WASHINGTON (Reuters) – Damage to a fan blade on a failed engine on a United Airlines Boeing 777 flight is consistent with metal fatigue, based on preliminary assessment, President US air accident investigator said Monday

The Pratt & Whitney PW4000 engine broke down on Saturday with a “loud bang” four minutes after takeoff from Denver, National Transportation Safety Board (NTSB) chairman Robert Sumwalt told reporters following a initial analysis of flight data recorder and cockpit voice recorder

He said he was not sure the incident was consistent with an engine failure on another United flight to Hawaii in February 2018, attributed to a fatigue fracture in a fan blade

“What is 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 engine that broke down on the 26-year-old Boeing Co 777 and lost parts over a Denver suburb was a PW4000 used on 128 planes, or less than 10% of the world’s fleet over 1,600 delivered 777 jumbo jets

In another incident on Japan Airlines (JAL) 777 with a PW4000 engine in December 2020, the Japan Transportation Safety Board reported finding two damaged fan blades, one with a crack of metal fatigue An investigation is underway

The focus is more on engine maker Pratt, and analysts expect little financial impact on Boeing, but the PW4000 issues pose a new headache for the aircraft maker as he is recovering from the much more serious crisis of the 737 MAX Boeing’s flagship narrow-body plane was grounded for nearly two years after two fatal crashes

The fan blade of the United engine will be examined on Tuesday after being airlifted to a Pratt lab where it will be examined under the supervision of NTSB investigators

The US Federal Aviation Administration (FAA) said on Monday it had already assessed whether to adjust fan blade inspections following the December incident in Japan after reviewing maintenance records and conducted a metallurgical examination of the fan blade fragment

Boeing has recommended airlines suspend aircraft use while the FAA identifies an appropriate inspection protocol, and Japan has imposed a temporary flight suspension

Pratt & Whitney, owned by Raytheon Technologies Corp, has recommended airlines increase inspections in a plan that is under review by the FAA, sources with knowledge of the matter said Pratt did not respond immediately to a request for comment

The FAA has announced that it plans to issue an Emergency Airworthiness Directive soon that will require intensified fan blade inspections for fatigue

“United Airlines has grounded all affected aircraft with these engines, and I understand the FAA is also working very quickly and Pratt & Whitney has reiterated or revised a service bulletin,” Sumwalt said “It appears that action is taken “

In March 2019, after United 2018 engine failure attributed to fan blade fatigue, the FAA ordered inspections every 6,500 cycles A cycle is take off and landing

South Korea’s transport ministry said on Tuesday it had instructed its airlines to inspect fan blades every 1,000 cycles following Pratt’s advice after the United incident

Sumwalt said the United incident was not considered an unconfined engine failure as the containment ring contained the parts as they flew out

The NTSB will investigate why the engine cowl separated from the aircraft and also why there was a fire despite indications that the engine fuel was cut, Sumwalt added

Industry sources said that although the engine is made by Pratt, the cowl, or crankcase, is made by Boeing Boeing referred questions on the part to the NTSB

Nearly half of the world’s PW4000-equipped Boeing 777 fleet operated by airlines such as United, JAL, ANA Holdings, Korean Air and Asiana Airlines had already been grounded amid slumping demand. of travel due to the coronavirus pandemic

Reporting by David Shepardson in Washington and Jamie Freed in Sydney; additional reporting by Tracy Rucinski in Chicago, Joyce Lee in Seoul and Tim Hepher in Paris; Editing by Kim Coghill and Gerry Doyle

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Boeing 777

Global News – FI – United Boeing 777 Engine Damage Due to Metal Fatigue: NTSB

Source: https://www.reuters.com/article/us-boeing-777-ntsb/damage-to-united-boeing-777-engine-consistent-with-metal-fatigue-ntsb-idUSKBN2AN03S