What are the non-destructive testing techniques commonly used in the aviation industry?

What are the non-destructive testing techniques commonly 

used in the aviation industry?

In the aviation industry, non-destructive testing (NDT) technology plays a vital role in reducing costs and ensuring personnel safety.

Safety is important to every industry, and aviation is especially true, because a small defect or mistake can lead to tragedy. In addition to costing a lot of money, the tragedy caused by defects also threatens people's lives. Therefore, it is necessary to analyze the safety and reliability of raw materials and components through the use of a series of inspections at all stages of production and maintenance.

Non-destructive testing technology is a key group of these evaluation methods used in the production, manufacturing and maintenance of raw materials and parts. All of these methods require thorough analysis to detect any defects in the test object.

Non-destructive testing technology can also be used as a quality assurance measure in the evaluation and certification of aircraft components. Ignored defects or inconsistencies in the production process can lead to expensive repairs and replacement parts, which can erode the company's finances. If serious damage occurs, the cost will increase so much that a part or the entire aircraft part must be thrown away.

During regular maintenance, non-destructive testing techniques can also be used to identify defects and wear effects. The problem can be solved as soon as it appears. However, solving the problem once does not guarantee that it will not recur. With these in mind, the following non-destructive technologies are commonly used in the aviation industry:

Vision check:

Visual inspection by well-trained personnel can reveal cracks, leaks and rust, which is one of the most commonly used NDT techniques. Most visual inspections are performed using equipment such as magnifying glasses, special lighting, endoscopes, cameras, and/or magnifying glasses. This NDT technique is usually used in the process of conducting other tests.

Laser test method:

Laser testing is a category of NDT technology, which can be divided into three different technologies: holographic testing, laser profile measurement and laser shear imaging. In holographic testing, lasers are used to identify changes on the outside of the material after heating, vibration, or pressure, and then the results are compared with a control sample without pressure to reveal any defects.

The laser profiler is completed by a high-speed rotating laser equipped with micro-optical elements. Laser profilers are used to identify cracks, corrosion, obvious wear and other defects, and can detect surface changes by generating 3D images.

In laser shear imaging, the laser is used to produce images both before and after the surface is stressed. Compare the generated images to identify any defects or degradation.

Liquid penetration test

Liquid penetration testing is considered to be a cost-effective conventional detection technique, which is often used in the maintenance, repair and overhaul (MRO) process of aero engines. The process is very effective and includes several steps to ensure reliable results.

First, the test object is cleaned and dried; then, a colored liquid is poured on the test surface, where it can penetrate into tiny cracks and be seen. After it penetrates into the cracks or holes, the liquid is dried. The excess liquid is rinsed off, and then the test object is usually inspected with ultraviolet light. Any defects or blemishes are usually very obvious.

Acoustic emission test

This non-destructive testing technology uses sensors to identify short-lived vibrations of ultrasonic waves emitted from cracks or crevices on the test surface. Leakage, corrosion results, and stress areas can all be identified by acoustic emission assessment, which makes it a suitable step in pressurized vessel testing. It is widely used to identify defects in fittings, joints, welds, bolts and adhesive bonds. The process is comparable to sonar, which can also record and evaluate sound wave reflections.

Eddy current test

The technology uses alternating current coils to place conductive test components in an electromagnetic field to identify surface and subsurface defects, including cracks, holes, wear, and thermal damage. When electromagnetic fields are applied to metals, any defects will destroy the electromagnetic fields. One of the main advantages of eddy current technology is that it produces a digital record for in-depth analysis.

Magnetic particle test

This method also requires the application of a magnetic field to the test item. However, this also involves applying the magnetic particles in dry form or in liquid suspension. These particles are made of different colors, and many are fluorescent to increase visibility under proper lighting. This program is commonly used to identify structural problems in ferromagnetic aircraft components, such as yokes, coils, and magnetic heads.

Infrared evaluation

This technology requires infrared imaging of the surface of the object. It can identify damages such as delamination, corrosion and bond degradation by finding irregularities in heat flow on materials or parts.