Hi Gottfried and all,
>So you will see, that the connection in series is the latest recommendation.
>This
would reduce the fuel-flow trough the pumps and the returning fuel from the
pressure regulator by 50%. On the other hand, the series-installation would
reduce a lot of the filter problems as well.
>
>
>
Just like you I'm a Rotax 914 builder and pilot, though I'm not a Europa
builder.
The discussion on gascolator is most interesting.
Concerning the pumps,
*Series mounting :* very strange suggestion indeed on the part of Rotax,
since each pump offers a significant restriction to fuel flow. I
questioned our Rotax importer and he could see no technical reasons for
this odd installation.
*Parallel mounting :* the Rotax installation manual is obviously wrong,
since the Pierburg pumps are more or less "transparent" to fuel flow.
With no check valve in series with each pump, the fuel will flow back
through the other pump when only one is operating.
Pierburg documentation shows the classical installation in parallel with
two check valves.
The Rotax importer could see no reasons not to use the Pierburg "normal"
circuit.
So we installed the pumps in parallel, with two check-valves.
There is a finger screen in each of the wing tanks, then one in-line
auto fuel filter on each line issuing from the tank, then the fuel
enters a common Andair mini gascolator before the Y fitting to the pumps
and then through the firewall to the engine fuel regulator.
Each tank has its sump and drain, as required by the FAR 23.
We never experienced any engine trouble.
We found some carbon particles in the tank drains for a few hours after
building, and the in-line filters were changed within the first 25
hours, with carbon particles and aluminum filings on the "paper". But
the finger screens were always clean, and no particle or water found its
way to the gascolator.
FWIW,
Regards,
Gilles Thesee
Grenoble, France
http://contrails.free.fr
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