U.S. flight regulators have ordered further investigation into Boeing planes after a United Airlines flight using a Pratt & Whitney engine emergency landed over the weekend.
The 26-year-old Boeing 777 shed debris over Denver on Saturday after its right engine, a P&W4000, failed mid-flight.
United Airlines and Japan have grounded all Boeing 777s with the Pratt & Whitney engine until further notice.
A video on social media captured a cloud of black smoke trailing the Honolulu-bound aircraft on Saturday, shortly after it departed Denver International Airport.
There were 231 passengers and 10 crew on board.
United said the plane returned safely to the airport without any reported injuries, but debris scattered the city of Broomfield Saturday afternoon.
The Pratt & Whitney engine has grounded several flights over the last few years…
Japan's transport ministry said that early last December, a Boeing 777 returned to its departure point after its left engine failed and in 2018, another Honolulu-bound flight experienced engine failure 30 minutes after departure.
That incident prompted a U.S. Federal Aviation Administration investigation into the PW4000 engines a year later.
According to the FAA, United is the only U.S. airline using the Boeing 777s.
Boeing said its tech team is supporting U.S. regulators with its current investigation.
Pratt & Whitney was not available for immediate comment.