Lightning Protective Seal Cap for Aircraft Fasteners
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Solution Overview
Problem
Existing sealants for fasteners fail to effectively prevent electrical arcing from lightning strikes and corrosion in applications such as aircraft fuel tanks, where they are exposed to harsh environments and fluids.
Innovation Solution
A seal cap containing an uncured sealant that cures upon exposure to actinic radiation, forming a strong bond with the fastener and preventing electrical arcing by positioning over the fastener, with options for translucent or transparent materials to allow visual inspection and high dielectric breakdown strength for enhanced protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing sealants are used for fasteners in aircraft fuel tanks, then the fasteners are sealed, but they fail to effectively prevent electrical arcing from lightning strikes and corrosion in harsh environments
Solution Approach 1:
The patent employs a composite sealant composition comprising a polysulfide polymer base resin, a polyamide hardener, and a metal powder filler (such as aluminum or zinc). This composite structure combines the corrosion resistance and flexibility of polysulfide with the electrical conductivity of metal powder, creating a material that simultaneously protects against both corrosion and electrical arcing from lightning strikes.
2Reliability
If a seal cap is made opaque for protection, then protection is provided, but visual inspection becomes difficult
Solution Approach 1:
The patent incorporates pigments or dyes into the sealant composition that provide color coding or visual indicators. The sealant can be formulated with specific colors to indicate cure status, application completeness, or to simply provide visual contrast for easier inspection while maintaining protective functions. This allows the sealant to remain visually detectable without compromising its protective properties.
3Productivity
If the sealant cures quickly upon exposure to actinic radiation, then productivity increases, but complete curing throughout the sealant volume may be insufficient
Solution Approach 1:
The patent formulates the sealant with a composition that includes porogens or creates a microporous structure during curing. These micro-pores allow actinic radiation to penetrate deeper into the sealant volume, ensuring complete curing throughout the entire thickness while maintaining rapid surface curing for productivity. The porous structure acts as channels for radiation transmission and subsequent uniform crosslinking.
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
The solution effectively prevents electrical arcing and corrosion, maintaining structural integrity and safety in exposed applications by forming a durable, radiation-cured seal that transmits light for visual inspection and withstands high electrical stresses.
Implementation Method 1
a quantity of an uncured sealant that is curable by the application of actinic radiation so as to bind the seal cap to a fastener
Implementation Method 2
the sealant containing seal cap prevents electrical arcing to the fastener from a lightning strike
Data Source
AI summary
A lightning protective seal cap comprising a seal cap that defines an interior, and a quantity of an uncured sealant that is curable by the application of actinic radiation so as to bind the seal cap to a fastener. The interior of the seal cap contains the quantity of uncured sealant, the seal cap is positionable over the fastener such that at least a portion of the fastener resides in the interior of the seal cap, and when the seal cap is in position over the fastener, the sealant containing seal cap prevents electrical arcing to the fastener from a lightning strike.