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drmax

Well Known Member
Are these caps suppose to be water proof. I may have mine outdoors on a trip and didn't know if a special cover is available, or if they are already water proof. Thx for any info. DM
 
Which type do you have ?? I think all of them are "suppose" to be water tight .. but some might stand up better over time when left outside for extended period ...
 
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As a precaution, I just but some clear packing tape over them when it is going to be left outside. I remove it when I preflight before the next flight. I heard that because they are recessed and the shaft going down the middle they do not seal 100%.
 
They leak

Caps are not watertight. They will leak. If left ouside for long periods you will find water in the fuel when you sump the tanks. I know.;)
 
Might check this out... but I think fuel lube is a thread sealant. It works for a while then makes it worse on o rings. Some use DOW 4 or similar lube. There is a very toxic lube that is used for carb rebuilds that stays slippery in contact with fuel. Expensive. I cover the caps when prolonged rain is expected and I am parked out. Got a blob of rainwater in January that did not show up until 4th flight, even though I sumped before each. It forced a landing... and subsequent hot brakes etc. (not much runway left when it faltered on takeoff)
I sump a large quantity now, into a clear jar. If clean, I put it back in the tanks.
I also am not a fan of running the electric pump in order to get a sample from the gascolator. It pumps so hard that I suspect turbulence would mix the water and fuel temporarily. Just a theory. I prefer to let it run out slowly, as gravity and venting allow. Seems like any water at the bottom of the gascolator would have a greater chance of getting out and being seen in the sample.
Any contrary ideas, theories or practices welcome in a heart beat.
 
drmax said:
Are these caps suppose to be water proof. I may have mine outdoors on a trip and didn't know if a special cover is available, or if they are already water proof. Thx for any info. DM
Click to expand...

Not at all... not taped off you could get water in the tanks.
 
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15 years of flying RV's and never, not once, have I had water in fuel tanks. Plenty of overnighters outside, in rain, snow, and even under sprinklers (parked in grass once and the sprinklers came on overnight).
 
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