What happened
During a night flight, the pilot experienced a significant mechanical issue when oil began spreading across the windshield and heavy smoke entered the cockpit through the cabin heater. The pilot opened the cabin windows to clear the smoke, reduced power, and turned back toward the airport. Oil pressure dropped to 5 PSI, prompting the pilot to descend for a landing on a visible road illuminated by moonlight.
As the aircraft approached the ground, the engine began to rattle. The pilot aligned with the road but briefly lost sight of it due to clouds obscuring the moon. Just before landing, the pilot spotted a guy wire and maneuvered to avoid it. The aircraft stalled and hit a ditch, causing the nose and left main gear to shear off. The aircraft continued through bushes, hit a fence, and nosed over.
The investigation
An examination of the wreckage revealed that two oil lines had rubbed together until one wore through. The oil lines were supposed to be protected by a rubber spacer and a clamp. Either the clamp had failed or was not installed. Subsequently, the rubber spacer had moved, allowing the lines to rub against each other.
Findings
The primary factors contributing to the accident included the failure of the oil line protection system, specifically the movement of the rubber spacer and the absence or failure of the clamp. This allowed the oil lines to wear through, leading to oil leakage, cockpit smoke, and eventual engine failure during the night flight.