X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 27 Jan 2011 14:42:57 -0500 Message-ID: X-Original-Return-Path: Received: from web57503.mail.re1.yahoo.com ([66.196.100.70] verified) by logan.com (CommuniGate Pro SMTP 5.4c2a) with SMTP id 4828457 for lml@lancaironline.net; Thu, 27 Jan 2011 12:36:50 -0500 Received-SPF: none receiver=logan.com; client-ip=66.196.100.70; envelope-from=casey.gary@yahoo.com Received: (qmail 65270 invoked by uid 60001); 27 Jan 2011 17:36:16 -0000 DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=6e2oczg2aFX2+sKHXrdJTk0pdhXsFQoEnszNUwKoiOrQi76OgpFNHf2j1/i9N98JeuRmjJ/hdiAbrcRC/gW909NBzspForB19JLkGH1nV+vDpgf19B9YI3/3mDyaNbVZ4MN++OmoD1Hujrt8YyMckUvXsH91vjy44CH0yP0O3X0=; X-Original-Message-ID: <705392.64318.qm@web57503.mail.re1.yahoo.com> X-YMail-OSG: sh6sJrMVM1mhPZX5wVJfP1ilDy9EEuRKQj7dSQU8WZ1f6Oc 1bttd5qGWVX7wLb.qglCtpF7pYkSu9yl.tpEXA5gcsJBxmpPhOjEHt8LvHlM aFrdJlWhbGX8bRkUG3GFN8sPz6wd.75_fyELpvBzdQZV6YOcm5MSyRYkqcW7 w8D35bp36cgU2GXM6cnGWRJdDERu9ODReppnKE7vehvHU_.zexfwxI1KezPq 4nt23gJg7TRaFZWrR4r5Km6vlLXuJytIT5VE9wOtWRyt6OeaDBD4Pcq_HaG9 GNK6AD7qaZzFhm56zHPWzThaA9Mq84bt3zmTsFv0ves0pU.EiQBVCMct4xlz nVAyfwFCt Received: from [75.10.204.198] by web57503.mail.re1.yahoo.com via HTTP; Thu, 27 Jan 2011 09:36:16 PST X-Mailer: YahooMailRC/555 YahooMailWebService/0.8.107.285259 References: X-Original-Date: Thu, 27 Jan 2011 09:36:16 -0800 (PST) From: Gary Casey Subject: Re: Engine mount cracks X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-1772201320-1296149776=:64318" --0-1772201320-1296149776=:64318 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable All the comments below are true, but I believe the root cause is design-rel= ated =0Aand there has been a lot of discussion about this on the the ES for= um. The =0Amount absolutely begs for a tube to connect the two front mount= s. The force on =0Athese tends to spread the mounts roughly in line with t= he axis of the mount =0Abolts. Besides adding a connection, a diagonal bra= ce is also a very good thing =0Ato add. The other shortcoming is the stiff= ness (or lack thereof) in the nose =0Agear mount area. Imagine holding bot= h arms to the front and then twist both =0Aclockwise and then counterclockw= ise - this is the the loading on the nosegear =0Amount plates that causes t= he problem. This is the probably the motion that =0Acracked the tube in th= e photos. The solution is to weld a transverse beam (a =0Aflat plate will = do) between the two plates. Lancair has recently modified the =0Amount b= y adding such a flat plate - a good thing. But they have also added =0Agus= sets where Michael's welder suggested - a completely inadequate cure, in my= =0Aopinion. And, as many owners have found, it doesn't take a nose gear s= himmy =0Aevent to cause the failure.=0AGary Casey=0A=0A=0AMichael,=0A =0AI = make a living making aerospace parts=E2=80=A6.Boeing is my largest customer= =E2=80=A6.so I =0Athink my advice is sound.=0A4000 series steels like 4130= , 4330 and 4340 are susceptible to cracking after =0Aweld if they are not = preheated and post heated during the weld process. I do =0Anot know what = material your engine mount is made of but the 4000 series steels =0A(chrom= e moly) are quite popular for this kind of application. I would be very = =0Aleery of welding or re-welding steel tube and not knowing what kind of = steel it =0Ais. Additionally, the quality of weld on your engine mount is= not very good. =0AI would suggest replacing the mount unless you can con= firm what material the =0Amount was made from. If you choose to repair th= e mount, Lancair should have =0Aspecified the material and the fab house s= hould have material certs from the =0Aoriginal build. Whether or not that= information is still available=E2=80=A6.I don=E2=80=99t =0Aknow. Finding= a good welder at an airport may be challenging. Another =0Athought=E2=80= =A6losing the nose gear due to mount failure would be very expensive.=0A = =0ACraig Berland=0AIV-P N7VG=0A =0A =0A<
All the comments below are true, but I believe the root caus= e is design-related and there has been a lot of discussion about this on th= e the ES forum.  The mount absolutely begs for a tube to connect the t= wo front mounts.  The force on these tends to spread the mounts roughl= y in line with the axis of the mount bolts.  Besides adding a connecti= on, a diagonal brace is also a very good thing to add.  The other shor= tcoming is the stiffness (or lack thereof) in the nose gear mount area.&nbs= p; Imagine holding both arms to the front and then twist both clockwise and= then counterclockwise - this is the the loading on the nosegear mount plat= es that causes the problem.  This is the probably the motion that crac= ked the tube in the photos.  The solution is to weld a transverse beam (a flat plate will do) between the two plates.    Lanc= air has recently modified the mount by adding such a flat plate - a good th= ing.  But they have also added gussets where Michael's welder suggeste= d - a completely inadequate cure, in my opinion.  And, as many owners = have found, it doesn't take a nose gear shimmy event to cause the failure.<= br>Gary Casey

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Michael,

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I make a= living making aerospace parts=E2=80=A6.Boeing is my largest customer=E2=80= =A6.so I think my advice is sound.

4000=0A series steels like 4130, 4330 and= 4340 are susceptible to cracking =0Aafter weld if they are not preheated a= nd post heated during the weld =0Aprocess.  I do not know what materia= l your engine mount is made of but =0Athe 4000 series steels (chrome moly) = are quite popular for this kind of =0Aapplication.  I would be very le= ery of welding or re-welding steel tube =0Aand not knowing what kind of ste= el it is.  Additionally, the quality of =0Aweld on your engine mount i= s not very good.  I would suggest replacing =0Athe mount unless you ca= n confirm what material the mount was made from. =0A If you choose to = repair the mount, Lancair should have specified the =0Amaterial and the fab= house should have material certs from the original =0Abuild.  Whether= or not that information is still available=E2=80=A6.I don=E2=80=99t =0Akno= w.  Finding a good welder at an airport may be challenging.  Anot= her =0Athought=E2=80=A6losing the nose gear due to mount failure would be v= ery =0Aexpensive.

 

Craig Berland

IV-P N7VG

 

 

<<The=0A two attached images show a cr= ack in the engine mount on my Lancair =0AIV-P. #4637 shows context and #464= 1 details. The opposite side cracked =0Ain a similar fashion two years ago.= (I have not had nose wheel shimmy.)


I=0A would like advice on ap= propriate repair. My mechanic is suggesting some=0A form of gusset which co= uld improve the overall strength and prevent a =0Afuture occurrence.
I wonder if this might not be asking for trouble.

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