On February 28, 2003, about 1020 mountain standard time, an experimental RV-3, N87BC, experienced a total loss of engine power and made a forced landing on a dirt access road about 4 miles north of Deer Valley, Arizona. The airplane nosed over after encountering rocks on the road. The pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. The commercial pilot, the sole occupant, was not injured; the airplane sustained substantial damage. The personal local flight departed Deer Valley about 0945. Day visual meteorological conditions prevailed, and no flight plan had been filed. The primary wreckage was at 33 degrees 47.30 minutes north latitude and 112 degrees 07.45 minutes west longitude. In a telephone interview the pilot related that while flying in the area north of Deer Valley he noticed a decrease in engine power. The pilot applied carburetor heat and turned on the fuel boost pump; he also manipulated the throttle. In the pilot's written statement, he said he thought the engine problem was due to carburetor ice. When the engine quit, the pilot declared an emergency and advised the tower he was making a forced landing. The pilot chose to land on a dirt service road that was on the east side of Highway 17, about a 1/ 2 mile south of Highway 74. The accident site was approximately 4 nautical miles north of Phoenix Deer Valley, Arizona (DVT). The dirt road was muddy due to previous rain showers. After touchdown the airplane's landing gear struck a rock that was submerged in the mud. The airplane came to rest inverted. The pilot was not able to extract himself from the wreckage without assistance from witnesses who stopped to help. PERSONNEL INFORMATION A review of Federal Aviation Administration (FAA) airman records revealed the pilot held a commercial pilot certificate with airplane single and multiengine land ratings and an instrument airplane rating. The pilot held a third-class medical certificate that was issued on March 21, 2002. It had the limitations that the pilot must wear corrective lenses and possess glasses for near & intermediate vision. The pilot reported a total flight time of 3,000 hours. He logged 50 hours in the last 90 days, and 15 in the last 30 days. He had en estimated 40 hours in this make and model. METEOROLOGICAL INFORMATION The closest official weather observation station was DVT, which was located 4 nautical miles (nm) south of the accident site. The elevation of the weather observation station was 1478 feet msl. A routine aviation weather report (METAR) for DVT was issued at 1009. It stated: skies 2600 feet scattered, 3100 feet scattered, 9000 feet broken; visibility 10 miles; winds from 210 degrees at 6 knots; temperature 52 degrees Fahrenheit; dew point 43 degrees Fahrenheit; and altimeter 29.93 InHg. A generic carburetor icing probability chart used by Safety Board investigators showed the ambient temperature and dew point conditions to have been within the region marked "serious icing at cruise or climb power." TESTS AND RESEARCH The Safety Board investigator examined the wreckage at Air Transport, Phoenix, Arizona, on March 3, 2003. The airplane was secured to a steel pole to prevent the airplane from moving. The wooden propeller was removed, which had been broken during the accident sequence, and a loaner propeller was attached. The airplane was refuled with the fuel that had been removed during the recovery process. The engine was started and conducted a run-up. No anomalies were noted. The engine ran smooth thru all realms from idle to full power. The factory representative stated the carburetor heat and magneto drops were in the normal range. The fuel pump's rubber diaphragm was unbroken and investigators blew air through the lines. The plunger in the fuel distribution valve moved freely, the rubber diaphragm was unbroken, and investigators did not observe any contamination. The fuel nozzles were open and the screens were clean. The fuel selector valve was in the left main position.