The first answer is to incorporate grounding straps while under
construction, but for those who have missed this opportunity, we've
installed entire ground-strap systems in already-completed Lancair-IVPs and
other composite aircraft. The technique involves embedding the braided
copper ground straps full-length along the wing trailing-edge cove and
tying-in static wicks and other items by running stringers out from the main
straps. Aileron wicks are grounded via dedicated strap across the
wing-aileron gap. Don't want to encourage current flow through the hinges.

Don't know how I'd ground the wing tie-down hard-points on a completed plane
if they were surrounded by wet fuel bays. Maybe someone else on the list has
done this. I can imagine milling a shallow channel in the lower wing skin
over the spar cap from the tie-down to the wing root and floxing in a ground
strap, closed out with a scarfed carbon-fiber patch and peel-ply. I'd
definitely want to analyze to make sure this did not compromise the
torsional strength and stiffness of the wing.

Make sure all your sealed cavities are vented. We recently repaired damage
to a Lancair-IVP from an airborne lightning strike on the left wingtip. The
current passed through a lens cover retaining screw and nutplate, across the
interior of the wingtip to another lens retaining screw and out. Screws were
each clearly burned, and the clear lens cover was burned/melted at each
screw hole. Bigger problem was that a compartment in the wingtip had been
closed out but not vented, and the entire trailing edge of the wingtip blew
out. It's hard to say if a small vent hole would have prevented the
delamination, but there was no vent at all in this case.

Oh, and stay clear of thunderstorms...

Best Regards,

Larry Graves
AirCrafters Builder Education & Assistance
140 Aviation Way, Watsonville, CA 95076
Tel: 831-722-9141 Fax: 831-722-9142
 www.AirCraftersLLC.com



> Larry -
>
> How would you do this, especially if the wings are closed out?
>
> Thanks,
>
> John
>