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Getting back to the original topic for a moment -
One factor that hasn't yet been discussed is
whether or not you require your backup to use a different sensing method
than your primary instruments. The Trutrak appears to use a solid-state
gyro, which the Chelton also appears to use. Therefore, an external
anomaly (static, EM interference, vibrations at a certain
frequency (actually happened, though not to a Chelton), alien
death rays while flying over New Mexico, whatever) that compromises the sensing
element of your primary display will also compromise your backup.
An AI's display is based on a
spinning rotor - pretty hard to get any more basic than that. Not
exactly high tech, but we know pretty well what can cause them to provide
misleading information (that whole accelerating/decelerating/climbing/descending
stuff from the instrument rating test). Provide power, the rotor spins,
you know which way is up.
Personally - and I have absolutely no data to back
this up - I don't think we've found all of the failure modes of these
solid-state gyros yet (although from what I read, the experimental community is
finding a lot of them). I tried in vain to convince a pair of builders at
my local EAA chapter that backing up one EFIS with another solves one particular
failure mode but leaves you vulnerable to a bunch of other ones, especially if
the backup EFIS is a lower priced one from the same vendor. Maybe it's
just me...
A few years ago, I got to see the cockpit of an
F/A-18, and there among the million or so of dollars of redundant display
screens was a gyro AI and airspeed and altitude steam gauges. Just one of
those things that make you go, "Hmmmmm...."
Gary Fitzgerald
LNC2 standard build
~70%
steam gauges + AOA
Engine: TBD
St. Charles,
MO
I spoke to the Tru Trak representative at Sun n
Fun and he stated that there are stall warnings built in to the system and
that I could "retrain" myself to interpret the ADI properly.
Nevertheless, I am concerned that in a difficult situation, I would interpret
the Tru Trak in the way I would a standard AI. Your thoughts and
advice?
D. Brunner
Legacy N241DB
hoping to fly in
June
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