The search and rescue helicopter was called out to a potential rescue and medical retrieval of a man who had fallen from a waterfall at Barrington Tops which is a mountainous/wilderness area. Due to extensive cloud cover, approaching last light and a lack of contact with ground personnel, the pilot-in-command elected to land near Barrington Guest House. 900 metres south east of the guest house was a paddock apparently suitable as a helipad. While flying a right downwind leg at about 60 knots and 500 feet in very light drizzle, the pilot and crew/passengers searched for powerlines and other potential obstructions. Powerlines parallelling the intended landing direction were seen. One of the crewmen searched for wires by looking out through the only sliding door fitted, which was on the left side of the helicopter. A normal approach was flown. When the helicopter was about 20 knots and 25 feet above the ground, the crewman sitting in the left front seat suddenly detected a spurline running across the approach path. He called out a warning to the pilot but it was too late. The helicopter struck two wires. The pilot immediately lowered the collective in an attempt to land as soon as possible. The landing was heavy. The helicopter impacted the ground in a slightly nose down attitude while banked slightly to the left. The wire strike was at the level of the rotating swashplate. Cyclic control was probably lost when the control rods above the swashplate were damaged by the wires. The spurline was particularly difficult to see. Rising ground ahead of the wires, in the direction of landing, camouflaged the wires. The pole at the end of the spurline was somewhat hidden by trees and light drizzle reduced visibility. A wire strike protection device was not fitted on the helicopter. SIGNIFICANT FACTORS The following factors were considered relevant to the development of the accident: 1. The powerline was particularly difficult to see because of its location, the surrounding terrain and foliage. 2. Visibility was reduced due to light drizzle.