On September 17, 1997, about 1100 eastern daylight time, a Hughes 269A helicopter, N6786M, registered to Pasco County Mosquito Control District, operating as a Title 14 CFR Part 91, local public-use flight, lost engine power and impacted with water during a forced landing near Tarpon Springs, Florida. Visual meteorological conditions prevailed, and no flight plan was filed. The helicopter was substantially damaged. The commercial-rated pilot was not injured. The flight had originated from Ancolote Island, Florida, at 1055. The flight had departed the island after completing a mosquito control inspection, and was at a low altitude, when the pilot reported that the engine lost power. The pilot said he was at a cruise setting of "23 inches [manifold] plus 2800 rpm," at an altitude of 200 feet above the water, when the engine started "missing" and "failed to develop enough power to maintain flight." He said the engine sputtered and regained full power. The pilot was setting up for an autorotation, with a forward airspeed of "50 knots." The pilot said "...[he] split the needles, engine rpm [was] approximately 2,000 rpm, plus missing, at the flair or decel [sic] point, 50 feet above the water, the engine came back on line." The pilot then "joined" the needles and established an attitude to continue flight, when the landing skid contacted the water. A test run was performed on the engine from N6786M under the supervision of the FAA. According to the inspector's statement, "...due to damage to the magneto's and the ignition harness...these components had to be repaired prior to running the engine." The test run of the engine revealed that "it ran normal at all power sittings...the reason for losing power...[could] not positively be determined."