Fuel Contamination

Wednesday, April 19, 2023 at 12:05 PM ET

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Sampling the tanks is probably the easiest way to detect contamination, even though it often means a little time groping around for a belly drain. FAA Advisory Circular AC 20-125, Water In Aviation Fuels, notes that water in fuel is either dissolved or free. Free water is visible as “slugs,” which is FAA-speak for the water you might see at the bottom of a fuel sampler cup, as shown here. On The Cover: Sumping fuel tanks prior to takeoff is a time-honored practice with real-world safety implications. The pictured contaminant is water, but it could be almost anything else. Note that fuel-related mishaps account for a startling number of accidents. For more on this topic, see the article beginning on page 13. Image by the Editor-In-Chief.

Key Takeaways:

Fuel contamination, primarily from water condensation or tank material degradation, is a serious aviation safety risk that necessitates diligent prevention through pre-flight sumping, proper fueling supervision, and topping tanks to minimize air space.
Pilots must be prepared to respond to engine failure caused by contamination using the "Glide, Grass, Gas" procedure, which involves establishing best glide, selecting a landing site, and troubleshooting fuel systems.
External factors like incorrect fuel type from FBOs or static electricity during fueling also pose risks, underscoring the importance of supervising fueling and ensuring proper grounding.

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Everything seemed routine. I was cruising along in nice weather. The satellite radio played soft music in the background. Suddenly, the engine began coughing, and quickly lost power. I tried manipulating the throttle but nothing changed; it almost seemed like it wasn’t connected to the engine at all. I looked around for options, not panicking yet, but a step or two closer.

Just as suddenly, the engine started working again and, after assessing the situation, I concluded that there had been a momentary fuel contamination episode and decided it was okay to continue to my destination.