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  1. #25
    Senior Member Clay Hammond's Avatar
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    Feb 2010
    Location
    Salmon River Airfield, 9B8
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    280

    Default Re: Vibrations

    Pull the prop and put it on a homemade prop balancer in your hangar or shop. (a round stick of sort or fashion laying across two sawhorses...etc.). If the prop favors one blade over the other there's the beginning of your troubles...and maybe all of it. Start eliminating your causes.

    If it is weighted one side versus the other, and it was balanced 1.5 years ago, and it is still on the same engine...then I would venture that prop was stored improperly. Nothing you can do but store it horizontal and wait. You can do that on the plane and just deal with the vibes until they hopefully go away. Or pull the prop and put another one on, store the wood prop in a horizontal position in a stable climate and let time do its thing.

    If the prop is balanced statically when not installed...then: When the prop was dynamically balanced 1.5 years ago how was the weight added? To the prop bolts or onto the spinner backing plate? I don't think they generally use the composite backing plates on the Cubcrafters spinners to mount balance weight because they are fairly light duty. If it IS on the backing plate though, are you 100% sure that the backing plate and prop were indexed correctly when reinstalling? If not then you gotta either experiment and fiddle with it to find that exact old position or do a re-balance. If the weight was on the bolts are there indexing marks as to which bolt with regard to the hub? And how was prop indexed to the engine. This ALL applies with a dynamic balance. The dynamic balance creates a harmonious condition with the rotating masses of the engine also. Everything has to be lined back up the same or you will not be in the same condition as it was previously. If this is not the case or you're not sure then you gotta re-balance.

    Short take: Make sure your prop is balanced by itself (and is tracking straight and true also), then make sure it is balancing with the engine just the same as it was before.

    Good luck.
    Last edited by Clay Hammond; 02-05-2018 at 06:44 AM.
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