What happened
On a flight traveling from Disley, Saskatchewan, to a private airstrip near Kenaston, an Aces High Cuby II ultralight aircraft entered a fatal spin. The flight included a scheduled stop in Davidson, where wind conditions were noted to be increasing. While flying approximately 300 to 500 feet above the ground, witnesses observed the aircraft bank steeply and pitch nose-down. The aircraft rotated several times before impacting the ground southeast of the destination airstrip. The accident resulted in 2 fatalities, involving the pilot and a passenger.
The investigation
The investigation focused on the aircraft's aerodynamic stability and the environmental conditions at the time of the crash. Investigators examined the aircraft's center of gravity (C of G) and found that recent modifications and a thicker application of paint on the aft fuselage likely moved the C of G beyond the permitted rearward limit. Additionally, the investigation looked into the flight control surfaces, specifically the aileron gap seals. While aluminum seals were present, the required tape seals were missing, which reduced the aircraft's lateral stability.
Meteorological data revealed that the flight path passed through unstable air, with witnesses reporting several "dust devils" in the area. These atmospheric vortices can produce significant wind shear. The engine and propeller were inspected and found to be in working order with no evidence of mechanical failure prior to the impact.
Findings
- The aircraft encountered gusty winds and wind shear that likely exceeded its aerodynamic capabilities.
- The aircraft's center of gravity was likely positioned beyond the aft limit, reducing pitch stability and increasing stall susceptibility.
- The absence of tape aileron gap seals reduced the lateral stability of the aircraft.
- The aircraft entered a stall and subsequent spin from which recovery was impossible at the low altitude of the flight.