What happened
On July 26, 2019, a Beech A36 departed from Sylt bound for Münster/Osnabrück with three occupants on board. During the initial departure from Sylt, a passenger noted a stall warning during a particularly aggressive takeoff. The flight proceeded under visual flight rules at FL65.
During the approach to Münster/Osnabrück airport, the pilot reported an engine failure and indicated that an emergency landing outside the runway would be necessary. Following the engine failure, the landing gear was retracted, though a passenger noted an attempt to extend it again. The aircraft approached the landing site at an angle of approximately 45 degrees before suddenly banking hard to the right and stalling. The aircraft struck a cornfield roughly 660 meters from the threshold of runway 07. The impact resulted in 3 serious injuries and the destruction of the aircraft.
The investigation
The BFU investigation focused on the cause of the engine failure and the subsequent flight path. Investigators examined the aircraft's maintenance records, which showed the last 100-hour inspection had been completed recently. The investigation also analyzed radar data, which revealed that at the time of the engine failure report, the aircraft's groundspeed was approximately 60 knots—well below the recommended best glide speeds of 110 KIAS or 85 KIAS.
Technical examination of the engine revealed that the right magneto was defective, exhibiting high secondary winding resistance. While the engine was generally functional, the failure of this magneto could lead to significant power loss, especially when the fuel mixture is enriched during approach. Investigators also noted that the landing gear had pierced the wings during impact, indicating a high vertical force component consistent with a low-altitude stall.
Findings
- The primary cause of the accident was that the aircraft undershot the minimum required airspeed following the engine failure, leading to an unrecoverable stall at low altitude.
- A defective right magneto contributed to the engine's inability to maintain power.
- The pilot's limited recent experience with the specific Beech A36 model and high stress levels following the engine failure were contributing factors.
- High ambient temperatures (35°C) increased the density altitude, which reduced engine performance.