What happened
On June 6, 2020, a private flight was underway from Gießen-Lützellinden airfield. The pilot, accompanied by a flight instructor acting as a safety pilot, had paused at the airfield to wait out rain showers. After briefly clearing water from the wings, the pilot proceeded with the takeoff from runway 25.
During the takeoff roll, witnesses observed the nose wheel lifting off the ground. Immediately after liftoff, the TL Stream aircraft rolled to the left and yawed toward the south. The aircraft's airspeed was noted as low. Shortly after departing the runway, the aircraft pitched forward from an altitude of approximately 20 meters, striking the ground. The flight instructor, seated in the rear, reported that the aircraft entered an aerodynamic stall and rolled onto its back before impacting the ground nearly vertically.
The investigation
The BFU examined the aircraft, which had recently undergone a significant engine upgrade from a 100 hp Rotax 912 ULS to a much more powerful 154 hp Edge Performance 912 STi. Investigators analyzed flight data from the aircraft's Garmin G3X system, which provided a reference for the aircraft's performance during previous flights. The investigation also reviewed the aircraft's weight and balance, noting that the total weight was near the 600 kg maximum and the center of gravity was positioned slightly aft due to luggage in the rear compartment.
Findings
- The primary cause of the accident was the failure to maintain minimum airspeed during the takeoff phase.
- The aircraft's recent conversion to a higher-powered engine significantly altered its takeoff characteristics, making it difficult to control at full power.
- The pilot's limited experience with this specific engine configuration contributed to the loss of control.
- Wet wings from recent rain showers reduced lift and increased the required takeoff speed.
- The aft center of gravity position contributed to a rapid increase in the initial climb angle, further complicating the flight path.