Self-indexing Nut Plate for Aircraft Spanner Bars
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Solution Overview
Problem
The existing methods for attaching wire support hardware to spanner bars in commercial aircraft are inefficient due to the lack of visual sightline, requiring manual dexterity and resulting in increased part count and installation time.
Innovation Solution
The use of self-indexing nut plates with undercut posts and a locking member that engage with a pattern of holes and lands on the spanner bars, allowing for easy alignment and secure locking without the need for additional fasteners or tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional nuts and washers are used to attach wire support hardware to spanner bars, then the attachment can be secured, but the installation time and part count increase due to blind installation requirements
Solution Approach 1:
The patent combines the washer and nut into a single integrated nut plate component. The nut plate includes a body with a mounting surface that functions as the washer, and an internally threaded bore that receives the fastener, eliminating the need for separate nut and washer parts and reducing installation steps
Solution Approach 2:
The nut plate is designed with self-aligning features including posts with enlarged caps that fit into holes in the spanner bar, and a bore that is offset to align with the hole when the posts are properly positioned. This self-alignment mechanism eliminates the need for blind installation and manual dexterity, allowing the component to guide itself into the correct position
2Reliability
If traditional nuts and washers are used for each fastening operation, then the attachment can be secured, but the part count increases
Solution Approach 1:
The patent merges multiple functions into a single nut plate component: the mounting surface acts as a washer to distribute load, the internally threaded bore serves as the nut to secure the fastener, and the offset bore alignment provides self-positioning. This consolidation reduces the part count from three separate components (washer, nut, fastener) to two (nut plate, fastener)
Solution Approach 2:
The nut plate performs multiple functions simultaneously: it provides a bearing surface against the spanner bar, receives and secures the threaded fastener, and guides alignment through its offset bore design. This multi-functionality eliminates the need for separate specialized components for each function
3Productivity
If blind installation is required due to lack of visual sightline, then the attachment can be completed, but manual dexterity is required and installation difficulty increases
Solution Approach 1:
The nut plate incorporates self-aligning posts with enlarged caps that physically guide the component into the correct position on the spanner bar. The offset bore automatically aligns with the hole when the posts are properly seated, eliminating the need for visual sightline or manual dexterity during installation
Solution Approach 2:
The posts with enlarged caps act as intermediaries between the nut plate and the spanner bar holes. These posts provide physical guidance and constraint, mediating the alignment process and allowing the installer to simply push the nut plate into place without requiring visual feedback or complex manual manipulation
Data Source
AI summary
An aircraft comprises a plurality of spanner bars. Each spanner bar has a pattern of mounting holes separated by lands. A plurality of nut plates engage the spanner bars. Each nut plate includes a body having a mounting surface against one of the spanner bars; and first and second posts extending from the mounting surface and through respective holes in the corresponding spanner bar. Each post has an undercut portion that abuts against one of the lands. Each nut plate further includes a locking member occupying a space between one of the posts and the lands to prevent the nut plate from disengaging the corresponding spanner bar.