On August 20, 2002, about 1100 eastern daylight time, a Bell 47-D1, N4702S, registered to an individual, struck a mobile landing platform during a landing near, Union, South Carolina. Visual meteorological conditions prevailed at the time. No flight plan was filed for the agricultural flight that was being conducted under 14 CFR Part 137. The helicopter was substantially damaged. The commercial-rated pilot reported serious injuries. The flight had originated from the same platform about 1000. According to the FAA inspector, that was at the crash site, the helicopter had completed an agricultural spraying flight and was in the processes of landing to refuel and re-load chemicals at a portable platform. As the helicopter approached the pad the tail rotor struck a trailer that was close to the pad. The helicopter then flipped forward coming to rest upside down on the other side of the trailer. The pilot told the FAA inspector, that he had no mechanical difficulties before the crash, and that everything was operating "normally." At the time of the accident there was about a 5 to 7 knot crosswind. The pilot was given an NTSB Pilot/Operator Accident Report Form 6120.1/2, by the FAA inspector, but a completed form was not received.