Incident Details
A flight instructor and a student pilot were conducting power-off stall maneuvers in a local practice area. In preparation for a power-off stall, the student pilot executed a flow checklist—setting the fuel valve to both and mixture to rich—and reduced power to slow the aircraft. Shortly after this procedure, the engine lost total power. The engine failed to restart, and the flight instructor performed a forced landing to a field. During the landing, the airplane impacted a fence.
Post-Incident Engine Examination
After the incident, an engine run was conducted. During this run, the engine repeatedly lost total power when the throttle was reduced to the idle position. An engine manufacturer representative then adjusted the mixture control wheel on the fuel injector unit, rotating it eight turns toward the lean setting. Following this adjustment, the engine was restarted, and when the throttle was reduced to idle, the engine continued to run without losing power.
Fleet Inspection Findings
An inspection of the operator's fleet revealed that the idle mixture controls on several other airplanes of the same make and model were also out of adjustment. No further details were provided regarding the extent of the discrepancy or corrective actions taken.