On July 26, 1995, about 1520 eastern daylight time, a Piper PA-12, N3036M, collided with a ditch, following a rapid engine acceleration, during hand starting by the pilot, at North Myrtle Beach, South Carolina. The airplane was operated by Barnstormers Flite Signs, Inc. under the provisions of 14 CFR Part 91, and visual flight rules. No flight plan was filed for the local banner tow operation. There were no injuries to the commercial pilot, and the airplane was substantially damaged. The flight was originating at the time of the accident. The pilot had stopped the airplane about 1/4 mile from the operator's banner handling personnel to change hooks. The operator stated that chocks should have been in the airplane to accommodate "hand propping," since the airplane is not equipped with an electrical/starting system. There were no chocks in the airplane at the time of the accident. The operator also stated that the throttle was not in the idle position, and when the engine started the airplane taxied away from the pilot and into a ditch.