Non-Intrusive Aircraft Fuel Pressure Sensors With Sealed Guide Tubes
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Solution Overview
Problem
Existing fuel level sensors in aircraft fuel tanks are intrusive and require manual access for installation, replacement, or maintenance, posing challenges in terms of convenience and efficiency.
Innovation Solution
A system utilizing a guide tube and optic fiber, where the guide tube is sealed to the aircraft's vertical wing spar and an optical pressure sensor is optically coupled to the optic fiber, allowing for non-intrusive installation, removal, and maintenance of fuel level sensors without accessing the fuel tank interior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional fuel level probes are used, then fuel level measurement is achieved, but manual access to fuel tank interior is required for installation and maintenance
Solution Approach 1:
A guide tube is introduced as an intermediary component that extends from the fuel tank exterior through the wing spar into the fuel tank interior. The guide tube serves as a conduit through which the optical fiber sensor can be routed, allowing the sensor to access the fuel level measurement position without requiring direct manual access to the tank interior. The guide tube is sealed to the wing spar structure and positioned to allow sensor insertion while maintaining structural integrity.
Solution Approach 2:
The sensor system is divided into separate functional components: the guide tube structure mounted on the exterior, the optical fiber running through the guide tube, and the sensing element positioned at the interior endpoint. This segmentation allows the guide tube and mounting structure to be installed independently during aircraft construction, while the optical fiber and sensor can be accessed and replaced from the exterior without entering the fuel tank.
2Ease of repair
If manual access to fuel tank interior is required, then sensor replacement is possible, but maintenance time and complexity increase
Solution Approach 1:
The guide tube acts as a mediator that provides a pre-established pathway from the exterior to the sensor location. During maintenance, technicians can simply access the guide tube opening from the exterior, insert or replace the optical fiber sensor through the guide tube, and seal it back. This eliminates the need to access the fuel tank interior, significantly reducing maintenance time and complexity while keeping the same sensor replacement capability.
3Device complexity
If optical fiber is routed through guide tube, then non-intrusive mounting is achieved, but sealing requirements increase
Solution Approach 1:
The guide tube itself serves as the sealing intermediary between the exterior mounting point and the interior sensor location. By providing a dedicated sealed conduit through the wing spar structure, the system maintains sealing integrity while allowing the optical fiber to pass through. The guide tube is sealed at its exterior endpoint to the wing spar structure, creating a sealed pathway that protects against fuel leakage while enabling non-intrusive sensor mounting.
Solution Approach 2:
The optical fiber is enclosed in a flexible protective sheath that can be inserted through the guide tube and sealed at the interior endpoint. This flexible sheath protects the optical fiber while allowing it to be routed through the rigid guide tube structure. The sheath can be sealed at its interior endpoint using standard sealing techniques, maintaining fuel containment while enabling sensor functionality.
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
Facilitates easy installation, removal, and maintenance of fuel pressure sensors without manual access to the fuel tank, reducing intrusion and maintaining structural integrity while using non-metallic materials for the guide tube and optic fiber.
Implementation Method 1
An optical pressure sensor is optically coupled to the optic fiber proximate a second end of the guide tube opposite the first end
Data Source
AI summary
A system includes an aircraft fuel tank defining an interior configured to store fuel for flight. The interior is defined by a plurality of tank walls including a vertical wing spar of a wing. An opening is defined through the vertical wing spar. A guide tube has a first end sealingly engaged in the opening of the vertical wing spar to prevent leakage between the guide tube and the opening. An optic fiber extends through the guide tube, sealingly engaged to the first end of the guide tube to prevent leakage between the optic fiber and the first end of the guide tube. An optical pressure sensor is optically coupled to the optic fiber proximate a second end of the guide tube opposite the first end.