On April 22, 2012, about 0745 Pacific daylight time, N499CC, a Cub Crafters Inc. CC11-100, nosed over following a precautionary landing near Monmouth, Oregon. The airline transport pilot, who was operating the airplane as a sport pilot and was the sole occupant, was not injured. The airplane sustained substantial damage. The airplane was being operated under Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed. According to the pilot, shortly after departing from a private airstrip, the engine sputtered. Due to the low altitude of the airplane, the pilot immediately initiated a precautionary landing and was unable to perform any troubleshooting. The airplane landed in a grass field. During the landing roll, the airplane nosed over. The pilot reported departing with 18 gallons of fuel onboard and he had sumped the fuel tanks while conducting the preflight checks. Prior to departure, the pilot had checked the carburetor heat and it checked normally. The pilot indicated that it seemed moisture may have gotten into the fuel system. Following the accident, the engine was test run using the airframe fuel system. There were no operational anomalies. Because the airplane rested inverted following the accident, the fuel drained out and was unable to be sampled. The carburetor icing probability chart from Federal Aviation Administration (FAA) Special Airworthiness Information Bulletin (SAIB): CE-09-35 Carburetor Icing Prevention, June 30, 2009, showed a probability of serious icing at cruise power at the temperature and dew point reported at the time of the accident.