![Knowing what kind of fuel your aircraft takes is basic pilot knowledge. [Credit: Meg Godlewski]](https://www.flyingmag.com/wp-content/uploads/sites/2/2025/06/self-fuel-scaled.jpeg)
Question: I am a low-time pilot in a rainy part of the world. I know we’re supposed to check the fuel for contamination during the preflight inspection, but how do you make sure you get all the water contamination out of the fuel tank? A guy at my airport tells a story about the time his engine quit just after takeoff because there was water in the fuel. The airplane had been on the ramp in the rain for a few days, and he sumped it and got a clean sample, but it still happened. How do I prevent this?
Answer: I too live in a rainy part of the world, and many of the aircraft I fly are kept on the ramp. The best way to keep water from getting in the fuel tanks is to make sure the rubber gaskets on the fuel caps are in good condition and the caps on securely.
- READ MORE: Fueling Speculation: Sumping for Safety Still Critical to Preflight Checklist
- READ MORE: Does a Low Flying Complaint Automatically Equal an FAA Violation?
Sumping technique is also important. An old-timer taught me the trick of gently jostling the aircraft at the beginning of the preflight inspection to get the fuel to move around so that any contaminant, such as water, moves to the lowest point of the tank where it will be, in theory, sumped out. Nudge the wings until you hear the fuel moving, give it about 10 minutes to settle, then sump.
Do this after you refuel as well.
Anytime there’s even the slightest water contamination, continue to sump until you get at least three clean samples.
You didn’t mention how many sump points there are on your aircraft. For many years Piper and Cessna training aircraft had sump points under the wings and at least one on the belly often activated by a knob inside the engine or, in the case of the Cardinal, in the cockpit. When Cessna brought forth the R and S models of the C-172, they added additional sump points for a total of 13—five on each wing and three on the belly. Do all of them.
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