A Northern Underground firefighter and a Broomfield cop walk towards a large chunk of an airplane engine in the Kirby Klements front yard on Elmwood Street near 13th Avenue E. on February 20, 2021.
Andy Cross | Denver Post | Getty Images
United States National Transportation Safety Board (NTSB) Chairman Robert Sumwalt said Monday damage to a fan blade of a failed Pratt & Whitney engine in a United Airlines Boeing 777-200 is consistent with metal fatigue, according to a preliminary assessment.
During a press briefing, Sumwalt said it was not clear whether Saturday’s failure of the PW4000 engine shortly after takeoff was consistent with another engine failure on another United flight to Hawaii in February 2018, attributed to a stress fracture in a fan blade.
In another incident with the same type of engine on a Japan Airlines 777 in December 2020, the Japan Transportation Safety Board reported finding two damaged fan blades, one with a metal fatigue crack.
The United motor’s fan blade will be examined on Tuesday after being transported to a Pratt & Whitney lab where it will be examined under the supervision of NTSB investigators.
“What’s important is that we really understand the facts, circumstances and conditions surrounding this particular event before we can compare it to any other event,” Sumwalt said.
The Federal Aviation Administration plans to issue an Emergency Airworthiness Directive soon that will require intensified fan blade inspections for fatigue.
The FAA in March 2019 after the February 2018 engine failure United attributed to fan blade fatigue ordered inspections every 6,500 cycles.
Sumwalt said the United incident was not considered an unconfined engine failure because the containment ring contained the parts as they flew away.
There was minor damage to the aircraft body but no structural damage, he said.
The NTSB will look into why the engine cowl separated from the plane and also why there was a fire despite indications that the engine fuel was cut, Sumwalt added.