Aircraft Seal-Cover Assembly for One-Sided Fastener Isolation
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Solution Overview
Problem
Existing methods for securing metallic fasteners to structures, such as fuel tanks, require access to both sides and involve complex installation processes, which can be time-consuming and difficult in confined spaces, and do not effectively prevent electrical transmission during electromagnetic events or lightning strikes.
Innovation Solution
A seal-cover assembly that allows for one-sided installation of a fastener and securement of a cap to the structure prior to fastener installation, using a nonconductive cap and conductive insert, which isolates the fastener from the structure and prevents electrical transmission, and includes a washer for anchoring the cover unit and a sealant for additional sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a containment cap is used to completely cover and electrically insulate the end portion of a metallic fastener, then electrical isolation and prevention of unwanted sparks or current transmission is improved, but installation complexity increases because access to both sides of the fuel tank is required and the cap must be installed after the fastener is secured
Solution Approach 1:
The cap is installed on the fuel tank before the fastener is secured, allowing the containment and insulation features to be in place beforehand. This preliminary installation simplifies the overall process by eliminating the need to access both sides of the tank during fastener installation, while still providing the required electrical isolation when the fastener is later inserted through the pre-installed cap
2Reliability
If a containment cap is installed after the metallic fastener is secured to the fuel tank, then electrical isolation is achieved, but installation time and cost increase due to requiring access to both sides of the fuel tank
Solution Approach 1:
The cap is pre-installed on the fuel tank before the fastener is secured, eliminating the need for post-fastener installation steps. This preliminary action reduces installation time by allowing the fastener to be installed through the pre-positioned cap from a single side, while maintaining the electrical isolation function
3Object-affected harmful factors
If a containment cap is used to prevent transmission of hot matter and electrical current, then safety is improved, but the installation process becomes more difficult in confined spaces
Solution Approach 1:
The cap is installed beforehand on the fuel tank in accessible areas, so that during fastener installation in confined spaces, the cap is already in position and does not require manipulation in difficult-to-reach areas. This preliminary placement maintains the safety functions while improving ease of operation during the actual fastening process
Solution Approach 2:
The containment function is separated into a distinct cap component that can be installed independently before the fastener installation. This segmentation allows the cap to be installed in accessible areas while the fastener is installed in confined spaces, making each operation easier while maintaining both safety functions
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
Facilitates faster, simpler installation of fasteners in confined spaces while preventing electrical transmission and fluid leakage, enhancing safety and reducing installation time and costs.
Implementation Method 1
The containment cap electrically insulates the end portion of the metallic fastener and completely contains the end portion of the metallic fastener. Electrically isolating and completely containing the end portion of the metallic fastener via the containment cap prevents unwanted sparks, unwanted transmission of hot matter, or electrical current transmissions, from entering the surrounding structure upon an electromagnetic effect (EME) or lightning strike event.
Data Source
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AI summary
A seal-cover assembly for a structure including a first side and a second side opposing the first side. The seal-cover assembly includes a cap defining a recess, and an insert fixed to the cap within the recess to form a cover unit. The cover unit is configured to be secured to the first side of the structure. The seal-cover assembly includes a fastener configured to be disposed through the structure from the second side of the structure. The fastener is attached to the cover unit relative to the second side without accessing the first side of the structure. Additionally, an aircraft includes the structure and the seal-cover assembly as discussed above. Furthermore, a method of assembling the seal-cover assembly to the structure includes the cover unit secured to the first side of the structure such that an interior of the cover unit is inaccessible from the first side.