What happened
During a cattle mustering operation, the pilot altered the original flight plan after spotting additional livestock. Instead of returning to base after the initial task, the pilot decided to move the original herd into the main yards. While flying south towards the yard entrance, likely intending to land and open a gate, the helicopter struck a SWER powerline. The impact caused the aircraft to lose control and collide with the ground in an inverted position. The helicopter subsequently rolled over, coming to rest on its right side with the front of the right skid collapsed.
The investigation
The investigation focused on the visibility of the powerline and the pilot's situational awareness. The SWER line was extremely difficult to identify because it lacked contrast against the background, had no visible markers, and the nearest power pole was outside the pilot's primary field of view. While poles from a separate 3-strand network were visible, their presence may have provided a false sense of security regarding the absence of wires in the immediate area.
Analysis of the left skid revealed marks suggesting the wire struck at an oblique angle, sliding along the skid toward the front crosstube. The low forward airspeed at the time of impact likely prevented the wire from being severed. Additionally, investigators found that the ELT remote switch was set to the ARMED position, though the transmitter itself had been deactivated to the OFF position. While the cause of this deactivation was unknown, the wreckage was located promptly due to a nearby witness.
Findings
- The SWER line was difficult to detect due to a lack of visual markers, poor background contrast, and the positioning of the nearest pole.
- The pilot's change in flight plan meant that hazards at the main yards had not been recently assessed, as there was no prior intention to use that specific area during this mission.
- The presence of visible 3-strand network poles may have led to a false sense of security regarding the presence of other wires.
- The oblique angle of the impact and low airspeed likely prevented the wire from breaking upon contact.