The cameraman was filming a car from the right rear side of the helicopter which had the door removed. The car was travelling north-west at about 60 km per hour along a quiet country road through very open terrain. The helicopter flew at about 30 feet above the ground and about 100 metres from the left rear of the car. During the first filming run the pilot noticed a school bus driving north towards a "T" intersection through which the car would pass. He decided to avoid flying low over the bus and to remain well clear of a house just beyond the intersection. While distracted by the moving bus he veered from the planned flight path and pulled up over a powerline which followed the road used by the bus. The top strand of the powerline passed just over the front of the left landing skid, slid back to the crosstube and began to drag the helicopter to the ground. While the pilot counteracted the inflight effects of being snagged by the powerline, the main rotor severed the tail boom, shortly before the helicopter impacted the ground. On impact the fuselage and cabin broke up, the fuel tank split, and the left landing gear separated but there was no fire. The pilot was experienced in the filming role and was familiar with the area. A strong, gusty, northerly wind caused mechanical turbulence but conditions were suitable for filming.