Segmented Spanwise Beam Structure for Center Wing Box Access

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Solution Overview

Problem

The existing access holes in aircraft center wing boxes present ergonomic challenges and risks of workplace injury and damage due to peak strains at the corners of the cutouts, limiting user access for assembly and maintenance.

Innovation Solution

A segmented spanwise beam section with increased height and optimized access hole design, featuring spaced-apart web sections and chord members, which reduces stress concentrations and provides alternate load paths, enhancing ergonomics and structural integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a continuous web of material is used to maintain structural integrity, then strength and rigidity are improved, but access hole size is reduced due to peak strain constraints at corners

Engineering Contradiction:
Improvestructural integrityVSAvoidaccess hole size
Core Design Contradiction:
StrengthVSArea of stationary object

Solution Approach 1:

The continuous web of material is divided into multiple segmented web sections spaced apart from each other. This segmentation allows the access hole to extend across the gaps between segments, increasing its overall size while each individual segment maintains sufficient web material to limit peak strains at its own corners. The segmented configuration enables larger access openings without compromising structural integrity.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If access hole size is increased to improve ergonomics, then ease of operation is improved, but peak strains at corners increase causing structural damage

Engineering Contradiction:
ImproveergonomicsVSAvoidpeak strain
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

By segmenting the continuous web into multiple spaced-apart web sections, the patent creates multiple smaller access holes within the overall access area. Each small web section maintains adequate material thickness and spacing to limit peak strains at its corners, while collectively providing a larger effective access opening that improves ergonomics.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The segmented web configuration provides different local characteristics: web material is present at specific locations to limit peak strains, while gaps between segments allow for larger overall access. This local variation in material distribution optimizes both structural integrity and ease of access.

Inventive Principle:
Principle #3Local quality

3Ease of operation

If web material is reduced to increase access hole size, then ease of operation is improved, but structural strength deteriorates

Engineering Contradiction:
Improveaccess easeVSAvoidweb material strength
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The web material is segmented into multiple discrete sections rather than reducing the total amount of material. Each segment maintains sufficient material quantity to provide structural strength, while the spacing between segments creates larger effective access openings. This segmentation strategy increases access ease without compromising the strength of individual web sections.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4368499B1Segmented spanwise beam for enhanced center wing box access
Publication Date: 2026.01.28 THE BOEING CO
  • EP4368499B1 patent drawingFigure 1~2
  • EP4368499B1 patent drawingFigure 3~4
  • EP4368499B1 patent drawingFigure 5

AI summary

An aircraft (100), a center wing box assembly (150) for an aircraft (100), and a spanwise beam section (155) for a center wing box assembly (150) that includes a segmented structural configuration with an optimized access hole (155e) to accommodate user access into an interior space of the center wing box for purposes of assembly and maintenance. The center wing box assembly (150) includes a first spanwise beam section (155a), a second spanwise beam section (155b), spaced from the first spanwise beam section (155a), and a plurality of chord members (155c, 155d) serving as load-bearing structural reinforcement members for the first spanwise beam section (155a) and the second spanwise beam section (155b). The chord members (155c, 155d) extend across the space between the first spanwise beam section (155a) and the second spanwise beam section (155b) to connect the first spanwise beam section (155a) and the second spanwise beam section (155b) in a manner which defines an access hole (155e) at the interior space.