U.S. air safety regulators were considering whether to require more inspections of certain Pratt & Whitney engines before a flight from United Airlines Holdings Inc. fell apart over a city near Denver on Saturday, the Federal Aviation Administration said.
The revelation came when US security researchers said they found evidence of “damage consistent with metal fatigue” on one of the engine’s fan blades that had been largely ripped off. That loose blade then apparently shoved off part of a second blade that was also broken, Robert Sumwalt, chairman of the National Transportation Safety Board, said at a news conference Monday night.
Mr. Sumwalt said investigators are investigating why an outer casing, known as a hood, came off, as well as why the damaged engine continued to burn even after the fuel was turned off by the flight crew.
Last weekend’s incident was the third in a series of failures involving the same engine and aircraft types in recent years. US regulators had previously ordered instructed inspections of fan blades following an earlier engine failure on another United flight with a Boeing 777 in 2018. When an engine broke down on a Japan Airlines Co. flight in December. to Tokyo, which led to a re-audit of the FAA. .
There were similarities between the incident in Japan and that in Colorado. Japan’s Transport Safety Board said a fan blade that broke off that engine shows signs of metal fatigue. Another knife had been broken roughly in half.