From: "Finn Lassen finn.lassen@verizon.net" <flyrotary@lancaironline.net>
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Date: Thu, 9 Apr 2026 09:15:57 -0400
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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Subject: RWS PSRU input shaft oil seal -- again
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I must have damaged the oil seal when removing or reinstalling the RD-1C 
PSRU on my RV-3B. (I removed and reinstalled it by the mount plate -- 
didn't split it.) Leaking badly.

Had used a National 350909 seal. 1" (shaft) x 1.5" (bore) x 0.312".

I'm wondering if really has to be 0.312" thick (wide). 0.25" appears to 
be more common.

Trying to find a replacement, I'm now seeing that seals are limited to 
5,000 RPM, 7 psi and 212 degree F for Nitrile (Burna-N).

Anyone have any suggestions for a suitable replacement seal that won't 
cost $60?

Finn

P.S. Will probably also have to increase main oil return line to 1/2" 
like I did with the RV-4 to reduce pressure.