Aircraft Wing Isolator Fitting for Lightning Protection
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Solution Overview
Problem
Aircraft fuel tanks face the challenge of preventing electrical discharges, such as lightning strikes and static, from igniting fuel due to the transmission of electrical currents through metallic ribs, which existing technologies have not adequately addressed.
Innovation Solution
The implementation of an isolator fitting system comprising a first and second isolator mounted to metallic ribs, with a conduit extending through openings and a nut housed within a nut housing segment, creating a tracking distance to electrically insulate the conduit from the ribs and dissipate electrical charges, while supporting fluid pipes and preventing sliding movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a conduit is mounted directly to a metallic rib to support fluid pipes, then structural support is provided, but electrical discharge from lightning strikes can travel through the rib and ignite fuel
Solution Approach 1:
An isolator fitting is introduced as an intermediary component between the metallic rib and the conduit. This isolator fitting provides structural support for mounting the conduit while simultaneously preventing electrical discharge from traveling through the rib, thus resolving the contradiction between needing structural support and preventing lightning strike transmission.
2Reliability
If electrical insulation is provided between the conduit and rib, then lightning strike protection is improved, but the complexity of the mounting system increases
Solution Approach 1:
The isolator fitting merges multiple functions into a single component: it provides structural support for mounting the conduit, establishes electrical insulation between the rib and conduit, and creates tracking distance to prevent electrical discharge. By combining these functions, the design achieves reliable lightning strike protection without proportionally increasing system complexity.
Solution Approach 2:
The isolator fitting serves multiple purposes simultaneously: it acts as a mounting bracket for the conduit, provides electrical insulation, and creates tracking distance for lightning protection. This multi-functionality allows the system to achieve high reliability for lightning strike protection while minimizing the increase in device complexity.
3Reliability
If tracking distance is created to electrically insulate the conduit from the rib, then electrical insulation is improved, but the space required for the mounting system increases
Solution Approach 1:
The isolator fitting is designed to nest around the conduit while maintaining the required tracking distance from the rib. This nested configuration allows the electrical insulation and tracking distance requirements to be met without proportionally increasing the overall volume of the mounting system, as the isolator fitting utilizes the existing space around the conduit.
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 effectively isolates electrical discharges from fuel tanks, reducing the risk of ignition and providing reliable electrical insulation and charge dissipation, thereby enhancing lightning strike protection and safety.
Implementation Method 1
a tracking distance being defined between the outer surface of the conduit and the opening wall to electrically insulate the conduit from the at least one rib
Implementation Method 2
providing an electrical bonding path for other electrical discharges, such as static and electrical currents generated by fuel sloshing in the fuel tank
Data Source
AI summary
An isolator fitting for an opening in a metallic rib of an aircraft wing. The isolator fitting has first isolator mountable to the rib to position a first isolator opening in alignment with the opening of the rib. A second isolator is mountable to the rib and has a nut housing segment defining a second isolator opening to be positioned in alignment with the opening of the rib. A conduit extends between a first end and a second end, and a nut is mountable about an outer surface of the conduit to abut against the first isolator and mount the conduit thereto. The conduit is positionable to extend through the opening of the rib and through the first and second isolator openings to position the nut within the nut housing segment of the second isolator such that the nut housing segment is positioned between the nut and the rib.