YUMA, Ariz., April 3 (UPI) -- Cracks have been found in the Southwest Airlines jet whose roof tore open in midair, a source told ABC News as 300 flights were canceled Sunday.
ABC, citing a source close to the investigation, reported the fatigue cracks were discovered when investigators examined the plane closely following the Friday incident.
It was not known how those cracks formed or their role in making the ceiling of the Boeing 737 tear open at 36,000 feet.
No one was seriously injured as the plane, on a Phoenix-Sacramento flight, safely executed an emergency landing at a military base in Yuma, Ariz.
Southwest spokeswoman Brandy King told The Baltimore Sun another 300 flights from 72 airports were canceled Sunday as the airline inspected 79 planes.
The 15-year-old jet had made more than 39,000 takeoffs and landings, all stressing its skin.
Reviewing the 737's repair records, ABC found at least a dozen fuselage crack repairs, which is not out of the ordinary.
Southwest said it was working with the National Transportation Safety Board and Federal Aviation Administration to find the cause of the "depressurization event."