Incident Overview
A domestic passenger cross-country flight experienced a total loss of engine power while in cruise. The pilot successfully landed the airplane at a nearby Naval Air Station following the loss of power.
Pilot Report
The pilot reported hearing a loud bang during cruise flight, and oil became visible on the aircraft's windshield. Concurrent with the loud bang, the propeller came to an abrupt stop.
Postaccident Engine Examination
Postaccident examination of the engine revealed extensive corrosion and mechanical damage throughout the compressor and power turbine assemblies. The compressor disk assembly was essentially intact; however, all of the compressor turbine blades were fractured and displaced. The fracture surfaces were all approximately 0.250 inches above the corresponding blade platform.
Metallurgical Analysis
Examination of the fractured compressor turbine blades indicated that the blades fractured in a tensile overload condition. The overload fractures were due to a weakening of the underlying base material caused by the presence of sulphidation corrosion. The sulphidation corrosion was evident through approximately half of the thickness of the blades' airfoil, reducing the blades' effective load-bearing capabilities. The material composition of the turbine blades met drawing requirements, and no metallurgical anomalies were found.