Lightning Strike Protector for Aircraft Fasteners
Solution Overview
Problem
Current methods for protecting nuts and bolts in aircraft fuel tanks from lightning strikes are complex and costly, lacking a simple and cost-effective solution for establishing an electrical barrier.
Innovation Solution
A lightning strike protector with a frusto-conically shaped cap and insert, featuring protrusions for secure engagement and a polysulfide sealant, which forms an interference fit to create a reliable electrical barrier against lightning strikes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional sealant coating methods are used to protect nuts and bolts from lightning strikes, then electrical protection is provided, but the device complexity and manufacturing cost increase
Solution Approach 1:
The protector is divided into two main segments: a cap portion and an insert portion. The insert portion includes engagement features that secure it to the nut or bolt, while the cap portion receives sealant. This segmentation allows for simplified manufacturing and assembly compared to traditional multi-step sealant coating processes.
Solution Approach 2:
The insert portion is pre-formed with engagement features (protrusions or threads) that are designed to securely attach to the nut or bolt before the sealant is applied. This preliminary preparation of the insert ensures proper positioning and secure attachment, eliminating the need for complex field application procedures.
2Reliability
If traditional sealant coating methods are used, then electrical barrier protection is achieved, but manufacturing cost increases
Solution Approach 1:
By separating the protector into cap and insert portions, each can be manufactured independently using standard molding techniques for the plastic components, with the sealant applied only to the cap portion. This reduces material waste and simplifies the manufacturing process compared to traditional methods requiring manual or complex automated sealant coating.
Solution Approach 2:
The sealant is contained within the cap portion in a controlled manner, allowing for precise control of sealant quantity and distribution. This parameter control reduces material usage and eliminates the need for expensive specialized coating equipment or processes.
3Reliability
If protrusions are added to the insert for secure engagement, then attachment reliability improves, but manufacturing complexity increases
Solution Approach 1:
The engagement features (protrusions or threads) are localized to specific areas of the insert portion, specifically designed to match corresponding features on the nut or bolt. This localized complexity only where needed maintains overall simplicity while ensuring secure attachment at critical points.
Solution Approach 2:
The insert portion is made from a single material (thermoplastic or thermoset plastic) that provides both structural integrity and the engagement features. This use of a single composite material simplifies manufacturing compared to assembling multiple separate components, while still providing the necessary engagement complexity.
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
The solution provides effective Zone 2 protection by securing the sealant around the nut or bolt, preventing spark ignition and ensuring the structural integrity and safety of the aircraft during lightning strikes.
Implementation Method 1
a cap defining a top and a downwardly extending cap wall adapted for receiving a sealant... which forms an interference fit to create a reliable electrical barrier against lightning strikes
Data Source
AI summary
An electrical protector with a central axis includes a cap defining a top and a downwardly extending cap wall, and insert defining a ring and an upwardly extending insert wall, at least three protrusions extending inwardly from an interior surface of the insert wall toward the central axis, and a sealant disposed at least within the cap. The cap wall engages the insert wall, thereby establishing a connection between the cap and the insert. The protrusions are adapted to engage a structure, thereby securing the electrical protector onto the structure.