On April 30, 2012, about 1530 central daylight time, an experimental, amateur-built RV-6A, N819RS, operated by a private individual, was substantially damaged during a forced landing, after it experienced a partial loss of engine power during the initial climb after takeoff from the J-22 Ranch Airport (16FL), Milton, Florida. The private pilot sustained minor injuries. Visual meteorological conditions prevailed and no flight plan was filed for the flight destined for Bayou La Batre, Alabama. The flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. According to Federal Aviation Administration (FAA) records, the airplane was issued a special airworthiness certificate on July 30, 1992, and was purchased by the pilot on November 28, 2002. The pilot reported that he departed 16FL from runway 18, a 3,000-foot-long, turf runway; however, during the initial climb, the airplane began to experience an intermittent loss of engine power, which continued during the flight. The pilot maneuvered the airplane for a landing to runway 36; but he overshot the runway and performed a forced landing to a field. During the forced landing, the nose gear collapsed, and the airplane nosed-over and came to rest inverted. The pilot exited the airplane before it was consumed by a postcrash fire. A witness, who observed the takeoff, reported that the engine sounded normal until the airplane began to climb. At that point it began to sound like it was "missing" and he observed black smoke coming from the exhaust. The airplane was equipped with a Lycoming O-320-B1A, 160-horsepower engine. Examination of the airframe and engine by an FAA inspector, and subsequent partial disassembly of the engine by a representative of the engine manufacturer and an NTSB investigator did not reveal any mechanical malfunctions that would have precluded normal operation. The carburetor, gascolator, fuel pump, and fuel lines were destroyed by fire and could not be examined. In addition, the propeller remained attached to the engine and did not display any evidence consistent with rotation. The airplane had been operated for about 25 hours since its most recent condition inspection, which was performed on December 28, 2011. In addition, at the time of the inspection, the engine had been operated for 3,201 hours total time since new, and 117 hours since overhaul. The weather reported at airport located about 10 miles east of the accident site included a temperature of 31 degrees Celsius (C) and a dew point of 18 degrees C. Review of an FAA Carburetor Icing Envelope chart placed the reported temperature and dew point in the "serious icing at glide power" area of the chart.