Dielectric Nut Retainer Strip for Lightning-Safe Wing Fasteners

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Solution Overview

Problem

Aerospace vehicle manufacturers face challenges in providing lightning protection for composite components, particularly in thin wings where access to fasteners is difficult, and existing solutions either add weight and drag or are not easily removable.

Innovation Solution

A fastening system using a dielectric nut retainer strip with anti-rotation features, caps, and conductive coatings, which allows for electrical isolation and easy removal of fasteners while maintaining structural integrity and minimizing weight and drag.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If access panels are added to allow inspection and removal of fasteners, then ease of operation is improved, but weight and drag increase

Engineering Contradiction:
Improveaccess to fastenersVSAvoidwing weight
Core Design Contradiction:
Ease of operationVSWeight of moving object

Solution Approach 1:

The patent merges the fastener head and access features directly into the aerodynamic surface of the wing, eliminating the need for separate access panels. The fastener heads are exposed on the upper surface, allowing inspection and removal without additional panels, thus maintaining ease of operation while reducing weight and drag.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts the access panel function from the wing structure and integrates it directly into the fastener design. By making fastener heads accessible on the upper surface, the patent removes the need for separate access panels, achieving both weight reduction and maintained operability.

Inventive Principle:
Principle #2Taking out (Extraction)

2Ease of operation

If access panels are added to allow inspection and removal of fasteners, then ease of operation is improved, but drag increases

Engineering Contradiction:
Improveaccess to fastenersVSAvoiddrag
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent merges the access function with the aerodynamic surface by exposing fastener heads on the upper surface. This integration eliminates separate access panels that would create drag, while maintaining ease of operation for inspection and removal.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts the access panel function and integrates it into the fastener design itself. By making fastener heads accessible on the upper surface, the patent removes the need for additional panels that would increase drag, achieving both reduced drag and maintained operability.

Inventive Principle:
Principle #2Taking out (Extraction)

3Ease of manufacture

If fasteners are inserted from accessible side crimping on inaccessible side, then ease of manufacture is improved, but ease of repair deteriorates

Engineering Contradiction:
Improvefastener installationVSAvoidfastener removal
Core Design Contradiction:
Ease of manufactureVSEase of repair

Solution Approach 1:

The patent inverts the traditional fastener approach by exposing the fastener heads on the upper accessible surface rather than hiding them. This allows both installation and removal/inspection to be performed from the same accessible side, improving ease of repair while maintaining ease of manufacture.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent makes the fastener system dynamic and reversible by allowing easy removal and reinstallation from the accessible upper surface. This enables maintenance personnel to remove, inspect, and replace fasteners without complex procedures, significantly improving ease of repair while keeping manufacturing simple.

Inventive Principle:
Principle #15Dynamics

4Strength

If traditional fastening systems are used in thin wings, then structural integrity is improved, but ease of operation deteriorates

Engineering Contradiction:
Improvestructural integrityVSAvoidaccess to fasteners
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The patent moves the fastener heads to the upper surface dimension, making them accessible from above rather than requiring access from the lower side or through panels. This spatial repositioning maintains structural integrity in thin wings while dramatically improving ease of operation for inspection and removal.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 system effectively isolates fasteners electrically, provides easy access for maintenance, and reduces the weight and drag associated with traditional access panels, while ensuring the structural integrity and lightning protection of aerospace vehicle components.

Implementation Method 1

A dielectric nut retainer strip (34) having one or more fastener thru holes (36), an integrally formed nut retention pocket (35) adjacent to each of the one or more fastener thru holes (36)... effectively isolates fasteners electrically

Methodology Applied
Scientific EffectDielectric isolation: Dielectric

Implementation Method 2

at least one fastener comprising a conductive coating... ensures the structural integrity and lightning protection of aerospace vehicle components

Methodology Applied
Scientific EffectConductive coating: Conduction (electrical)

Data Source

PatentUS12270426B2Apparatus and methods for lightning protection and locating of fastener nuts with dielectric materials
Publication Date: 2025.04.08 THE BOEING CO
  • US12270426B2 patent drawing
  • US12270426B2 patent drawing
  • US12270426B2 patent drawing

AI summary

A fastening system for aerospace vehicles including a dielectric nut retainer strip formed of dielectric material and having at least one fastener thru hole and at least one cap receiver portion. Also included are an anti-rotation nut retainer portion integrally formed in the dielectric nut retainer adjacent to the at least one fastener thru hole, a cap configured to mate with the at least one cap receiver portion, a fastener covered in a conductive coating, and an anti-rotation nut configured to fit in the anti-rotation nut retainer portion and couple with the fastener.