An uncontained engine failure that led to a fatality on a Southwest 737-700 on 16 April recalls key details of a similar incident involving the same aircraft and engine type about 20 months ago over the Gulf of Mexico.
About 11:15am on 17 April, Southwest flight 1380 flying from New York-LaGuardia to Dallas-Love Field suffered an apparent uncontained failure of the left CFM International CFM56-7B engine and diverted to Philadelphia International airport. One of the 149 passengers and crew on board the aircraft was killed.
Pictures of the aircraft engine after landing indicate that the inlet separated during the flight. Debris from the engine assembly punctured the fuselage, shattering one window in the passenger cabin.
On 27 August 2016, a 737-700 operating flight Southwest 3472 also experienced an uncontained failure of a CFM-567B engine while enroute from New Orleans to Orlando. Pieces of the engine punctured the fuselage but did not cause any deaths nor casualties.
Asked about similarities between flights 3472 and 1380, National Transportation Safety Board chairman Robert Sumwalt said it was too early to draw parallels between the two incidents.
“We want to look at this particular event and see what the factors are surrounding this and maybe they’re related and maybe not,” Sumwalt says. “We need to understand what’s going on here.”
When asked by FlightGlobal for the status of the investigation and flight 3472 and any pending recommendations related to fan blade containment, Sumwalt replied: “I don’t have that information right now. Our focus is getting out the door at headquarters and getting on this airplane so we can get up to Philadelphia.”
The fan blades recovered from flight 3472 20 months ago showed classic signs of fatigue cracking, the NTSB initial investigation findings released in September 2016 showed.
A year later, the US Federal Aviation Administration published an airworthiness directive in response to the flight 3472. The rulemaking required airlines operating the 737-700 with certain models of the CFM56-7B engine to inspect the fan blades for fatigue crack growth using an ultrasound technique.
The engine on the 737-700 on flight 1380 had operated for 40,000 cycles, including 10,000 cycles since its last overhaul.