I've found that the black cotton covered fuel tube is totally intolerant of
mechanical stress once it has got fuel in it and had to replace all mine
prior to first flight.
The downside of polyurethane is that it can tear relatively easily and will
not bend tightly without kinking. The latter can be solved by binding with
plastic spiral wrapping, but preferably the sort that is used for hydraulic
hose chafe-protection, which is much stouter than the electrical variety.
Duncan McF
----- Original Message -----
From: <MJKTuck@cs.com>
Subject: Europa-List: Fuel Tubing Choice
>
> Hi folks,
>
> I am taking the opportunity to change the fuel sight gauge to a new piece
of
> tubing (polyurethane tubing 0.25 ID) which will run up the passenger side
> seat back and found today when I put fuel back in the tank that I had a
small
> leak which was soaking the cloth covering on the short piece of black
rubber
> tubing from the tank to the 'tee-piece' and also from the tee to the fuel
> drain (again black cotton covered tubing).
>
> I thought it might be the new piece of tube somehow not sealing correctly
but
> after more investigation determined that the black cotton covered tubing -
> which has to be bent through 90 deg - and which had been joggled around a
bit
> while I was installing the new piece - was cracked and weeping fuel.
>
> I took it off and dissected it and sure enough although the inside looked
> smooth, when you bend it, it shows lots of tiny crack/pin holes.
>
> I will have to replace it. I thought I might use the Aircraft Spuce
supplied
> Polyurethane tubing which they say is unaffected by fuel and has good
> abrasion and tear resistance (it's tough stuff to cut and kind of rubbery
to
> the touch), or should I go for the Bing Alcohol Resistant Fuel Line which
> features 'excellent resistance to gasoline, oil, etc.?'.
>
> I couldn't find the black cotton covered type in the Aircraft Spruce book
but
> I am not overly impressed by it anyway.
>
> Any comments on my choice would be welcomed.
>
> Regards,
> Martin Tuck
> N152MT
> Wichita, Kansas
>
|