Aircraft Pylon Attachment Clevis and Pin System
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Solution Overview
Problem
The increasing diameter of dual-flow jet engines poses a challenge in locating the engine attachment pylon and wing attachments within the restricted vertical space, requiring improved mechanical strength and reduced deformation to maintain aerodynamic performance.
Innovation Solution
The design incorporates a primary structure pylon box with a top spar extending under the wing box, featuring two front lateral attachments with clevises and pin systems that allow for closer engine placement while maintaining structural continuity and absorbing forces in multiple directions, thereby optimizing space and reducing mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine diameter is increased to satisfy bypass ratio requirements, then the engine performance is improved, but the vertical space between the wing element and the engine is reduced
Solution Approach 1:
The attachment system transitions from a conventional vertical arrangement to a configuration where the top spar extends horizontally under the wing box. This dimensional change allows the attachment points to be distributed both vertically and horizontally, effectively utilizing three-dimensional space to accommodate larger engine diameters while maintaining adequate clearance.
Solution Approach 2:
The top spar of the pylon box is positioned to extend under the wing box, creating a nested configuration where the pylon structure is partially contained within the wing's structural envelope. This nesting approach optimizes space utilization and reduces the overall vertical footprint of the engine-attachment-wing assembly.
2Volume of moving object
If the attachment pylon is relocated to accommodate larger engine diameters, then the engine size is increased, but the structural strength and deformation control are compromised
Solution Approach 1:
The attachment system is divided into multiple discrete attachment points distributed along the extended top spar, rather than concentrating all attachment forces at a single location. This segmentation distributes the mechanical loads across multiple structural elements, maintaining strength while accommodating larger engine dimensions.
Solution Approach 2:
The top spar extends horizontally under the wing box, creating a longer moment arm and distributing attachment forces over a greater distance. This dimensional extension enhances structural strength by reducing stress concentrations and improving load distribution across the wing-box interface.
3Device complexity
If conventional attachment systems are used, then the design is simple, but the engine diameter must be limited due to restricted vertical space
Solution Approach 1:
The extended top spar serves multiple functions: it provides attachment points for the engine pylon, acts as a structural reinforcement element, and distributes loads across the wing box. This multi-functionality allows the system to accommodate larger engines without proportionally increasing complexity, as the same structural element performs multiple roles.
Data Source
AI summary
To bring a pylon box of an aircraft engine attachment pylon as close as possible to a wing box, two lateral front fasteners are provided. Each of the fasteners comprises a clevis secured to the wing box, the clevis comprising two webs, at least one of which passes through an upper spar of the box, the upper part of one of the two opposite lateral flanges of a lower transverse rib of the box reinforcement, the upper part of an associated lateral panel, and a pin system passing through the clevis and the two upper parts.