ECP Probe for Aircraft Wing Fitting Inspection
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Solution Overview
Problem
Conventional non-destructive inspection methods are unable to accurately inspect bushed fastener holes in aircraft wing attachment fittings without requiring the removal of the wing, due to the structural modifications made during life extension programs which cause magnetic interference and reduce sensitivity to defects.
Innovation Solution
A specially designed Electric Current Perturbation (ECP) probe with a drive coil and differential receive coil arrangement, positioned with a ferrite core to minimize steel interference, allowing for accurate inspection of modified wing attachment fittings without wing removal, using conventional eddy current instrumentation and an index scanner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional NDI methods are used to inspect bushed fastener holes, then inspection can be performed without wing removal, but measurement precision is insufficient to detect defects in modified structures
Solution Approach 1:
The patent changes the electromagnetic parameters of the inspection system by using a dual-coil ECP probe with specific coil configurations and ferrite cores to optimize the electric current perturbation field for detecting defects in bushed holes while minimizing interference from surrounding steel structures
Solution Approach 2:
The patent introduces a ferrite core as an intermediary material between the drive coil and the aluminum structure being inspected. The ferrite core concentrates and directs the magnetic flux, enhancing the sensitivity to defects while reducing the impact of interfering steel components in the inspection area
2Strength
If steel structures are added to extend aircraft life, then structural strength is improved, but magnetic interference increases and reduces inspection sensitivity
Solution Approach 1:
The patent converts the harmful magnetic interference from steel structures into a beneficial effect by using the ferrite core to concentrate magnetic flux. The steel structures that cause interference are actually utilized to enhance the magnetic field concentration, turning the harmful interference into a useful field concentrating mechanism
Solution Approach 2:
The ferrite core acts as an intermediary that mediates between the drive coil and the steel structures. It concentrates the magnetic flux in a controlled manner, allowing the inspection system to distinguish between the magnetic signature of defects and the interference from steel components
3Strength
If bushing holes are created for repairs, then structural integrity is maintained, but inspection difficulty increases due to the complex stack-up configuration
Solution Approach 1:
The patent segments the inspection problem by using a dual-coil probe system that can independently characterize different layers of the stack-up configuration. The drive coil and receive coil work together to separate the magnetic signals from different materials (aluminum, steel, bushing materials), allowing inspection of each layer independently despite the complex configuration
Solution Approach 2:
The patent changes the electromagnetic parameters of the inspection system to optimize penetration depth and sensitivity for the specific stack-up configuration. By adjusting the coil spacing, ferrite core properties, and excitation frequency, the system can distinguish between defects in different layers of the bushed hole assembly
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
Enables rapid and accurate detection of flaws in bushed fastener holes, even in areas with significant steel interference, without the need for wing removal, thereby extending the life of aircraft structures while maintaining inspection sensitivity.
Implementation Method 1
The basis of the system and method of the present invention revolves around the design of a compliant ECP probe... capable of adjusting to the surface inside dimension of the fastener hole... uses a drive coil and a differential receive coil arrangement
Implementation Method 2
uses a drive coil and a differential receive coil arrangement... that significantly improve the sensor discrimination
Implementation Method 3
The ECP probe positions a receive coil in conjunction with a drive coil (and its ferrite core) in a manner that minimizes steel interferences in the inspection area
Data Source
AI summary
A device and methods for using the device, that permit the rapid and accurate inspection of aircraft wing attachment fittings, including those wing to fuselage attachments modified according to a Structural Life Extension Program (SLEP). Such aircraft life extension programs often result in the placement of fitting stack-up components that tend to challenge the ability of standard inspection sensors and techniques to achieve accurate readings. A specially designed, contact compliant, Electric Current Perturbation (ECP) probe is used. The ECP probe positions a receive coil in conjunction with a drive coil (and its ferrite core) in a manner that minimizes steel interferences in the inspection area. The ECP probe works with conventional eddy current instrumentation with an index scanner to allow for flaw location within a particular stack-up layer and/or within the area around the attachment aperture. Data acquired through the use of the system and method of the present invention allows for the rapid discernment of flaws and defects in the area adjacent the probe placement.