The pilot reported that as the Flight Design CTLS was descending through about 4,700 feet mean sea level, the engine began to run rough and eventually lost complete power.
He noted that the engine monitoring system indicated that there was no fuel flow, despite the airplane having about 16 gallons of automobile fuel still available.
Several attempts to restart the engine were unsuccessful. He requested radar vectors from air traffic control to the nearest airport; however, he was unable to reach the airfield in Sandwich, Ill., so the pilot made a forced landing to a cornfield.
A post-accident examination did not reveal any mechanical or fuel system anomalies that would have precluded normal engine operation, and the engine subsequently started and ran without any anomalies.
Additional examination of the fuel system revealed that an ample amount of uncontaminated automobile fuel was available.
The weather conditions at the time of the accident were conducive to the accumulation of carburetor ice during engine operations at descent engine power settings. Additionally, the pilot’s use of automobile fuel increased the likelihood of carburetor ice accumulation because it is more volatile and therefore absorbs more heat from the mixing air when vaporizing for engine consumption.
The pilot stated that he did not apply carburetor heat after the loss of engine power. It is likely that the pilot’s use of automobile fuel and his flight in weather conditions that were conducive for carburetor icing resulted in the formation of carburetor ice during the airplane’s descent.
The NTSB determined the probable cause as the pilot’s failure to recognize the formation of carburetor ice during cruise descent and apply carburetor heat, which resulted in the total loss of engine power.
NTSB Identification: CEN13LA398
This July 2013 accident report is are provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.