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Thread: prop won't cycle.

  1. #1
    S2D's Avatar
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    prop won't cycle.

    Have an IO-520 that the prop wont cycle completely. put another old prop governor on it and it got worse.
    I just dug up two more governors, but if neither of them work, I have to suspect the transfer collar inside the engine. Been so many years since I've seen this problem, but I seem to remember that there was a way to check the collar with pressure. Any Ideas before I have to pull the engine apart??
    I may be wrong but that probably won't stop me from arguing about it.

  2. #2
    www.SkupTech.com mike mcs repair's Avatar
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    cracked crankshaft at transfer collar.... check oil screen, ours was PACKED TIGHT full of metal and hard to get out

  3. #3

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    Scroll down to the section about the oil transfer system.
    https://www.avweb.com/news/maint/pro..._195565-1.html
    Thanks S2D thanked for this post

  4. #4
    www.SkupTech.com mike mcs repair's Avatar
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    spiral crack a transfer collar hole in crank, it actually "opens up" under load

  5. #5

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    Let me preface this by saying, “I don’t know anything about this topic.”

    I was a new to aviation, just out building time, and low time wonder.

    i remember a C210 that had a jerky and surging prop. I happened to be the guy that took the prop to the prop shop, and I recall the maintenance facility showing me the red with rust internal workings of the prop.

  6. #6
    jon s. blocker's Avatar
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    I had the inside crankshaft journal plug, on my 0360 come unseated, and the prop would not cycle because the preasure was going out the back side of the front crankshaft journal. Had to remove the prop, replace the rear plug and restake the plug. Very simple but had to figure out why the prop would not cycle since everything else worked. Just a thought. Jon

  7. #7

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    That 1/8” pipe plug behind the oil tube inside the crank is Lycoming specific. And frustrating!
    Last edited by stewartb; 06-17-2018 at 01:06 PM.
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  8. #8
    jon s. blocker's Avatar
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    Thought it probably was, but it was just a shot in the dark. I made a tool that slide down inside the shaft, past the offset oil stand tube, to replace and stake the plug behind it. I guess a one time tool, who else would have that kind of luck, Jon
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  9. #9
    nanook's Avatar
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    Make sure the drive spline is not worn/stripped, before you get too far into it...
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  10. #10
    S2D's Avatar
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    Thanks for the replies. Another governor didn't cure it, so looks like a teardown is the only option.

    Sent from my E6810 using Tapatalk
    I may be wrong but that probably won't stop me from arguing about it.
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  11. #11
    skywagon8a's Avatar
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    I didn't hear you say that you had tried another prop.
    N1PA
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  12. #12
    S2D's Avatar
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    Yea, I suppose I better just in case it's sticking.

    Sent from my E6810 using Tapatalk
    I may be wrong but that probably won't stop me from arguing about it.

  13. #13
    180Marty's Avatar
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    Let us know what you find. I always thought the half moon key and gear on the camshaft looked kind of mickey mouse.

  14. #14
    S2D's Avatar
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    Will do . It does cycle some . Better when it's cold. Got worse when we had to switch from 100w to Phillips 20-50 cause our supplier ran out of 55s of aeroshell

    Sent from my E6810 using Tapatalk
    I may be wrong but that probably won't stop me from arguing about it.

  15. #15
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by S2D View Post
    Will do . It does cycle some . Better when it's cold. Got worse when we had to switch from 100w to Phillips 20-50 cause our supplier ran out of 55s of aeroshell

    Sent from my E6810 using Tapatalk
    Did this happen over a long time or all of a sudden. Ours was pilot flying along and Bang went flat pitch. He limped to a sand dune. We went down to try to diagnose next day. Fine on ground, but half way through patch went flat pitch again. Changed governor same thing. 3rd test flight engine went over 3000 rpm shook, threw the alternator belt off. Stepfather graves propeller and pushed fore and aft and said crankshaft cracked. Was the second one he'd been flying in that broke. Oil screen was packed tight by then


    Sent from my iPhone using SuperCub.Org mobile app

  16. #16
    S2D's Avatar
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    Not sudden but over a short period of time .

    Sent from my E6810 using Tapatalk
    I may be wrong but that probably won't stop me from arguing about it.
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  17. #17
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by S2D View Post
    Not sudden but over a short period of time .

    Sent from my E6810 using Tapatalk
    Cracked crank. What did oil screen look like?


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  18. #18
    S2D's Avatar
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    Clean

    Sent from my E6810 using Tapatalk
    I may be wrong but that probably won't stop me from arguing about it.
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  19. #19
    www.SkupTech.com mike mcs repair's Avatar
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    prop won't cycle.

    DING!! Lightbulb in my head just turned on. If cracked crank through hole in crank at transfer collar, you will be able to LOOK INSIDE crankshaft with propeller removed and see crack


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  20. #20

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    Isn't there an old service bulletin about IO-520 transfer collars? I can find one from 1978 but it seems like there was a more recent one.

  21. #21
    S2D's Avatar
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    Well I'd have never guessed. Turned out to be the propeller after all. Swapped props and it works fine.

    Sent from my E6810 using Tapatalk
    I may be wrong but that probably won't stop me from arguing about it.

  22. #22
    skywagon8a's Avatar
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    Lucky you!
    N1PA
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  23. #23
    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by S2D View Post
    Well I'd have never guessed. Turned out to be the propeller after all. Swapped props and it works fine.

    Sent from my E6810 using Tapatalk
    Sludge? Wonder if a flush will help? No idea.



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