X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.123] verified) by logan.com (CommuniGate Pro SMTP 5.3.4) with ESMTP id 4180729 for flyrotary@lancaironline.net; Sat, 27 Mar 2010 08:38:14 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.123; envelope-from=eanderson@carolina.rr.com Return-Path: X-Authority-Analysis: v=1.0 c=1 a=aZptCi5Qn3UA:10 a=ayC55rCoAAAA:8 a=arxwEM4EAAAA:8 a=QdXCYpuVAAAA:8 a=7g1VtSJxAAAA:8 a=ekHE3smAAAAA:20 a=UretUmmEAAAA:8 a=Ia-xEzejAAAA:8 a=nUuTZ29dAAAA:8 a=JED3Nu3KkG3tWZCXIzsA:9 a=luUVt-COECFrT9L7wsYA:7 a=C6a4IBKZZGP8llRX7TpyNuGhC2gA:4 a=CjuIK1q_8ugA:10 a=1vhyWl4Y8LcA:10 a=EzXvWhQp4_cA:10 a=NT2DlSLDVcH5BEB6:21 a=zZzXBj3-gYSY0ARC:21 a=SSmOFEACAAAA:8 a=Ivf9R8h2oTUok4IbN54A:9 a=0mKy-JZXE-nzr7wUeB0A:7 a=uB1VONUm0zSwdIYrX_22Kao6NpQA:4 a=xwt7fhTZwQL4Sf31:21 a=l9FKpH9ssGwNZRpg:21 X-Cloudmark-Score: 0 X-Originating-IP: 75.191.186.236 Received: from [75.191.186.236] ([75.191.186.236:1689] helo=computername) by cdptpa-oedge04.mail.rr.com (envelope-from ) (ecelerity 2.2.2.39 r()) with ESMTP id C5/23-08012-11CFDAB4; Sat, 27 Mar 2010 12:37:38 +0000 From: "Ed Anderson" Message-ID: To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Adaptor plate rivets - Al' 20B Date: Sat, 27 Mar 2010 08:37:47 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_003C_01CACD88.C728B2E0" X-Mailer: Microsoft Office Outlook, Build 11.0.5510 In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 thread-index: AcrNaJyJicLj0IokTAeyv6W++oLvgwAQTWQg This is a multi-part message in MIME format. ------=_NextPart_000_003C_01CACD88.C728B2E0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Excellent photos showing the wear, Al. I agree with you, you may have had many more hours on the unit without problem. But, as you know once things start to go, the process can escalate rapidly, one rivet fails, two fail, then three and who knows the remainder after some point may fail in cascade fashion - with the remaining rivets failing with increasingly more ease as they carry more of the load. So the thing could possibly "unzip" suddenly. There's always another airshow - good call in my opinion. Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm _____ From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Al Gietzen Sent: Saturday, March 27, 2010 1:47 AM To: Rotary motors in aircraft Subject: [FlyRotary] Adaptor plate rivets - Al' 20B 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 'Front' side of the plate (the side toward the prop) is shown in the first photo. This side is easily seen when the drive is on. Everything looks fine. * The 'Back' 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'll also note all the streaks coming out from the spline. Does that mean the spline is wearing? No, I'd say that's just grease that lubed the spline, and what was in the idler bearing hole at 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 'clockwise' 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 is a slight bevel around the inner steel bushing (third photo). These snubbers have about 125 hours on them; and suggest there is a 'service life' 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 - 125-150F. * Almost 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 the plate when holding with my hands. Whatever movement I had previously noted with my 'sensitive fingertip' test when jogging the prop on the plane I'd say was very small, like .001". (apparently I have very sensitive fingertips:-)) * I noted when turning the rivets that when rotated 90 degrees they were tight. This suggested that 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 one side where it was in the spine flange (see shiny area in blurry photo 'Rivet1'), and when rotated 180 the shiny area that was in the plate (blurry photo Rivet2). Sorry, couldn't 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. 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 point 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" and 'close tolerance bolts are nominally .190", so that's a good fit. Regular AN bolts are .002.-003 smaller dia. I measured the combined thickness of the flange and the plate at .350"; the grip length on an AN173-6A is nominally .375, but measures more like .400 so is good with an AN-960 washer. Al G __________ Information from ESET NOD32 Antivirus, version of virus signature database 3267 (20080714) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com ------=_NextPart_000_003C_01CACD88.C728B2E0 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

Excellent photos showing the wear, = Al.

 

I agree with you, you may have had = many more hours on the unit without problem.  But, as you know once = things start to go, the process can escalate rapidly, one rivet fails, two = fail, then three and who knows the remainder after some point may fail in cascade = fashion – with the remaining rivets failing with increasingly  more ease as = they carry more of the load.  So the thing could possibly = “unzip” suddenly.

 

There’s always another = airshow – good call in my opinion.

 

Ed

 

From: = Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Al Gietzen
Sent: Saturday, March 27, = 2010 1:47 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] = Adaptor plate rivets - Al' 20B

 

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 ‘Front’ side of the plate (the side toward the prop) is = shown in the first photo. This side is easily seen when the drive is on. Everything looks fine.
  • The ‘Back’ 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’ll also note all the streaks coming out from the = spline.  Does that mean the spline is wearing? No, I’d say = that’s just grease that lubed the spline, and what was in the idler = bearing hole at 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 ‘clockwise’ 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 is a slight bevel around = the inner steel bushing (third photo). These snubbers have about 125 hours on = them; and suggest there is a ‘service life’ 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 – = 125-150F.
  • Almost 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 the plate when holding with my hands. Whatever movement = I had previously noted with my ‘sensitive fingertip’ test = when jogging the prop on the plane I’d say was very small, like .001”. (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 direction = of the applied load. I further verified this after removing a couple = rivets and noting the wear on one side where it was in the spine flange (see = shiny area in blurry photo ‘Rivet1’), and when rotated 180 = the shiny area that was in the plate (blurry photo Rivet2).   = Sorry, couldn’t 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.

 

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 point 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” and ‘close tolerance = bolts are nominally .190”, so that’s a good fit.  Regular AN = bolts are .002.-003 smaller dia. I measured the combined thickness of the flange = and the plate at .350”; the grip length on an AN173-6A is nominally .375, = but measures more like .400 so is good with an AN-960 = washer.

 

Al G

 



__________ Information from ESET NOD32 Antivirus, version of virus = signature database 3267 (20080714) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com

------=_NextPart_000_003C_01CACD88.C728B2E0--