On September 5, 2002, at 1130 central daylight time, a Beech B-55, N8821M, registered to West Properties and operated by a commercial pilot, caught fire during engine start at Hawkins Field, Jackson, Mississippi. The personal flight was operated under the provisions of Title 14 CFR Part 91 and visual flight rules, with no flight plan filed. Visual weather conditions prevailed at the time of the accident. The airplane was substantially damaged, and the commercial pilot was not injured. The flight was originating at the time of the accident. While starting the left engine, the pilot noticed smoke coming from the left side of the left engine cowling. At approximately the same time, flight line personnel ran toward the airplane with a fire extinguisher pointing to the left wing, which had caught fire. The pilot aborted the engine start, shut off electrical power, closed the fuel valves, and exited the airplane. A loud bang was heard and the left wing exploded. Examination of the airplane revealed the left wing spar had structural damage and the left wing was fire damaged. Further examination showed that the left wing fuel quantity transmitter unit had been leaking fuel. There were also blue fuel stains on the top of the rubber bladder style fuel tank. The maintenance history of the fuel quantity transmitter was not determined. The annual airframe inspection was completed on April 16, 2002, at which time the airframe had accumulated 4307 hours.