Accident Summary
While on approach to the destination airport, the pilot reported engine problems and attempted to land in a field short of the runway. During the forced landing, the left wing struck the ground, causing the airplane to tumble through an impact sequence.
Engine and Carburetor Examination
Postaccident examination of the engine revealed debris and corrosion inside the carburetor and the main jet passage. No other mechanical anomalies were found that would have precluded normal operation. A Safety Board metallurgist examined the carburetor and identified the debris as a combination of lead and soil that had accumulated over time, and the corrosion indicated prolonged exposure to water. The particles likely restricted the flow of the air-fuel mixture in the main jet, eventually leading to a reduction or loss of engine power once significant buildup had occurred.
Carburetor Maintenance History
The airframe and engine logbooks contained no entries indicating the carburetor had ever been overhauled in its 46-year service history. The carburetor manufacturer had issued a service bulletin recommending overhaul at either the engine manufacturer's recommended time between overhauls or every 10 years, whichever came first. Although service bulletins are not mandatory, the investigation noted that had the carburetor been inspected at those intervals, the corrosion and debris might have been identified and the fuel system contamination corrected.
Shoulder Restraint System
The aircraft was not equipped with a shoulder harness restraint system. The pilot and front seat passenger sustained fatal head and upper torso injuries, attributed to lack of upper body restraint during the impact sequence. The airplane manufacturer had issued Service Bulletin No. 980 in 1995 for installation of shoulder harnesses on that make and model. The pilot/owner had purchased the shoulder harness kit but had not installed it; the still-packaged kit was found in the debris field by the investigation team.