Aircraft Linkage Preload Strap for Load Reversal Noise

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Solution Overview

Problem

Aircraft linkage assemblies experience free play due to manufacturing tolerance stacking, leading to audible noise during load reversals, and current solutions like tighter tolerances increase costs.

Innovation Solution

The implementation of a strap assembly within the linkage assembly to preload and bias the link assembly, restricting movement within the free play clearance during load reversal, thereby reducing noise without increasing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-generated harmful factors

If components are manufactured with tighter tolerances to reduce free play, then noise during load reversal is reduced, but manufacturing cost increases

Engineering Contradiction:
Improvenoise during load reversalVSAvoidmanufacturing cost
Core Design Contradiction:
Object-generated harmful factorsVSEase of manufacture

Solution Approach 1:

The strap assembly is installed and tensioned before the linkage assembly is subjected to operational loads. This preliminary action pre-loads the linkage components, eliminating free play clearance between parts before load reversal occurs, thereby preventing noise without requiring tighter manufacturing tolerances

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention changes the mechanical state of the linkage assembly by introducing pre-load through the strap assembly. This parameter change (from zero pre-load to positive pre-load) eliminates the clearance that causes noise during load reversal, achieving noise reduction while maintaining standard manufacturing tolerances

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If standard manufacturing tolerances are used, then manufacturing cost is reduced, but free play movement and noise during load reversal increase

Engineering Contradiction:
Improvemanufacturing costVSAvoidnoise during load reversal
Core Design Contradiction:
Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The strap assembly acts as an intermediary element that connects and pre-loads the linkage components. This mediator applies continuous tension to eliminate free play clearance between components, preventing noise during load reversal while allowing standard manufacturing tolerances to be used

Inventive Principle:
Principle #24Intermediary (Mediator)

3Object-generated harmful factors

If the linkage assembly is preloaded with a strap assembly, then free play movement is restricted and noise is reduced, but device complexity increases

Engineering Contradiction:
Improvenoise during load reversalVSAvoidlinkage assembly complexity
Core Design Contradiction:
Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The strap assembly serves multiple functions simultaneously: it pre-loads the linkage assembly to eliminate free play, provides continuous tension to prevent component separation during load reversal, and acts as a simple structural connector. This multi-functionality achieves noise reduction without proportionally increasing complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

This solution effectively reduces noise during load reversals by preloading the linkage assembly with a strap, limiting movement within the free play clearance, and does so without the need for tighter tolerances, thus maintaining cost-effectiveness.

Implementation Method 1

a strap coupled to the link assembly at the first fitting and at the second fitting based on the free play clearance as defined by the manufacturing of the link assembly. The strap is further configured to bias the link assembly to restrict movement of the link assembly within the free play clearance during load reversal in the joint

Methodology Applied
Scientific EffectTensile force: Tension

Data Source

PatentEP4074592B1Preloaded aircraft linkage assemblies with reduced noise during load reversal
Publication Date: 2025.04.16 GULFSTREAM AEROSPACE CORP
  • EP4074592B1 patent drawingFigure 1
  • EP4074592B1 patent drawingFigure 2~3
  • EP4074592B1 patent drawingFigure 4~5

AI summary

An aircraft includes a fuselage, a wing extending out from the fuselage, and a joint coupling the wing to the fuselage. The joint includes a first fitting fixed to the fuselage, a second fitting fixed to the wing, a link assembly pivotably coupled to the first fitting and to the second fitting, and a strap coupled to the link assembly at the first fitting and at the second fitting based on the free play clearance as defined by the manufacturing of the link assembly. The link assembly is configured to support the wing during operation of the aircraft and has a free play clearance defined by a manufacturing of the joint falling within a designed dimensional tolerance of the joint. The strap is further configured to bias the link assembly to restrict movement of the link assembly within the free play clearance during load reversal in the joint.