Flight History
The aircraft had departed from another airport earlier the same day. During the initial flight, the pilot noticed that the engine oil pressure was low. As a result, the pilot diverted from the original destination to another airport. While en route to the diversion airport, the engine oil pressure gauge dropped to zero.
Post-Divergence Inspection
After landing, the pilot inspected the aircraft's engine oil system for leaks. No leaks were found, and the oil quantity was correct at 7 quarts. Despite the earlier low oil pressure indication, the pilot elected to continue the flight.
Subsequent Power Loss and Landing
Approximately one hour into the resumed flight, the aircraft's propeller went to low pitch. Thirty seconds later, the engine lost power. The pilot executed a precautionary landing in a field.
Engine Examination
Upon examination of the engine, a hole was found in the engine case. The No. 2 piston rod had failed. The rod exhibited signs of excessive heat, characteristic of oil starvation. The reason for the initial loss of oil pressure could not be determined.