Southwest Airlines expected to cancel 70 more flights, or 2 percent of its Monday schedule, as it inspected older planes for cracks in the fuselage.
The airline canceled about 600 flights and grounded 79 planes over the weekend after a Boeing 737-300 jet sprang a 5-foot hole in the roof shortly after takeoff from Phoenix on Friday. The plane made an emergency landing. Southwest said no one was seriously injured.
Spokeswoman Brandy King said Monday morning that Southwest had inspected 33 similar planes and returned them to service and expected to complete checks on remaining grounded planes by late Tuesday.
Southwest said three planes had cracks similar to those in the Phoenix jet and would be repaired before they fly again.
The Federal Aviation Administration requires airlines to regularly inspect planes for cracks, which may result from metal fatigue caused by pressurizing the cabin while climbing to cruising altitude and decompressing as they drop lower before landing.
The Southwest jet with the torn roof was 15 years old and had made nearly 40,000 takeoff and landing cycles.
Boeing produced more than 1,100 of the 737-300 from 1984 to 1999. About 760 remain in use, including 195 in the U.S., according to aviation research firm Ascend Worldwide Ltd. Southwest has about 170, US Airways has 19 in its fleet.
US Airways said Monday it had not grounded nor done additional inspections if its 737-300s.