Damage to a fan blade on an inoperative engine on a flight of a United Airlines Boeing 777 is consistent with metal fatigue, based on a preliminary assessment, the chairman of the investigator said on Monday. American on air accidents.
The Pratt & Whitney PW4000 engine broke down with a “loud bang” on Saturday four minutes after takeoff from Denver, National Transportation Safety Board (NTSB) Chairman Robert Sumwalt told reporters after an initial scan of the logger. flight data and cockpit voice recorder.
He said it was not clear whether 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.
Air India is the only carrier to have Boeing 777s in its fleet. But none of these planes are equipped with P&W 4000-112 engines. There would therefore be no impact on national airlines.
Jet Airways had a fleet of Boeing 777s, which has been grounded since its closure.
“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 – less than 10% of the global fleet of 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 metal fatigue crack. An investigation is underway.
More focus on engine maker Pratt and analysts expect little financial impact on Boeing, but PW4000 issues pose new headache for the aircraft maker as it recovers of the much more serious crisis of the 737 MAX. Boeing’s flagship narrow-body aircraft was grounded for nearly two years after two fatal crashes.
The United motor’s fan blade will be examined on Tuesday after being transported to a Pratt lab where it will be examined under the supervision of NTSB investigators.
The US Federal Aviation Administration (FAA) said 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 under review by the FAA, sources familiar with the matter have said. Pratt did not immediately respond 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 looks like action is being 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 a takeoff and a landing.
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 plane’s 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.
Industry sources have said that although the engine is made by Pratt, the hood, or crankcase, is made by Boeing. Boeing referred questions about the coin to the NTSB.
Nearly half of the global PW4000-equipped Boeing 777 fleet operated by airlines such as United, JAL, ANA Holdings, Korean Air and Asiana Airlines had already been grounded amid falling travel demand due to the Covid-19 pandemic.