What happened
On the afternoon of December 24, 2015, a pilot intended to conduct a flight at the Gießen-Lützellinden special landing field. Around 15:10 local time, the pilot informed an acquaintance of his intention to perform a sightseeing flight. Shortly thereafter, at approximately 15:35, witnesses observed an Aerospool Dynamic WT9 falling almost vertically toward the ground west of the airfield.
The aircraft was located in a forested area near Münchholzhausen, approximately 880 meters from runway 07. The impact caused significant damage to the surrounding vegetation and the aircraft itself. The pilot sustained fatal injuries due to polytrauma resulting from the impact.
The investigation
The BFU examined the wreckage and the engine components. The investigation included a teardown of the Rotax 912 ULS engine and its components, conducted by the manufacturer in the presence of the BFU and aviation experts. The investigation also covered the aircraft's fuel system, including the fuel gauges and the electrical auxiliary pump.
Investigators analyzed the wreckage distribution, noting that the fuselage broke forward of the tailplane boom and the wings were separated from the fuselage at the wing roots. The investigation also reviewed the pilot's flight experience and the maintenance history of the aircraft, which had undergone its last annual inspection in May 2015.
Findings
Technical examination of the engine, exhaust system, and ignition components revealed no malfunctions or mechanical failures that could have caused an engine failure. The carburetors were inspected and found to be in proper condition, and the fuel gauge LEDs were functioning correctly. All observed damage to the engine and components was attributed to the high-energy impact with the ground.
The aircraft fell in a nearly vertical descent, and the investigation found no evidence of a mechanical cause for this flight path.