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Thread: Goofy CO levels

  1. #1
    sbmackie's Avatar
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    Default Goofy CO levels

    Sitrep: CO meter registers rising CO levels while taxiing (very low levels). Fluctuates. Clears if we are parked. Spikes during climb under medium and high powers. Dissipates straight and level or descent regardless of power settings. Cabin heat off. Sometimes I taxi with the side slider open. Cabin vent position doesnít have any effect. Moving CO detector has no effect.

    Seems related to deck angle. Any ideas?

  2. #2
    Wag-builder's Avatar
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    Default Re: Goofy CO levels

    Is your exhaust stack short? They really close to the bottom of the fuselage and CO will rise during climb, I put a longer stack on my son's plane to greatly reduce this, but it did not completely stop it.

  3. #3
    sierrasplitter's Avatar
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    Default Re: Goofy CO levels

    Or you may have a cracked exhaust.

  4. #4
    sbmackie's Avatar
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    Default Re: Goofy CO levels

    This does not clearly explain to me why the CO rise is related to the relative wind. If I were a cracked exhaust, would it not be an constant issue. Worth an inspection, though.

  5. #5
    sbmackie's Avatar
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    Default Re: Goofy CO levels

    Sticks down about 7 inches or so.

  6. #6
    Wag-builder's Avatar
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    Default Re: Goofy CO levels

    Is that 7"beloew the belly of the fuselage? How well is the belly of your airplane sealed and is your firewall sealed? I know my 56 PA-22 will see CO increase to about 10-15 ppm on full power climb, but will decrease to 0 in cruise. I will sometimes see an increase under 1000 RPM decent also, but the rise is less than 15 ppm.

  7. #7
    sbmackie's Avatar
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    Default Re: Goofy CO levels

    Quote Originally Posted by Wag-builder View Post
    Is that 7"beloew the belly of the fuselage? How well is the belly of your airplane sealed and is your firewall sealed? I know my 56 PA-22 will see CO increase to about 10-15 ppm on full power climb, but will decrease to 0 in cruise. I will sometimes see an increase under 1000 RPM decent also, but the rise is less than 15 ppm.
    Yes, 7 inches below the cowl. No idea on firewall/belly sealing, as don't know what to look for. Guess I can check all the holes punched in the firewall for wires, etc. My increase on the ground is 11 ish PPM, more during any climbs, but returns to zero once level. I'll put on "ignore" until annual in November.

  8. #8
    J Ryd's Avatar
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    Default Re: Goofy CO levels

    Place the detector near the heater outlet and check with heat on/off etc. Have a copilot stick their head under there to read it. That should rule out (or in) a cracked exhaust I would think?
    Mine reads about 12ppm on climbout but pretty much 0 when level or decent. It was higher before I put a shock boot cover on.

    Sent from my SM-G892A using Tapatalk
    ​Jan
    1960 PA22-150 "Spud"

  9. #9
    akflyer's Avatar
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    Default Re: Goofy CO levels

    typical to have it coming in under your doors or through leaks in the gear fairings during climb. It is pretty well established and documented. Extend the exhaust or seal up the belly and doors.

    If the exhaust was cracked and it was coming in through the heater it would be constant and rising the entire flight.

  10. #10
    sbmackie's Avatar
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    Default Re: Goofy CO levels

    Did that. No change. What is a shock boot cover? Gonna change the shocks at annual in November.

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