Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Thu, 16 May 2002 23:51:15 -0400
Message-ID: <redirect-1240066@logan.com>
From: Dan O'Brien <danobrien@cox.net>
Subject: All electric versus vacuum/electric instruments
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I am interested in builders' thoughts about having all electric gyros 
instead of the more standard system with vacuum driven heading and attitude 
indicators and an electric turn coordinator.  I've noticed that the Cirrus 
is dual electric, and the Columbia may be going that direction.  Ignoring 
the fact that electric gyros are more expensive, I am specifically 
interested in people's opinions about the following:

1. How much redundancy is required in an all electric system for it to be 
as safe as the "standard" vacuum/backup vacuum/electric system?  By 
"standard" system I mean a vacuum driven heading and attitude indicators, 
the precise flight backup vacuum system, and an electric turn 
coordinator.  Are vacuum systems so unreliable that even a system with one 
battery and one alternator is preferred?  If not, would a system with one 
battery and two alternators be preferred?  Two batteries and two alternators?

2. What are the failure modes in the different "all electric" systems that 
one needs to worry about most?

3. Beyond the Aeroelectric Connection (http://www.aeroelectric.com/), where 
can I get more information about this?

Thanks much.