Three-Piece Failsafe Clevis for Easier Aircraft Assembly

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Solution Overview

Problem

Existing underwing support fittings with failsafe clevises in aircraft deployment systems face challenges such as complex and costly assembly due to tight tolerances and varying grip lengths, leading to higher rejection rates and increased manufacturing costs.

Innovation Solution

A three-piece failsafe clevis design with laterally adjacent components of equal thickness, allowing for single grip length fasteners and simplified assembly, while maintaining structural performance and compliance with fail-safe requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional two-piece failsafe clevis design is used, then structural strength and fail-safe requirements are met, but manufacturing complexity and assembly difficulty increase due to tight tolerances and varying grip lengths

Engineering Contradiction:
Improvefail-safe requirementVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The clevis is divided into three separate pieces (two outer pieces and one center piece) that can be manufactured independently with standard tolerances. Each piece is attached to the skin separately, eliminating the need for complex multi-surface alignment between inner and outer portions while maintaining fail-safe structural requirements through the distributed attachment points.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If tight tolerances are specified for machined parts to ensure proper fit-up, then structural performance is maintained, but manufacturing cost and rejection rate increase

Engineering Contradiction:
Improvefit-up toleranceVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

By segmenting the clevis into three independently manufactured pieces with standard tolerances, the design eliminates the need for tight multi-surface alignment tolerances. Each piece can be manufactured separately using conventional machining processes without requiring expensive tight tolerance controls or post-manufacturing shimming operations.

Inventive Principle:
Principle #1Segmentation

3Adaptability or versatility

If varying grip lengths are used for fasteners to accommodate different assembly configurations, then adaptability is improved, but assembly time and cost increase

Engineering Contradiction:
Improveassembly flexibilityVSAvoidassembly speed
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The three-piece clevis design enables all fasteners to have the same grip length since each piece is attached to the skin independently at different locations. This uniformity allows use of standard fastener lengths throughout the assembly, eliminating the need for multiple fastener inventories and reducing assembly time compared to accommodating varying grip lengths.

Inventive Principle:
Principle #33Homogeneity

Data Source

PatentEP4059835B1Three piece failsafe clevis
Publication Date: 2024.05.01 THE BOEING CO
  • EP4059835B1 patent drawingFigure 1A
  • EP4059835B1 patent drawingFigure 1B
  • EP4059835B1 patent drawingFigure 1C

AI summary

A three piece failsafe clevis (20) includes a center portion (102) having a center top surface (111), a planar first outer surface (112) and a planar second outer surface (114). The second outer surface (114) is oppositely oriented to the first outer surface (112). A channel (118) in the center portion is configured to receive a tension and compression member (37). A left lateral portion (202) is connected adjacent the first outer surface (112). The left lateral portion has a planar first inner surface (209) received against the first outer surface (112) and a left top surface (210) coplanar with the center top surface (111). A right lateral portion (302) is connected adjacent the second outer surface (114). The right later portion has a planar second inner surface (309) received against the second outer surface (114) and a right top surface (310) coplanar with the center top surface (111).