Self-Adjusting Wing Rib Seal for Stringer Aperture Tolerances
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Solution Overview
Problem
The existing methods for sealing mouseholes in aircraft wing structures are time-consuming, create access issues, and are not easily adaptable to dimensional tolerances, especially in composite materials, leading to increased inspection and rework, and weight penalties.
Innovation Solution
A self-adjusting seal system comprising a first seal part engageable with the rib and a second seal part engageable with the stringer, featuring a saddle with downwardly depending legs and a bridging portion that accommodates tolerance variations, allowing for automatic sealing upon assembly and enabling CNC machining before wing box closure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If seal plates are individually fitted to each mousehole after wing assembly, then sealing accuracy is improved, but manufacturing time and complexity increase significantly
Solution Approach 1:
The seal plate is pre-assembled to the rib before wing assembly, with preliminary positioning features that enable automatic alignment with the stringer. This preliminary action eliminates the need for time-consuming post-assembly fitting while maintaining sealing accuracy through pre-configured positioning elements.
Solution Approach 2:
The seal plate incorporates self-aligning features such as tapered edges and complementary positioning surfaces that automatically adjust to the stringer's position within tolerance ranges. This self-service mechanism eliminates the need for manual measurement and adjustment, reducing assembly time while maintaining precise sealing.
2Manufacturing precision
If seal plates are fitted after wing assembly, then sealing precision is improved, but access difficulty and operational complexity worsen
Solution Approach 1:
The seal plate is pre-positioned and secured to the rib before the wing box is closed, taking advantage of accessible positioning. This preliminary action eliminates the need for difficult post-assembly access operations while maintaining sealing precision through pre-configured alignment features.
Solution Approach 2:
The sealing system is divided into modular components: the seal plate attached to the rib, and the stringer with its own positioning features. This segmentation allows the seal plate to be prepared and positioned independently in an accessible manner before final assembly, improving ease of operation while maintaining precision.
3Manufacturing precision
If traditional seal fitting methods are used, then sealing accuracy is improved, but drilling complexity and swarf generation increase
Solution Approach 1:
All drilling and fastening operations for the seal plate are completed before wing assembly, when full access is available. This preliminary action eliminates the need for complex post-assembly drilling through restricted access, reducing manufacturing complexity while maintaining sealing accuracy through precise pre-positioning.
4Adaptability or versatility
If manholes are formed in covers to allow access for seal adjustment, then adaptability to tolerance variations is improved, but structural integrity and weight worsen
Solution Approach 1:
The seal plate incorporates self-adjusting features that automatically accommodate tolerance variations in stringer positioning without requiring manual intervention or access holes. The self-service mechanism includes compliant elements and adjustable fastening systems that adapt to dimensional variations while maintaining seal integrity, eliminating the need for weight-penalty manholes.
Data Source
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AI summary
A seal for sealing an aircraft fuel tank, an aircraft wing rib and stringer sealing assembly, an aircraft wing fuel tank, an aircraft structural wing box, an aircraft wing and a method of sealing an aperture are disclosed. The seal is for sealing a wing rib to a stringer passing through an aperture in the rib at a variable position in the aperture. The seal includes self-adjustment means to absorb any tolerance when forming the seal, upon the stringer being assembled into the aperture in the rib.