WASHINGTON (Reuters) – US National Transportation Safety Board (NTSB) Chairman Robert Sumwalt said Monday damage to a fan blade in a Pratt & Whitney engine that failed in a United Airlines Boeing 777-200 is consistent with metal fatigue, review .
In a newsletter, Sumwalt said it was not clear whether the PW4000 engine failure on Saturday with a ‘loud bang’ four minutes after takeoff is consistent with another engine failure on another Hawaii-bound United flight in February 2018 that was attributed to fatigue. break in a fan blade.
The engine that broke down on the 26-year-old Boeing Co 777 and stalled parts over a Denver suburb was a PW4000 used on less than 10% of the global fleet of 777 wide-body jets.
In another incident with Japan Airlines (JAL) 9201.T 777 with a PW4000 engine in December 2020, Japan’s Transport Safety Board reported it found two damaged fan blades, one with a fatigue crack. An investigation is underway.
The focus is more on the engine manufacturer Pratt & Whitney and analysts expect little financial impact for Boeing, but the PW4000 problems are another headache for the planemaker recovering from the much more serious 737 MAX crisis. Boeing’s flagship narrowbody jet was grounded for nearly two years after two deadly crashes.
The United engine’s fan blade is being examined Tuesday after it flew to a Pratt & Whitney lab, where it will be examined under the supervision of NTSB researchers.
“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.
Boeing advised airlines to discontinue use of the aircraft, while the FAA had established an appropriate inspection protocol and imposed a temporary suspension of flights on Japan.
The Federal Aviation Administration plans to issue an emergency airworthiness directive soon that will require more intensive inspections of the fan blades for fatigue.
The FAA ordered inspections every 6,500 cycles in March 2019 following the February 2018 United engine failure attributed to fan blade fatigue. A cycle is a take-off and a landing.
Sumwalt said the United incident was not considered a non-contained engine failure because the containment ring contained the parts as they flew out.
There was minor damage to the fuselage but no structural damage, he said.
NTSB will investigate why the hood separated from the plane and also why there was a fire despite evidence that the fuel to the engine had been turned off, Sumwalt added.
Pratt & Whitney, owned by Raytheon Technologies Corp, said on Sunday it was working with regulators to review inspection protocols.
Almost half of the global fleet of 128 airline aircraft, including United, JAL, ANA Holdings, Korean Air and Asiana Airlines, was already on the ground due to a drop in travel demand due to the coronavirus pandemic.
Reporting by David Shepardson in Washington and Jamie Freed in Sydney; additional reporting by Tracy Rucinski in Chicago Edit by Kim Coghill and Gerry Doyle