ANC22FA069 · Story Charles Brad TT FOX

According to witnesses, the airplane took off on runway 08 and then turned back toward the airport. The pilot made a radio call that he was turning downwind for landing. The accident occurred during the fifth flight of the phase 1 test flights after the pilot finished building the airplane. Witnesses heard changes in the engine rpm they described as the engine revving, going to idle, and surging. They also reported that the airplane was traveling “fast,” with pitch oscillations; the airplane approached the gravel runway in a right-wing-low turn as if it was going to land. The airplane then pitched down abruptly before striking trees about 60 to 80 ft before penetrating the side of a hangar, where it came to rest. Data downloaded from an onboard device showed the airplane turned crosswind after takeoff then entered a right downwind for the runway. Once abeam the departure end of the runway, the airplane stopped its climb, began a descent, and turned toward the approach end of the intersecting gravel strip. The data also showed that the engine rpm changed from idle to maximum three times in the last 8 seconds of flight. Examination of the airplane revealed no mechanical malfunctions or anomalies that would have precluded normal operation. The reason for the rpm oscillations and pitch variations could not be determined with the available information. Given the witness statements and that the pilot was turning toward the gravel runway, it is likely that he was experiencing an issue with the airplane that could not be determined with the available information.

Verbatim NTSB analysis and probable cause from the NTSB dataset