Posted for "Douglas Brunner" <douglasbrunner@earthlink.net>:

 Colyn,
 
 I understand your comments about reliability being more than just the
reliability of the
 instrument.  If the instruments are electric, the electrical system needs to
be reliable too.
 
 In the first place the TruTrak ADI does have an option for battery backup.
(from the website:
 "Backup battery option - $100" )  I intend to get the backup battery option.
 
 Second, I plan to have a dual alternator, dual battery setup with the
avionics bus feeding
 from either.  And even if I lose both alternators, the batteries should give
me a good hour of electricity.
 
 I don't know what to do about a "fried wiring harness" except to say that I
don't see how an
 electric Mid-Continent instrument would necessarily  fare any better than the
Trutrak ADI.
 
 Since I have flown many hours behind a vacuum AI with no backup (Recently I
got
 a backup electric AI for my Mooney - largely because of the failure of my
vacuum AI) it seems
 to me that dual electric AI are a definite step up.
 
 I am also not sure exactly what "gyro enhanced vertical speed" means.  If
someone has a good
 explanation, I would like to hear it.
 
 D. Brunner

"""      I'm betting on tru-trak for my auto-pilot and I expect their ADI really
is quite reliable and I like that
  (I think) it has it's own battery backup.   I'm not clear exactly how they
do pitch.  the ad says "gyro
  enhanced vertical speed" which sounds like it's either baro or gps, which is
another variable in the reliability equation.
"""