Lightning protection fastener, aircraft assembly, and method of manufacturing aircraft assembly component
A long-life lightning protection fastener or the like to prevent explosion for aircrafts at low cost is provided, the fastener having a light weight, ensuring sufficient lightning protection, and having extremely less failures and high reliability. A ring-shaped ring member 40 A made of resin is mounted on a collar 26 . This ring member 40 A is interposed between a member 22 and the collar 26 and is in intimate contact with both of the member 22 and the collar 26 , thereby sealing an interface with the member 22 for sealing and preventing the occurrence of an arc at an outer perimeter edge of the collar 26.
1. A lightning protection fastener comprising:
a fastener body provided in order to fasten at least two of members configuring an airframe of an aircraft, the fastener body penetrating through holes formed in all of the members;
a fastening member mounted on a portion of the fastener body projecting from the members in order to fasten the members together; and
a ring member made of an insulating material, the ring member being interposed in a compressed state between at least one of an outside diameter of a head of the fastener body and an outside diameter of the fastening member, and the members,
wherein the ring member is fitted in a groove formed on the outside diameter of the head of the fastener body or on the outside diameter of the fastening member.
2. The lightning protection fastener according to claim 1 , wherein the groove has a tapered surface with a diameter gradually reduced as being away from the members.
3. The lightning protection fastener according to claim 2 , wherein the groove has a parallel surface parallel to the surfaces of the members, and the ring member is interposed between the parallel surface and the surfaces of the members.
4. The lightning protection fastener according to claim 1 , wherein an edge part adjacent to an inner perimeter surface of the groove and an outer surface of the fastener body or the fastening member is formed to have an obtuse angle.
5. The lightning protection fastener according to claim 1 , wherein at least one of the ring member and the groove includes means preventing the ring member from being detached from the groove.
6. The lightning protection fastener according to claim 1 , further comprising a second ring member made of an insulating material, the second ring member being interposed in a compressed state between an inner perimeter part of the fastening member and the members.
7. The lightning protection fastener according to claim 1 , wherein
when one of the two members is a fuel tank,
a sealing material for preventing fuel from leaking from the one member to the other member is applied onto at least one of an interface between the two members, an interface between the fastener body and the two members, and a portion between a tip of the fastener body and the fastening member.
8. An aircraft assembly, wherein at least two of members configuring an airframe of an aircraft are fastened by the lightning protection fastener according to claim 1 .
9. A method of manufacturing an aircraft assembly requiring an explosion prevention measure by using the lightning protection fastener according to claim 1 , comprising the steps of:
placing at least two members as superposed;
forming a fastener hole in the superposed at least two members so that the fastener hole penetrate therethrough;
applying a sealant onto a contact surface between the two members, and placing again the at least two members as superposed while squeezing out the applied sealant to surroundings of the contact surface;
inserting the fastener body into the fastener holes of the at least two members so that the fastener body penetrates therethrough; and
mounting and fastening a collar onto the fastener body, the collar having a ring made of an insulating material fitted in advance in a groove provided at an outside diameter of a contact surface with the members.
10. The lightning protection fastener according to claim 1 , wherein the ring member is insert-molded onto the fastener body or the fastening member such that the ring member is integrally formed with the fastener body or the fastening member.