widgeon,
Conductance of structures is an important part of the qualification process, especially with lightening. Look at the bonding straps, and the underlying conductive mesh or film that we use on composites to assure that they behave electrically as if they were metal.
I think that the static electricity build up is a function of the mechanical static charge generation in dry snow or heavy sand. The ground crew should alsways use a grounded insulated wand to draw off the charge when they hook up loads. Letting the hoist hook touch first is also SOP.
The voltage numbers are impressive, it takes 25000 volts to make a spark that jumps 1 inch, for example. But voltage is only the measure of the electrical pressure that has built up, and does not tell us what is the amount of electricity that can flow. The charge (total amount of electricity) is quite small, so the net damage this spark can cause is small.
Really bad cases of charge build-up cause St. Elmo's fire, which is beautiful. I have had this on airplanes in clod dry snow, and it is beautiful but harmless (unless it affects the radios enough to blank nav and comm!)
This subject is often mixed up with the sparks seen on NVG films (or described by NGV wearers). Those sparks are not static caused, they are piezoelectric, caused by the sand crystals emitting when they are bounced off the blades. Crystals do this as their internal electron balance is shuffled when they are deformed. These electrical effects are why crystals are used on the tips of phonograph needles, where their small voltages are amplified as music, for example.