RISEN 915 iS — Glendive , MT

What happened

The pilot was conducting a personal cross-country flight in his experimental, amateur-built airplane, and the accident occurred on day nine of the flight.

The airport manager at the departure airport reported that he assisted the pilot with fueling the airplane with about 15 gallons of fuel. He reported that the engine sounded like it was at full power during takeoff; however, the airplane appeared to climb slower than he expected to about 300-400 ft above ground level (agl). The main landing gear were up but the nose gear appeared to be partially extended and had not completely retracted. He watched the airplane maintain a low altitude at a low airspeed until he observed a “wing drop,” and the airplane subsequently made two turns in a “flat spin” with about a 45-60° nose-down attitude as it descended behind terrain.

Postaccident examination revealed no anomalies with the airframe or engine that would have precluded normal operation. Damage signatures and witness accounts indicated that the engine was producing power at the time of the accident. The debris path was consistent with a steep impact angle.

Evidence suggests that the pilot failed to maintain airspeed during the climb, which resulted in an exceedance of the airplane’s critical angle of attack and a subsequent aerodynamic stall/spin. The pilot had texted the aircraft kit manufacturer that he was having problems with the engine overheating; however, had made modifications to the cooling system that appeared to be successful, according to his texts with the owner of a similar airplane. The airplane’s emergency parachute was found deployed at the accident site. Since the parachute was unfurled, it is likely that the parachute deployment was the result of ground contact.

Evidence suggests that the pilot failed to maintain airspeed during the climb, which resulted in an exceedance of the airplane’s critical angle of attack and a subsequent aerodynamic stall/spin. The nose landing gear did not retract fully after takeoff. Although this may have created a distraction for the pilot that resulted in a loss of airspeed while he was troubleshooting the nose landing gear retraction, the investigation was not able to determine the reason for the pilot’s loss of control.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.