From: "R & A Colebrook" <rossann@azstarnet.com>
To: "Lancair List" <lancair.list@olsusa.com>
Subject: VISION MICROSYSTEMS ENGINE INSTRUMENTS
Date: Thu, 21 Jan 1999 17:56:11 -0700
Message-ID: <01be45a2$00b2f820$4628c5a9@rossann.olympus.net>
Mime-Version: 1.0

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Richard Perry asked for comments.

I have the separate instrument version of their system in my 235.  It works
well.  I chose the separate instrument version to get bigger dials for my
geezer eyes.  The integrated displays look a little too small to suit me,
but that is matter preference.  I did not include the fuel quantity system,
the clock, or the air temperature options.  I have the fuel flow rate system
and it is accurate for flight fuel flow rates but understates the fuel flow
at taxi conditions.  This is no big problem, just expect an additional half
gallon to be required at fill up for taxing in and out.   Have the poor-boy
capacitance fuel quantity system from Sky Sports inserted from the  wing
tip into extended wing tanks (but not fuel all the way to the tip).  The
gauges and the "Fuel Remaining" function of the Vision System agree quite
well as long as I remember to update the "Fuel Aboard" function when I add
fuel.  The back lighting of the gauges works excellently, no sun problems,
no
night viewing problem with a dimmer rheostat installed. (Incidentally the
back lighting and dimmer can be powered separately from the CPU to combine
dimming with other lights, a nice touch).

Now the down side.  I had two CPU failures in the first ten hours, one of
which produced smoke (fortunately on the ground).  Both times there was a
short circuit inside the CPU.  I think it was really the same failure twice
and was due to sloppy quality control of soldering.  Both times I got good
customer support and a quick turnaround on repairs (about ten days) and a no
cost loan of equipment to reset the hour meter.

These failures brought home to me that an inflight failure with this system
causes a complete failure of all engine instrumentation which to me means
landing at the closest suitable airport and staying there until the system
is fixed.  I therefore negotiated a discount priced spare CPU to carry in
the airplane.  A replacement CPU has to be tailored to each installation to
get the limits set correctly and getting a replacement for a AOG would take
days at best.

There is also a battery in the CPU to keep its memory alive.  This battery
is good about 4 years.  That was about the time for me between system
purchase and flight test.  So if the CPU is hard to get at it might be smart
to install a new battery at the last time the CPU is easily accessible.  The
system works with a dead battery but has no memory.

Ross W. Colebrook (N7828)