External Fluid-Tight Fastening for Aircraft Wing Panel Assembly
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Solution Overview
Problem
The existing methods for assembling aircraft wings require personnel to enter the confined wing box for fluid-tight connections, increasing safety concerns and costs, and are not suitable for all aircraft types, particularly those with compartmentalized fuel systems where fluid-tightness is less critical.
Innovation Solution
A fluid-tight mechanical fastening system that allows external connection of skin panels to ribs using a bushing with a flange, a nut plate, and a bolt, along with seals to maintain fluid-tightness without requiring personnel to enter the wing box, utilizing materials like titanium alloys and polymeric materials for strength and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If personnel enter the confined wing box to assemble skin panels to ribs, then fluid-tight connections can be achieved, but safety risks and manufacturing costs increase
Solution Approach 1:
Instead of entering the confined wing box interior to perform fastening operations, the invention reverses the approach by performing all fastening operations from the exterior of the wing box. The fastening system includes a fastener that extends through the skin panel and rib with external access, allowing assembly personnel to work from outside the confined space while still achieving fluid-tight connections between components.
2Reliability
If personnel enter the confined wing box to assemble skin panels to ribs, then fluid-tight connections can be achieved, but manufacturing costs increase
Solution Approach 1:
The invention reverses the traditional assembly approach by performing all fastening operations from the exterior rather than requiring entry into the confined wing box. This external fastening method reduces manufacturing costs by eliminating the need for specialized confined space entry procedures, safety equipment, and additional personnel requirements while maintaining fluid-tight connection reliability.
3Ease of manufacture
If skin panels are externally connected to ribs, then safety risks and manufacturing costs are reduced, but fluid-tightness becomes difficult to achieve
Solution Approach 1:
The fastening system employs a nested structure where the seal is positioned within the fastener assembly, specifically between the fastener body and the skin panel or rib. This nested arrangement allows the seal to be effectively compressed and seated during external fastening operations, ensuring fluid-tight connections are achieved while maintaining the advantage of external assembly access.
Solution Approach 2:
The seal acts as an intermediary element between the fastener and the structural components (skin panel and rib). This intermediary seal ensures fluid-tightness by creating a barrier that prevents fluid leakage at the joint, while the fastener itself provides the mechanical connection from the exterior, thus mediating between the requirements for external assembly and fluid-tight performance.
4Reliability
If a complex fastening system with multiple components is used externally, then fluid-tightness can be achieved without entering the wing box, but device complexity increases
Solution Approach 1:
The invention merges multiple functions into a single integrated fastener component. The fastener combines mechanical fastening capabilities with integrated sealing functionality, eliminating the need for separate seal applications or additional fastening steps. This unified approach achieves fluid-tight connections from the exterior while reducing the overall complexity of the fastening system compared to using multiple separate components.
Data Source
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AI summary
A structural assembly including a first member (12) having an external side and an internal side, the first member defining a first member through-bore, a second member (14) having an external side and an internal side, the second member defining a second member through-bore aligned with the first member through-bore, and a mechanical fastening system (100) including a bushing at least partially received in the first member through-bore, the bushing defining a bushing through-bore and including a flange, wherein the flange is positioned in a gap between the internal side of the first member and the external side of the second member, a nut plate connected to the internal side of the second member, the nut plate defining a clearance bore aligned with the second member through-bore and the bushing through-bore, the nut plate including a nut, and a bolt extending through the bushing through-bore and into threaded engagement with the nut.