We don't talk a lot about electrical stuff here, but we probably
should. A couple of months ago there was an on-airport engine-out
crash landing of an LS V8 powered P51 replica in CA, and a
subsequent discussion on the HBA forum with the non-builder,
non-flying owner asking what could have gone wrong. He could offer
almost no info about the way the plane was set up, but Eliot Seguin
was doing what was supposed to be a simple flying off of the
insurance company-dictated 5 hours flight time when the failure
happened, and he just posted a long Youtube video on the flight and
accident sequence.
https://www.youtube.com/watch?v=4PHTVTw_Y2A
I found the video very hard to watch due to the visual edit cuts
every second or two, but the after-action analysis is worth the hour
you'll spend watching.
Guys, the builder of that a/c seemed to find every possible way to
make the electrical system failure-prone. Seguin describes the
elaborate steps they took prior to him flying the a/c to inspect the
airframe, but they apparently totally ignored the electrical system.
Because of that, the choices the builder made almost certainly
caused the original gear issue, and then caused the total electrical
failure that took out everything in the a/c, including the engine.
There
is no justification for wiring an a/c the way this one was wired.
With most of us running automotive style engine control,
electricity is obviously quite critical to engine operation. We
really should do Failure Mode Effects Analysis on the whole plane,
including the electrical system, but with electrically dependent
engines, it's critical. Draw your schematic. Look at *every single
wire*. Pretend that it got broken, and ask what happens, and then
ask what plan you have in place to work around it. Then short it to
ground, and ask the same questions. (You can get very different
effects.) Move to the next wire, and do it again. Rinse; repeat.
Then fail each component and ask the questions.
Don't let any one electrical issue cause the engine to stop, or
cause more than momentary distraction from normal flight. Most of us
know about the Aeroelectric Connection email list, but if you don't,
please sign up for the list and get the book (relatively inexpensive
in print; free for download). If you're not absolutely confident in
your electrical design decisions (or maybe even if you are), get
peer review. The AEC list is best, but at least ask here if you
don't want to sign up over there. There are a *lot* of wrong ways to
wire an a/c.
I hate it that the FAA's accident database will now show yet another
crash 'caused' by an alternative engine, when in fact it was caused
by uninformed/bad electrical design decisions made by the builder.
OK, rant mode off...
Charlie