Serrated Roller Tray Fitting for No-Drill Aircraft Floor Beam Assembly
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Solution Overview
Problem
The installation of fixed length roller tray segments in aircraft cargo handling systems is hindered by assembly tolerance accumulation in fuselage integration zones, requiring post-final assembly drilling that introduces foreign object debris and increases costs.
Innovation Solution
A serrated fitting system that includes a serrated surface for engagement with a serrated plate attached to pre-installed floor beams, allowing for no-drill installation by using oversized pre-drilled holes and a fastener that bypasses the load path through the serrated fitting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If post-final assembly drilling is performed to attach roller tray segments, then installation accuracy is improved, but foreign object debris increases and costs increase
Solution Approach 1:
The serrated plate is pre-installed on the floor beam before final assembly, and the oversized hole is pre-drilled at a known location. This preliminary positioning allows the roller tray segment to be attached without requiring post-assembly drilling, thereby eliminating the source of foreign object debris while maintaining installation accuracy through the serrated engagement mechanism.
Solution Approach 2:
The serrated plate acts as an intermediary component between the floor beam and the roller tray segment. It provides a pre-positioned interface with an oversized hole that accommodates tolerance accumulation, allowing the fastener to engage without precise drilling while the serrated surfaces provide the necessary mechanical engagement for accurate positioning.
2Manufacturing precision
If post-final assembly drilling is performed to attach roller tray segments, then installation accuracy is improved, but costs increase
Solution Approach 1:
The serrated plate with oversized hole is pre-installed before final assembly, eliminating the need for costly post-assembly drilling operations. This preliminary positioning reduces manufacturing costs by avoiding rework and additional drilling equipment requirements while maintaining installation accuracy through the serrated engagement mechanism.
3Adaptability or versatility
If traditional drilling methods are used to accommodate tolerance accumulation, then adaptability to tolerance variation is improved, but foreign object debris increases
Solution Approach 1:
The hole dimension is intentionally made larger than the fastener diameter, creating an oversized hole that accommodates tolerance variation in floor beam spacing. This parameter change allows the fastener to engage at different positions within the oversized hole, adapting to tolerance accumulation without requiring precise drilling, thereby eliminating foreign object debris generation.
4Ease of operation
If pre-drilled holes with dimensions greater than fastener diameter are used, then ease of installation is improved, but positioning precision worsens
Solution Approach 1:
The serrated plate serves as an intermediary that combines an oversized hole for easy fastener insertion with serrated engagement surfaces that provide precise positioning. The oversized hole allows tolerance accommodation and easy installation, while the serrated teeth on both the plate and fitting engage to prevent movement, thereby maintaining positioning precision despite the oversized hole.
Solution Approach 2:
The connection interface is segmented into two functional parts: the oversized hole for tolerance accommodation and easy insertion, and the serrated engagement surfaces for precise positioning and load transfer. This segmentation allows each part to perform its specific function optimally without compromising the other.
Data Source
AI summary
A serrated fitting and method for installing fixed length roller tray segments spanning an aircraft fuselage integration zone. The serrated fitting includes a first surface for attachment to a fixed length roller tray segment. The serrated fitting also includes a serrated surface for engagement with a serrated plate attached to a floor beam of an aircraft. A fastener connects the serrated surface to the serrated plate and the floor beam through a pre-drilled hole in the floor beam. The pre-drilled hole is larger than the diameter of the fastener to accommodate accumulated tolerance between joined fuselage sections at a fuselage integration zone.