Carbon Monoxide

Re: Carbon Monoxide

Posted by TMcC


I have a carbon monoxide detector and have been getting readings in the 20s when I close the vents. Living and flying in GA I usually do not fly with the vents closed and almost never use heat or defrost. On a previous annual we looked closely at the firewall and sealed any area that was a possible source.

Recently on a cross country I opened the heat and the level actually went down. The pilot I was flying with, suggested that perhaps it was coming from air entering in the back of the plane.

I wondered if foam I had removed from the spar area that sealed air from the wing to the fuselage could have opened a pathway for the bad air. I removed the insulation after reading that it can cause corrosion if it traps water.

1980 PA28-181

Any thoughts are appreciated.


  • get the muffler looked at asap. Verify no issues with muff or joints.


    48 yrs A/P IA DAL aircraft inspector. 172N

  • That it went down with the heat on strongly suggests it is not the muffler or cuff but worth checking out regardless. In the RV-10 I owned we could get CO coming in from the AC system condenser system before we sealed it up.

    There is often an exit for air at the aft the of fuselage on the underside. If it is back flowing you might get CO inside the plane. I would say it is more likely you are picking up air from the exit and it is coming into the cabin and then it is flowing out at the wing roots to the low pressure area on the wings.

    If you put a CO monitor aft by this fuselage vent I bet it would read higher.

    Resealing the wing roots would likely help. There is really no safe exposure level for CO.

    Eric Panning
    1981 Seneca III
    Hillsboro, OR (KHIO)

  • If you are familiar with the plumbing on the heat/defrost system,,,, check the muffler. carl

    I know why it goes down with the heat on.

    48 yrs A/P IA DAL aircraft inspector. 172N

  • Are you flying with, or taxiing with the apple core window open? I found that my CO detector would go off with the apple core port open and had a zero CO detection with it closed. I have a P28B.

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