Fouling plugs during flight?

Discussion in 'Flight Following' started by Ryanb, Sep 7, 2020.

  1. Ed Haywood

    Ed Haywood Pre-takeoff checklist

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    When I lean too close to peak EGT, I get detonation. At least I think I do. Sharp raps in my seat frame, irregular, 2 or 3 per second. Enriching to drop temp by 50 degrees F makes it go away. Can you suggest a better procedure to avoid this? Should I be leaning further instead of enriching?
     
  2. flyingron

    flyingron Touchdown! Greaser! PoA Supporter

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    At high power settings you want to stay away from the peak EGT (especially on the slightly rich side). Once you're at recommended cruise, you can set the mixture wherever you like.

    I'll concede the Mike Busch procedure mentioned earlier probably works. I just bring back the fuel flow to a nominal setting (many FF gauges are marked for this setting anyhow, by altitude) while climbing. At cruise, I'll go LOP with the analyzer, releaning with major altitude change. It doesn't seem that the MB method is particularly easier or advantageous unless you spend a lot of time in the climb.
     
  3. WannFly

    WannFly Final Approach

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    every time i read this discussion it gives me a headache .. so at cruise i fly at 60 % power and leave the red knob where it burns the least amount of fuel :happydance:
     
  4. midlifeflyer

    midlifeflyer Touchdown! Greaser!

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    That's actually a very good point. To some degree it becomes like many other things where the availability of more accurate tools leads to measuring football fields with a micrometer. I recall first seeing it for the first time maybe 20 years ago, watching a student doing a runup using a digital RPM gauge. Took forever to get exactly 1700 RPM.
     
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  5. idahoflier

    idahoflier Line Up and Wait PoA Supporter

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    Start by watching these:




    People may agree or disagree with the content, but they give good information and background for you to formulate your own opinions and/or perform more research...
     
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  6. Ed Haywood

    Ed Haywood Pre-takeoff checklist

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    I appreciate your sharing those resources, but Geez, do I really have to watch THREE HOURS of video? :eek:

    I just wanna know if I pushed the mixture control the wrong way when I got detonation.
     
  7. Capt. Geoffrey Thorpe

    Capt. Geoffrey Thorpe Touchdown! Greaser! PoA Supporter

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    I don't recall much on detonation, but if you watch, setting the speed to 1.5 is a must. After you get used to that, you can sometimes push to 1.75.
     
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  8. idahoflier

    idahoflier Line Up and Wait PoA Supporter

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    IIRC the majority of the videos are Q&A. Speeding it up is a great suggestion!
     
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  9. Jeff767

    Jeff767 Pre-takeoff checklist

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    I read your post wrong as you do state you are using CHT in the climb. If however you must stay full rich to keep your CHT’s to 400 I would spend some time checking all your baffles and double check the timing on both mags.
     
  10. idahoflier

    idahoflier Line Up and Wait PoA Supporter

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    No worries! Have checked the baffles. I guess I could check the timing, but... This is a Skyhawk with an Air Plains O-360 conversion. I spoke to someone in the Air Plains engineering department and he told me I could expect to see 425°F - 430°F in climb. I have also heard that engines running hot is not an uncommon occurrence for Skyhawks. I had a Maple Leaf exhaust fairing installed and now I'm seeing CHT's right at 400°F on the hottest cylinders...
     
  11. Jason Larkin

    Jason Larkin Pre-Flight

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    This video does a great job of explaining leaning. Granted he is using an engine monitor, but is still very helpful.
     
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  12. Capt. Geoffrey Thorpe

    Capt. Geoffrey Thorpe Touchdown! Greaser! PoA Supporter

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    Bummer. It's for Bonanza fans. What about the rest of us?

    (OK, seriously, yea, nailed it.)
     
  13. Jeff767

    Jeff767 Pre-takeoff checklist

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    If you are actually getting detonation at cruise power settings leaning something is very wrong. You did not put what type engine or fuel used but regardless I would ground the aircraft and at a minimum borescope the cylinders and check ignition timing. Even short periods of detonation can cause extensive engine damage. Ignition timing way off is about the only way to detonate a normally aspirated engine running 100LL.
     
  14. Jason Larkin

    Jason Larkin Pre-Flight

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    Haha, yeah it's a Bonanza, but he does the BEST job of explaining everything!