Aircraft Fuel Tank Vent Line Lightning Protection
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Solution Overview
Problem
Aircraft fuel tanks mounted in the fuselage pose unique lightning protection challenges due to their location within Zone 2 regions, requiring extensive and weight-added venting systems to safely vent fuel, which results in reduced flow rates and pressures.
Innovation Solution
The implementation of lightning-protected vent lines for fuselage-mounted fuel tanks, featuring a vent conduit with a flame arrestor positioned at a specific distance from the vent opening (L/D > 5) or a conduit segment length significantly longer than the diameter (L1/D1 > 10), to provide effective lightning protection and safe venting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuselage-mounted fuel tanks use conventional venting systems to vent fuel safely, then lightning protection is improved, but device complexity and weight increase due to extensive piping and fittings
Solution Approach 1:
The invention extracts the flame arrestor as a separate, dedicated component and positions it at a specific distance from the vent opening. This extraction allows the venting system to achieve lightning protection through a single, well-positioned component rather than extensive piping networks, thereby reducing device complexity while maintaining reliability
Solution Approach 2:
The flame arrestor acts as an intermediary element between the fuel tank and the external environment. By positioning it at a specific distance from the vent opening, it mediates the lightning protection function, allowing the system to achieve safety without requiring complex extensive piping and fittings
2Reliability
If fuselage-mounted fuel tanks use extensive piping to vent fuel safely, then lightning protection is improved, but fuel flow rate and pressure decrease
Solution Approach 1:
The invention extracts the flame arrestor as a separate, dedicated component and positions it at a specific distance from the vent opening. This extraction allows the venting system to achieve lightning protection through a single, well-positioned component rather than extensive piping networks, thereby maintaining fuel flow rate and pressure while improving reliability
Solution Approach 2:
The invention changes the critical parameter from extensive piping length to a specific dimensional ratio (L/D > 5) for the flame arrestor positioning. This parameter change enables the system to achieve lightning protection with minimal impact on fuel flow rate and pressure, as the flame arrestor itself rather than extensive piping provides the protective function
3Reliability
If fuselage-mounted fuel tanks use extensive piping and fittings to vent fuel, then lightning protection is improved, but system weight increases
Solution Approach 1:
The invention extracts the flame arrestor as a separate, dedicated component and positions it at a specific distance from the vent opening. This extraction allows the venting system to achieve lightning protection through a single, well-positioned component rather than extensive piping networks, thereby reducing system weight while maintaining reliability
Solution Approach 2:
The invention uses the flame arrestor component itself, positioned at a specific distance from the vent opening, to provide the lightning protection function that would otherwise require extensive piping and fittings. This approach copies the protective function into a compact, weight-efficient configuration
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 solution minimizes the risk of lightning-induced explosions and maintains efficient fuel flow and pressure by positioning vent openings in low-risk zones, reducing the need for extensive piping and weight, thus enhancing safety and operational efficiency.
Implementation Method 1
A flame arrestor is positioned in the conduit between the coupling and the vent opening
Data Source
AI summary
Lightning protected vent lines associated operatively with aircraft fuselage fuel tanks (i.e., on-board fuel tanks that are not physically located in an aircraft's wing but instead are physically located within the aircraft's fuselage structure) are provided which include a vent conduit, a coupling at a proximal end of the vent conduit for fluid connecting the vent conduit to the fuel tank, a vent opening positioned at a distal end of the vent conduit and at an external location of the fuselage and a flame arrestor positioned in the conduit between the coupling and the vent opening. The vent conduit will have an effective axial dimension (L) between the coupling and the vent opening and the flame arrestor will be positioned in the conduit at an effective separation distance (D) between an inlet of the flame arrestor and the vent opening such that L/D is greater than 5. Alternatively, the flame arrestor may be omitted, but the vent conduit will then have at least one linear conduit segment to provide an effective axial dimension (L1) of the vent line conduit between the coupling and the vent opening which is at least ten times greater than the vent conduit diameter (D1).