Aircraft Fuel Pipe Assembly Device Preventing Fuel Accumulation
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Solution Overview
Problem
In double-skinned aircraft fuel pipes, maintenance operations can fail to completely drain fuel from assembly devices, leading to false leak indicators during flight, as fuel accumulates in low points of the coupling devices and migrates to the drain, causing unnecessary maintenance searches.
Innovation Solution
An assembly device with a fitting that extends between the external pipes of two sections, having a shape complementary to the internal coupling device, positioned in the lowest portion to prevent fuel accumulation and migration, utilizing materials like fluorosilicone or foam to ensure effective fuel retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coupling device is designed to connect external pipes, then the assembly device can join pipe sections, but fuel accumulates in low points of the coupling device causing false leak indicators
Solution Approach 1:
A fitting is introduced as an intermediary element between the first and second external pipes. This fitting acts as a mediator that prevents fuel accumulation in the coupling device's low point while maintaining the connection function. The fitting's complementary shape to the coupling device's internal portion creates a barrier that stops fuel from migrating to the drain, thus resolving the false leak indicator problem without complicating the overall assembly device structure.
2Measurement precision
If the drain is positioned to remove fuel from low points, then fuel leaks can be detected, but accumulated fuel in the coupling device migrates to the drain causing false positives
Solution Approach 1:
The fitting is designed to utilize the harmful effect of fuel accumulation by converting it into a beneficial barrier. The fitting's position and shape are specifically designed to intercept fuel at the low point of the coupling device, preventing it from reaching the drain. This transforms the potential harmful accumulation into a useful fuel-trapping mechanism that actually improves leak detection accuracy by preventing false positives.
3Reliability
If the fitting is positioned in the lowest portion of the coupling device, then fuel accumulation is prevented, but the fitting complexity increases
Solution Approach 1:
The fitting is designed with local quality by giving it a specific complementary shape that matches the internal portion of the coupling device. This localized design feature, rather than a complex overall structure, achieves the fuel retention function. The fitting's shape is optimized specifically for its position in the lowest portion of the coupling device, creating a simple yet effective solution that prevents fuel accumulation without requiring complex design throughout the entire assembly device.
Data Source
AI summary
An assembly device between two sections of a double-skinned fuel pipe of an aircraft has a clamp for assembling the internal pipes, a coupling device for assembling the external pipes, a fitting extending between the ends of the external pipes of the first and second sections, with a shape complementary to the shape of an internal portion of the coupling device, and such that its section through any cutting plane perpendicular to the longitudinal axis common to the coupling device and the external pipes contains the smallest surface delimited by: a line corresponding to the intersection of the internal surface of the coupling device with this cutting plane and a straight line cutting said line at two points, this straight line being tangential to the orthogonal projection in this cutting plane, of the internal surface of the external pipes of the first or of the second section.