US Patent 10301033 Foamed energy absorptive fastener seal cap

A fuel tank system comprising a fuel tank, a number of fasteners, and a number of covers. The number of fasteners has a number of ends extending into an interior of the fuel tank. The number of covers is configured to cover the number of ends of the number of fasteners. A cover in the number of covers comprises a housing configured to cover an end of a fastener in the number of ends, a deformable material associated with an interior side of the cover, and cells that are present within the deformable material. The deformable material is configured to contain energy within the cover in which the energy is caused by an electromagnetic event.