Incident Overview
During a local dual instructional flight, the pilot reported that the aircraft developed a vibration and a substantial loss of power. The aircraft was forced to land off the airport in an area of high vegetation.
Post-Incident Examination
Examination of the aircraft revealed that the #3 cylinder was not developing compression. When the propeller was rotated, the piston did not respond. The #3 cylinder assembly and piston were removed for further inspection. The connecting rod bearing was found to be badly scored, with no apparent lubrication visible. Additionally, one connecting rod bolt was found sheared.
Laboratory Analysis
A sample of the engine oil was analyzed and found to contain a slightly high content of dirt. High contents of aluminum and copper were also noted in the oil sample.