From: "Marvin Kaye" <marv@lancaironline.net>
Subject: Mounting the Crossbow 500 AHRS
To: lml
Date: Wed, 09 Jul 2003 12:17:27 -0400
Message-ID: <web-2460290@logan.com>
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We just received the Crossbow 500 AHRS for Ted's airplane and are getting 
ready to install it where the old #400 went.  Our original #400 platform is a 
bit small and so we'll be extending it with an aluminum mounting plate to 
accommodate the larger #500.  I have a question for those of you who have 
already installed your #500 AHRS regarding the fasteners.... there is a single 
1/4" hole on the front edge and a 1/4" slot on the back edge intended for 
positioning purposes, but the 4 mounting holes themselves are .290 in 
diameter, and I'm curious what others have done out there to provide for a 
good fit between the fasteners and the mounting holes.  I'm loathe to use 1/4" 
bolts and have all that slop in there, to me that option isn't acceptable. 
 The other options I've come up with are 1) sleeve the holes with bushings to 
accommodate standard AN4 (making a bushing with an .020 wall shouldn't be too 
difficult, although it would be decidedly easier to bush for -3) bolts; 2) 
drill & ream the mounting holes to .312 to accept -5 bolts; 3) purchase some 
5/16 shoulder bolts and turn down their shoulders to the .290 dimension.  Yep, 
I've got a lathe that will allow me to do the turning ops, but I'm hoping to 
learn what others of you have done about this, if anything.  I'm anxious to 
hear your comments.

         <Marv>