Ejection Seat Cushion Straps for Secure Fit and Easy Removal
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Solution Overview
Problem
Existing aircraft ejection seat cushions are difficult to remove and install without damage due to their stiffness and the proximity of rear pull-the-dot fasteners to the seat back, leading to frequent tearing during maintenance.
Innovation Solution
The seat cushion design features rear edge securing straps with pull-the-dot fasteners at their ends, allowing for easier access and removal by maintenance crew members, combined with hook and loop fasteners for additional stability during use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the seat cushion is made stiff to withstand military service rigors, then the reliability and strength are improved, but the ease of operation deteriorates because maintenance crew members cannot easily access the pull-the-dot fasteners between the cushion and seat back
Solution Approach 1:
The fastening system is segmented into multiple independent components: pull-the-dot fasteners at the front edge, pull-the-dot fasteners at the rear edge, and hook-and-loop fasteners distributed across the cushion. This segmentation allows maintenance personnel to access and operate each fastener type independently, with the rear pull-the-dot fasteners being accessible from below the cushion without requiring fingers to be inserted between the cushion and seat back.
Solution Approach 2:
The cushion itself acts as an intermediary element that provides access to the rear pull-the-dot fasteners. By designing the fasteners to be located at the rear edge of the cushion rather than directly against the seat back, the cushion structure enables maintenance personnel to reach and operate the fasteners from below, eliminating the need to insert fingers into the tight space between cushion and seat back.
2Device complexity
If the pull-the-dot fasteners are affixed directly to the bottom of the seat cushion, then the device complexity is reduced, but the ease of operation worsens because the stiffness of the seat cushion prevents maintenance crew members from releasing the fasteners from underneath
Solution Approach 1:
The fastening function is segmented across multiple locations and types: front edge pull-the-dot fasteners, rear edge pull-the-dot fasteners, and distributed hook-and-loop fasteners. This segmentation distributes the attachment function throughout the cushion structure, allowing rear fasteners to be positioned where they are accessible from below while maintaining overall structural integrity.
Solution Approach 2:
The rear pull-the-dot fasteners are positioned at the rear edge of the cushion, utilizing the third dimension (depth/positioning in space) to create accessibility from below. Rather than placing all fasteners on a single plane or directly against the seat back, the design extends the fastening interface to the rear edge where maintenance personnel can access them from the bottom side of the cushion.
3Strength
If the seat cushion is made stiff to maintain secure attachment during high-speed maneuvers, then the strength and stability are improved, but the ease of manufacture worsens because the cushion is often damaged during maintenance due to its stiffness
Solution Approach 1:
The attachment system is segmented into multiple independent fastening mechanisms distributed across the cushion: front pull-the-dot fasteners, rear pull-the-dot fasteners, and hook-and-loop fasteners. This segmentation allows the cushion to maintain its stiff, damage-resistant structure while providing multiple accessible points for maintenance personnel to release attachments without applying excessive force to any single location.
Solution Approach 2:
The design incorporates preliminary action by providing multiple pre-positioned fastening points and alternative attachment methods (pull-the-dot and hook-and-loop systems) that enable maintenance personnel to easily detach the cushion before any damage can occur during the maintenance process.
Data Source
AI summary
A seat cushion for an aircraft seat includes a plurality of rear edge securing straps attached to the lower surface of the seat cushion. The rear edge securing straps each have a free end that includes a pull-the-dot fastener that engages a corresponding pull-the-dot fastener at the rear edge of the seat pan. The length of the rear edge securing straps is selected so that when the seat cushion is installed, the rear edge securing straps are pulled substantially flat so that the seat cushion is firmly held in place. The seat cushion is easily removable because the pull-the-dot fasteners are at the ends of the rear edge securing straps rather than affixed directly to the bottom of the seat cushion. Therefore, when the front edge of the seat cushion is released, the seat cushion can be lifted up enough to allow the cushion to be released without pulling at the bottom of the seat cushion.