Spark containment cap

A fastening system comprising:

• a spark containment cap including:
• a cap body defining an air cavity arranged to enclose the end of the fastener, and including an annular base terminating at a base rim which surrounds an opening into the air cavity;
• and
• an annular skirt to provide an annular sealing volume extending around the base rim arranged to receive an annular bead of a curable sealing material around the opening into the cavity to provide a seal between the cap body and the structure to seal a volume of gas within the cavity;
• and
• a fastener engaging portion configured to engage a threaded portion of the fastener so as to secure the cap to the fastener, and
• a fastener comprising a threaded portion, the cap body being configured to receive at least a part of the fastener so that the threaded portion of the fastener engages with the fastener engaging portion of the spark containment cap.

A method of securing a fastener and a spark containment cap to a structure, the cap including a cap body having a cavity, and the method comprising:

• inserting the fastener through an aperture in the structure;
• drawing a fastener sleeve of the fastener towards the structure such that at least part of the sleeve is caused to deform outwardly against the structure;
• placing a spark containment cap over the fastener and engaging a fastener engaging portion of the cap with a threaded portion of the fastener to hold the spark containment cap against the structure;
• providing an annular bead of uncured sealing material between the structure and the cap;
• and
• curing the bead of sealing material.