What happened
On August 13, 2020, a Robinson R44 RAVEN I helicopter, registration OK-HLS, was involved in an accident in a garden on the eastern edge of Žamberk, Czech Republic. The pilot had previously landed on his private property for a short break and was preparing for a recreational flight with three passengers.
During the takeoff, at an altitude of approximately 2 to 3 meters AGL, the helicopter began to rotate to the left. The pilot attempted to correct the movement using the pedals, but the aircraft continued to spin around its vertical axis. During the uncontrolled rotation, the main rotor blades struck a large tree located near the takeoff site. The impact caused the helicopter to tilt sharply and crash onto its left side. All four occupants managed to exit the cabin on their own. While most passengers were uninjured, two passengers were transported to the hospital for observation due to neck pain.
The investigation
The ÚZPLN investigation examined the pilot's experience, the aircraft's maintenance history, and the takeoff conditions. The investigation established that the pilot had recently completed intensive training and had some experience with the OK-HLS type, but had limited experience flying the aircraft at a total weight near its maximum takeoff weight (MTOW).
Investigators found that the takeoff location was in violation of local regulations, as the distance to a nearby residential building was only approximately 20 meters, whereas regulations require a minimum of 100 meters. The investigation also noted that the takeoff site, while large, did not allow for a safe departure over obstacles for a single-engine helicopter under the specific weight and balance conditions of that flight.
Findings
- The primary cause of the accident was the improperly chosen takeoff method and subsequent loss of control during the hover phase.
- The pilot failed to react correctly and timely to the unwanted directional changes of the aircraft.
- The aircraft's total weight and center of gravity had changed significantly from the previous flight, making the takeoff much more demanding in terms of required control coordination.
- Contributing factors included the pilot's limited experience with high-weight takeoffs and a potential wind gust that may have exacerbated the rotation.
- The takeoff site was unsuitable due to its proximity to residential structures and the presence of obstacles.