DALLAS — Southwest Airlines sought more time last year to inspect jet-engine fan blades like the one that snapped off during one of its flights Tuesday in an accident that left a passenger dead.

The airline opposed a recommendation by the engine manufacturer to require ultrasonic inspections of certain fan blades within 12 months. Southwest said it needed more time, and it raised concern over the number of engines it would need to inspect. Other airlines also voiced objections.

It wasn’t until after Tuesday’s accident that the Federal Aviation Administration announced that it will soon make the inspections mandatory. It is unclear how many planes will be affected by the FAA order. Airlines including Southwest say they have begun inspections anyway.

An engine on a Southwest jet exploded over Pennsylvania on Tuesday, and debris hit the plane. Jennifer Riordan, a 43-year-old bank executive from Albuquerque, New Mexico, was sucked partway out of the jet when a window shattered. She died later from her injuries. The Boeing 737, bound from New York to Dallas with 149 people aboard, made an emergency landing in Philadelphia.

Investigators said the blade that broke off mid-flight and triggered the fatal accident was showing signs of metal fatigue — microscopic cracks from repeated use.

The National Transportation Safety Board also blamed metal fatigue for the engine failure on a Southwest plane in Florida in 2016 that was able to land safely.