I don't know what happened to my previous post in this thread, but what showed
up in this forum version had nothing of what I sent in the email. Here's what
I wrote earlier:
I'll take a short swing at it, by simply describing my thought process & resulting
decisions. I decided that *buses* don't fail. As long as they're installed
properly and inspected regularly, they should be given the same confidence as
wing spars. Power supplied to one could fail, in which case a backup source should
be available. With that starting point, I planned two buses; one with *everything*
for the electrically dependent engine, and the other for airframe power.
Crossfeed ability between the two. Individual circuits protected by individual
fuses, protecting the bus. I have redundant fuel pumps, etc, but both are
controlled from the engine bus. Even then, switchology was still more complicated
than I wanted, but it was stripped down as clean as I could reasonably
get it with the 'unconventional' engine.
Trying to power each item (if you're doing the pumps, the ECUs need it too, etc
etc) from multiple source buses seems to me like planning for multiple failures
in the same function-path on the same flight, a possibility so remote that
the mitigation attempts actually increase the risk, and it's also a strong magnet
drawing one into pilot overload if something does go south in flight. We
manage to mismanage stuff in stressful situations even with all the control motions
being hardwired by decades of flying. A radical departure in 'switchology'
beyond that absolutely required, and/or multiple added layers, seems to me
to make it more likely that something minor will become something major very
easily.
Just my thought path and results; yours will likely vary.
Charlie
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Charlie
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http://forums.matronics.com/viewtopic.php?p=513484#513484
