Accident Details
During the initial climb after takeoff, the engine began to run roughly and then stopped completely. The pilot executed a forced landing in a clearing adjacent to the runway. To achieve this, he intentionally stalled the aircraft and allowed it to mush into the ground, resulting in a hard landing.
Pilot Actions
The pilot reported that the aircraft was fueled with a mixture of 100LL aviation gasoline and automotive fuel. He also stated that the carburetor heat checked normally before takeoff. However, the carburetor heat was left in the ON position while the aircraft was positioned for takeoff on the runway.
Fuel Mixture and Carburetor Heat
The supplemental type certificate (STC) for automotive fuel indicates that carburetor ice will form earlier with auto fuel under conducive atmospheric conditions. The pilot's use of a fuel mixture including automotive gasoline may have increased the risk of carburetor icing.
Carburetor Icing Conditions
Carburetor icing conditions existed at the time of takeoff. The combination of using automotive fuel and leaving the carburetor heat on during ground operations may have influenced the engine's performance during climb, though the specific role of these factors is not detailed in the source.