Incident Overview
According to the pilot, approximately 25 minutes into the flight, the engine began to run rough and shook "violently." Shortly thereafter, blue smoke emerged from the engine cowling and filled the cabin. The pilot shut down the engine and attempted a forced landing on an exposed sand bar adjacent to a river.
Impact and Damage
Upon touchdown, the nose landing gear and both main landing gear assemblies collapsed. The impact caused substantial damage to the aircraft's firewall and both wings.
Post-Event Examination
An examination of the engine revealed that a brass quick-drain fitting installed in the engine's oil pan had unscrewed and fallen out. The quick-drain fitting was not secured with safety wire.
Probable Cause
The probable cause of the engine failure was the loss of oil through the unscrewed quick-drain fitting, which was not secured with safety wire, leading to the subsequent forced landing and damage.