According to the pilot, the takeoff was normal and as the helicopter accelerated forward, the right door of the helicopter came open. The pilot, who was seated in the right seat, reacted by attempting to secure the door and subsequently lost control of the helicopter. The helicopter impacted the ramp. During the impact, the left skid separated, the right skid was crushed up and bent out, and the firewall and tailrotor were bent. The pilot reported that there were no mechanical failures or malfunctions prior to the accident. He did state that he had checked the security of the door with elbow pressure prior to departure but postulated that the securing pin was not fully engaged.