REFLECTOR: Fuel Tank Fitting

[Craig and Denise Woolston]

I'm embarrassed to even ask this question, but frustration leads me no
choice.  Some how John and I have managed to build an airplane in our garage
that actually flies, but somehow can't manage to make a vessel which will
hold liquid without leaking.  So I'm looking for suggestions and trying to
get a feel for whether we did something odd or not.

 

We made our tanks, sealed with Jeffco, bonded AL hardpoints to the inside
fuselage wall, drilled and tapped for AN fittings for both vent and feed
lines.  Is this not what other people are doing?

 

It appears that we have gotten three out of the four sealed.  We have been
able to confirm (soapy bubbles) that one of the feed lines is leaking where
the thread cut through the fuselage side.  The fuel then travels b/t the
layers of glass until it shows up outside the fuselage at the gear leg
penetration.

 

We've been working on this since Nov. without success.  I've lost track of
the number of fixes we've tried, in summary, we replaces the hardpoint, we
re-coated from the inside, we've glue the fitting in, etc.  It appears that
every fix tests okay on the ground, but fails after we fly.   The latest fix
that has failed was a complete fill of the hole (minus the threaded AL
part), covered with BID, re-drilled and tapped because it appeared that some
of our threads actually cut through fiberglass layers so we ground the
fiberglass away and backfilled with microglass.

 

What are we missing?

 

Craig

N541SW "Blue Streak"

 

 

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