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Thread: Pucker moment at departure end, 400ft agl

  1. #1
    Spdcrazy's Avatar
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    Default Pucker moment at departure end, 400ft agl

    Ok smart short wing people. Took my bird up today. And had a bit of a pucker. Did a low approach to check runway condition and as I throttled up and nosed up a bit (nothing crazy) the engine sputtered. I was on the left tank. Since then I've learned my fuel gauge on that side doesn't work. But I dipped the tank and I have about 3in of fuel with the A/C sitting on the ground.

    Also, my mag drop on the right mag is about 200rpms. I'm working on that one now and I don't feel that should equate to my sputter but it's knowledge none the less.


    While I might end up embarrassed, I hope y'all see something I did obviously wrong. I'm a very low time time pilot and was with my CFI working on my tailwheel endorsement now. Thanks in advance.

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  2. #2
    Wag-builder's Avatar
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    Default Re: Pucker moment at departure end, 400ft agl

    You say you made a low approach, were you at a low RPM during that approach? What was the temp and dewpoint? Were you by any chance using carb heat, you may have picked up a little bit of carb ice.

  3. #3
    Spdcrazy's Avatar
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    Default Re: Pucker moment at departure end, 400ft agl

    Quote Originally Posted by Wag-builder View Post
    You say you made a low approach, were you at a low RPM during that approach? What was the temp and dewpoint? Were you by any chance using carb heat, you may have picked up a little bit of carb ice.
    I don't recall exact numbers but I was probably 16-1800rpm. Throttle to full, not snappy but maybe a bit quick? Temps were in the high 40s. And rather dry. I don't recall the dewpoint spread. But this evening had a spread of 20 or so.

    Carb ice is a possibility but I don't believe there was enough moisture around. CO is rather dry most often.

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  4. #4
    Administrator Steve Pierce's Avatar
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    Default Re: Pucker moment at departure end, 400ft agl

    I would check the plug gaps and find out what that 200 rpm mag drop is about. Carb ice maybe, or a rich mixture and full throttle engaging the accelerator pump putting in extra fuel maybe it was too much fuel at one time for the ignition system to handle.

  5. #5
    Spdcrazy's Avatar
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    Default Re: Pucker moment at departure end, 400ft agl

    Quote Originally Posted by Steve Pierce View Post
    I would check the plug gaps and find out what that 200 rpm mag drop is about. Carb ice maybe, or a rich mixture and full throttle engaging the accelerator pump putting in extra fuel maybe it was too much fuel at one time for the ignition system to handle.
    This sounds like a good possibility. I pulled the plugs last night and will get them cleaned. The front plugs were wet, back plugs dry. Not sure what to make of that.

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  6. #6
    sierrasplitter's Avatar
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    Default Re: Pucker moment at departure end, 400ft agl

    Damn Dude . That will clean your shorts. Like most I would guess either carb ice ( was there any dew that morning ?) or too much throttle too quick. Keep working on it

  7. #7
    Vagabondblues's Avatar
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    Default Re: Pucker moment at departure end, 400ft agl

    ''The front plugs were wet, back plugs dry. Not sure what to make of that.''

    Just guessing here but if the Field elevation at Aurora Colorado is 5,400 feet and you add in the 400 feet AGL that makes a pressure altitude of about 6,000 feet.

    Was the mixture at full rich for take off? Thinner less dense air changes the basic air/fuel stochimetric. in other words its too rich.
    Last edited by Vagabondblues; 03-11-2019 at 08:20 AM.

  8. #8
    Spdcrazy's Avatar
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    Default Re: Pucker moment at departure end, 400ft agl

    Quote Originally Posted by Vagabondblues View Post
    Just guessing here but if the Field elevation at Aurora Colorado is 5,400 feet and you add in the 400 feet AGL that makes a pressure altitude of about 6,000 feet. Was the mixture at full rich for take off? Thinner less dense air changes the basic air/fuel stochimetric of 12 to 1 to something more like 8 to 1.
    Good thinking. But no. I always leaned it out during run up at minimum. with that being said, I have blown up an engine or 2in vehicles by running it too lean. So I expect I have a tendency to run a tad more Rich than I should. But definitely not full rich.

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  9. #9
    Spdcrazy's Avatar
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    Default Re: Pucker moment at departure end, 400ft agl

    Took my plugs out and showed them to a local shop. They expect the mag drop is due to the front cylinder plugs fouling from oil. The front cylinders have about ten hours on them is all. He recommended me to clean them up, and give it a good high rpm cross country. Put a couple hours on it.

    This doesn't exactly fix my sputter that I had. But it's a step in the right direction. I kind of think Steve might be right on with it being rich momentarily when the Accel pump functioned and such.

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