Accident Overview
A private certificated pilot was conducting a visual flight rules, personal cross-country flight under Title 14, CFR Part 91. The float-equipped airplane experienced a loss of engine power during the initial climb after takeoff. The pilot executed a 180-degree turn toward the departure lake, but the airplane stalled and struck trees.
Pilot's Account
The pilot reported that the airplane had been moored for a week in rainy conditions with the fuel tanks three-quarters empty. On the morning of the accident, he fueled both tanks with a mixture of aviation and auto fuel. The preflight inspection and engine run-up were normal. He used carburetor heat while the engine was idling but did not use it during step-taxi or takeoff. As the airplane climbed over trees along the shore, the engine backfired twice and then stopped completely.
Investigation Findings
At the accident site, an NTSB investigator observed five to six pieces of "chopped" wood, each approximately 18 inches long and 2 inches in diameter, that appeared to have been cut by the propeller during the uncontrolled descent. The engine was not accessible and was not examined. The airplane was disassembled by the pilot's agents and placed in storage.
The pilot noted that with the airplane on floats, the wings were in a more level attitude compared to when on the tailwheel, which could allow any water in the tanks to move away from the sumps. He also stated that his practice of standing on the front of the floats while taking fuel samples might have moved contaminants away from the sumps. In his opinion, the loss of power was due to water contamination of the fuel, resulting from leaving the tanks partially empty during a rainy period combined with a flawed sumping procedure.