SAIB: CE-10-40 Water contamination of fuel tank systems

Recent safety information on Cessna 150, 170, and 172 series airplanes caused us to re-examine our efforts on preventing accidents and incidents due to water contaminated fuel. Water may enter the fuel tank system via any penetration in the wing fuel tank. Water in the fuel may come out of solution, settle and make its way to a drain location in the form of a blob, pea, or BB-shaped translucent mass found at the bottom of the sampler cup. Water suspended in the fuel may lead to a cloudy or hazy appearance in the sampler cup. Water may have dissolved in the fuel, but the conditions have not yet occurred to cause the water to come out of solution and perhaps adhere to the dry tank upper surface or walls (similar to condensation). Understanding this; all pilots, owners, operators, maintenance and service personnel of these type airplanes should assume some water exists in the fuel tank system on the airplane.