Lightning protection fastener and cap for lightning protection fastener

A cap for a lightning protection fastener to be attached so as to cover a tip of a fastener member that fastens a first member and a second member with each other,

• wherein the cap is made of an insulating material and comprises an opening for accommodating the tip of the fastener member, and
• an end part of the cap on the opening, the end part facing the first member or the second member, comprises
• a plane orthogonal to an axis line of the cap and
• a tapered face formed on an outer circumferential side of the plane.

A lightning protection fastener comprising:

• a fastener member having a shaft that penetrates a first member and a second member so as to fasten the second member to the first member that constitutes an airframe of an aircraft, the shaft protruding toward at least one of the sides of the first member and the second member;
• a cap, made of an insulating material, that is attached so as to cover the shaft of the fastener member that protrudes toward at least one of the sides of the first member and the second member;
• and
• a sealant, made of an insulating material, that is filled into the cap to seal a space between the cap and the fastener member,
• wherein the cap has an abut portion that abuts against the fastener member or a fastening member that is fastened to the fastener member, and
• a clearance is formed between the cap and a surface of the first member or between the cap and a surface of the second member while the abut portion abuts against the fastener member or the fastening member, so that the sealant is filled in the clearance.