From: RWolf99@aol.com
Message-ID: <689d946.368b9f61@aol.com>
Date: Thu, 31 Dec 1998 10:59:29 EST
To: lancair.list@olsusa.com
Subject: Tire Clearance with Closeout Rib
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I had a problem early on with insufficient clearance between my main gear
tires and the cockpit closeout rib.  I sent a note to the LNN several
years ago.  It seems relevant now, so here it is again:

I have a problem with my 320 ... and I'm not alone.  I have less than 3/8"
clearance between my main gear tire and the cockpit closeout rib on one
side of the aircraft.  Almost half of the 320/360's I crawled under
at Oshkosh '96 had the same problem.  How can you avoid this and, if it's
too late, how can you fix this?

When it comes time to bond the cockpit closeout rib in place, the main
gear leg forward pivot bearing is already attached to the front spar.
It should be a simple matter to lay the gear into proper position by
placing the assembled gear leg into the forward bearing, but it is not.
I screwed this up and, evidently, so did several others.

When you lay the gear in position, the forward end is guaranteed to be
in place by the forward bearing.  The aft end is eyeballed to be
approximately straight fore and aft.  Eyeballing this is not good enough!
A better solution is to measure the distance between the BL-50 rib and
the gear leg at the forward end and use a spacer at the aft end to ensure
the distance is uniform.  (This assumes that the BL-50 rib is in place
as it is on the fast-build kits.)

In addition, tape a 3/8" spacer to the bottom of the tire.  And of course,
inflate the tire to rated pressure first.  I used a 3/8" spacer on the
tire but only eyeballed the fore/aft straightness, and this is where I
probably messed up.

Okay.  Suppose you've done all this and still you need more clearance?
The closeout rib is 3/8" thick.  If you cut away the fiberglass on
the rib and scoop out the honeycomb, you can get all the clearance you
need.  (Still, hog out only as large an area as you need, and no more.)
Fill in the honeycomb around the edges with micro and lay in 2 plies of
new glass to replace what you cut out.  As with any fiberglass patch,
make sure the glass overlaps the patched area by at least 1 inch all around.
(n.b.  The cockpit closeout rib ply orientation is 0-90-0, not the normal
45-45).

This solution has been reviewed and approved by Don Goetz at Lancair.


- Rob Wolf
rwolf99@aol.com

p.s.  While I wrote this blurb in 1996, I just did the patch two weeks ago...


[Another consideration is that the tires are going to expand a bit with
altitude.  What passes for plenty of clearance at sea level with the tires
inflated to 35psi may well turn into constant pressure on the closeout
rib when you get to 8 or 10 kft.  I inflated my tires to 55psi when I
planned the clearance for the closeout rib, and wound up with an
extra 3/16" of room as a result.  FWIW.  <Marv>]