Incident Summary
While descending to an airport for a fuel stop, the engine started to vibrate and subsequently lost total power. The pilot initiated a forced landing, and the airplane came to rest upright in a field approximately 3 miles from the intended airport.
Preflight and Maintenance
Prior to the flight, the engine oil and filter were changed. During the preflight inspection, the pilot noted 6 quarts of oil in the engine. Examination after the event revealed approximately 3 quarts of oil remaining in the engine.
Engine Examination
All four connecting rod journals and connecting rod caps and straps displayed discoloration and heat signatures consistent with oil starvation. The inverted oil system's separator contained a black residue that partially blocked the separator ports.
Manufacturer Guidance
According to the engine manufacturer's service instruction, loss of oil from the breather fitting could be caused by an excessive amount of residue in the oil separator and oil line. The instruction recommends disconnecting the oil system from the engine and flushing it with a petroleum solvent every 300 hours of operation.
Maintenance Records
No logbook entries were noted for compliance with the service instruction; however, such an entry was not required by Federal Aviation Regulations.