N123SD

The pilot indicated that the purpose of the flight was to finish the post annual flight check and to check the autorotational rpm during a simulated engine out condition. The pilot was flying in the left seat and there was an observer in the right seat. He entered a 180-degree autorotation and at 70 feet above ground level, began a gradual flare. During the flare, the helicopter contacted the asphalt surface of the taxiway. The helicopter hopped and then came to a stop. The pilot initiated another pattern and power recovery autorotation. He then hover taxied to the maintenance hangar ramp area and performed a normal shutdown. Post flight inspection revealed a wrinkle in the tail boom.