Jeff,
I agree hardware fails. Lots of mechanical
gyros also fail without a lot of feedback. A cross check between multiple sensors
is always needed.
When that hardware is
electrical/software it will also fail in potential obscure ways, but usually
quite obviously. Having independent systems makes it highly unlikely that they
will fail at the same time. Unless it’s an electrical system failure.
For me with an ALL electric panel
planned, dual redundant electrical systems is a requirement. Including two
batteries. The thing that can take out the electrical system is a lightning
strike. I do plan on some heavy MOV s (Metal Oxide Varistor) to keep any damage
localized and not fry the entire electrical system. This is being used on lots
of type certified aircfraft (VLJ) to limit this type of damage.
Knowing I fly an aircraft that really does
not like ice or electricity will keep me out of a lot of really serious IFR
stuff.
Every one has their own level of
confidence. I assure you that if I find any instability in my equipment during
my flights I will re-evaluate my situation and make adjustments to my system. It
sounds like you have traveled on the bleeding edge with the Chelton/Crossbow
combo. There is a lot more history on devices now.
I am glad to not be on this bleeding edge.
There are a few of us that are now on the ALL ELECTRIC bleeding edge. We will
let you know how it goes. I fully expect that before I quit flying you will be
hard pressed to find one of those “peanut” gauges except in the “antique”
aircraft category, and I am not that young …
r.t.s.
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of VTAILJEFF@aol.com
Sent: Wednesday, December 19, 2007
9:50 AM
To: lml@lancaironline.net
Subject: [LML] Re: Skoppe lancair
4 pt
in over 1000 hours flying the LIVP and
Chelton combo I have had:
1. a total electrical failure (all
screens go immediately dark-- not good when you are IMC over Jackson
Hole). Three mechanical peanut gauges bought me enough time to
recover. I had tow alternators at the time but it was a battery failure that
took the entire system down.
2. an AHRS go bonzo without any
EFIS cautions on an IMC flight creating some confusion as to what was
happening. Comparing the EFIS to the mech gauges and TC helped sort things out.
The AHRSA went back to Crossbow.
3. a heading failure with no EFIS
announcements caused by too much steel near the AHRS (towbar). Don't place any
steel within feet of your magnetic flux gate.
4. I have also had two occasions where a
stray electron took down the entire Air Data and Engine display . One due to a
TIT probe failure-- I was the beta tester there and the other was a short
forward of the firewall coming in through the EAU taking the EAU out of the
loop.
Although IMC occupies only 10-15 % of my
total flying-- it is during that time that the solo pilot can ill afford a
primary system instrument failure. A robust backup system is in order. The days
of having a vacuum failure fly the TC are over for most of us. Consider
how you are going to diagnose a failure -- and not all are announced by the
EFIS and how are you going to get home.
Consider how you are going to fly the
airplane with no electrical power or with every screen dark or so screwed up
nothing electronic is usable. It will happen-- and not in clear blue and 22.