X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from qw-out-2122.google.com ([74.125.92.24] verified) by logan.com (CommuniGate Pro SMTP 5.3.4) with ESMTP id 4180715 for flyrotary@lancaironline.net; Sat, 27 Mar 2010 08:24:47 -0400 Received-SPF: pass receiver=logan.com; client-ip=74.125.92.24; envelope-from=rwstracy@gmail.com Received: by qw-out-2122.google.com with SMTP id 3so2515401qwe.25 for ; Sat, 27 Mar 2010 05:24:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:received:in-reply-to :references:date:x-google-sender-auth:received:message-id:subject :from:to:content-type; bh=DJyB23fgwTIqCLKT4z78xKSREgyKtUkkKYF4thu68E0=; b=BD7zfnScvku4HSwmF6iqPTK3AkfIE3r2pg+iktXQdw/d1mpey6Syx8aFoMaPB+R9p9 qz5F5aeoahy+6YcCy6EKKNBVp5068lMOsEOH0ftZA+6pKIaLo2u3hgJrA1IWuQWAJwnk hN3SLl+6dZY16yCzr21VVSvtRhWIVkaOLcSyg= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type; b=FQcnpc8EwmrzaCFNsPQj2glxvPYD95dXvjFgNKgxm04FRSZwBzQpQW4cb0sHzBM19I nHiYmBQBQx5oJ08EGVERE+3GPuanuSfXPL0zW7RerqTjyrZfgf0wmVhtzboqsD+n9yUP gB1bYtDnDOjLqY3vF/ZfU/KQ3i2M+XDGAPi1s= MIME-Version: 1.0 Sender: rwstracy@gmail.com Received: by 10.224.60.211 with HTTP; Sat, 27 Mar 2010 05:24:11 -0700 (PDT) In-Reply-To: References: Date: Sat, 27 Mar 2010 08:24:11 -0400 X-Google-Sender-Auth: a1c584d56fc037ed Received: by 10.224.103.69 with SMTP id j5mr794208qao.158.1269692651515; Sat, 27 Mar 2010 05:24:11 -0700 (PDT) Message-ID: <1b4b137c1003270524w180f1cbu11c1f99778bdfc7a@mail.gmail.com> Subject: Re: [FlyRotary] Adaptor plate rivets - Al' 20B From: Tracy Crook To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=000feaf1481777b25c0482c75bac --000feaf1481777b25c0482c75bac Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Good info Al. I saw the 'set' on the rubber dampers long ago (after about 150 total hours) and started checking it at intervals from 100 to 300 hours. The se= t did not change significantly so in my opinion the dampers only need to be replaced if the rubber material itself is starting to deteriorate. Mine haven't after 1200+ hours. The set will be noticeable after very few hour= s so replacing them at that point would get old in a hurry. I'm leaning more and more toward the -6AD rivet solution on the damper dis= k but close tolerance bolts are certainly good too. Tracy On Sat, Mar 27, 2010 at 1:46 AM, Al Gietzen wrote: > I took the re-drive off today for examination of the damper plate and > rivets. Here are my findings and observations. Somewhat detailed for the > average user, but could be useful for Tracy. > > > > - The =91Front=92 side of the plate (the side toward the prop) is show= n in > the first photo. This side is easily seen when the drive is on. Everyt= hing > looks fine. > - The =91Back=92 side (toward the flywheel/ring-gear) is shown in the > second photo. Here the streaks from the rivets are easily seen. These= are > the rivet heads. > - Of course you=92ll also note all the streaks coming out from the > spline. Does that mean the spline is wearing? No, I=92d say that=92s = just > grease that lubed the spline, and what was in the idler bearing hole a= t the > end of the shaft. It is likely that some portion of the streaks from = the > rivets could just be oily dirt. > - Note that the elastomer snubber bushings are all thinner on the > =91clockwise=92 side than on the other. They have taken a permanent se= t in the > direction of the applied load. It is more apparent on the front side o= f the > plate where there is a slight bevel around the inner steel bushing (th= ird > photo). These snubbers have about 125 hours on them; and suggest there= is a > =91service life=92 to these, and they should be replaced at some inter= val. These > snubbers may run hotter in my pusher where they are at cowl exit temp = =96 > 125-150F. > - Almost all of the rivets could be rotated in the holes with a pair o= f > pliers; some were rather tight, others just snug; just one or two that > rotated with reasonable ease. I could not detect any movement between = the > spline flange and the plate when holding with my hands. Whatever movem= ent I > had previously noted with my =91sensitive fingertip=92 test when joggi= ng the > prop on the plane I=92d say was very small, like .001=94. (apparently = I have > very sensitive fingertipsJ) > - I noted when turning the rivets that when rotated 90 degrees they > were tight. This suggested that they were wearing only in the directio= n of > the applied load. I further verified this after removing a couple rive= ts and > noting the wear on one side where it was in the spine flange (see shin= y area > in blurry photo =91Rivet1=92), and when rotated 180 the shiny area tha= t was in > the plate (blurry photo Rivet2). Sorry, couldn=92t seem to get the c= amera to > focus that close in, but you get the picture. > - I conclude that the wear on the rivets is due to the somewhat > cyclical loading from the engine to the prop, and would be expected to= be > worse on the 20B, or 13B run at significant boost just due to the grea= ter > HP. > > > > So; did I over-react in canceling my trip to Nevada? Yeah, I think so. > This would have operated safely for many more hours. However; at some po= int > these rivets needed replacing, and over-reacting where safety is involved= is > not a bad idea. > > > > Further; in regard to replacing with bolts, the holes mic at .190-.191=94= and > =91close tolerance bolts are nominally .190=94, so that=92s a good fit. = Regular > AN bolts are .002.-003 smaller dia. I measured the combined thickness of = the > flange and the plate at .350=94; the grip length on an AN173-6A is nomina= lly > .375, but measures more like .400 so is good with an AN-960 washer. > > > > Al G > > > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html > > --000feaf1481777b25c0482c75bac Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Good info Al.=A0

=A0I saw the 'set' on the rubber dampers l= ong ago (after about 150 total hours) and started checking it at intervals = from 100 to 300 hours.=A0=A0 The set did not change significantly so in my = opinion the dampers only need to be replaced if the rubber material itself = is starting to deteriorate.=A0 Mine haven't after 1200+ hours.=A0=A0 Th= e set will be noticeable after very few hours so replacing them at that poi= nt would get old in a hurry.

I'm leaning more and more toward the=A0 -6AD rivet solution on the = damper disk but close tolerance bolts are certainly good too.=A0=A0
Tracy

On Sat, Mar 27, 2010 at 1:46 AM, A= l Gietzen <ALVen= tures@cox.net> wrote:

I took the re-drive off today for examination of the damper plate and rivets.=A0 Here are my findings and observations. Somewhat detailed for the average user, but could be useful for Tracy.

=A0=

  • J= )
  • =A0=

    So; did I = over-react in canceling my trip to Nevada? Yeah, I think so. This= would have operated safely for many more hours.=A0 However; at some point these rivets needed replacing, and over-reacting where safety is involved is not a bad idea.

    =A0=

    Further; i= n regard to replacing with bolts, the holes mic at .190-.191=94 and =91close tolerance bolts are nominally .190=94, so that=92s a good fit.=A0 Regular AN bolts are .002.-003 smaller dia. I measured the combined thickness of the flange and = the plate at .350=94; the grip length on an AN173-6A is nominally .375, but measures more like .400 so is good with an AN-960 washer.

    =A0=

    Al G

    =A0=


--
Homepage: =A0http:/= /www.flyrotary.com/
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