One of 24 fan blades from the Southwest jetliner forced to an emergency landing Tuesday was missing, National Transportation Safety Board Chairman Robert Sumwalt said Wednesday.
The University of Dayton Research Institute (UDRI) tests fan blade casings or housings for their ability to withstand emergencies, bird strikes and other sudden strikes.
One passenger died in the emergency landing of the Dallas-bound Southwest Airlines flight Tuesday.
Media reports said the woman found herself sucked out of an opening of a broken window when an engine part broke off and smashed into the window. She hung out the opening for many minutes, Hollie Mackey, who sat next to the victim, and Amy Serafini, who was in the row behind the woman, CNN reported.
Kevin Poormon, UDRI research engineer and group leader in impact physics, has not seen the Southwest aircraft and could not speculate as to the cause of the catastrophe.
“We don’t know exactly what happened,” Poormon said Wednesday at UDRI’s Shroyer Park labs off Irving Avenue. “We know there was a failure in the engine, obviously.”
The CFM56-7B engine is produced by a joint venture of General Electric and Safran SA, a French company. The joint venture, CFM International, is based in Butler County’s West Chester Twp.
Reuters News Service reported that CFM is sending some 40 technicians out to assist Southwest with its investigation into the incident.
CNN and others paraphrased Sumwalt as saying there was evidence of metal fatigue where the blade attaches to a hub.
UDRI tests fan cases or housings for jet engine fan blades. Using a long “gun” propelled by a huge compressor, engineers launch blades or blade fragments into fan casings to demonstrate that the casings can “contain these threats to the engine,” Poormon said.
Engine manufacturers spend hundreds of millions on safety, trying to adhere to strict Federal Aviation Administration mandates.
“From our standpoint, we do individual tests where we are shooting blades into the cases,” Poormon said. “It gives them (manufacturers) preliminary information for their designs.”
For normal everyday operation, the casing or “shroud” does not need to be as robust as it is, he said. But aircraft and engine designers, with the FAA, want the casing to be light and yet strong enough to handle emergencies.
“Like the engine blades themselves, they’re a lot more robust than they need to be for their everyday operation — because of bird strike requirements,” he said.
Said Poormon: “These events that you hope never occur are really the driving factor in the design of these things.”
A UDRI spokeswoman said the institute has been called on to help investigate accidents in their aftermath. In 2013, a UDRI research chemist said institute researchers believed they found a “plausible cause” for the explosion of a fuel tank in the 1996 crash of TWA flight 800 in New York, a crash that killed all 230 people.
But there was no way to know Wednesday whether UDRI would be involved in any way in the investigation of the Southwest flight.
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