Fuel cap air pressure

Whenever I open my passenger-side wing fuel cap on my 1961 Cessna 182D, I feel and hear and big rush of air coming out. I'm worried the tank is creating a vacuum that could disrupt fuel flow. Has anybody experienced this before?


  • If it were a vacuum you'd have a heck of a time getting the fuel cap off. I would advise checking ALL the vents for your fuel system.

  • Scott ShererScott Sherer COO Forum Moderator

    I concur!

    Scott Sherer
    Wright Brothers Master Pilot, FAA Commercial Pilot
    Aviation Director, Cessna Owners Organization Forum Moderator and Cessna Owners Author.

    Need help? Let me know!

  • "I feel and hear and big rush of air coming out."
    Just to confirm Hill, it's vacuum and not pressure in the fuel tank?
    If vacuum, is it both Tanks showing this vacuum? My thoughts are it developed because of a blockage in your forward facing vent tube (on the left wing placed behind the Wing Strut joint on my 182A) AND the vents on both fuel caps are blocked, a pretty rare occurrence. My plane has a crossover vent tube connecting both Bladder Tanks together. More clues where the blockage might be; if there's an uneven fuel tank burn or just the RH tank sucks air when removing it's Tank Cap.
    Where ever it is, you've got to clear up that vent system before you take that back plane up in the air. A collapsing bladder does not count as a venting solution and you don't want to be forced to make an unscheduled engine-out landing because of fuel starvation. Would be wise to get an A&P involved and Logbook entries made. They're schooled to fix these problems, and this is a serious one.


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