Incident Overview
During a pullup for a turnaround maneuver, the engine separated from an agricultural airplane. The aircraft subsequently lost control and impacted the ground in a flat attitude within a field.
Investigation Findings
A post-accident investigation examined the engine mount attachment bolts. The upper right engine mount bolt, which attaches to the firewall, had failed due to fatigue. The lower right attachment bolt had also failed prior to the engine separation, but its fracture surface was too heavily damaged to determine the cause of failure. The upper left and lower left attachment bolts were found to have necked down at their respective fractures, indicating overload failure.
Conclusion
The investigation determined that the engine separation resulted from the fatigue failure of the upper right engine mount bolt, with the lower right bolt having failed earlier from an undetermined cause. The left-side bolts failed from overload during the separation event.