United Airlines grounds Boeing 777s after engine failure

February 23, 2021.

United Airlines grounded twenty-four of its Boeing 777s on Sunday after one aircraft experienced an engine failure and distributed debris over a northern Denver suburb this weekend. The airline’s voluntary decision came as the Federal Aviation Administration said it plans to order increased safety inspections for the type of engine involved, which uses a unique hollow fan blade. Two of those blades were fractured, the National Transportation Safety Board said Sunday after an initial investigation, and several blades were damaged.

“We reviewed all available safety data following yesterday’s incident,” FAA Administrator Steve Dickson said 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 uncontained right engine failure on United Airlines Flight 328 happened just minutes after the Hawaii-bound Boeing 777-200 took off from Denver International Airport on Saturday afternoon. No one on the plane or on the ground was injured.

Twenty-four of United Airlines’ Boeing 777 planes with Pratt & Whitney 4000 series engines will be temporarily grounded until the airline and federal regulators can ensure the aircraft meets safety standards, United Airlines said in a statement. Boeing on Sunday night said it supported decisions to ground 777 aircraft powered by those engines.

Three aviation experts commented that the blades, which spin rapidly inside the engine, were a potential culprit for the engine failure — though they cautioned that they can only speculate on the cause, and that it was too soon to know whether maintenance, old age or an external force — like a bird — contributed to the problem. The aircraft involved had been flying since 1995 and was certified by the FAA until 2022, according to federal records. The model is a “very reliable older airplane,” aviation safety expert John Cox said, and uncontained engine failures are rare.

The NTSB said Sunday that while the engine was severely damaged, the rest of the plane escaped relatively unscathed. It will take months for the board to determine what caused the failure, but they said one fan blade fractured near the root and another broke at its midpoint. United Airlines has a total of fifty-two Boeing 777s with Pratt & Whitney 4000 engines in its fleet, but twenty-eight are not currently in use. The airline said in its statement that it will swap out other planes for the grounded 777s and expects the move will inconvenience a “small number of customers.”

The FAA’s directives means Boeing 777s in other airlines’ fleets may be removed from service due to increased inspections, Dickson said. Details of the order, which was not immediately issued Sunday evening, were not available. The Boeing 777 model already is being phased out among a few large airlines throughout the world, including Qatar Airways, Nippon Airways, Japan Airlines and Emirates. In May, Delta announced it was retiring all 18 of its Boeing 777 planes in favour of newer, more fuel-efficient aircraft.

Well-maintained planes can fly safely for more than 40 years, said Cox. And while the COVID-19 pandemic has led to layoffs and furloughs in the airline industry, those shortages would not change what aircraft maintenance is required, according to Ross Aimer, a retired United Airline pilot and CEO of Aero Consulting Experts. “It doesn’t change the particular procedures that have to be done on the engine,” Aimer said. “It would take longer with fewer people, but they don’t skip it because of fewer people.”

Mike Robertson, a retired FAA inspector and Army pilot who reviewed photos and videos of the incident, said the root cause of a failure could have happened between the rigorous, frequent inspections that planes undergo — like if a rock got into the engine between flights. In that case, he said, the failure would not be considered a maintenance issue. Or a budding crack could have been missed during an inspection, which would be a maintenance issue, though Robertson cautioned he didn’t know what happened in this case.

Cox said that pilots and flight crews train for this type of situation — even if passengers were terrified — and the plane’s safe landing shows that safety measures did work. “The airplane is tolerant of even a major failure like this,” he said. Cox added that the Boeing 777 can fly on one engine, although an uncontained engine failure will make for a bumpy ride, which a few passengers Saturday noted happened as they were returning to DIA.

“I know everybody was scared on it,” Cox continued. “And what would have been most unnerving is that when you have an engine with this kind of problem, it will vibrate, and the plane will feel like it is shaking. That is to be expected, but it would be very unnerving for passengers.”

Saturday’s flight left Denver International Airport (DIA) at around 1:04 p.m. and reached an altitude of some 13,400 feet before the pilots turned back toward DIA at about 1:10 p.m., according to the flight tracking website FlightAware. The aircraft landed safely at 1:29 p.m.

There have been eight uncontained engine failures since 2016, Cox said, though he didn’t immediately respond to a question on whether that was in the U.S. or worldwide. The planes landed safely in each case — although a passenger on a 2018 Southwest Airlines flight from New York to Dallas was killed when debris from an uncontained engine failure broke the plane’s window.

“They’re going to look very carefully at what caused the failure,” Cox said of the NTSB, “and then backtrack that to the entries on what inspections were done and what they found — all those kind of questions — to make sure it wasn’t somehow something that happened and wasn’t caught in maintenance.”

KJM Today Opinion

The Boeing 777 often referred to as 'The Triple-Seven', has proved itself to be one of the most reliable and safe airliners in which to fly. United Airlines were the launch customer for the earliest versions of the type, the 777-200, similar to the one involved in this incident and took delivery of its first at the end of May 1995.

Despite now being up to twenty-six years old, the early versions of the Boeing 777 have continued to fly for a number of airlines around the world and the aircraft has safely flown millions of miles, transporting huge numbers of passengers to and from their destinations on every continent. This incident has been reported around the world (with some reports indulging in the usual hysteria over such incidents) but engine failures - or indeed any failure of the aircraft itself or the procedures followed to maintain them - are extremely rare. Caution therefore needs to be exercised and jumping to conclusions avoided.

A Boeing 777-300 of Japan's All Nippon Airlines

Kevan James

Like all things however, even the 777 must come to the end of its design service life at some point and later versions of the type have been replacing not only the 777-200 but also the Boeing 747 - the 777-300 being a case in point.

As with almost everything the COVID-19 pandemic has adversely affected air travel but the newest versions of the Boeing 777 will be seen for many years yet, along with other new types, once the airline industry begins its recovery.

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