Boeing has recommended that any airline flying the Pratt & Whitney 4000-112 powered Boeing 777 should ground them pending an investigation into the United Airlines flight which suffered an uncontained engine failure on Saturday.
Investigators are now searching for a key piece of evidence to determine what caused the engine to fail: a fan blade that broke in two. Experts said finding the other piece is critical.
Japan has ordered its domestic airlines to ground all Boeing 777s, in response to an incident Saturday where a plane engine caught fire shortly after takeoff.
The regulatory moves involving Pratt & Whitney 4000 engines came after a United Airlines 777 landed safely at Denver International Airport on Saturday after its right engine failed.