N370WM - Aircraft Aircraft Registration

Failure of the pilot-in-command to recognize that the main rotor rpm was decreasing and his failure to maintain the main rotor rpm during the autorotative landing resulting in a hard landing. Contributing to the accident was the partial loss of engine power due to partial blockage of the engine air inlet screen. Also contributing was inadequate inspection of the airplane following maintenance by other maintenance personnel for their failure to remove a paint masking roll from the canopy. Additionally, inadequate preflight of the helicopter by the pilot for his failure to observe the roll of paint masking material and weight and balance exceeded.