As a result of the recent discussion on fuel pressure I thought I might
add my viewpoint to the forum.
My Europa is at the test flying stage (3 hours completed). It has a
non-standard fuel system which puts the pumps in parallel with each pump
getting its supply from separate sides of the tank. Each tank outlet has
its own individual shut-off valve (both left open for normal flight). The
mechanical pump has a primer bulb which helps to avoid vapour locking on a
hot start as well as providing a head of pressure to the mechanical pump
just before a cold start. Each side has its own gascolator giving further
redundancy capability. The outlet of the mechanical pump has a pressure
switch which, as well as providing a warning in the event of a drop of
fuel pressure, brings on the electrical pump when it is in the auto mode.
The two halves of the system are joined by a NRV from the mechanical side.
This system has the following benefits.
1. In the event of the mechanical side failing due to blockage, leakage or
vapour lock the pressure switch automatically brings on the electrical pump
supplying fresh cool fuel from a different source direct to the
carburettors.
2. It provides a sensible way of having a known reserve level.
3. As many unplanned engine stoppages are fuel management related this
system does the management for the pilot bringing his/her attention to any
faults at the same time.
It is easy to prove the system by closing the mechanical side shut-off
valve or putting the electrical pump to auto before start. When the
mechanical pump is re-established a push of the reset button allows the
mechanical side to take over again provided it is providing sufficient
pressure.
The system seems to work well so far and might be of interest to anyone who
is concerned about the risk of vapour lock or blocking of
filters/gascolators from tank debris. As it is a major departure from the
normal system it has been approved by the PFA subject to satisfactory
flight testing. A few more hours should show whether my trust in this setup
is well founded or not. After that some of you might like to try it for
yourselves.
Further text details are attached to this e-mail. If there are no problems
with it after next summer then I might approach the PFA to set it up as
another Europa Club mod.
Nigel Charles
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