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Cummings Spinner on IO-390 Hartzell CS

bkervaski

bkervaski

Hellloooooooo!
Testing
I'm mounting a Cummings Spinner on an IO-390 w/Hartzell CS prop. Easy going, but I'm at the point to where I need to align and final drill the spinner.

I'm unsure of the clearance I should give the blade holes for the prop at rest.

I'm also not sure if there is a way to rotate the blades to check clearance, didn't want to damage anything.

Only get one shot at alignment so seeking advice or experience!

Edit: Prop is mounted on the airplane, not torqued or safe-tied.
 
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Bill, You probably know, but they have a download on the cummings website telling how to install their spinner. It is the article that was in the March 2015 issue of Kitplanes.
 
The spinner has the cut outs for the blades already. i just aligned the back of the spinner with the back of the back-plate. centered the blades within the cutouts.
 
@pilotkms How did you make sure when the blades rotate they cleared the spinner cut-outs in all positions?
 
At the root of the blade they are round or close to it. Been awhile but i eye-balled it as I recall. I Put the blade in the center and have had no issues. Mine is a Hartzell BF.
 
Are u talking about the filler pieces behind the blade ? If so, Hartzel provided a template for those pieces.
 
If you want to check and make sure the blade will not touch the spinner at its full range of pitch, you can sandwich one of the blade between two piece of wood (2x4 with clamps with enough arm a three foot long should do it) and rotate it.

I would love to see a picture as I am planning on the same spinner.
 
I used the 2x4 method to twist the prop to check alignment ... turned out good! (thanks, all)
 
oap.jpg
 
Clearance.

Hi Bill,

How much clearance do you have at full course pitch? I’ve only got 3/32’s. Anyone else care to chime in?

Thanks,

Merrill
 
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