Mailing List flyrotary@lancaironline.net Message #30010
From: Tracy Crook <lors01@msn.com>
Subject: Re: [FlyRotary] Tension bolt protection sheet
Date: Mon, 6 Feb 2006 10:58:22 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Just another point of view.
If the tension bolts are installed with the recommended procedure of putting a spiral bead of RTV on them to prevent vibration fatigue, the bolt is not likely to break in the first place. If somehow it does anyway, they always (AFAIK) break at the threaded end.  The RTV will prevent the bolt from backing out.
 
Tracy (paranoid about adding hardware/weight to my plane)

 
Al,
I understand your problem with the loose bolts. The thing I need to mention is why would anyone have a main engine external bolt or nut that isn't safety wired?  I plan to wire all my nuts as this will prevent anything from falling out if a stud does break.
Bill Jepson
 
Hi Bill,
 
I used a technique the rotary racing crowd uses to prevent a stud/bolt from backing out of the engine into the flywheel/flex plate.   A thin sheet of steel (aluminum might do) the area of which covers all the tension bolts is used to cover  the engine tension bolt heads.  This sheet is attached using the  using the rear main bearing/gear support bolts.  This sheet prevents any bolt from backing out should it break.  I put a spot of silicone on head of each bolt to dampen any vibration of the sheet.
 
I recall at least one incident  where a tension bolt did back out, but fortunately the individual (Perry Mic, I believe) was using the 35 lb manual flywheel which simply bent the bolt out of the way.  A flex plate may not survive such an encounter.
 
Ed
 
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
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