14CFR25.581 requires protection against catastrophic effects from lighting, so why did FAA issue AD2019-23-12 to address safety issue regarding potential ignition in fuel tank due to hot current so many years after issuing type certificate to the Boeing? why didn't FAA engineers and Boeing engineers predict fault currents?
So engine characteristics plug is chained to engine to prevent connecting wrong plug by fools so the chain is foolproofing structure, correct me if I'm wrong.
Patent No.US20100167567
is a connector with foolproof structure that is protruded inside the receiving hole for blocking an insertion of an incompatible plug