A United Airlines flight has been forced to make an emergency landing in Denver after one of its engines blew apart.

The Boeing 777, which was bound for Hawaii, returned to Denver airport not long after take-off over the weekend, while the explosion rained pieces of wreckage down on suburban neighbourhoods below.

According to passengers on board, the aircraft was almost at cruising altitude and the captain was giving an announcement when a loud bang shook the cabin followed by a bright flash.

David Delucia told ABC News he was sitting across the aisle from the failed engine and that the plane began to “shake violently”, lost altitude and began to “go down”.

“When it initially happened, I thought we were done. I thought we were going down,” he said.

Delucia said he and his wife took their drivers’ licences out of their wallets and put them in their pockets so they could be identified if the plane crashed.

Those on the ground also saw the explosion, including Colorado local Tyler Thal, who noticed a commercial plane flying unusually low while out for a walk with his family.

“While I was looking at it, I saw an explosion and then the cloud of smoke and some debris falling from it,” he said, according to ABC News.

“It was just like a speck in the sky, and as I’m watching that, I’m telling my family what I just saw and then we heard the explosion.

“The plane just kind of continued on, and we didn’t see it after that.”

United Airlines Boeing 777 operating as flight 328 flying from Denver – Honolulu suffered a serious engine failure on takeoff.

It made an emergency landing and everyone is ok.

Check out these pieces of the engine falling from the sky…pic.twitter.com/1IyBj6Nlf2

— Rex Chapman🏇🏼 (@RexChapman) February 20, 2021

One local, Kirby Klements, said a massive piece of debris crushed the cab of his truck and pushed the vehicle into the dirt.

“If it had been 10 feet (three metres) different, it would have landed right on top of the house,” he said.

“And if anyone had been in the truck, they would have been dead.”

Image source: Broomfield Police Department via ABC News.

The United Transportation Safety Board for the US’s chairman Robert Sumwalt told press two fan blades in the engine broke due to metal fatigue.

He said investigators were trying to determine how long the blades had suffered fatigue.

CBS Denver reported that the plane was 26 years old, but the US Federal Aviation Administration (FAA) said it couldn’t determine if the engine that failed was originally part of the plane of installed later on.

“Our mission is to understand not only what happened but why it happened so that we can keep it from happening again,” Sumwalt said.

United Airlines said in a statement that the flight returned safely to Denver and was met by emergency crews as a precaution. The airline said there were no injuries on board among the 231 passengers and 10 crew members.

“Following an emergency landing by United flight 328, we ensured our customers were comfortable and cared for at Denver International Airport while we prepared another aircraft to get them to Honolulu,” the airline said.

“The majority of customers originally on UA328 are currently on their way to Honolulu on a new flight, UA3025, which is scheduled to land at 10:40pm local time.

“Those who did not wish to travel with us this evening were provided hotel accommodations. We will continue to work with federal agencies investigating this incident.”

The airline also confirmed it was temporarily removing 24 Boeing 777 aircraft powered by Pratt & Whitney 4000 series engines from its schedule.

“We’ve been in touch with regulators at the NTSB and FAA, and will continue to work closely with them to determine any additional steps that are needed to ensure these aircraft meet our rigorous safety standards and can return to service,” United said.

“As we swap out aircraft, we expect only a small number of customers to be inconvenienced.”

Boeing said in a statement on 21 February that it has been actively monitoring the recent events related to United Airlines flight 328, and has recommended the suspension of the 69 in-service and 59 in-storage 777s powered by Pratt & Whitney 4000-112 engines until the FAA identifies the appropriate inspection protocol.

“Boeing supports the decision yesterday by the Japan Civil Aviation Bureau, and the FAA’s action today to suspend operations of 777 aircraft powered by Pratt & Whitney 4000-112 engines,” the aircraft manufacturer said.

“We are working with these regulators as they take actions while these planes are on the ground and further inspections are conducted by Pratt & Whitney.

“Updates will be provided as more information becomes available.”

Featured image source: Twitter/Michaela Giulia via News Hub NZ