Originally Posted by
ZeBedie
Is this anything new, or are 30+ year old A320 carbon structures layered in the same way?
Not likely. Most of the carbon structures on older aircraft are not primary structure that's subject to strict lightning protection requirements. The issue is not so much lightning damage to the structure itself (although a lightning attachment can cause localized damage to composite structure), it's the induced voltages that are transmitted to the wiring below. Those induced voltages can damage the interfacing electronics if they get too high. The requirements for induced lightning voltages to the avionics is already higher on primary composite construction (e.g. 787, A380) then they are for conventional aluminum construction. So if the lightning protection on composite structure is degraded, it can affect the avionics.
EASA/FAA cover all this in the continued airworthness requirements, including sampling programs where they go out and measure electrical bonding and resistances on in-service aircraft.