The commercial pilot was making a positoning flight under Title 14, CFR Part 91. The pilot said he had shuttled passengers to an oil platform, and was returning to pick them up. He said as he approached the platform helipad, the tail rotor struck the safety netting surrounding the landing area. The pilot said there were no mechanical problems with the helicopter prior to the accident, but that the tail rotor gearbox and tail boom were substantially damaged during the accident.