thinking out of the box here....
I know of 3 airframes [mil and civ over 30 years onthejob] that had circulating current issues along with their associated bond/earth configurations once in service..
2 of them were FBW as well, both with fair % composites construction.....the one left was the F4 in it's final years of service....
....corrosion, intergrannular and especially the less than obvious galvanic, leading to bonds and earthing paths going "high" resistance.....currents finding their "own" way through ex areas...
...just saying...
ref..
Corrosion of Aluminum and Aluminum Alloys - Google Books chap 5
Which, Lyman,
brings us neatly round to our original opening gambits, electrical installation "quality" from that photograph....
