NTSB: Southwest engine failure lost fan blade

WASHINGTON – The Southwest Airlines engine that failed last month allowed debris to puncture the Boeing 737-700’s engine casing and fuselage, according to federal investigators.

A 5-inch by 16-inch hole was found in the left fuselage just above the wing of Flight 3472, according to an update Monday from the National Transportation Safety Board. The passenger cabin wasn’t penetrated, but it depressurized while landing, the board said.

The flight Aug. 27 from New Orleans to Orlando diverted to Pensacola, where it landed without injuries.

The board investigates aircraft and other transportation accidents in an effort to determine what went wrong and make recommendations to prevent similar problems in the future.

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One of the engine’s fan blades separated from its hub during the flight, but wasn’t recovered. The surface of the fractured fan blade showed curving crack lines consistent with fatigue, the board said.

No surprises were found with the surface or the material in the fan blade, which was manufactured from a titanium alloy and coated with a copper-nickel-indium allow, during scanning with electron microscopy and X-ray spectroscopy, the board said.

The investigator in charge of the case is Tim LeBaron, who is leading a team of experts in airworthiness, power plants and metallurgy.

The investigation will include a non-destructive examination of the blade surfaces for cracks and a review of engine maintenance records.