Originally Posted by
chewing4gum
However, it must also be said that the earth strip on the underside of the refuelling cars also provides double protection if other systems fail.
Technically, the bonding between the aircraft and fueling system structure is the primary requirement. The goal is to eliminate the static potential between the fuel system and aircraft and not grounding it to earth. Several older references still incorporate earth grounding but the current go to guidance does not. So those "earth strips" don't really provide a backup to the primary bonding.