What happened
While performing a turn at a low airspeed, the aircraft began to buffet, exhibiting characteristics of an approaching aerodynamic stall. In an effort to recover, the pilot lowered the aircraft's nose to increase velocity, leveled the wings, and applied full engine power. Simultaneously, the pilot began jettisoning the cargo load. Despite these actions, the pilot could not maintain sufficient altitude, and the aircraft ultimately struck the ground.
The investigation
The investigation examined the aircraft's performance during the maneuver, specifically looking at the impact of the full load and the presence of vortex generators on the aircraft's aerodynamics. While the pilot suspected the engine was underperforming compared to previous flights, investigators found no evidence of engine malfunction prior to the turn. Although the engine sustained extensive damage during the impact, post-accident inspections revealed no mechanical issues. The investigation also considered how the pilot's recent experience with a more powerful aircraft might have influenced their perception of the engine's power output during the critical phase of the turn.
Findings
- The aircraft was operating at a full load during the maneuver.
- The combination of the full load, the presence of vortex generators, and the limited power margin between normal and maximum engine output contributed to the loss of altitude.
- There was insufficient height available to recover the aircraft once the aerodynamic buffet began.
- The aircraft's inability to counteract the effects of the turn was exacerbated by the lack of additional power available above normal operating levels.