What happened
On July 1, 2016, a pilot conducted a training flight at Schaffhausen airfield (LSPF) using an electric-powered ES-Trike (Delta-Trike). This flight marked the pilot's first operation from this specific airfield following recent regulatory changes in Switzerland regarding electric-powered weight-shift aircraft.
After assembling the aircraft on the airfield, the pilot performed a functional check and departed from runway 07. During the initial phase of the flight, an eyewitness observed the aircraft departing with a slight tailwind and experiencing some instability. The pilot performed several circuits, noting turbulent conditions and a wind shift that necessitated a change in approach direction toward runway 25.
During the final approach, the pilot attempted to increase airspeed using the electric motor to compensate for a low approach speed. This maneuver resulted in a wing stall, causing the aircraft to descend rapidly and strike the ground approximately 100 meters past the runway threshold. The impact was severe enough to cause the aircraft to bounce briefly before the wing pitched forward and slammed into the ground. While the pilot escaped without injury, a third party on the ground sustained minor injuries.
The investigation
SUST examined the circumstances surrounding the flight, including the pilot's experience and the aircraft's technical configuration. The investigation confirmed that the aircraft was an Atos-model wing equipped with a 10 kW brushless electric motor powered by a 14-cell Lithium-Polymer battery. The investigation also reviewed the pilot's recent flight history, noting that while the pilot had decades of experience with hang gliders, the use of this specific electric trike had been primarily limited to operations in France due to previous Swiss regulations.
Findings
- The primary cause of the accident was that the pilot undershot the minimum required airspeed during the final approach.
- The loss of airspeed led directly to a wing stall.
- The aircraft sustained heavy damage to the wing, keel, tail unit, and landing gear.