On July 13, 1995, at 0930 central daylight time, a Grumman G- 164A, N9949, was substantially damaged while landing following a loss of engine power near Simmesport, Louisiana. The commercial pilot was not injured. The airplane was being operated by W.D. Flyers of Simmesport, Louisiana, under Title 14 CFR Part 137. Visual meteorological conditions prevailed for the aerial application flight, for which a flight plan was not filed. In an interview with a Federal Aviation Administration inspector, the pilot reported that the engine lost power during initial takeoff climb. The pilot elected to continue straight ahead into an open field. Subsequently, the aircraft impacted the ground in rough and uneven terrain coming to rest in the inverted position. Post accident examination of the engine revealed that the top portion of the valve area for the number 7 cylinder separated from the engine resulting in the loss of engine power. The engine had accumulated 131 hours since the last overhaul.