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

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

The US 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 on Saturday as pieces of the engine's casing rained on suburban neighbourhoods.

None of the 231 passengers or 10 crew were hurt, and the flight landed safely, authorities said.

United is among the carriers that has grounded the planes.

FAA Administrator Steve Dickson identified the focus on the stepped-up inspections as hollow fan blades unique to the Pratt & Whitney PW4000 engine model and used solely on Boeing 777s.

Dickson's statement said the conclusion was based on an initial review of safety data and would likely mean grounding some planes.

Robert Sumwalt, chairman of the National Transportation Safety Board, said during a virtual news conference Monday night that a fractured fan blade found in the engine had visible signs of damage consistent with metal fatigue. The broken blade hit and fractured the blade next to it as the engine broke apart, according to a preliminary investigation.