X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-iw0-f183.google.com ([209.85.223.183] verified) by logan.com (CommuniGate Pro SMTP 5.3.4) with ESMTP id 4180657 for flyrotary@lancaironline.net; Sat, 27 Mar 2010 06:06:45 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.223.183; envelope-from=msteitle@gmail.com Received: by iwn13 with SMTP id 13so7371492iwn.14 for ; Sat, 27 Mar 2010 03:06:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:received:message-id:subject:from:to:content-type; bh=OVvfPhan2a4AsSmVN6ZNAqjFebD1qlhb/V/iQpUjlRc=; b=q3Y5Zd7776rh5pgd4fEsusRYmWfswgb7+vJuxXzFtdm9zauqYi8T9JFkeo69IqnoEv YqORAqeokxrQ6FGVLgO5LosYd/q+5Bpo636N1cTUceBgMSjCcPSVABk5O4J74Ttfu937 XxOreYpALUcSVfocToUm2CgArHIULXtf0gxns= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=PTXVJSzMcbKMPGSZxh+AY9BqLU/w84VyFLYTQNPMFsMSx8alc2+cwJ/sfM+zHH8M8K dKowTJrh0Sdk8Hi3FvATATbcIcxOM5v3PISW9tanY9qv3GcmrEJqg2mmLZXroc4W+hm0 Zqd0LyQdSkeWwaGtahrkykIkcEKrZlMFjvYyI= MIME-Version: 1.0 Received: by 10.231.185.94 with HTTP; Sat, 27 Mar 2010 03:06:08 -0700 (PDT) In-Reply-To: References: Date: Sat, 27 Mar 2010 05:06:08 -0500 Received: by 10.231.182.213 with SMTP id cd21mr1085945ibb.93.1269684368066; Sat, 27 Mar 2010 03:06:08 -0700 (PDT) Message-ID: <5cf132c1003270306w134211d8iae6c034072ecc8@mail.gmail.com> Subject: Re: [FlyRotary] Adaptor plate rivets - Al' 20B From: Mark Steitle To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0016363b87ccbc4a770482c56dbb --0016363b87ccbc4a770482c56dbb Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Good report Al. It is interesting that there are streaks from only the bac= k side. Is it possible that you have cleaned the front side but due to accessibility, didn't clean the back side? I received my close tolerance bolts and swapped out the AN-6A bolts. The close tolerance bolts were definitely snugger in the holes, but all could b= e installed by hand without needing to be tapped or driven in with a hammer. I'll report back with a status report in 50 hrs. Mark S. On Sat, Mar 27, 2010 at 12:46 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 > > --0016363b87ccbc4a770482c56dbb Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Good report Al. =A0It is interesting that there are streaks from only the b= ack side. =A0Is it possible that you have cleaned the front side but due to= accessibility, didn't clean the back side? =A0

I re= ceived my close tolerance bolts and swapped out the AN-6A bolts. =A0The clo= se tolerance bolts were definitely snugger in the holes, but all could be i= nstalled by hand without needing to be tapped or driven in with a hammer. = =A0I'll report back with a status report in 50 hrs. =A0

Mark S.

On Sat, Mar 27, 20= 10 at 12:46 AM, Al Gietzen <ALVentures@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.<= /span>

=A0

  • Th= e =91Front=92 side of the plate (the side toward the prop) is shown in the first photo. T= his side is easily seen when the drive is on. Everything looks fine.
  • Th= e =91Back=92 side (toward the flywheel/ring-gear) is shown in the second photo.=A0 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. =A0Does 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 at the end of the shaft.=A0 It is likely that some portion of the streaks from the rivets could just = be oily dirt.
  • No= te that the elastomer snubber bushings are all thinner on the =91clockwise=92 side than on the other. They have taken a permanent set in the direction of the applied load. It is more apparent on the front side of the plate where there i= s a slight bevel around the inner steel bushing (third photo). These snubb= ers have about 125 hours on them; and suggest there is a =91service life=92 to these, and they should be replaced at some interval. These = snubbers may run hotter in my pusher where they are at cowl exit temp =96 125-1= 50F.
  • Al= most all of the rivets could be rotated in the holes with a pair of 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 th= e plate when holding with my hands. Whatever movement I had previously n= oted with my =91sensitive fingertip=92 test when jogging 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 th= at they were wearing only in the direction of the applied load. I further verified this after removing a couple rivets and noting the wear on on= e side where it was in the spine flange (see shiny area in blurry photo =91Rivet1=92), and when rotated 180 the shiny area that was in the plate (blurry photo Rivet2).=A0=A0 Sorry, couldn=92t seem to get the camera 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 greater HP.

=A0

So; did I over= -react in canceling my trip to Nevada? Yeah, I think so. This would h= ave 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; in re= gard 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


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