On May 28, 2002, about 1430 eastern daylight time, a Bell 47G-2, registered to S and J Investments, LLC., dba Wing and Rotor, Inc., operating as a Title 14 CFR Part 91 instructional flight, crashed while attempting a liftoff at the Flagler County Airport, Bunnell, Florida. Visual meteorological conditions prevailed and a visual flight rules flight plan had been filed. The rotorcraft received substantial damage, and the student pilot, the sole occupant, was not injured. The flight was departing when the accident occurred. According to the student pilot, as he landed the rotorcraft, a sandbag on the right side floorboards being used for ballast shifted forward, but he was able to counter the weight shift and successfully completed the landing. He put a piece of cloth under the sandbag in an attempt to prevent further slippage, but as he lifted into a hover, a slight sideward slide in the grass caused the sandbag to again shift position on the floorboards. This caused the rotorcraft to roll toward its right side, resulting in a dynamic rollover to the right. The student stated that had he pushed the collective down and applied full left rudder, the accident could have been prevented. According to an FAA inspector, the student's physical stature is small, and he required sand bags as ballast on the right seat and floor for weight and balance considerations. The seat sandbag was secured by seat belt, but the floor sandbag was not secured and migrated on the cockpit floorboards toward the right seat flight controls during flight. The student landed at Flagler County Airport to secure the floor sandbag, but as he lifted off to continue flight, the ballast shifted again. The rotorcraft suffered a dynamic rollover, and came to rest on its right side.