The pilot/owner stated that the helicopter was at or near its maximum allowable gross weight and required maximum engine power to hover in ground effect. After a brief local flight, the pilot completed an approach to the parallel taxiway beyond the parking area. Instead of performing a 180°pedal turn over the pavement to reverse course, the pilot initiated a teardrop-shaped turn. The helicopter turned to the right below effective translational lift (ETL) airspeed, the terrain sloped away from beneath the helicopter and once in an out-of-ground effect, higher power-demand condition, the engine could not produce the necessary power to maintain full operating rpm. The helicopter then descended below the height of the taxiway, the pilot attempted to perform a landing to rough, sloping terrain, and the helicopter rolled over and came to rest on its side. Following the accident, the pilot stated that during the accident the helicopter was performing "beautifully." He provided a comprehensive review of the events and suggested that better preflight and inflight performance planning, and inflight power management would have prevented the accident.