The only negative I see is not being able to run the tank out without killing
the engine.  With all the tanks you're talking about having, that's probably
not a big deal, but the RV-3 only has two 15 gallon tanks, so using every last
gallon is useful


If you get any more of those level sensors you could do what I did. I bought
the "Fuel Guardian" from Aircraft Extras, but instead of mounting them in a
tank as it was designed, I rethreaded them to fit into a 1/4" AL "T" (used
proseal on the threads)and I installed each one on the lines from each wing
selector valve (one for each side with 3 tanks to select on each side). As
soon as air is sensed in this line I get a big flashing light on the panel and
I switch tanks. I've found that I can run the engine at cruise power for ~45
secs before the existing fuel is drawn out of the line, giving plenty of time
to switch tanks. And in repeated (many times) ground tests, I've also run it
untill the engine began to die then switched tanks, turned on Facet pump and
recovery is immediate. I've also run it until I knew that most of the line
must have air in it, switched pumps to other wing while still producing power,
then slected a full tank on the previous wing and switched pumps back again
(did I lose anybody?:-),in an attempt to see the effect of a large slug of air
going through the injectors (I'm a returnless system, so all air must go
through injectors), and the engine continues to run without a hickup. It's my
conclusion that the Facet pumps combined with the FI pumps move so much fuel,
so fast that the system can handle small amounts of air.
Todd Bartrim

C-FSTB RV-9endurance
13B Turbo