What happened
On 11 March 2018, a Steen Skybolt, registration G-NMUS, was conducting a private flight near Taldrwst Bach, Amlwch, Anglesey. While cruising at approximately 1,500 ft agl over a wind farm, the aircraft's Lycoming IO360 CIA engine began shuddering before the propeller ceased rotation.
Recognizing the emergency, the pilot identified a suitable field to the right of the flight path that had been recently passed. During the maneuver to reach this landing site, the pilot maintained a bank angle of roughly 15° and an airspeed of approximately 100 mph, which was significantly above the aircraft's straight and level stall speed of 56 mph. However, as the aircraft descended to about 400 ft agl over a wooded area, it entered a stall and the right wing dropped. This resulted in a nose-down spin of approximately 270°, ending in a collision with trees at the edge of the woods. The impact caused substantial frontal damage to the engine, fuselage, and both the upper and lower wings. The pilot, wearing a helmet and full harness, escaped the open cockpit without injury.
The investigation
The investigation was based on the aircraft accident report form provided by the pilot. Investigators examined the flight parameters, including the pilot's management of bank angle and airspeed during the forced landing attempt. Data from the aircraft's two g-meters were reviewed, revealing a peak deceleration of -10g during the impact. The investigation also noted the pilot's experience level, specifically that while the pilot had 1,205 total flying hours, only one hour had been completed on this specific aircraft type.