I. Introduction
In PART I of this three-part paper [1], the significance of fasteners in the aircraft lightning effects has been introduced [2], [3]. More specifically, in the confined zone as fuel tanks where the sparking effects around the fasteners can be critical, this issue is monitored following a specific standard [4]. Notwithstanding the protections against sparking effects [5]–[7], they do not prevent the sparking occurrence but they confine it to avoid the ignition of the fuel vapor. As a consequence, the importance of the understanding of the sparking effects has been highlighted in part I. Moreover, according to [4], the knowledge of the current distributions through the aircraft is needed in order to protect the fuel system and to optimize the fasteners number when mechanical constraints are alleviated. Few fastener models have been developed as circuit model [8] or still three-dimensional (3-D) modeling [4]. Whatever the fastener model, one of the main parameters is the contact resistances in the lightning bandwidth. Most of the time, the uncertainties about the values of these resistances are ignored due to the difficulty to develop a characterization method dealing with measurement. The engineers are compelled to use nominal resistances values by fastener class estimated around few milliohms [3], [9], [10] in their fastener models. A method based on statistical analysis for taking into account these uncertainties has been presented in [1]. It allows us to define a probability law for the equivalent resistance of a fastener whatever the type of this one. This law has been established only for the fasteners which have been subjected to a lightning injection. This result has been easily used to supplement the simple fastener model (SM) built with a wire and a resistance. Nevertheless, if the fastener model is composed by several resistances as in [3] and [8], the statistical model cannot be directly applied.