Southwest announced another round of flight cancellations as it checks planes for fuselage cracks like the one that tore a meter-long hole in the hull of a flight above Arizona Friday. The airline has canceled more than 60 flights so far today, but is expected to cancel a total of 100 by the day’s end. It grounded about 300 flights over the weekend. Cracks have been found in at least three 737-300 planes since the checks began. It’s the second time Southwest has dealt with fuselage cracks: In July 2009, the airline inspected all its 737-300s after a one-foot hole ripped open at the top of a jet’s hull during a flight.