It has not been a good weekend for Southwest Airlines. The carrier grounded dozens of planes and canceled hundreds of flights after a hole opened up in the fuselage of a plane in mid-flight on Friday. Investigators subsequently found widespread cracking in that plane. And now comes news that cracks have been found in at least three more Southwest jets.

According to the AP, Southwest has confirmed that two of its Boeing 737-300s are showing sub-surface cracking that will need to be repaired, and the National Transportation Safety Board has confirmed the existence of a third plane with developing cracks.

The airline grounded 79 Boeing 737-300s following Friday’s incident, in which a flight from Phoenix to Sacramento was forced to make an emergency landing at a military base in Yuma, AZ. It is hoping to have all the grounded planes inspected by Tuesday.

The AP reports that there are nearly 300 Boeing 737-300s in use by U.S. airlines. But the FAA would not say whether or not it would require other carriers to inspect their jets:

The NTSB also could issue urgent recommendations for inspections on other 737s if investigators decide a problem has been overlooked. The agency’s investigation has not determined that the cracks caused the rupture, but it is focused on that area.

NTSB: Cracks similar to those found in damaged Southwest Airlines jet found in 3 other planes [Chicago Tribune]

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