At 08:47 PM 3/14/2010, you wrote:
><thorn@starflight.aero>
>
>Thanks Bob,
>
>I was out of town on business when you came through Houston with
>your class so my wife attended without me (but I'm doing the electrical...?)
>So, I missed the previous debates, discussions on the AMS subject. I think
>you've convinced me that we don't need an AMS.
Yes, I recall meeting your wife and commiserating over
your absence!
>With the addition of a 43 lb electric A/C system in our little Lancair
>Legacy, we're working to trim some weight out. We've saved 17 lbs with an
>MT prop vs. the Hartzell. If it were not for the weight concern I'd
>probably opt for the dual alternator/dual battery system (or if I were going
>dual electronic ignition). It seems that the Z-12 power grid is an
>excellent, reliable architecture for us.
I agree.
>I'm not yet convinced that the Essential/Endurance Bus adds that much value.
Where does it DEVALUE? If you subscribe to the notion that
modern avionics have outlived the myths that promulgated
the AMS, then the task remaining is to craft a failure tolerant
system. The E-bus goes to that point. Further, it provides the
means by which electrical loads during an alternator-out configuration
can be predicted in advance. This is critical to an easily implemented
and well considered plan-B.
>Though, if I found myself IFR with electrical problems (aka panic:))
Why panic? That's the whole point of the plan-B exercise.
We KNOW that things are going to break. If one has plans
for every contingency, then where's the driver for panic?
>the idea of flipping a couple switches to reconfigure would probably
>look like genius... It seems, though, that it might improve
>reliability more for Z-12 to have dual parallel battery contactors.
>What do you think about that?
If that's what you want to do, by all means. But you'd probably
be flying one of a few dozen aircraft in the history of aviation
that was so equipped.
There are tens of thousands of airplanes that have successfully
launched and recovered into IMC with less reliable equipment,
heavier electrical loads and wired like a 1965 C-172.
Accidents having root cause in electrical system failure are
already exceedingly rare . . . and many if not most of those
could have been mitigated if not avoided by understanding
(well considered plan-B) and good preventative maintenance
(batteries, belts, attach brackets, etc) on the part of the
owner. Z-12 or any other z-figure offers a recipe for
success that has been filtered through years of
discussion and actual practice on thousands of airplanes.
Rather than stirring in new ingredients, it would seem
a better plan to deduce ways in which the architecture
fall short of mitigating demonstrable risks.
Then there's the matter of WHERE to put things and
HOW to wire them all up. Risks to your future in-flight
comfort will be driven more by the processes by which
you carry out the plan than the ingredients that go
into the plan. This idea is supported by the numerous
dark-n-stormy night stories we've studied here on the
list. We've also been privy to information from the
gleaned from the wreckage of several airplanes. NONE
of those events were forced by the failure of
single pieces of of properly installed hardware.
Bob . . .
