Sealed Cap Assembly for Aircraft Fastener Sealing

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Solution Overview

Problem

There is a need for an improved insulated and sealed cap to protect fastener components and substrate openings in aircraft from fluid leakage and electrical discharges while maintaining minimal weight and structural integrity, especially in environments with corrosive and volatile fuels.

Innovation Solution

A lightweight, rigid sealed cap is designed with an outer cap component filled with a sealant material and an inner collet that forms a slip fit over the fastener, extruding a uniform sealant layer onto the substrate, which cures to create a secure and insulating seal, with tapered ribs for locking and a Faraday shield option for electrical protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional sealing cap is used to protect fastener components from fluid leakage and electrical discharges, then protection and sealing are improved, but weight increases and structural integrity may be compromised

Engineering Contradiction:
Improvesealing effectivenessVSAvoidcap weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The cap is divided into two main segments: an outer cap component and an inner collet. The outer cap component contains sealant material that is extruded to form the sealing bead, while the inner collet provides structural support and electrical insulation. This segmentation allows each component to be optimized for its specific function while keeping overall weight minimal.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The sealant material undergoes a parameter change from a soft, extrudable state during installation to a cured, rigid state after installation. This allows the sealant to be applied in a controlled manner and then become structurally sound, providing effective sealing without requiring excessive material weight.

Inventive Principle:
Principle #35Parameter changes

2Strength

If a rigid and sturdy sealed cap is used to withstand maintenance procedures, then structural integrity is improved, but weight increases

Engineering Contradiction:
Improvestructural integrityVSAvoidcap weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The cap assembly uses composite construction combining the outer cap component, inner collet, and sealant material. This composite structure provides enhanced structural integrity and resistance to maintenance procedures while keeping individual component weights low, achieving strength without excessive weight.

Inventive Principle:
Principle #40Composite materials

3Reliability

If a sealed cap is used to prevent fluid leakage and electrical damage, then protection is improved, but device complexity increases

Engineering Contradiction:
Improveprotection capabilityVSAvoidcap structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The inner collet is nested within the outer cap component, with the sealant material positioned between them. This nested arrangement provides multiple protection functions (sealing, electrical insulation, mechanical support) within a compact structure, reducing overall complexity while maintaining comprehensive protection capability.

Inventive Principle:
Principle #7Nested doll (Nesting)

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 provides a sturdy, lightweight seal that effectively prevents fluid leakage and electrical damage, maintaining structural integrity during maintenance and ensuring efficient fuel protection with minimal weight addition.

Implementation Method 1

The outer cap component is then displaced toward the substrate to extrude the sealant material into a thin and substantially uniform insulation layer

Methodology Applied
Scientific EffectExtrusion: Extrusion

Implementation Method 2

then permitted to cure

Methodology Applied
Scientific EffectCuring:

Data Source

PatentEP2681459B1Insulated and sealed cap assembly for a fastener component
Publication Date: 2017.04.05 PHYSICAL SYSTEMS INC
  • EP2681459B1 patent drawingFigure 1
  • EP2681459B1 patent drawingFigure 2~3
  • EP2681459B1 patent drawingFigure 4

AI summary

An insulated, sealed cap overlies and protects a fastener component or the like on a substrate in association with a substrate opening. The sealed cap includes an outer cap component filled partially with a selected sealant material and assembled with an inner collet sized and shaped to fit with a slip fit about the fastener component such as a nut or the like at one side of a selected substrate, such as the skin of an aircraft. An inboard edge of the inner collet seats on and substantially seals with the substrate. The outer cap component is then displaced toward the substrate to extrude the sealant material into a thin and substantially uniform layer joined with an extruded outer bead on the substrate, and then permitted to cure. Tapered ribs on the inner collet effectively lock with the outer cap component during sealant material curing and subsequently.