Southwest Airlines will begin a round of “enhanced inspection procedures” for CFM International engines following a preliminary finding that a fan blade bore signs of metal fatigue in a fatal acccident on 17 April, a US National Transportation Safety Board official says.

The call for inspections came several hours after an engine failed on Southwest flight 1380, which was operated by a Boeing 737-700, about 11:15 am, puncturing the fuselage and wing with pieces of the failed left engine. Although enroute from New York-LaGuardia to Dallas Love Field, the crew diverted to Philadelphia International airport. One passenger was killed during the accident.

An NTSB 'Go Team' dispatched to Philadelphia focused on the missing Number 13 fan blade in the left engine, which had separated at the point where the blade attaches to the hub.

“Our preliminary examination of this was that there was evidence of metal fatigue where the blade separated,” says NTSB chairman Robert Sumwalt.

The fan blade failure marks the second such event in a CFM56-7B installed on a Boeing 737-700 since August 2016. In that incident, the NTSB blamed metal fatigue for a similar fan blade separation in a separate Southwest Airlines 737-700. In 2017, the US Federal Aviation Administration issued an airworthiness directive in response to that incident, mandating ultrasonic inspection procedures for certain CFM56 engines.

It was not yet known if the engine onboard flight 1380 on 17 April was subject to the inspections called for under the airworthiness directive, Sumwalt says.

He adds that he has spoken by telephone with Southwest chief executive Gary Kelly, who informed him the airline would launch the enhanced inspections across the fleet. It was not immediately clear if Southwest would inspect the fan blades on all CFM56-powered 737s, or a subset of the fleet.

Source: Cirium Dashboard