Primary finding
Probable cause
A power loss due to fuel starvation from a faulty rubber seal in the mechanical fuel pump while operating over unsuitable terrain. An additional cause was the use of inadequate standards for the production of the rubber seal.
Investigator assessment
Analysis narrative
The pilot experienced a power loss after takeoff at an altitude of 300 feet and ditched in the water. The investigation revealed a loose rubber seal in the mechanical fuel pump which blocked fuel flow out of the pump. The engineering drawing for the seal lacked an astm specification which covers the production of the rubber including the curing. The investigation found that when seals produced from rubber without this astm specification were exposed to aviation gasoline, they would swell. With sufficient exposure to gasoline, the seal will come unseated and float into the exhaust side of the pump, restricting fuel flow to the engine.
Source record
Factual narrative
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