On April 16, 1995, at 1730 central daylight time, a Bell 206B, N729CH, operated by a private instrument rated helicopter pilot, collided with the terrain during engine start at a private residence in Horseshoe Bend, Missouri. The helicopter was substantially damaged and the pilot was not injured. Visual meteorological conditions prevailed for the personal 14 CFR Part 91 flight. The helicopter was parked on a concrete helipad at the pilot's residence. He stated he normally tied down the main rotor blade to a lamp post in front of the helicopter. However, because of a storm approaching from the right side of the helicopter, he tied down the main rotor blades to the catwalk handrail. He stated that when he preflighted the helicopter he untied the skid tie-downs but forgot to untie the main rotor tie-down. He started the helicopter and when power reached 21%, he noticed the rotor blades had not turned. He stated he immediately rolled off the throttle but that the power was already at 60% and he heard a loud "pop." The main rotor blade had broken approximately three feet out form the pivot bolt attachment and the helicopter turned 90 degrees on the helipad. The main rotor blade, tailboom, and fuselage were damaged.