Lightning protected vent lines associated operatively with aircraft fuselage fuel tanks (i.e., on-board fuel tanks that are not physically located in an aircraft's wing but instead are physically located within the aircraft's fuselage structure) are provided which include a vent conduit, a coupling at a proximal end of the vent conduit for fluid connecting the vent conduit to the fuel tank, a vent opening positioned at a distal end of the vent conduit and at an external location of the fuselage and a flame arrestor positioned in the conduit between the coupling and the vent opening. The vent conduit will have an effective axial dimension (L) between the coupling and the vent opening and the flame arrestor will be positioned in the conduit at an effective separation distance (D) between an inlet of the flame arrestor and the vent opening such that L/D is greater than 5. Alternatively, the flame arrestor may be omitted, but the vent conduit will then have at least one linear conduit segment to provide an effective axial dimension (L1) of the vent line conduit between the coupling and the vent opening which is at least ten times greater than the vent conduit diameter (D1).