Aircraft Fuel Bladder Breakaway Valve Reaction Bridge
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Solution Overview
Problem
Embedding fuel bladders into aircraft fuselage poses challenges in ensuring crashworthiness and preventing fuel leakage, especially during events like fuel cell tear-away or structure separation, which complicates the integration and mounting process.
Innovation Solution
A flexible fuel bladder assembly with a breakaway valve system and non-contacting reaction features, such as a reaction bridge or collar, is integrated into the airframe to control fuel flow and prevent leakage by breaking the valve body upon stress, ensuring closure and securing the fuel bladder within the fuselage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fuel bladder is embedded into the fuselage, then the fuel storage is secured within the aircraft structure, but the mounting process becomes complicated and crashworthiness assurance becomes difficult
Solution Approach 1:
The mounting system is divided into separate modular components: the fuel bladder assembly with breakaway valve, the reaction bridge attached to the fuselage, and the reaction collar. This segmentation allows each component to be independently manufactured, installed, and tested, simplifying the overall mounting process while maintaining crashworthiness through the coordinated interaction of these modules during crash events.
Solution Approach 2:
The reaction bridge and reaction collar serve as intermediary elements between the fuel bladder assembly and the fuselage. These intermediaries provide a controlled interface that enables both secure mounting and predetermined failure modes, allowing the system to achieve both secure integration and simplified installation procedures.
2Reliability
If a secure mounting system is used to prevent fuel leakage, then fuel containment is improved, but the system complexity and difficulty of installation increase
Solution Approach 1:
The reaction bridge is pre-attached to the fuselage structure, and the reaction collar is pre-positioned on the fuel bladder assembly. This preliminary preparation of mounting components separates the complex securement function from the installation process, allowing workers to simply connect pre-prepared components rather than performing complex mounting operations in the field.
Solution Approach 2:
The breakaway valve with reaction collar is designed to automatically engage with the reaction bridge upon insertion, with the valve body itself serving as part of the mounting mechanism. The system uses its own structural components to achieve secure mounting without requiring additional fasteners or complex assembly procedures.
3Reliability
If the breakaway valve is designed to break upon movement, then fuel leakage is prevented, but the valve body strength is reduced
Solution Approach 1:
The valve body is designed with non-uniform strength distribution: the mounting portion has reduced strength to enable predetermined breakage at specific locations, while the sealing and flow control portions maintain full strength. This local differentiation allows the valve to sacrifice specific structural elements to prevent fuel leakage while maintaining the functional integrity of critical components.
Solution Approach 2:
The potential harm of valve body breakage is converted into a beneficial safety feature. The controlled fracture of the mounting portion upon excessive movement or crash forces automatically closes the fuel flow path, transforming what would be a failure mode into a protective mechanism that prevents fuel leakage into the cockpit or passenger compartment.
Data Source
AI summary
A flexible fuel bladder assembly for an aircraft includes a flexible fuel bladder positioned at an airframe and having an opening to allow a flow of fuel into and/or out of the fuel bladder. A breakaway valve is operably connected to the fuel bladder at the opening to control a flow of fuel therethrough. A non-contacting or loose fitting reaction feature is affixed to the airframe and is interactive with the breakaway valve such that movement of the breakaway valve relative to the reaction feature results in breakage of a valve body of the breakaway valve and closure of the breakaway valve to prevent flow of fuel therethrough while also allowing for a second reaction mode to cause breakage of a valve body should the connecting hose be pulled relative to the breakaway valve.