N7519V

The instructor pilot was performing flight checks on the single engine helicopter after maintenance had been performed. The instructor pilot and private pilot on board had completed three straight-in autorotations and one 180-degree reverse direction autorotation. The instructor setup on downwind and initiated a second 180-degree autorotation. But, when the turn was almost completed, the rotor RPM started to drop. The instructor decided to initiate a power recovery go-around. Power was applied but the helicopter continued to settle and hit the ground in a level attitude. The helicopter rolled on its left side and sustained substantial damage. Both occupants exited the aircraft unassisted and were not injured. No system anomalies were revealed.