“Metal fatigue” favored in damage to a United Airlines flight

Video capture of the flight in question, during which the engine ignited, on February 20, 2021 in Denver, United States. – Chad Schnell / AP / SIPA

“Metal fatigue” is now the preferred lead by the authorities to explain the spectacular incident that occurred last week on a United Airlines flight in the United States, which led to the immobilization of part of the global fleet of Boeing 777.

A Boeing 777-220 of the American company United Airlines which had just taken off Saturday from Denver in the United States with 231 passengers and 10 crew members saw its right engine catch on fire and lose its fairing. The pilots had to make an emergency U-turn. As the plane returned to the airport, a shower of debris, some large, fell on a residential area in suburban Denver.

Additional inspections

No one was injured on the ground and the aircraft was able to land safely. But the American aircraft manufacturer recommended Sunday evening the suspension of flights of the 128 aircraft concerned around the world, and a spokesperson confirmed to AFP on Monday that they were all immobilized.

Of these, 69 were in service, including 24 at United Airlines, 13 at Japan Airlines (JAL), 19 at All Nippon Airways (ANA), 7 at Asiana and 6 at Korean Air. The other 59 devices were stored separately. In the United States, the Federal Aviation Regulatory Authority (FAA) has ordered additional inspections on these Boeing 777s powered by Pratt & Whitney, and the National Transportation Safety Board (NTSB) is also investigating the ‘incident.

A blade found on a football field

“A preliminary on-site examination indicates damage consistent with metal fatigue,” Robert Sumwalt, president of the NTSB, said Monday at a press briefing. He also confirmed that two of the fan blades had been damaged. One of them was found on a soccer field, the other remained lodged in the engine.

FAA officials met with representatives from Boeing and Pratt & Whitney on Sunday evening. The US engine manufacturer said he was cooperating with the NTSB and “will continue to work to ensure the safe operation of the fleet”. United Airlines, for its part, has decided to withdraw the aircraft from its flight schedule and will continue to work “in close collaboration with regulators to determine additional steps”.

Maintenance problem?

The United Kingdom decided on Monday to ban its airspace to the Boeing 777s concerned. And Japan’s Transport Ministry said it had ordered more stringent inspections of the Pratt & Whitney engine after a Japan Airlines (JAL) 777 flying from Tokyo Haneda Airport to Naha on the island of Okinawa, experienced problems with “one engine from the same family” in December.

The Dutch authorities also announced Monday the opening of two investigations after the fall two days earlier of debris from a Boeing 747-400 cargo plane, which injured two people in the south of the Netherlands. Several experts believe, however, that the 777 incident in the United States is more of a maintenance or engine problem than of the design of the plane by Boeing. In service for more than 25 years without major accident, the device “has a very solid reputation”, underlined Michel Merluzeau, expert of the AIR firm.

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