widespread cracking across the entire fracture surface," a NTSB official said.
The entire section of the fuselage has been removed and taken to the NTSB testing lab in Washington. Experts told CBS 2's Lou Young the decompression was probably more gradual than it could've been -- first a hole in the inner skin and then loss of the outer metal plate.
"So the aircraft began to peel back the plate. That's when passengers could see the sky. That's when they heard what they really describe as a crackling, not a boom. Crackling would've been ripping it, would've sounded like gunfire," former airline pilot John Tristani said.
Southwest grounded 79 planes over the weekend and inspectors found similar cracks in three of them. The planes are being returned to service as they're inspected and cleared -- a process that should last until late Tuesday.
When asked if she feels safe getting on a plane, air traveler Angela Harvey told Young, "I do, I do. I feel, because, I feel that because they've increased they're maintenance on their double checking, so sometimes it's a little safer to fly after something like this."
"I have faith they'll inspect them thoroughly," passenger Roger May told CBS 2's Christine Sloan.
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Passengers at LaGuardia Airport were anxious over the news.
"I'm concerned but I need to get home," said Southwest Customer Monique Jones.
So what are investigators looking for as they inspect the 737s?
"Well, it could be a number of things. It could be corrosion that gets in there. It could be stress in that particular area," former NTSB investigator Al Yurman told Sloan.
Sloan then asked Yurman if the problem could have been caught during routine inspections.
"In order to find a crack it's a little bit more detailed -- something you can't see with your eye. You'd have to X-ray the aircraft or dye penetrate, where they put dye and the cracks show up," Yurman said.
Back in 2009 metal fatigue caused a hole to rip open on another Southwest 737. Months later, the airline paid out $7.5 million to settle charges that it missed safety inspections for cracks in the fuselage.
Yurman said all Boeing 737s could be scrutinized.
"What different stresses does Southwest go through versus an airplane that may fly for two hours at a time with not as many landings and takeoffs," Yurman said.
Cancellations and delays were expected for hundreds of Southwest Airlines passengers.
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