Bud,
I am one of the very many who greatly appreciate the knowledge you share
with the Europa community and all the time you spend to help us out when a
problem occurs. Your last posting puzzled me, however, because I have a
different experience:
You write:
>Again, Grand Rapids is the expert on the 2000 models years, programming and
setup. I just know it will work fine with one Floscan >on a 912S (where the
small amount of fuel through the return line with orifice is not counted)
when ordered direct from GRT with >the fuel flow option.
I have a 912ULS, GRT EIS with fuel flow option and installed the Floscan
that was supplied by GRT in the fuel line (I do not have the model number at
hand, but for this discussion it is not important). After calibration of
the flow reading, I found to my big surprise that the return flow through
the orifice was in the 10 litres range (roughly 4 gallons) per hours. As
the return flow varies with the fuel pressure (and therefore to some extent
depends on the engine RPM), I did not wish to base my "consumption reading"
on an unknown return flow to be subtracted. I therefore first installed a
shut-off valve in the return line (mounted on the tunnel side, to be
operated during flight) for short-period reading of flow during my test
flights, to determine consumption and most economical speed. Later, I have
replaced it with Electronics International's fuel totalizer, which has a
flow pickup both in the feed and the return line - superb instrument.
I was very surprised that the return flow is this high (at least in my
installation, where I think I have the restrictor with the correct orifice
installed!), but concluded that the reason is the very low viscosity in
gasoline compared to for example water.
It of course makes sense to have a significant return flow, as the objective
is to flush through the fuel system forward of the firewall with "cold"
fuel, especially on the ground when idling or taxiing, when the consumption
flow is very low, to reduce the risk of vapor lock.
Kind regards,
Svein
LN-SKJ
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