Originally Posted by
tdracer
It's more likely to do damage on carbon fiber composites than on aluminum (or other metals). Carbon conducts electricity fairly well, but has a much higher electrical resistance than aluminum (about two orders of magnitude if I recall correctly). This means there is much more local heating due to the strike and hence greater potential for damage.
I don't know about the F-18, but on the 787 there is a copper wire mesh incorporated into the composite layup during build to improve the electrical resistance and hence improve it's lightning protection. I suspect they do something similar on the F-18.
Shortly before I retired, I was observing a flight test on a 767 when we took a lightning strike during our descent to Paine (i.e. Everett). I was in the flight deck observing EICAS indications for my test when it happened - it didn't literally scare the crap out of me, but it came close
Based on the post flight inspection, it attached near the cockpit and exited at the wing root - doing a fair amount of damage to the (composite) wing-body fairing.
Back when the 787 was being developed, there was a fair amount of debate as to exactly how much metal Boeing were going to have to put into this lightning protection layer. Obviously the more the put in, the heavier it was going to be, but it would be better able to deal with a lightning strike. I also recall that it had to be put in the very outer layer, so that heating of the metal layer didn't damage the structural strength of the CF itself.
Airbus's use of GLARE is quite interesting - it's still aluminium from the point of view of lightning tolerance / metal working, but it's a whole lot lighter than plain aluminium. Not a bad way to have gone about things (for the A380, which is where they used it).
On the A350 I think (corrections most welcome for my hazy memory) Airbus went for ribbons of thin metal tape wrapped around the airframe to form a sparse metal cage, instead of a fine mesh layered everywhere. I suspect that this works quite well. The lightning is going to preferentially strike / depart from sharp bits of airframe (the charge gets concentrated there), so it's probably quite easy to have sufficient metal at these points to protect any CF structure underneath.
Regardless of which approach is best, it seems that we're not having either 787s or A350s falling out of the sky or being grounded by lightning strikes. I presume that by now one or two must have got a zap.