X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao101.cox.net ([68.230.241.45] verified) by logan.com (CommuniGate Pro SMTP 5.3.4) with ESMTP id 4178014 for flyrotary@lancaironline.net; Thu, 25 Mar 2010 01:26:41 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.45; envelope-from=alventures@cox.net Received: from fed1rmimpo03.cox.net ([70.169.32.75]) by fed1rmmtao101.cox.net (InterMail vM.8.00.01.00 201-2244-105-20090324) with ESMTP id <20100325052605.VUJK5695.fed1rmmtao101.cox.net@fed1rmimpo03.cox.net> for ; Thu, 25 Mar 2010 01:26:05 -0400 Received: from BigAl ([72.192.128.205]) by fed1rmimpo03.cox.net with bizsmtp id xHS41d0094S1t5C04HS4jF; Thu, 25 Mar 2010 01:26:06 -0400 X-VR-Score: 0.00 X-Authority-Analysis: v=1.1 cv=yjuDh3Ma92GrVaJxYD7gfORM7ilP1Knqouyx6SOEBcg= c=1 sm=1 a=Vegc0WxVmH5BHtpNDyThtA==:17 a=kNCamsRXz4jVCJ1kHboA:9 a=jx-GsQ7qu6Sg9RPAmcEA:7 a=yXr4R2bsNO9IGDHtdZCcVuJ-gqQA:4 a=CjuIK1q_8ugA:10 a=jrVHjVKRd3CMyZ2Hqp8A:9 a=umQvl4k6ONhnvqRLoOQA:7 a=BIgHSOLnnT8u9oyYe2K8kQG0ayoA:4 a=Vegc0WxVmH5BHtpNDyThtA==:117 X-CM-Score: 0.00 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: Adaptor plate rivets Date: Wed, 24 Mar 2010 22:25:52 -0800 Message-ID: <38DF21F1044F4E0F840E108773CEF8BB@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0012_01CACBA0.F6781070" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6856 In-Reply-To: Importance: Normal X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 Thread-Index: AcrLFBVDp5OdRGipT4mr7nKdEjhRsgAyd+0g This is a multi-part message in MIME format. ------=_NextPart_000_0012_01CACBA0.F6781070 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable =20 I tried to check my plate for smoking rivets today, but the shop head is against the flywheel and I can't see a thing. The round heads all seem fine. Couldn't detect any that seem loose or smoking or anything. Will just have to keep an eye on it. David Leonard =20 Dave; there is a way to check. =20 I went for further checks on mine today - had to make the decision = whether or not to fly it to Jean, NV, on Saturday for the CONTACT! Alternative Engine Fly-in. (First I went flying for about an hour just to make sure = I wasn't going to be deprived of my enjoyment before I had to fix it:-)) = I went to look for loose rivets, or to see is I could detect any relative movement between the spline adapter flange and the aluminum plate. =20 No way to get at the heads of the rivets without disassembly, and = everything 'looked' fine on the front side of the flange. So I pressed my = fingertips onto the plate, overlapping them onto the beveled edge of the flange; = then pulled a prop blade back and forth with the other hand. I could detect = that there was relative movement; however miniscule, as in maybe a few thousandths max, but it was there. I could not detect it visually, but I could feel it. So after some considerable deliberation, I decided that = this should be fixed before more flying. =20 =20 I suspect if I done the same thing many flight hours ago it would have = been similar, so a few more hours wouldn't really matter, but I had to = consider that aluminum rivets will work-harden, and become brittle, and then at = some point possibly subject to breaking, especially if there is any operating regime where there could be torsional vibration with force reversal. No = way of knowing when that point would be reached. =20 So I think you should give it the 'sensitive fingers' check, and feel = for relative movement. Not that you necessarily have to replace the rivets = right away, but if you are quite certain there is any relative movement it is definitely a cause for concern, and should be checked again after a few hours and see if you can detect a difference. =20 I'm planning on replacing the rivets with AN173-6A bolts, with MS21042-3 metal lock nuts over AN960-10L washers. Maybe Mark can tell us if the = thin washers are enough to sure the threads don't bottom out. About 4 or 5 of these bolts would be as strong as 20 aluminum rivets, but I guess all 20 would be good to distribute the stress in the aluminum plate. =20 Al G =20 =20 =20 =20 =20 ------=_NextPart_000_0012_01CACBA0.F6781070 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

 

I tried to check my plate for smoking rivets = today, but the shop head is against the flywheel and I can't see a thing.  = The round heads all seem fine.  Couldn't detect any that seem loose or = smoking or anything.  Will just have to keep an eye on it.   David = Leonard

 

Dave; there is a way to check.

 

I went for further checks on mine = today – had to make the decision whether or not to fly it to Jean, = NV, on Saturday = for the CONTACT! Alternative Engine Fly-in.  (First I went flying for about = an hour just to make sure I wasn’t going to be deprived of my = enjoyment before I had to fix itJ)  I went to look for loose rivets, or to see is I = could detect any relative movement between the spline adapter flange and the = aluminum plate.

 

No way to get at the heads of the = rivets without disassembly, and everything ‘looked’ fine on the = front side of the flange. So I pressed my fingertips onto the plate, overlapping = them onto the beveled edge of the flange; then pulled a prop blade back and forth = with the other hand. I could detect that there was relative movement; however miniscule, as in maybe a few thousandths max, but it was there. I could = not detect it visually, but I could feel it.  So after some = considerable deliberation, I decided that this should be fixed before more flying.  =

 

I suspect if I done the = same thing many = flight hours ago it would have been similar, so a few more hours wouldn’t = really matter, but I had to consider that aluminum rivets will work-harden, and = become brittle, and then at some point possibly subject to breaking, especially = if there is any operating regime where there could be torsional vibration = with force reversal.  No way of knowing when that point would be = reached.

 

So I think you should give it the = ‘sensitive fingers’ check, and feel for relative movement. Not that you = necessarily have to replace the rivets right away, but if you are quite certain = there is any relative movement it is definitely a cause for concern, and should = be checked again after a few hours and see if you can detect a = difference.

 

I’m planning on replacing = the rivets with AN173-6A bolts, with MS21042-3 metal lock nuts over = AN960-10L washers. Maybe Mark can tell us if the thin washers are enough to sure = the threads don’t bottom out. About 4 or 5 of these bolts would be as = strong as 20 aluminum rivets, but I guess all 20 would be good to distribute = the stress in the aluminum plate.

 

Al G

 

 

 

 

 

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