Posted for "glong2" <glong2@netzero.net>:

Marvin:
My Crossbow 500 AHRS has the 4 mounting bolts plus two high tolerance .25
inch holes for locating pins. I planned to mount my AHRS 500 on a mounting
plate using the sloppy fit .29 holes with 1/4 inch bolts. I will fly the
plane and make sure the AHRS is mounted correct, then match drill the .25
holes and install locating pins to serve as realignment pins when/if I have
to remove the AHRS unit. It seems as though the high precision holes were
meant for this.

Eugene Long
Lancair Super ES
glong2@netzero.net


[Thanks for the tidbit... after I sent the original post and got back to the project I started leaning along similar lines, but was hoping for a confirmation from someone about this approach.  Makes perfect sense, so I'll get the job done tomorrow.

While we're on the subject of Crossbows and EFISes, I fired up the panel today after putting the AHRS into position, just to make sure that we had communications and that the EFIS would display properly.  I noticed that when I rotated the AHRS in the roll axis the little airplane in the center 9of the EFIS) would remain aligned with the airframe, and the horizon would roll as expected.  When I rotated the AHRS in the pitch axis, though, the little airplane remained centered on the rising or falling horizon until I got to about 15-20 degrees, at which time a little ghost circle appeared in the center of the screen that looked to correspond with the nose up or nose down attitude relative to the displayed horizon.  Is this normal?  I was expecting the EFIS display to react similarly to what I'd see on a gyro horizon, with the airplane remaining in the middle of the display and the horizon moving around it.  Movements around the yaw axis appeared normal.  I confess that I haven't read the manual yet, but it'd be nice to know whether what I'm seeing is correct for an airplane sitting in the hangar (garage) or if there is a malfunction going on.  Any comments would be appreciated.

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