Boeing has recommended that airlines ground all 777s with the type of engine that blew apart after takeoff from Denver this past weekend. 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 Saturday. Pieces of the casing of the Pratt & Whitney PW4000 engine rained on suburban neighborhoods. The FAA identified the focus of the stepped-up inspections as hollow fan blades unique to the engine model and used solely on Boeing 777s. Boeing said 69 such planes were in service and another 59 in storage.