Dozens of Boeing 777 aircraft grounded after Denver engine failure incident

Photo (c) FrankvandenBergh - Getty Images

Similar incidents are rare, and aircraft are usually able to safely continue flight for several hours

After a United Airlines-flown Boeing 777 failed and rained debris over Denver on Saturday, Boeing has recommended the grounding of all 69 in-service and 59 in-storage 777s powered by Pratt & Whitney 4000-112 engines until the FAA establishes an appropriate inspection protocol. 

United Flight 328, with 231 passengers aboard, was forced to make an emergency landing at Denver airport. No one was reported injured either on the plane or on the ground.

"The plane started shaking violently, and we lost altitude and we started going down," David Delucia said, adding that he and his wife put their wallets in their pockets "in case we did go down, we could be ID'd".

United suffered a near-identical engine failure on one of its 777s in 2018 on a flight from San Francisco to Honolulu.

Planes grounded and investigations started

If bad things come in threes, then Boeing has to hope that 2021 will be the last of its three-year-long sidelining. It spent 2019 and 2020 trying to recover from the issues and crashes revolving around its 737 MAX aircraft before finally resuming production of the model in Spring, 2020.

In the wake of Saturday’s incident, United immediately halted operations of 24 of its 777 aircraft. Japan’s Civil Aviation Bureau also grounded planes with the Pratt & Whitney engine on Monday, and Korean Air Lines and Asiana Airlines idled theirs without a government mandate.

Japan’s Civil Aviation Bureau has seen this situation before. The ministry reported that a Japan Air Lines (JAL) flight was forced to return to Naha Airport due to an engine malfunction In December 2020. Interestingly enough, the JAL plane was the same age -- 26-years-old -- as the United Airlines plane in Saturday's incident.

Addressing the situation, Boeing said it is “actively monitoring” the event that occurred in Denver. Pratt & Whitney said it had “dispatched a team to work with investigators.” On the U.S. government side, the Federal Aviation Administration (FAA) said it has ordered “extra” inspections of Boeing 777 jets fitted with the Pratt & Whitney 4000. 

"We reviewed all available safety data following [Saturday's] incident," said FAA administrator Steve Dickson in a statement. "Based on the initial information, we concluded that the inspection interval should be stepped up for the hollow fan blades that are unique to this model of engine, used solely on Boeing 777 airplanes."

The good and bad news about engine failure

How bad is losing an engine in an incident like United’s? A modern twin-engine airliner suffering engine failure is designed to fly safely for hours with only one functioning engine. An example is a 2017 Paris to L.A. incident in which the crew took the aircraft to a lower altitude and diverted to Goose Bay, Canada, where it landed safely two hours later. Nonetheless, there are potential problems involved with engine failure. 

“The shrapnel from an uncontained failure, however, can cause serious damage to the rest of the plane, and if it passes through the cabin, it can be lethal. Experts say the failure in the Denver incident appears to have been uncontained, but the damage to the aircraft itself was thankfully minor,” said BBC special correspondent, Theo Leggett.

Leggett said it is also worrisome that the incident appears to be markedly similar to the aforementioned United Airlines 2018 incident.

“If the cause in this case is found to be the same -- and remember, it may not be -- that would raise questions about why the response to that incident from the manufacturer and regulators was unable to prevent a repeat,” Leggett said.

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