Fastener Spark Containment Cap With External Sealant Sealing
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Solution Overview
Problem
Existing spark containment solutions for fasteners on aircraft, such as those made from composite materials, face challenges in forming a sealed cavity effectively, leading to potential lightning-induced sparking and plasma or out-gassing issues due to the interference of annular skirts with other features and inadequate sealant distribution.
Innovation Solution
A spark prevention cap with an annular base and a flange or recess design that maximizes sealant contact area, allowing for improved retention and easier sealant application, combined with a sealing material distribution tool featuring outlet apertures for even sealant distribution, to form a sealed cavity around fasteners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an annular skirt is used in the cap design, then the cap can form a sealed cavity around the fastener end, but the skirt impairs location of the cap relative to other features and creates interference with surrounding components
Solution Approach 1:
The patent removes the problematic annular skirt from the cap design and replaces it with a simplified cap body that has a bottom surface directly abutting the panel. The sealing function is achieved through sealant applied to the cap body's external circumferential surface, eliminating the geometric complexity and interference issues caused by the skirt while maintaining sealing effectiveness.
2Ease of manufacture
If sealant is applied to the cap without a dedicated application surface, then the sealing process becomes difficult, but adding complex features increases manufacturing complexity
Solution Approach 1:
The patent provides a localized sealant application surface on the external circumferential surface of the cap body, specifically at regions where sealing is needed. This localized approach improves sealant application ease without requiring complex overall cap structure, as the sealant is applied only to specific external circumferential regions rather than requiring complex geometric features throughout the entire cap.
3Volume of moving object
If the cap is positioned close to other features, then space utilization is improved, but sealing effectiveness may be compromised
Solution Approach 1:
The patent uses sealant as an intermediary material between the cap body and the panel to create an effective seal. The sealant is applied to the external circumferential surface of the cap body and cures to form a sealed joint, allowing the cap to be positioned close to other features while maintaining sealing reliability through the flexible sealing capability of the sealant material.
Data Source
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AI summary
The present application relates to a spark prevention cap. The cap forms a sealed cavity around an end of a fastener protruding from a surface of a structure, for example an aircraft structure. The cap has a cap body with an annular base terminating at a rim. The rim surrounds an opening into a central cavity for receiving the end of the fastener. The annular base has an external circumferential surface extending from the base rim, and a mating feature on the external circumferential surface configured to contact a sealant material applied externally to the cap.