Which NDT Methods in Aerospace Are Most Reliable?

The dangers of undetected flaws call for the most advanced nondestructive testing (NDT) methods in aerospace. Failure to find flaws can lead to a host of workplace hazards and consumer dangers that can cause injury or worse. 

Two of the most trustworthy NDT methods in the aerospace industry are eddy current testing (ECT) and ultrasonic testing (UT). In particular, the array functionality of ECT and UT can enhance probing mechanisms, allowing users to find defects on a more comprehensive level. Eddy current array (ECA) and phased array ultrasonic testing (PAUT) can adapt to the complex contours of aerospace welds and detect precarious deviations. 

The Benefits of PAUT for the Aerospace Industry

PAUT is one of the most ideal NDT solutions in aerospace due to multiple beaming angles from a single probe, helping analysts find stubborn flaws in composite structures. PAUT is more advanced than standard UT, as the conventional method has a fixed beaming angle and focal point that cannot adapt to defects that are harder to pinpoint. Moreover, analysts have a harder time customizing inspection parameters with an ordinary UT campaign. 

On the other hand, PAUT can achieve the following: 

• Beam shape tailoring to find a diverse array of indications
• Multiple scans without changing the wedges or probes
• Enhanced in-depth focusing 
• Precise coverage using linear scanning 

Still, PAUT is only part of the equation, as technicians need an instrument that streamlines the inspection process with quality software and advanced capabilities. In terms of more outputs, higher caliber UT instruments should accept PAUT capabilities, in addition to the time reversal technique. Time reversal is a boon to the aerospace field due to its ability to scan composite materials and highly complex geometries. Time reversal is a proven application of PAUT for the inspection of composite structures after manufacturing. It consists of a real-time adaptation of the sound beam characteristics to compensate for varying probe-to-component misalignment conditions.  

One of the best UT solutions in the case of complex composite structures allows a combination of PAUT and time reversal. A combined technique can strengthen detection prowess and provide full coverage on composite materials. A PAUT and time reversal combination can provide better coverage and detection capability on various composite structures. 

Read about how automated test equipment can streamline aircraft NDT.

The Benefits of ECA for the Aerospace Industry

What separates ECA probes from standard ECT is the availability of multi-coil sets in a single probe. They can be positioned in diverse ways, such as off-axis, transversely, or longitudinally. With a single eddy current array probe, it’s possible for analysts to obtain more data from one pass of the probe. Technicians will also get enhanced accuracy, better repeatability, and faster inspection times. In fact, the array version of ECT can speed up inspection times by as much as 95 percent compared to other standard ECT methods like pencil probing. 

Analysts can also slow down the sample rate to achieve a better signal-to-noise ratio that can penetrate through thicker welding components, including multi-layered materials. A high-quality ECA method with a sound signal-to-noise (SNR) mechanism can read more defects during testing campaigns. 

Overall, the array functionality offers more options than conventional ECT, such as the ability to:

• Choose different coil sets based on the aerospace application.
• Test smooth and rough surfaces without hassle.
• Read multiple locations using a detachable encoder.

However, the instrument behind array power is the key to processing quality data. For the aerospace industry, look for a handheld ECT option, which provides easier access to hard-to-reach areas of aerospace components without causing heavy arm fatigue. This includes ECT devices that don’t require an electrical source and a long battery life that allows operators to use it for up to 10 hours. 

ECA tends to be better than other techniques. Magnetic particle testing (MPT), for instance, offers sub-standard testing data and requires an ever-present electrical source. In comparison, ECA provides portability, advanced signal quality, and the sensitivity needed to detect small cracks. Plus, it can detect corrosive sections through multiple layers using dual-frequency, dispelling unneeded signals from air gaps that obscure notable signals. This means that technicians are able to capture more data in a single pass. 

The Top NDT Methods in Aerospace 

When assessing NDT methods in aerospace, the array capabilities of ECT and UT provide more comprehensive examinations of many flaw types. ECA and PAUT offer more flexibility and in-depth reviews into some of the toughest deviations found in the aerospace industry. Both techniques can adapt to complicated materials and provide data that aerospace companies can confidently rely on. 

PAUT finds more flaws through its diverse angles from a single probe and custom beaming parameters. ECA provides a thorough understanding of flaws using different coil sets and powerful signal quality. With these NDT methods in aerospace, analysts can find dangerous flaws that typically remain hidden.

Zetec is a major provider of UT and ECT equipment in the aerospace industry, among other vital industries. Contact us today to get a tailor-made inspection plan and instrumentation for your aerospace detection campaigns.