X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 26 Aug 2007 10:21:52 -0400 Message-ID: X-Original-Return-Path: Received: from mta10.adelphia.net ([68.168.78.202] verified) by logan.com (CommuniGate Pro SMTP 5.1.11) with ESMTP id 2285470 for lml@lancaironline.net; Sun, 26 Aug 2007 10:18:50 -0400 Received-SPF: pass receiver=logan.com; client-ip=68.168.78.202; envelope-from=glcasey@adelphia.net Received: from [75.82.253.35] by mta10.adelphia.net (InterMail vM.6.01.05.02 201-2131-123-102-20050715) with ESMTP id <20070826141811.RYTF9920.mta10.adelphia.net@[75.82.253.35]> for ; Sun, 26 Aug 2007 14:18:11 +0000 Mime-Version: 1.0 (Apple Message framework v752.2) In-Reply-To: References: Content-Type: multipart/alternative; boundary=Apple-Mail-2--622707881 X-Original-Message-Id: <90F2D1B4-F8A6-4148-8A7A-884833312C3F@adelphia.net> From: Gary Casey Subject: Re: ES engine mount cracks and breaks X-Original-Date: Sun, 26 Aug 2007 07:18:09 -0700 X-Original-To: "Lancair Mailing List" X-Mailer: Apple Mail (2.752.2) --Apple-Mail-2--622707881 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=WINDOWS-1252; delsp=yes; format=flowed I was concerned about the structural integrity of the standard =20 Continental engine mount when I first saw mine. My calculations =20 showed that the CG of the engine/prop combination was approximately =20 at the front mount location, so it holds the total weight of the =20 engine. Then the loading on the tubes turns out to be not down, like =20= one might think, but outward in line with the axis of the mounts (the =20= rubber mounts are designed to be soft laterally and still axially). =20 There is very little strength or stiffness in this "spreading" =20 direction and fatigue loading in this direction could be expected to =20 cause failure in exactly the spot shown in the photos. The cure =20 would be a tube connecting the two engine mount locations, absorbing =20 the outward loading. As for the failures of the tubes in the back, =20 I'm not so sure. The drag link imposes most compressive loads back =20 there unless the nose gear moves laterally quite a bit, but Lon =20 didn't report any significant shimmy issues. I'm wondering if the =20 engine didn't move around because of the cracks at the front, causing =20= the fractures at the rear. On my Lycoming mount I eliminated the =20 "cage" of small-diameter tubes at the back and connected the engine =20 mount locations and the drag link directly to the center firewall =20 mount with "full size" tubes. One reason I like the Lycoming =20 mounting system is that the mounts are close to the firewall so that =20 all connections between the engine and firewall can be direct and stiff. Gary Casey ES #157, Lyc IO-540 On Aug 25, 2007, at 2:44 PM, Lancair Mailing List wrote: > Lancair Mailing List Digest #2080 > > 1) ES engine mount cracks and breaks > by "Jim Nordin" > > This digest is sent to you because you are subscribed to > the mailing list . > For archives and help click http://lancaironline.net/Lists/lml/ > LML website: http://www.lancaironline.net/maillist.html > > From: "Jim Nordin" > Date: August 25, 2007 2:35:37 PM PDT > To: lml@lancaironline.net > Subject: ES engine mount cracks and breaks > > > Here=92s a note from Lon Kelley regarding his ES motor mount issues. =20= > I hope these pictures will encourage you all to examine closely =85 =20= > very closely =85 your motor mount. Personally I don=92t see how there =20= > wasn=92t a very serious accident because of this problem =85 Lon and =20= > Pam were just plain lucky. > > Jim Nordin > > > From: PKkelle@aol.com [mailto:PKkelle@aol.com] > Sent: Saturday, August 25, 2007 3:40 PM > To: panelmaker@earthlink.net > Subject: ES engine mount > > > Jim, here is some information on the recently discovered engine =20 > mount problems in my ES. The pictures are attached and show some =20 > major breaks and widespread cracking in the welds. It is my opinion =20= > that these cracks indicate improper welding procedures in my mount, =20= > and there may also be a problem in other early ES mounts. I have =20 > not got any professional opinion on the welds, and really don't =20 > intend to, but the cracks all appear to be in the heat-affected =20 > zone adjacent to the weld, and this is the area of concern in most =20 > high carbon material where embrittlement might occur. > > > I believe these cracks have been there for a long time, and we =20 > missed them during inspections. My only excuse for this is that =20 > they wouldn't be visible under the paint. What led to my finding =20 > them was some very rough taxiing at Sun N Fun, Oshkosh and a rough =20 > grass strip this summer. At the last oil change I specifically =20 > wanted to look at the nose-gear mount, and feel very lucky that we =20 > took the bottom cowling off, and I stuck my nose down there and =20 > chipped some paint back. Of course the two broken members were =20 > pretty obvious if you were looking. My plane has 1225 hours and =20 > this mount was made in 1994. > > > Incidentally, we sent our strut back to Lancair in about 1999, and =20 > Vern rebuilt it. We have not experienced serious shimmy with it, =20 > and I don=92t believe the weld cracks are associated with shimmy. =20 > Lon Kelley > > > > > > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.5.484 / Virus Database: 269.12.6/971 - Release Date: =20 > 8/24/2007 2:59 PM > > > > > > > > > --Apple-Mail-2--622707881 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=WINDOWS-1252 I was concerned about the = structural integrity of the standard Continental engine mount when I = first saw mine.=A0 My calculations showed that the CG of the engine/prop = combination was approximately at the front mount location, so it holds = the total weight of the engine.=A0 Then the loading on the tubes turns = out to be not down, like one might think, but outward in line with the = axis of the mounts (the rubber mounts are designed to be soft laterally = and still axially).=A0 There is very little strength or stiffness in = this "spreading" direction and fatigue loading in this direction could = be expected to cause failure in exactly the spot shown in the photos.=A0 = The cure would be a tube connecting the two engine mount locations, = absorbing the outward loading.=A0 As for the failures of the tubes in = the back, I'm not so sure.=A0 The drag link imposes most compressive = loads back there unless the nose gear moves laterally quite a bit, but = Lon didn't report any significant shimmy issues. =A0I'm wondering if the = engine didn't move around because of the cracks at the front, causing = the fractures at the rear. =A0On my Lycoming mount I eliminated the = "cage" of small-diameter tubes at the back and connected the engine = mount locations and the drag link directly to the center firewall mount = with "full size" tubes.=A0 One reason I like the Lycoming mounting = system is that the mounts are close to the firewall so that all = connections between the engine and firewall can be direct and = stiff.

