The U.S. Federal Aviation Administration said Wednesday it would order inspection of some 220 jet engines after investigators said a broken fan blade touched off an engine explosion on a Southwest Airlines flight, shattering a window and killing a passenger.

The order, called an air-worthiness directive, would require an ultrasonic inspection within the next six months of the fan blades on all CFM56-7B engines that have accrued a certain number of takeoffs.

The CFM56 engine on Southwest flight 1380 blew apart over Pennsylvania on Tuesday, about 20 minutes after the Dallas-bound flight left New York's LaGuardia Airport with 149 people on board.