CEN18LA013

The private pilot reported that, while in cruise flight, the engine started to sputter then experienced a total loss of power. The pilot attempted to restore power without success and conducted a forced landing to a field, where the airplane nosed over. The pilot stated that he did not use carburetor heat following the loss of engine power. A postaccident examination of the airframe and engine revealed no evidence of mechanical malfunction or failures that would have precluded normal operation. A review of the recorded weather information in the area indicated that the atmospheric conditions at the time of the accident were conducive to the accumulation of serious carburetor icing at any power setting. The total loss of engine power was likely due to an accumulation of carburetor ice. Had the pilot immediately applied carburetor heat, it is possible that it would have cleared the ice and restored engine power.

On October 12, 2017, about 1040 mountain daylight time, an amateur-built Murphy Rebel airplane, N734R, was substantially damaged during the forced landing to a field near Fort Collins, Colorado. The pilot, the sole occupant on board, sustained minor injuries. The personal flight was conducted under the provisions of 14 Code of Federal Regulations Part 91 without a flight plan. Visual meteorological conditions prevailed for the local flight that departed Vance Brand Airport (KLMO), Longmont, Colorado, about 1000. According to a statement from the pilot, while en route at an altitude of 9,000 feet the engine started "sputtering" and lost power. He attempted to restore power by switching fuel tanks and adjusting the throttle but was unsuccessful. During the forced landing to a field the airplane nosed over resulting in substantial damage to the fuselage and vertical stabilizer. The pilot stated that he did not use carburetor heat following the loss of engine power. He stated that he misunderstood the conditions which carburetor ice could form, believing it to be in visible moisture and clouds, like structural wing icing. He further stated that carburetor heat was only for instrument conditions. The National Transportation Safety Board Investigator in Charge examined the airplane following the recovery to a secure facility. The examination of the airplane, including the engine and fuel system, revealed no mechanical anomalies that would have precluded normal operation. The closest routine aviation weather report, taken at 1156, recorded a temperature of 52°F and a dewpoint temperature of 39°F. A review of the carburetor icing probability chart, located in the Federal Aviation Administration's Special Airworthiness Information Bulletin CE-09-35, dated June 30, 2009, revealed that the airplane was operating in an area favorable for the formation of serious carburetor icing at any power setting. In addition, weather computer model soundings taken around the time of the accident supported a favorable environment for carburetor icing at the operational altitude of the flight.