Hallo Europa Family
For safety reason I want to install a second Pierburg fuel pump. Both pumps
are below the reservoir level.
In the Europa builder manual of the Rotax 914 and also in the manuals from
Rotax they say two pumps in line (it is not series, as both pumps have a
bypass via check valves).
Others like Pierburg or other aircraft builder say pumps parallel, connected
to a double switch (Doppelschalter) where one positive cable (say from the
engine control) goes to one end and the other positive cable for the
auxiliary pump, which comes from a buss plate or direct from the battery
goes to the second part of the switch. That means, when the main pump fails
you disconnect with the double switch this line and immediately you have
connected the good pump. A full bypass flow by using the check valve lines
as made with the inline installation is not necessary, as this way would be
good only by planes where the reservoir would be above the engine like a
Piper cub.
The parallel installation with the double switch (you must be sure that at
first one pump is shut off before the other pump will get switched on) would
be much easier with much less leaking points.
So keep it simple as possible.
Do you agree or is that rubbish?
Have always safe flights (never suspend the laws) and all the best,
Bruno
|