Photo: The Canadian Press

Boeing has recommended that airlines ground all 777s with the type of engine that blew apart after takeoff from Denver this weekend, and most carriers that fly those planes said they would temporarily pull them from service.

The U.S. Federal Aviation Administration ordered United Airlines to step up inspections of the aircraft after one of its flights made an emergency landing at Denver International Airport Saturday as pieces of the casing of the engine, a Pratt & Whitney PW4000, rained down on suburban neighbourhoods. None of the 231 passengers or 10 crew was hurt, and the flight landed safely, authorities said. United is among the carriers that has grounded the planes.

FAA Administrator Steve Dickson said in a statement Sunday that based on an initial review of safety data, inspectors “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.”

Dickson said that would likely mean some planes would be grounded—and Boeing said they should be until the FAA sets up an inspection regime. Japan ordered the planes out of service, according to the financial newspaper Nikkei, while noting that an engine in the same family suffered trouble in December.

Boeing said there were 69 777s with the Pratt & Whitney 4000-112 engines in service and another 59 in storage.

United had 24 of the planes in service; it is the only U.S. airline with the engine in its fleet, according to the FAA. Two Japanese airlines have another 32 that are being pulled while Asiana Airlines grounded nine, seven of which were in service, until Boeing establishes a plan to fix the problems. Korean Air said it was discussing whether to ground 16 aircraft, six of which are in service.

“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,” Boeing said in a statement issued Sunday, referring to American and Japanese regulators.

The engine maker said it was sending a team to work with investigators.

The emergency landing this past weekend is the latest trouble for Boeing, which had its 737 Max planes grounded for more than a year after two deadly crashes in 2019 and is suffering amid the huge reduction in air travel due to the coronavirus pandemic. The Max planes began returning to the skies late last year—a huge boost for the aircraft maker, which lost billions during the grounding because it has been unable to deliver new planes to customers.