Return-Path: Received: from cdihost.cdicorp.com ([207.79.152.5]) by truman.olsusa.com (Post.Office MTA v3.5.1 release 219 ID# 0-52269U2500L250S0V35) with SMTP id com for ; Thu, 14 Oct 1999 17:02:01 -0400 Received: from JUPITER by cdihost.cdicorp.com via smtpd (for olsusa.com [205.245.9.2]) with SMTP; 14 Oct 1999 21:06:07 UT Received: from cdim-pts-mail.cdicorp.com (CDIM-PTS-MAIL [172.17.131.3]) by jupiter.cdicorp.com with SMTP (Microsoft Exchange Internet Mail Service Version 5.5.2448.0) id 4ZL158RC; Thu, 14 Oct 1999 17:06:07 -0400 Received: by CDIM-PTS-MAIL with Internet Mail Service (5.5.2448.0) id <4MKZWGMX>; Thu, 14 Oct 1999 17:03:47 -0400 Message-ID: From: "Rumburg, William" To: "'lancair.list@olsusa.com'" Subject: LNC 2 SB 050-0999 Date: Thu, 14 Oct 1999 17:03:45 -0400 X-Mailing-List: lancair.list@olsusa.com Mime-Version: 1.0 <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> Marv - I know this subject has been beaten pretty hard, but please allow me to say a final few words... First, both the main gear and its backup structure receive a lot of shock with the rubber "doughnut" installation (I won't even call them shock absorbers). Installing either of the new style shock absorbers is certain to alleviate the shock transmitted throughout the gear system, including the secondary attach point. Therefore, I consider this part of the fix. Second, installing the new full-width attach block that I recommend requires extra work, i.e. you have to use a hammer and chisel to break out the existing attach block that was installed as part of the fastbuild work. I had an early fastbuild kit (April 1989) with some poor fastbuild workmanship. The later fastbuild workmanship was dramatically improved. The secondary attach block in newer kits is,therefore, more likely to last longer, maybe forever. A word of caution before one decides to break out the existing block is that good fiberglass skills are required in the fitting and installation of a completely new block, especially in such a difficult to access area. For those who don't have confidence in their fiberglass skill, it may be preferable to simply do as the SB requires and simply add the brace. Bill Rumburg N403WR (Sonic bOOm) [While I (and undoubtedly others) can see the logic and benefit to your 'alternative' to the SB, I think it needs mentioning here that this is a builder-suggested modification which doesn't carry the factory's blessing at this point. I am pretty sure that if a builder who holds the repairman's certificate for the aircraft which he is servicing decides to install yours (or another) modified version of the attachment point referenced in this SB he can probably do so as he is signing off his own work and takes full responsibility for it. I don't know what effect this might have on one's insurance should that part fail and it was discovered that the SB hadn't been performed as specified. Additionally, anyone who needs to have the SB applied to their aircraft for them and for it to then be signed off by an A&P will probably have to do it the factory way without question, as the only documentation for the modification that currently exists in this regard is, in fact, the factory's SB. Considering the amount of discussion this subject has received over the past week or so, I didn't want there to be any confusion about the direction it was initially headed. Additionally, the stresses which seem to be causing the problem to this secondary attachment structure appear to be related to gear side loads and not the rubber donuts as you suggest. Severe side loads may be imposed regardless of what type of shock absorbing mechanism is incorporated into the gear leg, and are caused more by the gear leg's geometry than any of its individual components. Just my humble $0.02. ] >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> LML website: http://www.olsusa.com/Users/Mkaye/maillist.html