One-Sided Aircraft Fastener Venting for Lightning Damage Resistance
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Solution Overview
Problem
In aircraft construction, especially in smaller aircraft wings with confined internal spaces, existing fasteners are challenging to install one-sidedly from the exterior while effectively protecting the interior from electromagnetic damage caused by lightning strikes due to the introduction of discontinuities that can lead to superheated gas and particle penetration.
Innovation Solution
A fastener assembly comprising a bolt with a circumferential channel and multiple head channels, a sleeve with annealed material and slots, and a conductive coating, allowing for one-sided installation and venting of superheated gases and particles away from the aircraft interior during a lightning strike.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional fasteners are installed from the interior side of the skin, then secure fastening is achieved, but access to the fastener is difficult due to small and confined interior spaces
Solution Approach 1:
The fastener installation direction is inverted from the conventional interior-side approach to an exterior-side approach. The installation tool engages the fastener from the exterior of the skin and applies installation forces through the fastener body, allowing installation without access to the interior side where confined spaces prevent tool access.
2Strength
If fasteners are used to secure the skin, then structural assembly is achieved, but discontinuities are introduced that allow superheated gases and particles to penetrate into the aircraft interior during lightning strikes
Solution Approach 1:
A non-conductive sealant is introduced as an intermediary material between the fastener and the skin. This sealant fills the gap created by the fastener discontinuity and provides an electro-insulating barrier that blocks the path for electrical arcs and superheated gases, preventing them from penetrating into the aircraft interior while maintaining the structural fastening function.
Solution Approach 2:
The fastener system combines conductive materials (for structural strength and lightning conduction along the skin surface) with non-conductive materials (the sealant, for blocking arc penetration at the fastener-skin interface). This composite approach maintains the Faraday cage effect while sealing the discontinuities.
3Ease of manufacture
If the skin is made discontinuous with fasteners, then structural assembly is enabled, but the Faraday cage effect is compromised allowing electrical arcs to reach the interior
Solution Approach 1:
The non-conductive sealant acts as an intermediary that restores the protective function by filling and sealing the discontinuity created by the fastener. It bridges the gap between the fastener and skin, preventing electrical arcs from traversing through the fastener interface into the interior, thereby maintaining reliability while preserving manufacturing ease.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables secure one-sided installation of fasteners in confined aircraft spaces while preventing internal damage from electromagnetic effects by blocking and safely venting superheated gases and particles, thus protecting the aircraft interior from lightning-induced damage.
Implementation Method 1
a conductive coating which conforms to surface of said layered structures and which closes gaps between the layered structures, which include a conductive metal or fibers of a composite layer, and bolt
Implementation Method 2
The sleeve includes a portion of the sleeve which includes an annealed material
Data Source
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AI summary
A fastener assembly (10) includes a bolt (12) having a head (14) and having a shank (16). The shank defines threads, the bolt defines a channel (20) which extends circumferentially about the bolt, and the head defines multiple head channels (22) with a first end of each of the multiple head channels in communication with the channel (20) and a second end of each of the multiple head channels in communication with an outside of the head positioned at a top surface of the head (14). The fastener assembly further includes a sleeve (32) having threads compatible for engaging the threads of the bolt. The sleeve includes a portion of the sleeve including an annealed material (36) and multiple slots (38) defined through the sleeve. With the bolt positioned within the sleeve, each of the multiple slots (38) defined through the sleeve is positioned in communication with the channel (20).