What happened
During a takeoff attempt, a helicopter encountered an unexpected obstacle that led to a loss of control. As the pilot initiated the maneuver amidst east-south-easterly winds, they applied slight left cyclic to position the aircraft into a hover. During this process, the left skid made contact with a tree root that had been partially hidden by sand, making it invisible to the pilot prior to departure.
This contact caused the helicopter to begin rolling around the left skid. In an effort to stabilize the aircraft, the pilot applied right cyclic and attempted to lower the collective. However, before the collective could be lowered, the aircraft became light enough on its skids to drift toward the right. This lateral drift went unnoticed by the pilot. When the collective was subsequently lowered to settle the aircraft, the right skid struck the ground, triggering a dynamic rollover.
The investigation
Investigators focused on the conditions present during the departure phase and the pilot's awareness of the ground environment. The examination revealed that the tree root was obscured by sand, preventing the pilot from identifying the hazard before the maneuver began. The investigation also looked at the sequence of control inputs and the resulting movement of the aircraft during the transition to a hover.