Plug Insert for Aircraft Fastener Hole Protection
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Solution Overview
Problem
The existing divot removal process for fastener holes in aircraft panels is inefficient and prone to damage, as it requires multiple steps and can cause contamination during the boot panel overlay process, especially when dealing with fasteners like Dzus quarter-turn fasteners with metal sleeve portions.
Innovation Solution
A plug insert with a shank and longitudinal cavity is designed to be removably received in a fastener hole, featuring a barrier to prevent contamination and facilitate accurate removal of the boot panel divot, using a glass-filled nylon material for durability and a frustoconical side wall to ensure a precise fit, along with optional annular metal cap for added protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal drill bushing is used in the fastener hole during boot panel overlay, then the fastener hole is protected and aligned, but the process becomes complex and time-consuming with multiple steps required
Solution Approach 1:
The patent combines the drill bushing and the fastener sleeve into a single integrated component. The bushing is formed with an outer surface that directly engages the fastener sleeve, eliminating the need for separate installation steps. This integration maintains the protective and alignment functions while reducing process complexity and installation time.
Solution Approach 2:
The bushing is pre-installed in the fastener hole before the boot panel overlay process begins. This preliminary installation ensures that the fastener hole is already protected and aligned before any subsequent operations, preventing contamination and misalignment issues that would require additional corrective steps.
2Reliability
If the drill bushing outer surface is masked and primer is sprayed, then paint adhesion is improved, but the process time increases and contamination risk remains
Solution Approach 1:
The bushing material is selected or treated to have surface properties that inherently promote paint adhesion without requiring additional masking or priming steps. By changing the material parameters (surface energy, roughness, or chemical composition), the bushing achieves direct paint compatibility, eliminating time-consuming preparation steps while maintaining adhesion reliability.
3Measurement precision
If a pilot hole is back-drilled through the boot panel, then accurate alignment is achieved, but the risk of damaging the skin panel increases
Solution Approach 1:
The bushing acts as an intermediary guide structure that the drill bit follows during back-drilling. The drill bit engages the bushing's internal cavity, using it as a precise guide to maintain correct alignment and depth. This intermediary guidance system ensures accurate hole positioning while preventing the drill bit from deviating and potentially damaging the surrounding skin panel.
4Manufacturing precision
If the boot cutter is advanced axially to cut the divot, then precise concentric cutting is achieved, but the force required may damage surrounding areas
Solution Approach 1:
The bushing serves as a mediator that guides the boot cutter's axial advancement. The cutter engages the bushing's external surface, using it as a reference to maintain precise concentricity with the fastener hole. This guided approach distributes the cutting force evenly and prevents lateral deviations that could damage surrounding panel areas, achieving precise divot removal with controlled force.
Data Source
AI summary
A plug insert comprising a shank configured to be removably received in a fastener hole in a panel in a position where an outer end of the plug insert is disposed adjacent an outer surface of the panel. A longitudinal cavity is disposed within the shank and a barrier is disposed on the plug insert to protect against damage and/or contamination.