Primary finding
Probable cause
The loss of engine power which resulted from fuel starvation when the carburetor float valve stuck in the closed position. A factor was the soft field
Investigator assessment
Analysis narrative
The pilot completed refueling the airplane and took off to continue the banner tow operation. During climbout the engine lost power; the pilot's efforts to restore normal engine operation failed. The pilot established an emergency descent to a soybean field for a forced landing; during the touchdown phase of the emergency, the airplane nosed over. The post accident examination of the airplane disclosed that the engine operated normally between idle and the maximum rpm ranges. However, the carburetor examination, disclosed that the float valve would stick in the closed (fuel off) position. A review of the operator's refueling policy revealed that a blend of 100 low lead aviation fuel and automotive gasoline were used in airplanes granted a supplemental type certificate for automotive fuel. N9128d was granted an stc for the use of automotive fuel.
Source record
Factual narrative
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