Three days after a fatal accident on a Southwest Airlines flight involving a faulty engine, the Federal Aviation Administration on Friday issued an order for airlines to conduct emergency inspections of some engines of the same type as the one that exploded on the Southwest plane.
The FAA said airlines have 20 days to carry out ultrasonic inspections of fan blades on CFM56-7B engines that have made more than 30,000 flights. Such inspections, noted The New York Times, can “detect flaws or cracks not visible to the unaided human eye.”
Manufactured by CFM International, a joint venture between General Electric and France’s Safra Aircraft Engines, the CFM56-7B is one of the most widely used jet engines. The FAA said its directive would affect more than 350 engines in the U.S. and hundreds more worldwide.
The emergency order comes amid increased scrutiny of engine inspection processes following the death of a passenger on a Southwest Airlines flight from New York to Dallas on Tuesday.
Jennifer Riordan, 43, was partially sucked out of the Southwest plane when the Boeing 737-700’s engine exploded mid-flight and its debris smashed a window. Riordan died at a hospital after the plane made an emergency landing in Philadelphia. Several other passengers were injured in the ordeal.
The chairman of the National Transportation Safety Board, Robert Sumwalt, said on Wednesday that the engine had blown up after one of its blades had broken in two places.
The cause of the engine failure is still being investigated by the NTSB, but metal fatigue ― which can cause cracks and other weaknesses that are not visible to the naked eye ― has been suspected as a factor.
On the Sunday before the accident, a visual inspection of the engine had found no issues with it. Sumwalt said the cracks in the engine blade were “more than likely not detectable from looking from the outside,” reported the Times.
On Friday, the FAA said it was mandating inspections of certain engine blades after determining that the problem of cracks arising from metal fatigue “is likely to exist or develop in other products of the same type design.”
The agency said it had based its directive on a bulletin issued earlier in the day by CFM International, which recommended airlines carry out prompt ultrasonic inspections on fan blades on certain CFM56-7B engines.
Bloomberg noted that such inspections can be carried out without having to dismantle the engine and can be completed within about four hours per engine.
CFM International had issued a similar recommendation in 2016 after the failure of a CFM56-7B engine on another Southwest aircraft. An investigation into that incident is still underway, but the NTSB said it had also found evidence of metal fatigue.
Southwest had initially pushed back against CFM International’s recommendation that inspections be completed within 12 months and had asked for more time last year, reported The Associated Press. The airline eventually did begin conducting inspections of certain engine fan blades. A spokeswoman told AP that the airline had already inspected about half of the engine blades identified by the manufacturer’s recommendation before this week’s accident.
In a statement Friday, Southwest said its existing maintenance program “meets or exceeds all the requirements specified” in the FAA’s new order.
Several other domestic airlines, including Delta and American, also began inspections of certain engine fan blades last year following the 2016 incident, according to Bloomberg.
Though aircraft engine failures are very rare and the CFM56-7B engine has an otherwise excellent safety record, the two apparently similar engine failures have left some aviation experts concerned.
John Gadzinski, president of Four Winds Aerospace Safety, an aviation consultant, told HuffPost on Friday that the failures suggest that there could be a design flaw with the engine or something fundamentally wrong with the engine certification process.
“There are very specific regulation guidelines to ensure that if an engine does fail, that it doesn’t come apart and turn into little bombs. The housing of the engine is supposed to contain these fan blade failures,” Gadzinski said. “So it’s a fairly big deal for this kind of failure to happen.”
This story has been updated with Southwest’s response to the FAA’s new directive.