Grommet Hole Reinforcement and Lightning Strike Protection in Composite Structural Assembly
Aircraft design and assembly challenges include provision of hole protection from lightning strike in fastened joints, especially in the vicinity of fuel tanks or electrical services. Installation of interference fit fasteners helps minimize the effect of lightning strike and also enhances the durability and load transfer ability of the joint. However, these are known to cause laminate damage during installation which can degrade the fastener system performance. Use of a pre-installed expanded grommet into the hole prior to installing interference fit fasteners has been shown to greatly enhance the effectiveness of the joint as well as the conductivity of electrical current into the structure to minimize arcing or plasma discharge at the fastener in the event of lightning strike.