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