Incident Overview
On June 26, 2020, at 17:50 UTC, a Diamond DA20 C1 aircraft, registration SP-KPX, was conducting a training flight for flight instructor (FI) rating along the route EPMO-EPBC-EPPT-EPMO. Approximately 50 minutes into the 54-minute flight, after passing Skierniewice, the crew performed a simulated engine failure and forced landing exercise. When the instructor called for a go-around and the throttle was advanced, the engine ceased operation. The crew executed an emergency landing on a soft field between two rows of trees. The aircraft decelerated without a tendency to nose over, and the crew applied brakes, stopping about 10 meters from trees ahead. Neither crew member was injured, and the aircraft sustained no damage.
Investigation Findings
Post-incident inspection of the Continental IO-240-B engine with low-pressure fuel injection, including a 100-hour check, revealed no mechanical malfunctions; all engine parameters were within normal limits. Analysis of the flight data indicated that the engine failed during descent and when the throttle was moved to the maximum position. Weather conditions at the time, as per METAR reports, showed a temperature and dew point of 18°C, indicating 100% relative humidity. The flight occurred after a brief but intense thunderstorm. Research on piston engines indicates that throttle icing can occur even at relatively high temperatures, particularly with partial throttle openings typical of descent. Ice forms on the throttle plate due to condensation and freezing of water vapor, reducing airflow. In this incident, prolonged descent with the throttle at idle likely promoted ice accumulation. Advancing the throttle to full power then caused airflow restriction, leading to engine starvation.
Probable Cause
The probable cause of the incident was icing of the throttle plate in the engine's intake system, which, upon attempting to increase engine speed to maximum, resulted in engine starvation. Contributing factors included meteorological conditions conducive to throttle icing.
Recommendations
No safety recommendations were formulated by the investigating body.