The FAA’s proposed AD would, when effective, mandate that airlines perform an ultrasonic inspection on fan blades on CFM56-7 engines with more than 15,000 flight cycles within 18 months. It took one year after SWA Flight 3472 before the FAA issued a Notice of Proposed Rulemaking for an Airworthiness Directive (AD) to address this situation. The reason CFM called for ultrasonic inspections is to detect subsurface cracks that are not noticeable by visual inspections or fluorescent dye penetrant inspections. Referencing the SWA 3472 accident, CFM International stated that their investigation “identified a crack that initiated and propagated in Fan Blade dovetail up to final separation.” In order to detect cracks in fan blades when they initiate, CFM recommended an ultrasonic inspection of the dovetails “ as soon as possible,” but no later than September 24, 2017, for engines that have accumulated more than 15,000 flight cycles. In March and June 2017, CFM International issued and revised a service bulletin (CFM56-7B Service Bulletin 72-1019, Revision 1), and recommended that airlines conduct a one-time ultrasonic inspection of “high time fan blades dovetails” on CFM56-7 engines. showed curving crack arrest lines consistent with fatigue crack growth.”įAA and Industry Response to the SWA 3472 Accidentįortunately, no one was injured in the SWA 3472 accident, but given that a fan blade snapped off, the engine failed midair, and shrapnel struck the aircraft with such force as to cause a depressurization event, it should have sounded alarms within the industry. The NTSB has still not issued its final report, but the initial findings from the NTSB’s metallurgical examination of the fan blade reveal that the “fracture surface. The pilots declared an emergency and diverted to Pensacola International Airport. One of the metal fragments punctured the fuselage – leaving a 5-inch by 16-inch hole just above the left wing – causing the cabin to depressurize. Similar to the SWA 1380 accident, while Southwest’s aircraft was climbing through 31,000 feet and heading over the Gulf of Mexico, the left engine’s fan blade failed, which resulted in an uncontained engine failure and shrapnel to be hurled into the fuselage. The Boeing 737-7H4 aircraft, registered as N766SW, was powered by two CFM56-7B turbofan engines manufactured by CFM International. On August 27, 2016, Southwest Airlines operated a regularly scheduled commercial passenger flight, SWA Flight 3472, from New Orleans, Louisiana to Orlando, Florida. The responses from Southwest Airlines, CFM International, and the FAA to the SWA 3472 accident were inadequate and untimely. Foreshadowing things to come, the shrapnel from that engine explosion hit the fuselage at high speed leaving a large gouge and came dangerously close to hitting the cabin windows. Indeed, Southwest Airlines suffered a strikingly similar fan blade failure in 2016 – Southwest Airlines Flight 3472. Sadly, this accident was likely preventable, but there was a lack of urgency on the part of Southwest Airlines, CFM International (the engine manufacturer), the Federal Aviation Administration, and others. With one lawsuit pending and more on the horizon, a key question for the aviation industry and the traveling public is what happened, and could it have been prevented?īased on the National Transportation Safety Board’s preliminary investigation, metal fatigue caused one of the engine’s fan blades to fail, which set in motion a devastating sequence of events. From a dramatic inflight engine explosion, to shrapnel shattering a cabin window and depressurizing the airplane, to the tragic death of a woman who was sucked out of an airplane window at 32,000 feet, Southwest Flight 1380 will not soon be forgotten.
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