Accident Overview
The pilot reported that shortly after takeoff, the airplane lost engine power, prompting a landing in an open field south of the airport.
Post-Accident Examination
Post-accident evaluation and testing of the mixture control linkage revealed that the metering shaft rotated to the mechanical stop when actuated to the "idle cut-off" position. However, when the mixture control was actuated to the "full-rich" position, the metering shaft rotated only approximately 40 percent of its potential full travel and did not reach the mechanical stop. Further examination showed that the mixture control arm retaining nut was tight, but extensive wear was observed on the serrated mating surfaces of the mixture control arm and metering shaft. The serrated edges had worn smooth, and fretting type damage was noted on both surfaces.
Maintenance History
Maintenance records indicated that the airplane's original engine, a Continental IO-520, had been removed and the airframe was retrofitted with a factory rebuilt (zero time) IO-550-B in accordance with a Supplemental Type Certificate (STC). The certified airframe and power plant (A&P) mechanic who performed the maintenance stated that the mixture control arm, which was shipped with the engine, was installed in conjunction with the engine conversion.