Aircraft Bushing with Spring Elements for Grounding

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Solution Overview

Problem

In the aerospace industry, existing bushing technologies require tight tolerances to ensure proper grounding of components in fuel tanks, leading to increased manufacturing costs due to the need for precise engagement and sparking prevention, especially when dealing with carbon fiber reinforced polymers.

Innovation Solution

The development of bushings with a tubular body and spring elements that provide a conductive path for grounding, featuring a through-bore for fasteners and radially extending spring elements to ensure secure and conductive mounting, reducing the need for precise tolerances and preventing sparking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If tight tolerances are used for bushing engagement with fuel tank walls, then proper grounding and sparking prevention is achieved, but manufacturing costs increase significantly

Engineering Contradiction:
Improvegrounding reliabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The bushing incorporates spring elements that enable dynamic adjustment of the engagement interface. The springs allow the bushing to adapt to variations in hole positioning and wall thickness, maintaining reliable electrical contact without requiring tight manufacturing tolerances. This dynamic compliance resolves the contradiction by ensuring grounding reliability while permitting more relaxed manufacturing specifications.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention changes the physical state of the bushing from rigid to compliant by incorporating spring elements. This parameter change allows the bushing to deform and conform to the mating surfaces, ensuring consistent electrical contact despite variations in manufacturing tolerances. The spring mechanism transforms the engagement from a precision-fit rigid connection to a compliant connection that maintains reliability across a wider tolerance range.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If tight tolerances are used for bushing engagement, then proper electrical contact is ensured, but device complexity and manufacturing precision requirements increase

Engineering Contradiction:
Improveelectrical contact reliabilityVSAvoidengagement tolerance
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The spring elements provide dynamic compliance that compensates for tolerance variations in the engagement interface. The springs deform to accommodate misalignments and maintain consistent electrical contact, eliminating the need for tight manufacturing precision. This dynamic adaptation ensures reliable electrical contact while allowing more relaxed tolerance specifications.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The bushing performs self-adjustment through its spring elements, which automatically compensate for engagement variations. The spring mechanism self-regulates the contact pressure and alignment, ensuring reliable electrical contact without requiring precise manufacturing. This self-service capability eliminates the need for complex precision manufacturing processes.

Inventive Principle:
Principle #25Self-service

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 bushings effectively ensure adequate grounding and prevent sparking by providing a secure, conductive interface between components and fuel tanks, reducing manufacturing costs and improving reliability.

Implementation Method 1

a plurality of spring elements spaced circumferentially around the tubular body and extending longitudinally along the tubular body between the end regions

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2735745B1System comprising an aircraft component an aircraft object and an aircraft mounting assembly
Publication Date: 2020.06.17 THE BOEING CO
  • EP2735745B1 patent drawingFigure 1~2
  • EP2735745B1 patent drawingFigure 3
  • EP2735745B1 patent drawingFigure 4~6

AI summary

Bushings 50, 52, 53 include a tubular body 54 that defines a through-bore 56 for receiving a fastener 14 for mounting a component 10 to an object 12. The tubular body includes end regions 60 and a plurality of spring elements 58 spaced circumferentially around the tubular body and extending longitudinally along the tubular body between the end regions. Also disclosed are apparatus that include bushings, such as aircraft, and associated methods of utilizing bushings and of manufacturing bushings.