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Cowl rubbing prop hardware


Scottknoll

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We had a new prop installed (Hartzell Top Prop w/TKS). The lower cowl is rubbing the TKS slinger ring/hardware. I’ve read about cowl bumpers in other threads (J model) that are attached to the engine mount to keep air loads from pushing lower cowl up. The M20R IPC does not show these bumpers from what I can find. Prop isn’t exactly centered on the cowl, but I understand that’s normal for Ovations (maybe 1/4”). I’ve read the engine sag threads. On the ground, all hardware & the slinger ring has equal clearance from the cowl opening. So something must be changing in flight to cause contact. Any advice is appreciated!

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Why is it that Hartzel doesn’t clear up the installation issues, early on in the purchasing / installation process...?

It must be written somewhere...


The purpose of the STC is to document these challenges... specific to the plane... 

See if these details are there...

PP thoughts only not a mechanic...

Best regards,

-a-

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I also just had my prop (Hartzall) overhauled and when we reinstalled it we found the spinner had very little clearance between cowling and spinner. The prop shop replaced the flat washers (3 apiece) between the backing plate and the hub with spacers which he said was the way it should have been from the factory. We ended up removing the spacers (6) and replacing them with 3 flat washers per spacer and now I have the proper clearance again spinner to cowling. As far as I can tell the prop was never removed from the plane so it came out of the factory with the washers not the spacers. I don’t have a TKS system but this may solve your problem also.

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Are you sure its actively rubbing?  I had some wear show up that we couldn't explain, repaired and it hasn't come back.  After the fact, I remembered that I had the prop balanced while some other work was being done and I wasn't there to watch.  My unproven theory is that they ran the engine with the top cowl off and it pushed up and rubbed.

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Are you sure its actively rubbing?  I had some wear show up that we couldn't explain, repaired and it hasn't come back.  After the fact, I remembered that I had the prop balanced while some other work was being done and I wasn't there to watch.  My unproven theory is that they ran the engine with the top cowl off and it pushed up and rubbed.

Funny you mention that. Just heard from the MSC, and they are pretty positive that’s how it happened. They said a run up with the top cowl removed will allow lower cowl to ride up. We are going to have it repaired, and monitor for further contact.
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At first I'm thinking: that prop sure need a rebuild, he's got oil streaks everywhere.  But wait, they are going the wrong way!?  .... Must be a full feathering prop and those streaks come from backing into a tie down.  Can't fool me

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