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<39DFCFB8.E64C2F50@ameritech.net>
Fred Fillinger wrote:
> NTSB reports do seem to suggest also that fuel just spills more often
> than it spills & ignites. With the Europa, I have a theory that the
> fuselage is more crash-survivable than many others, and further if the
> people survive, so does the tank. So the weak link is the plumbing,
> and in an area where there's typically electric wiring. Anybody have
> some good engineering advice on the topic, rubber and/or alum?
I wasn't too happy with the standard fuel system design - especially the filters
- so I've gone all Andair... fuel tap, gascolator, drains. As for the fuel
lines,
I've modified the tank outlets to reverse the "internal" connections so that the
fuel feed exits via the AN fittings - the tank drains are still rubber/hoseclips
- less than ideal, buts as they are in an area least likely to be damaged in a
crash, not too much of a worry - at least if they do get damaged enough to spill
fuel, I reckon that it'll be all over anyway.
As to the fuel feeds/return - my primary requirement was that it be assembled
with AN fittings end to end - rubber hoses are OK, but they will need replacing
eventually (and over here, pressure testing after 6 years, and every 3 years
thereafter - a real pain in the ****) and there is some concern as to their
viability when changing from 100LL to unleaded.
Ali pipes are pretty durable, but in my experience if they are going to fail,
it'll be at the flare within the fitting - difficult to see and diagnose - and
they can occasionally be prone to pinholes where they are in contact with other
things - clips or anti-chafe measures that hold water in contact with the pipe.
In the end, I settled on stainless braid covered PTFE tubing (available from
Goodrich, Earls, etc) - the same as motorcycle brake lines, but in a larger
size:
they are indestructable (as in a crashed racing bike I saw a few years ago - the
front end was completely separated from the frame, but held on with the
(hydraulic) clutch line) They don't deteriorate with time, but they do have
their
own problems - the stainless braid makes a very effective cutting medium if
allowed to move (mine are covered with insulation, heat shrink tubing, or spiral
wrap, depending on the situation) and they are also the most expensive option -
as much as the Andair stuff.... but you pays your money and takes your choice.
As for the plumbing/electrics problem, as much as possible is separated (not
everywhere of course - fuel and electrics do come together at fuel pumps,
senders, etc) and the electrics are always positioned above the fuel - not the
other way around.
Miles
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