Southwest Airlines returned to its regular schedule today after finishing inspections on 77 Boeing 737-300s for fatigue cracking. The airline found “minor” subsurface cracking on two more airplanes yesterday, bringing the total to five airplanes that must remain out of service until Boeing recommends appropriate repairs and Southwest completes them. As of this morning, two more aircraft awaited inspection, which Southwest said it would perform within 24 hours. 

The FAA has notified Boeing operators that it would issue an emergency Airworthiness Directive today for a specific subset of the Boeing 737-300, -400 and -500 fleet. The action, prompted by the in-flight rupture of the fuselage a Southwest Airlines 737-300 on Friday, April 1, and subsequent findings of fatigue cracking on the Southwest Boeing 737s, will initially apply to a total of some 175 aircraft worldwide, 80 of them registered in the U.S. Southwest canceled some 670 flights since Friday’s incident.

Although Southwest Airlines operates most of the aircraft covered by the order in the U.S. and the AD applies to certain 737-500s, the airline said it believes it met the directive’s requirements with the inspection of the its Boeing 737-300s.