On December 9, 1986, a Cessna 170B (registration N2464D) was involved in an aviation accident near Madison, GA. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A witness saw the aircraft taxi slowly toward the departure end of the runway. About 30 minutes later, wreckage was found in a field east of the airstrip. Examination showed a near-vertical impact similar to a stall after takeoff. The #5 exhaust valve was seized open. Conditions were conducive to carburetor ice, and the aircraft was authorized to use auto fuel, which can promote icing.
Overview
A witness observed the aircraft taxiing at a very slow speed toward the departure end of the runway. Approximately 30 minutes later, the wreckage was located in a field east of the airstrip. No witnesses to the actual crash were identified.
Examination Findings
Examination of the wreckage indicated that the aircraft collided with the ground in a near-vertical attitude, similar to the behavior of an aircraft that had stalled after takeoff. The #5 exhaust valve was found seized in the open position.
Environmental and Operational Conditions
Meteorological conditions were conducive to carburetor icing. The pilot handbook cautions that carburetor ice can form on the ground while the engine is at idle speeds. Additionally, records indicated that the aircraft was authorized to use automotive fuel. An FAA advisory circular notes that carburetor ice forms in less time and at higher temperatures when using auto fuel compared to aviation gasoline.