US Federal aviation regulators are ordering United Airlines to step up inspections of all Boeing 777s equipped with the type of engine that suffered a catastrophic failure over Denver on Saturday.
United has also said it is temporarily removing those aircraft from service.
The announcements came a day after United Airlines Flight 328 had to make an emergency landing at Denver International Airport after its right engine blew apart just after take-off.
Pieces of the casing of the engine, a Pratt & Whitney PW4000, rained down on suburban neighbourhoods.
The plane with 231 passengers and 10 crew on board landed safely, with nobody on aboard of on the ground reported hurt, authorities said.
Federal Aviation Administration (FAA) administrator Steve Dickson said in a statement 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 National Transportation Safety Board said in a separate statement that two of the engine’s fan blades were fractured and the remainder of the fan blades “exhibited damage”.