Gary = Casey
ES #157, Lyc IO-540

On Aug 25, = 2007, at 2:44 PM, Lancair Mailing List wrote:

=A0 =A0 =A0 =A0 = Lancair Mailing List Digest #2080

=A01) ES engine mount cracks and = breaks
=A0 =A0 by "Jim Nordin" <panelmaker@earthlink.net><= /DIV>

This digest is sent to you because you are = subscribed to
=A0 the mailing list <lml@lancaironline.net>.
=
For archives and help click http://lancaironline.net/List= s/lml/

From: "Jim Nordin" <panelmaker@earthlink.net><= /FONT>
Date: August 25, 2007 2:35:37 PM = PDT
To: lml@lancaironline.net
Subject: ES engine mount cracks and = breaks


Here=92s a note from Lon Kelley regarding his ES = motor mount issues. I hope these pictures will encourage you all to = examine closely =85 very closely =85 your motor mount. Personally I = don=92t see how there wasn=92t a very serious accident because of this = problem =85 Lon and Pam were just plain lucky.

Jim Nordin

=A0

From: PKkelle@aol.com [mailto:PKkelle@aol.com]
= Sent: Saturday, August = 25, 2007 3:40 PM
To: = panelmaker@earthlink.net
= Subject: ES engine = mount

=A0

Jim, here is some information on the recently discovered engine = mount problems in my ES. The pictures are attached and show some major = breaks and widespread cracking in the welds. It is my opinion that these = cracks indicate improper welding procedures in my mount, and there may = also be a problem in other early ES mounts. I have not got any = professional opinion on the welds, and really don't intend to, but the = cracks all appear to be in the heat-affected zone adjacent to the weld, = and this is the area of concern in most high carbon material where = embrittlement=A0 might occur.

=A0

I believe these cracks have been there for a = long time, and we missed them during inspections. My only excuse for = this is that they wouldn't be visible under the paint. What led to my = finding them was some very rough taxiing at Sun N Fun, Oshkosh and a = rough grass strip this summer. At the last oil change I specifically = wanted to look at the nose-gear mount, and feel very lucky that we took = the bottom cowling off, and I stuck my nose down there and chipped some = paint back. Of course the two broken members were pretty obvious if you = were looking. My plane has 1225 hours and this mount was made in 1994. =

=A0

Incidentally, we sent our strut back to Lancair in about 1999, = and Vern rebuilt it. We have not experienced serious shimmy with it, and = I don=92t believe the weld cracks are associated with shimmy.=A0 Lon = Kelley



=

No virus found in this incoming = message.
Checked by AVG Free Edition.
Version: 7.5.484 / Virus = Database: 269.12.6/971 - Release Date: 8/24/2007 2:59 PM
 =

=
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= --Apple-Mail-2--622707881--