Incident Overview
While flying at an altitude of 2,000 feet MSL, the pilot encountered a sudden loss of engine power. The aircraft's oil pressure had dropped to zero, and attempts to restore full engine power were unsuccessful. The pilot executed a forced landing in a rough field located next to a horse race track.
Post-Accident Examination
Examination of the engine after the accident revealed that the oil dilution access plug was missing. This allowed the engine oil pump to cavitate, leading to the loss of power. The plug was not found at the accident site during the search.
Maintenance History
According to the aircraft owner, the engine had undergone an overhaul just six hours prior to the accident. Additionally, a service bulletin requiring the replacement of the originally installed plug with a square head plug equipped with a safety wire feature had not been accomplished.
Conclusion
The failure to install the updated plug as per the service bulletin resulted in the plug being lost in flight, causing the oil pump to cavitate and the subsequent loss of engine power. The forced landing was necessitated by the inability to restore power.