Message-ID: <3C145DA8.512B68F3@attbi.com>
Date: Sun, 09 Dec 2001 23:00:56 -0800
From: Bob <rbelshe@attbi.com>
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To: lancair.list@olsusa.com
Subject: L320 - nose wheel shimmy cracks engine mount?
References: <20011210053938.AAA12778@pop3.olsusa.com>
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I had serious shimmy problems when I first got my 235.  I bought it from
the builder in Wisconsin, and hired an experienced pilot to fly it to
Calif. for me.   Shortly after I finished checking out in the plane,
(about 12 hrs) the shimmy began.  It would not happen on every landing.
I tried wheel balancing, tightened up the nose wheel, low tire pressure,
etc.   It seemed like the shimmy was triggered by brake application on
roll-out, and once it started it wouldn't stop until the plane was down
to 20 mph or so.   I sent the nose strut to Lancair and they
disassembled it and said it was OK.  I put it back on.

The shimmy got worse....

I found I had a cracked engine mount, on both ends of the crosspiece
right above where the nose strut attaches.  Which came first, the shimmy
or the cracks?  I really don't know when it cracked, if it was
contributed to by some hard landings or what.  Then I found there is a
mod to increase the torsional damping in the nose strut.   This time the
strut was sent back to Lancair, who sent it to the manufacturer in
Australia for the damping mod.  This was in 1996.  I believe all more recent
struts already have this modification.  I pulled the engine and had a 
piece of thicker-walled tubing (same O.D.) tube welded into the mount 
where it cracked.  I have had absolutely no shimmy since.   
It now has about 200 hrs on it with the O235 engine, and another
200 hrs with a IO320 and it has been quite reliable.  The only other 
recommendation is to keep the proper pressure in the nose wheel (abt 28psi). 

Bob Belshe
Moraga, CA
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