Insulating Cap for Lightning-Resistant Aircraft Fasteners
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Solution Overview
Problem
Conventional lightning-resistant fastener systems for aircraft wings face challenges in maintaining insulation properties, workability, and reliability due to manual installation complexities and variability, leading to increased costs and potential arc discharge issues during lightning strikes.
Innovation Solution
A lightning-resistant fastener system featuring a conductive fastener with an engaging part and an insulating cap with an engaged part, allowing for precise positioning and easy installation, along with the use of an insulating sealant to ensure reliable insulation and arc prevention, even if the cap is dislodged.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cap is installed separately from the fastener main body with an air-gap to ensure insulation, then lightning resistance is improved, but the positioning precision and installation consistency deteriorate
Solution Approach 1:
The cap is divided into multiple sections (first cap portion and second cap portion) that can be installed separately onto the fastener main body. This segmentation allows each portion to be positioned and fixed independently, ensuring proper alignment and consistent air-gap maintenance while simplifying the installation process and improving positioning precision.
2Reliability
If adhesive or rubber coating is used to ensure cap insulation, then lightning resistance is improved, but installation time and labor cost increase
Solution Approach 1:
The cap portions are designed to be self-insulating through their material composition (resin or plastic) and structural design, eliminating the need for additional adhesive application or rubber coating steps. The cap itself provides the necessary insulation, allowing workers to simply install the cap portions onto the fastener main body without performing complex bonding or coating operations, thereby significantly improving installation efficiency.
3Reliability
If manual bonding or coating work is performed in narrow wing space, then insulation is improved, but workability and quality consistency deteriorate
Solution Approach 1:
The cap portions are designed to be self-insulating through their material composition (resin or plastic) and structural design, eliminating the need for additional adhesive application or rubber coating steps. The cap itself provides the necessary insulation, allowing workers to simply install the cap portions onto the fastener main body without performing complex bonding or coating operations, thereby significantly improving installation efficiency.
4Reliability
If the cap is made of insulating material with engaging part, then insulation and positioning are improved, but device complexity increases
Solution Approach 1:
The insulating function and positioning function are merged into a single integrated component - the cap portions. The cap portions are made of insulating material (resin or plastic) and incorporate engaging parts (such as engagement protrusions or grooves) that directly engage with the fastener main body. This integration eliminates the need for separate insulating components or complex assembly procedures, thereby reducing overall device complexity while maintaining reliable insulation and positioning.
Data Source
AI summary
There are provided a lightning-resistant fastener and a cap, which, while assuring sufficient insulation properties, provide improved workability and highly stable quality to thereby enable a reduction in the manufacturing cost of an airframe, and a method of mounting the lightning-resistant fastener. A hole 32 is formed in a cap 30, and a screw groove 32a is formed in the hole 32. The configuration enables the cap 30 to be reliably and easily positioned and installed on a fastener member 24 and reliably prevents the cap 30 from coming off after the installation thereof. This improves the workability to reduce the production cost while assuring sufficient insulation properties and enables the cap 30 to be installed with stable quality irrespective of workers. Preferably, the cap 30 is made of a resin in view of mass producibility, weight reduction, and the like.