Message text written by Fred Fillinger
> It would seem that if the left side
were water-contaminated, overwhelming its gascolator, the boost pump
may not supply clean fuel from the other side (relative pump
pressures). <
The electric pump gives a higher pressure (in my case 5psi versus 3psi) so
the electrical side should force the NRV closed. Both gascolators have a
mesh which should prevent water passing through and regular water drain
checks should remove the water at this point.
>The next step would be shutting off the left side valve.
The reverse might be where the right side is contaminated, boost is on
during during T/O or landing, and its pressure overrides the
mechanical pump. Disabling boost might then correct it, but which do
you do first?<
The idea of this system is not to have both sides working at once. The
electric pump is not on for take-off or landing but will come on if
required. I have heard it happen (more than once) in the series arrangement
where the engine has stopped because the electric pump has been slightly
defective and its problem has been masked until the mechanical pump failed.
With my system I can check either side independantly and any faults become
readily apparant whilst still protecting the engine from fuel starvation.
Nigel Charles
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