What happened
On June 17, 2017, at approximately 16:55 local time, a UFM13 aircraft, registered as HB-YKK, was performing a takeoff from Thun Airport (LSZW) under Visual Flight Rules (VFR). During the initial climb phase, the aircraft encountered a strong wind gust that caused it to lift off the runway prematurely. In an attempt to regain airspeed and prevent a potential stall, the pilot applied a sudden, forward control input. This maneuver was excessive, causing the aircraft to descend and touch down on the runway again. Due to the low ground clearance inherent in the aircraft's taildragger design and the compression of the main landing gear upon impact, the propeller made contact with the ground.
The investigation
The investigation focused on the sequence of events during the takeoff roll and the pilot's reaction to environmental conditions. Investigators examined the aircraft's flight characteristics and the impact of the wind gust on the takeoff performance. The inquiry established that the aircraft briefly lifted off the surface before the pilot's corrective action led to a secondary touchdown, which ultimately caused the propeller strike.
Findings
- The primary cause of the incident was an excessive forward control input following a sudden wind gust.
- The aircraft's taildragger configuration results in limited propeller ground clearance.
- The compression of the main landing gear during the secondary touchdown contributed to the propeller making contact with the runway.
- The incident resulted in light injuries to one person on the ground and light damage to the aircraft's propeller.