On 20 February 2021, a PW4077-powered Boeing 777-200 was climbing through 12,500 feet after departing Denver when a sudden right engine fan blade failure occurred leading to an engine fire which could not be fully extinguished until after landing. The Investigation found that the aircraft operator’s blade inspection process had been deficient and that the engine manufacturer’s prescribed blade inspection intervals were inadequate with both contributing directly to the in-service failure. It found that the consequences of the failure were worsened by inadequate design and testing of both the engine inlet and the main gearbox support structure.