What happened
On October 4, 2023, at approximately 16:03 UTC, an Evektor EV-97 SportStar RTC was conducting a solo time-building flight from Maribor Airport (LJMB) in Slovenia. The flight was part of a training program for a Slovenian flight organization. The aircraft was flying in Visual Flight Rules (VFR) conditions, originally planning to fly via Klagenfurt before deciding to return to Maribor to land before sunset.
While cruising at approximately 7,700 feet MSL, the pilot observed a drop in engine oil temperature. Shortly thereafter, at approximately 16:01 UTC, the engine RPM increased significantly. Within a minute, the aircraft experienced an abrupt loss of power, a drop in oil pressure, and the engine stopped completely as fuel flow returned to zero.
Following the engine failure, the aircraft's pitch increased to 40 degrees, and it entered a left-hand turn. This led to an uncontrolled aerodynamic stall and a developed spin. Although the pilot managed to recover the aircraft from the spin at approximately 4,000 feet MSL, the aircraft entered a deep stall/heavy sink condition. Despite the pilot's efforts to push the control stick forward to regain airspeed, the aircraft remained unresponsive and continued a steep descent. The aircraft ultimately impacted a mown field in Bösenort, Diex, with high vertical velocity, sliding several meters downslope.
The investigation
The Austrian Federal Safety Investigation Board (SUB) initiated an investigation following notification from Austro Control. The investigation examined the flight sequence, the pilot's licenses and experience, and the aircraft's maintenance and operational documents. Investigators also analyzed weather conditions, flight path records, engine data, and conducted a laboratory examination of the engine and fuel. The investigation also included a study of the engine's performance on a test bench and an assessment of the accident site.