<<The painter began sanding on the left wing, which was nearly empty of
fuel.
In the process he removed the fuel cap.  Then he replaced the fuel cap but
did not lock it.  After about 4 hours of sanding with an pneumatic sander,
the painter used an air gun to blow the sanding residue off of the wing.
The left wing then exploded.>>

Very unfortunate incident.  I wonder if my grounding plan would have a
beneficial effect on that type of problem.  My plan is to attach a ground
chain to the outer tube of the fuel sender, which comes close to the filler
neck.  The cap will connect to the other end of the chain, which will be
long enough to lay on the bottom of the tank under all conditions.  Idea is
that during refueling the chain will lay on the filler neck (which was
installed before I figured this out, so I don't have a way to permanently
ground that).  The chain will hopefully dissipate any charge buildup in the
fuel.  The fuel tank vent line is also ground via a 14-gage ground strap
bonded into the trailing edge of the wing (ahead of the flaps/ailerons).  I
can understand the static buildup problem experienced by the painter - the
plastic in our planes is almost a perfect insulator and will build a huge
charge.  I'd bet there was an arc between the skin or maybe the filler neck
and the fuel level sender.  I think it would be really good if our glass
planes could have been constructed with a strand or two of carbon built into
the weave.  Any conductivity would dissipate charges like that.

Gary Casey
ES #157