Patent ID: 7050286

Claim:
A method of fastening an outer aircraft skin to an inner substructure, the skin or both being made of a non-metallic fibre and resin composite material, using a fastener bolt, the method including the steps of: inserting the bolt through the outer skin and the substructure and securing the bolt adjacent an inner surface of the substructure such that a bolt head abuts the outer aircraft skin; applying a layer of electrically insulating material over the bolt head and the outer aircraft skin, and incorporating an electrically-conductive layer in the outer surface of the insulating layer, the conductive layer being configured so as to overlie and having edges extending laterally of the bolt head and being separated therefrom by insulating material, the layer of insulating material adjacent the lateral edges of the conductive layer being adapted to break down dielectrically before dielectric breakdown can occur in the insulating material separating the conductive layer and the bolt head, thereby to divert electrical current from a lightning strike away from the fastener and prevent arcing at the fastener.