In addition, assuming that most are using TruTrak APs, the autopilot itself
is ,essentially, a self contained system that will continue
to fly the aircraft without input from the any of the other AHARS systems. STEC
are also independent. Yes, a total electrical failure of an isolated dual
electrical system could render if non-functional, but that would also “kill”
electric DG, AI, HIS, etc. SO, are we going to put in a vacuum system to back
up a dual electrical system. Naturally, they are notoriously
prone to failure.
Regarding the premise of lightning, I
might suggest that if we are disabled by a strike in hard IFR conditions, then
we have already made a couple of other serious misjudgments? If anyone out
there has the illusion that flying can be made completely fool-proof, you might
need to rethink your involvement in aviation. Remember, fools are so dang
ingenious!
IVPT 725PT
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From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of PTACKABURY@aol.com
Sent: Wednesday, December 19, 2007
1:32 AM
To: lml@lancaironline.net
Subject: [LML] Re: Skoppe lancair
4 pt
In a message dated 12/18/2007 3:11:34
P.M. Pacific Standard Time, VTAILJEFF@aol.com writes:
Do you not consider a second independent
EFIS with it’s own ADAHRS as sufficient backup
Not a simple question--depends on the
power distribution design concept. My first reaction is to suggest you
consider the common elements between the two EFISs--and that would seem to be
only the pitot static system since the Dynon has its own separate
battery. When I designed my electrical system I started with an all electric
objective and did all I could to include simplicity as well as redundancy to
keep the motor running. For a number of reasons that resulted in two
Odyssey batteries and one alternator. Then I added a Chelton Pro--a
certified EFIS. So I felt comfy I had a good AHARS and two high quality
displays with redundancy. To provide a backup for the 2% of the time I am
in real IFR I decided a Dynon was the cost effective answer--I just could not
imagine a failure mode that would leave the motor running and kill both
EFISs. But maybe your imagine is different than mine.