Prop hub snap ring

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Tbopper
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Joined: Sun Dec 09, 2018 7:15 pm

Prop hub snap ring

Post by Tbopper » Thu Feb 21, 2019 7:28 am

The Pietenpol air camper I bought was disassembled. I am in the process of putting it back together. One area not cover by the plans is putting the propeller hub back on the engine. My problem is with the snap ring and the prop hub locking nut. I found an article by Bob Gehring on how to remove and install the prop, but nowhere in the article does it mention the snap ring except in the removal of the hub. My question is, how does one put the snap ring back on. Is it put on before or after the prop hub locking nut? Will it require a special tool to open it up for installation?

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taildrags
Posts: 243
Joined: Tue Mar 07, 2017 10:39 pm

Re: Prop hub snap ring

Post by taildrags » Thu Feb 21, 2019 10:12 am

Tbopper: need more information! What engine does your airplane have? Corvair? Ford? Continental? Each of those uses different prop hubs, and of those three, the only one that I've heard of that might use a snap ring is the Corvair. Not too many people used the snap ring on the Corvair safety shaft/hub setup, but it was a clever idea that I believe was pioneered by "One Sky Dog".

Oscar Zuniga
Medford, OR
Air Camper NX41CC, A75 power

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taildrags
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Re: Prop hub snap ring

Post by taildrags » Thu Feb 21, 2019 10:16 am

OK, now I've got it... you're referring to the tapered shaft prop hub on Continentals. The article on how to deal with this hub, by Bob Gehring and Steve Krog, is on the Flybaby site. I'll have to see what it says about the snap ring... my old A65 had the tapered shaft hub but I never had to remove it and my A75 has the flanged hub.

-Oscar

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taildrags
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Re: Prop hub snap ring

Post by taildrags » Thu Feb 21, 2019 10:47 am

Well, as near as I can tell from the prop hub removal/installation procedure (which, by the way, was also published in the Spring 2014 issue of the BPA Newsletter), the snap ring would be the last thing to go back into the hub after the propeller hub nut is installed and torqued. There is a snap ring retention tool that is slid into the snap ring gap to hold it expanded in its groove in the removal process so that the entire hub pops off of the tapered shaft. I take it that the snap ring is the last piece to be fitted in place, but I've never actually done it. Hopefully, a tapered shaft hub guru will chime in here...
tapered_shaft.JPG

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Richard Roller
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Location: Olathe, Ks.

Re: Prop hub snap ring

Post by Richard Roller » Thu Feb 21, 2019 10:52 am

The snap ring goes in the hub after the nut is installed. It's what the nut pushes against when you remove the hub from the tapered shaft of the engine.

Tbopper
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Joined: Sun Dec 09, 2018 7:15 pm

Re: Prop hub snap ring

Post by Tbopper » Thu Feb 21, 2019 1:42 pm

I neglected to state that the engine is a Continental A 65 with a tapered shaft . I see in the exploded view that the snap ring (number 19) is the last to go on. That is the answer to my question. I received the prop hub nut, key, snap ring and the saftey bolt and nut in a zip lock bag along with the question as to how it all goes back on. Thanks much for the help.

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taildrags
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Re: Prop hub snap ring

Post by taildrags » Thu Feb 21, 2019 3:02 pm

You may find that the safety bolt should be the last part to go in, otherwise you may have trouble slipping the snap over the nut past the safety bolt.

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taildrags
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Re: Prop hub snap ring

Post by taildrags » Thu Feb 21, 2019 10:46 pm

If I may wander off to the side just a little bit here, if I recall the situation with my old A65, it was not possible to remove the prop bolts from the hub with it installed on the engine... the back of the hub was just too close to the engine cases for the bolts to be able to back out. What this means is that if you change props and the new one isn't the same thickness as the old one, you had better fit it onto the hub with the correct length bolts the first time or else you'll either be pulling the hub back off to change the bolts, or else you'll be stacking washers or using a thicker crush plate if the bolts are a bit too long. If the bolts are too short, there isn't a choice but to pull the hub to swap them.

I will grant that there may be a trick to slipping the bolts out the back of the hub with it still installed on the tapered shaft, but I'll be darned if I ever found a magical position of the hub where the bolts could be pulled out the back.

Oscar Zuniga
Medford, OR
Air Camper NX41CC, A75 power

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