In message <001a01c6b639$f55ef530$e0513bcb@HomeWS1>, kevin pownall
<kevpow@iinet.net.au> writes
>I was interested but not surprised to read about an early flight engine
>failure in the last few days.
>
>Except that I ended in a field on the second flight it mirrors my experience
>exactly.
>
>I put lots of fuel through before first flight ,cleaned the filters etc. When
>after the engine failure I inspected the filters there was nothing obviously
>visible to block both the filters.
>
>When I posted the problem there were lots with a similar experience. It
>seems to be only in the early hours of flight that the blockages happen. I
>put a concertina filter in and have had no more problems.
>
>My view , without proof , is that some form of fine film comes off the
>interior of the tank in the first few flights.
>
>The problem seems to be specific to the Europa style tank not just to fibre
>glass aeroplanes.
>
>No one has been killed yet . Is it possible to warn all builders now of this
>possibility and ban the small Europa supplied filters before someone is
>hurt.
>
>Kevin Pownall kevpow@iinet.net.au
I believe you are right. I think the problem is related to the
polyethylene fuel tank. It is possible that the fuel can extract waxy
material from the polyethylene tank and more particularly any remaining
polyethylene swarf from the cutting of the access holes. The waxy
material could then coat the nylon filter elements. This series of
events is more likely to occur when the aircraft experiences temperature
cycles, hot testing and then cooling down in the hangar overnight. I
have mentioned this to Europa, but the reply has been that following the
Europa procedures this does not normally occur. All later tanks are
fluorine treated and this should reduce the extraction tendency.
However, there is not an easy solution. The present filters are easy to
inspect and relatively easy to clean. There is nowhere to put a more
conventional filter where it is realistically easy to clean and inspect.
The Andair mini-gascolator has very little more area than the Promax.
The larger gascolator is very difficult to dismantle and re-assemble. I
am no longer building a Europa, but if I were, I had been persuaded to
stay with the existing design, but I would clean the filters frequently
in the early stages. I would also fit a fuel pressure gauge and be
prepared to act quickly to change to the other tank outlet if the fuel
pressure dropped.
Ken Whiteley
Polyethylene Consultancy
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