Mark89114 Posted May 22, 2018 Report Share Posted May 22, 2018 I was coming out of Chicago the other day and temps were in the high single digits in Celcius and after I got through all of the visible moisture I looked out at my right wing and saw this white looking stuff building up behind the apparently now leaking fuel tank cap. Confounded me for a while as I was 100% sure it wasn't there when I left and then I looked back and it was gone. Best I can figure is the moisture coming off the gas cap combined with the evaporation of the fuel dropped the temperature locally enough to freeze what water was there. I just thought it was interesting. Now the fuel tank leaking is a new phenomenon, the line guys did really fill it up and I was able to push the cap down just a tiny smidge after I landed. That was on me, as I did visually check the quantity. I looked the gasket over and nothing looked odd, will just continue to monitor and see if this occurs again. Any advice appreciated. I did lose a couple of gallons I think. Quote Link to comment Share on other sites More sharing options...
flight2000 Posted May 22, 2018 Report Share Posted May 22, 2018 It could be just the picture, but the cap looks like it's canted forward slightly, meaning it's not seated properly. That would cause the gas to flow out exactly where the ice formed. Been there, done that.... Brian Quote Link to comment Share on other sites More sharing options...
Bryan Posted May 22, 2018 Report Share Posted May 22, 2018 "Been there, done that..." too! However, if the cap is sealed, could it be condensation, or moisture that collected inside the top of the fuel cap and got sucked out and down the wing. Based on the picture, it does look like it came from the fuel cap but no hint of Blue from 100LL. 1 Quote Link to comment Share on other sites More sharing options...
kmyfm20s Posted May 22, 2018 Report Share Posted May 22, 2018 Could just been from water puddle up in the fuel cap recess. As you picked up airspeed it blew backward and froze. Just a thought? 1 Quote Link to comment Share on other sites More sharing options...
MARZ Posted May 22, 2018 Report Share Posted May 22, 2018 Any fuel Mist at Mooney speed should evaporate the liquid (fuel) - that evaporation would lower the ambient temp - think MEK on your shop rag - that lower ambient temp would be the tipping point of actually freezing the moisture in the air..... just some thoughts... Quote Link to comment Share on other sites More sharing options...
thinwing Posted May 22, 2018 Report Share Posted May 22, 2018 Plus the canted cab created a burble so as the escaping fuel vaporized ,lowered temp below dew point ,ice accumulated in the shadow of that burble Quote Link to comment Share on other sites More sharing options...
Mark89114 Posted May 23, 2018 Author Report Share Posted May 23, 2018 Again it was just a random event I thought was reasonably interesting. Good catch on the fuel cap.....it was leaking a bit, I will make sure it is properly installed next time. Makes sense as I have had no issues with leakage in the past. Fly safe everybody. Quote Link to comment Share on other sites More sharing options...
Yetti Posted May 24, 2018 Report Share Posted May 24, 2018 If it was not hard to close and you can cant it like that without hammering down the lever, then it probably is not adjusted properly or your big oring is beyond its useful life. Quote Link to comment Share on other sites More sharing options...
carusoam Posted May 24, 2018 Report Share Posted May 24, 2018 That sure is an interesting ice formation... The cap is in need of attention... it is not flush like it supposed to be... The ice formation... Most likely caused by the cap interfering with the airflow locally... breaking up the protective boundary layer at that spot... as far as temperature goes... so much air going over the wing getting it’s pressure dropped does two things... The low pressure environment ... Drops moisture out of solution... allowing it to freeze... Drops the temperature into the freezing range... If fuel exited the tank... there would be a significant amount of blue to accompany that... If fuel is evaporating in the tank, the blue is being left behind, concentrating in the rest of the fuel... If your orings hold water above the caps or it is raining...and the caps aren’t sealing... you may see bubbles forming showing how much air is leaking out... To get fuel evaporation to drop that much moisture and freezing... think carb ice... that would be a lot of fuel dissapearing.... Great pics, mike! Best regards, -a- Quote Link to comment Share on other sites More sharing options...
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