An engine failure on a United Airlines flight from Colorado to Hawaii that rained aircraft parts over suburban Denver on Saturday has thrust the Boeing 777, aircraft engine types and fan blades into the spotlight.
The plane returned to Denver safely, and there were no injuries reported among the 231 passengers and 10 crew members or Colorado residents, but images from the incident and passenger reports have shaken travelers and left them with countless questions about one of the airline industry's go-to wide-body jets for Europe and Hawaii flights.
Video taken from inside the plane and posted to social media shows the right engine on fire and part of the engine cover missing. The piece landed in a yard in Broomfield, Colorado.
“The plane started shaking violently, and we lost altitude, and we started going down,” David Delucia, who was sitting directly across the aisle from the side with the failed engine, told The Associated Press. “When it initially happened, I thought we were done. I thought we were going down."
United only US airline with Boeing 777s powered by engine that failed Saturday
The Federal Aviation Administration said there are 128 older Boeing 777s powered by Pratt & Whitney 4000 engines.
United is the only U.S. carrier with planes with the affected engines. The airline had 24 in operation and 28 in storage during the pandemic before voluntarily grounding them late Sunday. United passengers will be accommodated on other flights.
The grounding is a step further than the FAA's directive to step up inspections on Boeing 777s with the Pratt & Whitney engines, specifically the fan blades.
The other airlines operating 777s with the Pratt & Whitney engines are in Japan and South Korea, the FAA said. They include Japan Airlines, ANA and Korean Airlines. The Japan Civil Aviation Bureau grounded them.
Yes, you still might be booked on a Boeing 777
United has 44 other Boeing 777s, all with GE engines, which are not affected by United's 777 grounding or the FAA directive. The airline will use one of those planes, for example, to fly between San Francisco and Taipei, Taiwan, in March instead of one of its grounded 777s, according to United spokesman Charlie Hobart.
American Airlines has 67 Boeing 777s in its fleet. They are powered by Rolls-Royce and GE engines, which also aren't affected by the FAA's directive. The planes were used for international flying before the pandemic and are now frequently used for flights within the USA, spokesman Sarah Jantz said.
Delta Air Lines retired its 18 Boeing 777s last year, earlier than planned because of the plunge in international travel under COVID-19 travel restrictions and health concerns. The final Delta 777 flight was a New York-to-Los Angeles flight in October. The airline, which began flying the jet between Atlanta and London in 1999, called it the end of an era and praised the jet as a "workhorse." Delta flew nearly 134,000 flights on the plane.
Delta CEO Ed Bastian said retiring a fleet as "iconic'' as the 777 was not an easy decision, given its role in the airline's international growth.
"I’ve flown on that plane often, and I love the customer experience it has delivered over the years,'' he said in a statement before the final flight last fall.
Aviation safety expert: Uncontained engine failures are rare but potentially catastrophic
United Flight 328 from Denver to Honolulu experienced what is called an uncontained engine failure.
That means parts exited the engine despite protective coverings and other safety measures.
Uncontained failures are more dramatic and tend to be more dangerous than other engine failures because of the potential damage the errant parts can inflict on the plane, according to Ed Coleman, chairman of the safety science department at Embry Riddle Aeronautical University in Prescott, Arizona, and director of the school's Robertson Safety Institute.
"When things come out of the engine, you don't know where they're going to go," he said. "Some puncture fuel tanks ... or they set something on fire."
In April 2018, an uncontained engine failure on a Southwest flight killed a 43-year-old mother of two.
The National Transportation Safety Board's investigation into the Southwest engine failure found that a crack in an engine fan blade caused it to break off and hit the fan cover at a critical point near some latches. The impact caused the cover to open and sent some parts into the fuselage. One part punctured a window, fatally injuring Jennifer Riordan, the passenger in the window seat.
Overall, the number of engine failures is "infinitesimally small," Coleman said. "This is an anomaly more than a routine thing.
"They're pretty rare because of the inspection procedures," Coleman said. "Engines have specific times that they get torn down and looked at."
Coleman, a former Air Force pilot, said pilots are routinely trained to handle engine failures, uncontained and contained. He said the United pilots' tone on air traffic control recordings during the incident underscores that.
"Their voices don’t even go up an octave," he said.
He has investigated military engine failures and experienced one uncontained engine failure in his career and about a dozen other engine failures that required him to shut down the engine.
United had a similar engine failure on another Boeing 777 flight to Hawaii
Saturday's incident wasn't the first uncontained failure for United on a Boeing 777 flight to Hawaii.
In February 2018, a flight from San Francisco to Hawaii, on a plane with the same Pratt & Whitney engine, lost its engine cover after a fan blade separated during the plane's descent into Honolulu.
The flight made an emergency landing, but there were no injuries to the 363 passengers and 10 crew members. The plane had minor damage.
New engine inspection procedures were put in place to avoid a repeat.
"When a fan blade breaks, it's usually because there's some kind of missed crack," Coleman said.
It's early, but the similarity between the two incidents will be zeroed in on by the NTSB, he said.
"My guess is they will look at those inspection procedures very closely and determine what was missed and how it was missed," he said.
The United Boeing 777 involved in the incident in 2018 returned to service at United. Late Saturday, United used the plane to fly passengers taken off Flight 328 on a later flight to Honolulu.
