Accident Overview
During a flight involving touch-and-go landings, the engine failed as the airplane was climbing on the upwind leg of the second touch-and-go. The pilot executed a forced landing, during which the airplane collided with trees and subsequently struck the ground.
Preflight and Engine Operation
The engine oil had reportedly been changed and replenished just prior to the flight. The engine was then started and operated for approximately 5 to 10 minutes. Both the pilot and the General Manager verified that the engine oil quantity was full before the flight departed.
Post-Accident Examination
An FAA airworthiness inspector examined the airplane two days after the accident. No evidence of oil discharge during flight was observed. Disassembly of the engine revealed that the Nos. 2 and 4 connecting rod bearings had failed, and the Nos. 1 and 3 connecting rod bearings were damaged. Only minimal oil was found in the engine. The oil pump gears showed no failure or malfunction.
Instrumentation Discrepancy
The hour meter historically indicated a greater elapsed time than the cable-driven tachometer during flights of varying lengths. However, during the accident flight, the tachometer elapsed time exceeded the hour meter time. The hour meter is electrically activated by a pressure switch that requires a minimum oil pressure of 3 psi. Post-accident testing of the hour meter and pressure switch revealed no malfunction.