A team from the National Transportation Safety Board reports that a preliminary inspection shows a metal fan blade failed, the same thing that happened two years ago. In that incident, a Southwest jet powered by the same type of engine landed safely in Florida after a blade separated from the engine.
But the incident Tuesday had fatal consequences. A woman passenger seated by a window died when metal debris from the engine shattered the window, hitting her and nearly sucking her out of the aircraft. Several other passengers were injured, but the plane landed safely in Philadelphia.
Investigators say metal fatigue was the likely cause of the accident, and Southwest Airlines has announced an acceleration of its program to inspect CFM56-7B engines used on its Boeing 737 aircraft.
The inspections won't be limited to Southwest jets. The Federal Aviation Administration (FAA) said it will issue an airworthiness directive that will require inspections of certain CFM56-7B engines.
The agency said it plans to require an ultrasonic inspection of fan blades when they reach a certain number of takeoffs and landings. Any blades that fail the inspection will have to be replaced.
According to Boeing, the CFM56-7B engine is used on more than 8,000 Boeing 737 jet aircraft.