Brent has written
much on this topic including "In my "Glazed and Confused"
presentation on "Glass Cockpits" I say that flying an aircraft with
a non-certified, non TSO'ed glass standby (Dynon et al) is like jumping out
of an airplane with only your main parachute and your standby plan is the
fact you are wearing real soft socks."
When I was young and
stupid (not long ago) I had thoughts of long overwater (think trans-Pacific)
flights. I also have experience with failure modes assessment analysis
(FMEA) which frequently shows up failure modes easily over looked.
After reviewing various electrical and instrument configurations I arrived at
a system design which is shown in simplified form in the attached
sketch. It consists of two alternators, two batteries, four busses, and
a lot of opportunities for cross tie. I use dual Chelton screens, with
PFD off the essential buss (many sources of power), the MFD off of the
avionics bus (which has many sources of power), and back up electric attitude
indicator (on essential buss), turn and bank (essential buss) and air speed
and altitude indicators.
You show me the failure
and I can show you the automated or manual work around. And critical
stuff is all double protected with circuit breakers and surge arresters (not
shown).
But even this
diagram is not as safe as it could be. What
about something simple like: a battery relay decides to go flotch? (One
already has done so.) That causes a main bus to go south forcing you to
a cross tie solution, not ideal. So not shown are by-pass switches and
fuses around the relay solenoids I added "just in case"
to provide redundancy on all supply routes.
I have a
mechanical and electrical fuel pump. And I have an electronic ignition
and a magneto.
Two of everything,
independent power modes, independent pathways, cross connects, multiple
layers of electrical spike and surge protection and independent and different
principles of gyroscopic display and electrical power supply. Now
one begins to achieve realistically (and defensible) high levels of
reliability.
If I could only achieve
the same with the pilot.