Safety inspectors have found what they describe as “widespread cracking” and fatigue on the fuselage of the Southwest Airlines Boeing 737 forced to make an emergency landing Friday when a large hole opened in the cabin mid-flight.

“Was the aircraft well maintained and should it have been maintained better? That is exactly why we are here, to look at why this problem occurred,” National Transportation Safety Board Member Robert Sumwalt said at a press conference broadcast from Yuma, Arizona, via Internet streaming, reports Reuters.

Southwest announced yesterday it would be grounding part of its fleet for further inspections, and already today, 19 planes had been sent back into service after inspections found no problems.

Around 600 flights have been canceled since the incident, which occurred on a flight from Phoenix to Sacramento, Calif., and the airline announced there would likely be more as they try to inspect the 79 Boeing 737-300 planes in its flight.

An official for the airline said the plane, which went from 36,000 feet to 11,000 feet in three and half minutes to make an emergency landing in Yuma, Ariz., was in compliance with its safety inspections requirements.

“What we saw with Flight 812 was a new and unknown issue,” said Mike Van de Ven, Southwest’s executive vice president and chief operating officer.

“We regret any customer inconveniences as a result of the inspections currently underway,” he said in a statement. Delays and cancellations are never the preference, however we are taking every precaution we can to ensure that our operation is safe.”

When the plane was inspected, evidence of “multi-site damage” was found, and widespread cracking across the entire fracture surface. The tear happened in a part of the plane that is concealed and not visible to the naked eye.

Widespread cracking found on Southwest plane [Reuters]

Previously: Southwest Grounding 79 Planes After Hole Opens in Fuselage Mid-Flight

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