On September 21, 1997, about 1445 eastern daylight time, a homebuilt Rotorway Exec 90, N94CJ, was substantially damaged as it impacted the ground during a forced landing at Carroll County Regional/Jack B. Poage Field (W54), Westminster, Maryland. The certificated private pilot/co-owner received minor injuries. Visual meteorological conditions prevailed and no flight plan was filed for the personal local flight conducted under 14 CFR Part 91. The pilot flew the helicopter in the traffic pattern for 40 minutes, performing takeoffs and landings. He reported that "at 200 feet on final approach with 19 inches of manifold pressure set, the engine stopped running." The pilot recalled glancing at the carburetor air temperature gauge and it was not in the yellow caution range. During the descent, the pilot maneuvered to avoid an embankment and impacted the ground damaging the tail boom and rotor blades. A Federal Aviation Administration (FAA) Inspector examined the helicopter. His examination revealed no mechanical malfunctions with the engine. The Inspector reported that the engine started and ran without any difficulty. A pilot, who had flown a another helicopter, told the Inspector that he was required to use carburetor heat that morning. The temperature/dew point recorded by the Automated Weather Observing System (AWOS) at W54 was: 57 degrees Fahrenheit and 38 degrees Fahrenheit, respectively. Utilizing the "Icing Probability Curves" charts, these temperatures combined with a glide power setting, placed the carburetor within the serious icing range. Examination of the helicopter revealed that the carburetor heat was preset prior to flight, and not accessible from inside the cockpit. After the accident, the FAA recommended to the manufacturer that a switch be placed in the cockpit. The manufacturer completed a modification allowing control of the carburetor heat from inside the cabin.