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‘750 Start gremlin.

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taysidedragon:

--- Quote from: Lobo on August 12, 2023, 12:01:09 AM ---On the other hand, light aircraft with piston engines have to drain fuel samples from special fuel drains every day  in the first pre-flight inspection. Transparent containers show separated water at the bottom.

--- End quote ---

To be fair here, the issue here is more related to faulty fuel cap seals with the aircraft standing out in rain, washing etc. Light a/c will typically have vertically mounted filler caps, and often recessed - which only exacerbates this. Bad fuel can too be an issue. I’ll stop washing the bike!
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Not correct.  Even aircraft hangared overnight get water in fuel. Any air space in the fuel tanks has water vapour content which condenses out when the temp drops. Most aircraft I'm familiar with have wing tanks so the filler caps are horizontal on the top surface of the wing. They are designed to prevent rainwater getting in, the same way that our fuel caps are.

Lobo:
Totally accepted Gareth, condensation in fuel is a concern, and apparently occurs at abouts 1ppm per degree Fahrenheit drop in temperature. At 30ppm upwards it begins to be a problem - enough condensation can lead to a hazardous volume of water in the fuel over time.
Regular fuel drains / topping the tanks of course keep this in check, minimising this as a direct cause of engine failure.

Interestingly, came across this: https://www.casa.gov.au/aircraft/airworthiness/airworthiness-bulletins/water-contamination-aviation-fuel-avgas/mogas

… where it quotes:
“An analysis of defect reports and accident investigations shows that there are five main causes of loss of power and engine failure due to water in the fuel; water entering the fuel tank via faulty fuel cap sealing; water contaminated fuel being pumped into the aircraft fuel tank during re-fuelling, and poorly executed post-refuelling / pre-flight water checks, compounded by unintended water retaining ridges in the bottom of fuel tanks, and flawed water drain location”

Certainly I agree dissolve water becoming free water within fuel (ie with change of temp) is an issue; tho’ hopefully kept at bay with protocols. In the context of engine failure however (this thread), and light aviation, it could be argued that other system failures are generally more to blame?
Cheers,
Simon

Nigel - at great expense have now purchased 4L of Castor oil…. 😬

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