777s with engine that blew apart should be grounded: Boeing

Boeing has recommended that airlines ground all of its 777s with the type of engine that suffered a catastrophic failure over Denver this weekend, as US regulators ordered United Airlines to step up inspections of those aircraft.

United said Sunday it is temporarily removing the aircraft from service, a day after one of its planes made an emergency landing at Denver International Airport because its right engine blew apart just after takeoff. Pieces of the casing of the engine, a Pratt and Whitney PW4000, rained down on suburban neighbourhoods.

None of the 231 passengers or 10 crew onboard was reported hurt, and the plane landed safely, authorities said.

US Federal Aviation Administration 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.”

The statement said that would likely mean some planes would be grounded — and Boeing said they should be until the FAA sets an inspection regime.

Japan, meanwhile, also ordered the planes out of service, according to the financial newspaper Nikkei, while saying that an engine in the same family suffered trouble in December.

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

United is the only U.S. airline with the engine in its fleet, according to the FAA, and it had 24 of the planes in service. Two Japanese airlines had another 32 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.

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 saw its 737 Max planes grounded for more than a year after two deadly crashes in 2019.

The planes began returning to the skies late last year — a huge boost for the aircraft maker, which lost billions during the Max grounding because it has been unable to deliver new planes to customers.

Video posted on Twitter from Saturday's emergency showed the engine fully engulfed in flames as the plane flew through the air.

Freeze frames from different video taken by a passenger sitting slightly in front of the engine and also posted on Twitter appeared to show a broken fan blade in the engine.

The U.S. National Transportation Safety Board said that two of the engine's fan blades were fractured and the remainder of the fan blades “exhibited damage.” But it cautioned that it was too early to draw conclusions about what happened.

United says it will work closely with the FAA and the NTSB “to determine any additional steps that are needed to ensure these aircraft meet our rigorous safety standards and can return to service.”

The NTSB said the cockpit voice recorder and flight data recorder were transported to its lab in Washington so the data can be analyzed.

NTSB investigations can take up to a year or longer, although in major cases the agency generally releases some investigative material midway through the process.

Japan's Ministry of Land, Infrastructure, Transport and Tourism said an engine in the PW4000 family suffered unspecified trouble on a JAL 777 flying to Haneda from Naha on Dec. 4, according to Nikkei. It ordered stricter inspections in response.

Japan Airways and All Nippon Airways will stop operating a combined 32 planes with that engine, Nikkei reported.