On December 7, 1993, at 1310 eastern standard time, a home built Wonder Van's Aircraft RV-6, N443MW, was substantially damaged following a collision with terrain during an emergency landing near Ridgeland, South Carolina. The airline transport pilot received minor injuries in the accident. The aircraft was being operated under 14 CFR Part 91 by the pilot. Visual meteorological conditions existed at the time, and no flight plan had been filed for the personal flight. The flight departed Lawrenceville, Georgia at 1200. The pilot reported that prior to his initial descent, the engine developed a slight vibration of increasing intensity. The pilot then noted that during the descent, the vibration increased and the electronic tachometer on the right magneto went to zero. The pilot then reported that blue smoke entered the cockpit and oil began spilling onto the windscreen, followed by an engine failure. The pilot executed an emergency landing in a cotton field approximately 7 miles west of the Ridgeland airport. During landing roll, the landing gear hit an area of soft dirt and the airplane flipped over, causing damage to the vertical and horizontal stabilizers, rudder, and left wing. Post accident investigation of the aircraft engine revealed that the right magneto had separated from the engine. There was a large hole in the top of the crankcase where the magneto had been mounted. The left magneto was also found in the early stages of separation. Both magnetos had been installed on the engine approximately 16 hours before the accident by a certified repair facility.