One-Sided Fastener Assembly for Lightning Gas Venting
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Solution Overview
Problem
The installation of fasteners in small aircraft structures, particularly in confined wing spaces, is challenging due to limited access for sealant application, and existing fasteners can cause internal damage from electromagnetic effects like lightning strikes due to discontinuities in the aircraft skin.
Innovation Solution
A one-sided fastener assembly with a bolt and sleeve design, where the sleeve includes annealed material and slots to block superheated gases and particles, allowing one-sided installation and preventing internal damage from electromagnetic events by directing them outside the aircraft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fasteners are installed from the interior side of the skin, then proper sealant application and EME protection are 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 installation to exterior-side installation. The bolt is inserted from the exterior through the skin, and the sleeve is installed from the exterior to engage the bolt, enabling one-sided installation while maintaining EME protection capabilities.
Solution Approach 2:
A specialized sleeve acts as an intermediary component between the bolt and the interior space. The sleeve is installed from the exterior, engages the bolt, and provides the necessary EME protection and sealing functions without requiring interior access for installation.
2Ease of operation
If the skin is made discontinuous with fasteners, then one-sided installation is enabled, but superheated gases and particles can penetrate into interior spaces causing damage
Solution Approach 1:
The sleeve incorporates an annealed material section that acts as a controlled weak point. During a lightning strike, this annealed section is designed to fail first, creating a controlled path for superheated gases and particles to exit through the sleeve's slots toward the exterior, rather than penetrating into the interior space. The harm of the lightning strike is converted into a controlled external venting mechanism.
Solution Approach 2:
The sleeve's slot configuration and annealed material are designed in advance to prevent the harmful penetration of superheated gases and particles into the interior. The slots are positioned and oriented to direct any potential harmful flow away from the interior space, and the annealed material is pre-positioned to fail in a controlled manner that protects the interior.
3Reliability
If sealant and cap systems are used to protect fasteners, then EME protection is achieved, but interior access is required for application
Solution Approach 1:
The sleeve structure integrates the EME protection function into the fastener assembly itself, eliminating the need for separate sealant application and cap installation steps that would require interior access. The sleeve's design with its slots and annealed material provides inherent EME protection and sealing capabilities that are self-contained within the exterior-installed components.
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 protecting the interior from damage caused by electromagnetic events like lightning strikes by blocking and venting superheated gases and particles effectively.
Implementation Method 1
A portion of the sleeve includes an annealed material
Implementation Method 2
electromagnetic effect (EME) of a lightning strike
Data Source
AI summary
A fastener assembly includes a bolt having a head and having a shank. The shank defines threads, the bolt defines a channel which extends circumferentially about the bolt, and the head defines multiple head channels with a first end of each of the multiple head channels in communication with the channel 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. The fastener assembly further includes a sleeve having threads compatible for engaging the threads of the bolt. The sleeve includes a portion of the sleeve including an annealed material and multiple slots defined through the sleeve. With the bolt positioned within the sleeve, each of the multiple slots defined through the sleeve is positioned in communication with the channel.