What happened
On April 28, 2022, a private flight departing from St. Gallen-Altenrhein Airport (LSZR) ended in a fatal accident near the shores of Lake Constance. The pilot, operating a Beech A36TC registered as HB-EJE, took off from runway 28 under visual flight rules. Shortly after passing the lake's shoreline at an altitude of approximately 400 feet, the pilot radioed that the aircraft was experiencing an engine failure.
Following the engine issue, the aircraft entered a left-hand turn. An air traffic controller observed the aircraft bank to 45 degrees, before the bank angle increased to 70 degrees. As the aircraft's nose pitched down significantly, it entered a high rate of descent and disappeared behind a building. The aircraft struck the shallow bottom of Lake Constance, resulting in the death of the pilot and the total destruction of the aircraft. The impact caused a minor fuel spill into the water.
The investigation
Investigators from SUST examined the wreckage and the aircraft's maintenance history. Technical inspections of the engine and fuel control components, including the throttle and fuel manifold valve, revealed no pre-existing mechanical defects. However, records from a recent 100-hour/annual inspection indicated that adjustments had been made to the fuel system, as fuel flow measurements during the inspection were at the lower limit of the required operational range.
Analysis of the fuel system highlighted that the auxiliary fuel pump's "HI" setting can cause an engine failure due to an overly rich mixture. Additionally, the investigation noted that the fuel selector switch was found in a position near the edge of its intended detent. The investigation also reviewed the pilot's flight controls and the aircraft's performance during the final moments of flight.
Findings
- The investigation found no evidence of mechanical failure in the engine or fuel delivery components that would have caused a loss of power.
- The loss of engine power may have been caused by operational errors, such as the incorrect positioning of the fuel selector switch or the accidental activation of the auxiliary fuel pump to the "HI" position.
- The primary cause of the accident was the initiation of a steep, low-altitude turn to return to the airport after the engine failure, which led to a stall and subsequent loss of control.