Incident Narrative
During descent for landing, the pilot noted a surge originating from the engine area. This surge was accompanied by an increase in engine RPM. Simultaneously, both the oil temperature gauge and the oil pressure gauge dropped to zero readings. The cylinder head temperature gauge indicated a value of 500 degrees. Smoke was observed coming from the engine area. Given these indications, the pilot elected to shut down the engine.
Landing
The aircraft performed a landing onto a soft cow pasture. During the landing roll, the aircraft nosed over and ended up inverted.
Examination Findings
A metallurgical examination of the engine components was conducted. The examination revealed evidence of heat damage and overstress fractures in the components inspected. Specifically, the oil pump drive key was found to have sheared.