Injectable Rib Foot Cleat for Aircraft Rib Mousehole Sealing
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Solution Overview
Problem
Sealing rib mouseholes in aircraft assemblies, particularly those between stringers and ribs in the dry bay area, is challenging due to complex geometries and large gaps, making it difficult to achieve a reliable and repeatable fluid-tight seal, especially given the oblique angles and accessibility issues within the wing structure.
Innovation Solution
A rib foot cleat with a channel lip is positioned over the stringer, attached to both the rib and stringer, and filled with curable sealant to create a fluid-tight seal, using a tool to form the channel lip and inject sealant pneumatically, ensuring central alignment and efficient sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If custom-trimmed flexible open-cell polyurethane foam filled with curable sealant is used to seal rib mouseholes, then a fluid-tight seal can be achieved, but the solution is costly to procure and time-consuming to assemble
Solution Approach 1:
The sealing solution is divided into modular components: a pre-formed foam element with integrated sealant reservoir and a separate application tool. This segmentation allows for standardized manufacturing of the foam element while enabling rapid deployment in the field without custom trimming for each location.
Solution Approach 2:
The sealant is pre-loaded into the foam element during manufacturing, and the foam element is pre-shaped to accommodate the mousehole geometry. This preliminary preparation eliminates the need for on-site trimming and sealant application, significantly reducing assembly time while maintaining seal integrity.
2Reliability
If metal cleats are attached over stringers and fastened to ribs and wing covers, then sealing can be achieved, but the process is complex and difficult to make repeatable
Solution Approach 1:
The invention extracts the sealant from the complex multi-component assembly process and integrates it directly into the foam element itself. The sealant is contained within the foam structure, eliminating the need for separate sealant application steps and reducing the overall complexity of the sealing process.
Solution Approach 2:
The foam element and sealant are merged into a single integrated component. The sealant is embedded within the foam matrix, creating a unified sealing element that combines the mechanical sealing function of the foam with the chemical sealing function of the sealant in one piece.
3Adaptability or versatility
If large mouseholes are used to accommodate geometrical variations, then adaptability is improved, but sealing reliability becomes more difficult to achieve
Solution Approach 1:
The foam element is designed with adjustable parameters including variable density, compressibility, and expandability. These parameter changes allow the foam to adapt to different mousehole sizes and geometries while maintaining consistent sealing performance. The foam can be compressed to fit smaller gaps or expanded to fill larger openings.
Solution Approach 2:
The foam element features varying local properties with different densities and compliance levels in different zones. This allows the sealing element to adapt to local geometric variations in the mousehole while maintaining overall seal integrity. The sealant distribution is also optimized locally to address specific gap patterns.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method provides a fast, repeatable, and cost-effective solution for sealing rib mouseholes, reducing assembly time and ensuring a reliable fluid-tight seal between fuel tanks and dry bays, accommodating geometrical variations and improving sealant distribution.
Implementation Method 1
filled with curable sealant to create a fluid-tight seal
Implementation Method 2
The channel lip may guide any excess sealant that may otherwise protrude from the first and/or second channel opening rim and be guided towards the stringer
Data Source
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AI summary
A rib foot cleat for sealing around a stringer passing through a rib mousehole in an aircraft assembly. The rib foot cleat has a body for attaching to a rib at a rib mousehole and defines a cleat channel configured to be arranged over the stringer. The rib foot cleat also has an injection hole through the cleat body which is in fluid communication with the cleat channel, to allow sealant material to be injected through the injection hole in to the cleat channel for sealing around the stringer.