Propeller Inspection NDT: How Aviation Pros Find the Right Equipment

A strong propeller inspection regimen requires enhanced Nondestructive Testing (NDT) techniques that can find both small and large defects. Even though NDT is the most advanced detection method, not all techniques are created equal. In fact, certain techniques, such as  visual inspection or dye penetrant testing, can fail to yield quality data at times.

To achieve comprehensive data during propeller inspections, the best NDT measures include eddy current array (ECA) for conductive materials and phased array ultrasonic testing (PAUT) for composite materials. The array versions can detect flaws entrenched in awkward positions, including minuscule aberrations that are hard to read with other techniques. This article will explain why ECA and PAUT are the best NDT techniques for propeller inspections. 

How to Find the Best Eddy Current Equipment for Propeller Inspection

Eddy current technology (ECT) can detect propeller abnormalities in the form of cracks, corrosion, and heat damage. It can also find deviations on surface and near-surface levels and is more suited for the inspection of flat surfaces than PAUT. ECT applies to conductive materials that react to magnetic fields generated by the instrumentation. In particular, ECA advances the eddy-current process by highlighting deviations with additional detail and shortening inspection times. An eddy current surface array probe can reduce inspection times by as much as 95 percent when compared to other forms of traditional probing. 

Overall, more advanced ECA probes can enhance the inspection of propellers in the following ways:

• Wider radius coverage with a single pass of the probe
• Adaptation to propeller contortions
• Multi-probe coil sets that can inspect a wide array of complex curvatures and geometries
• Detachable encoders that permit greater versatility 

With that said, you won’t get any of the ECA benefits unless you use equipment made by a reputable NDT provider. The best ECT instruments have industry-leading signal quality that can improve the probability of detection. Quality signal power should have the ability to detect even the slightest material losses. Corrosion can be one of the main challenges in propeller blades, which can compromise the integrity of the blade and degrade an aircraft’s propelling prowess. But an ECA solution can detect the presence of corrosion or material erosion better than many alternative NDT campaigns. 

ECA can also offer handheld functionality that allows analysts to move seamlessly throughout the inspection process with no need for bulky equipment or hardware. With other NDT methods such as magnetic particle testing (MPT), technicians need an ever-present electrical source that can limit mobility. MPT also requires additional prep time, and the process can get messy as technicians must use particle suspension fluids that are harmful, especially when used in tighter spaces.

ECA equipment, however, requires less surface prep and hazardous chemicals, giving professionals more time to focus on flaw-finding missions instead of cumbersome preparation procedures.

Regardless of the ECA benefits, the penetration depth of ECA is limited, as it cannot inspect propellers on a volumetric level. And ECA only applies to conductive materials and cannot adapt to composite structures. For composites and deeper inspections, PAUT is the appropriate choice. 

The Benefits of Advanced UT Campaigns

PAUT differs from conventional UT because it allows multiple probing angles from a single probe. A standard UT only affords static beaming options with no room for beam customizations or diverse angles during inspections. With PAUT, professionals can achieve the following advantages:

• Multiple beam angles that shorten the inspection process and yield fewer probe and/or wedge changes.
• Wave beam customizations that can cover more areas within a single probing session.
• The ability to detect parallel cracking that may be harder to assess with other NDT methods.
• Linear scanning that secures the best coverage and eliminates raster motion.

PAUT technology comes with the same portability and maneuverability as ECA instrumentation. But only a single type of portable PAUT instrument has a total focus method that includes up to one million data points to frame, with no other equipment able to foster resolution that can highlight propeller defects with such clarity.

When it comes to signal quality, the equipment should have bipolar pulsars that can probe through thicker components. The signal capabilities can detect material losses, in addition to corrosion detection schemes. It also has enhanced detection of planar defects in the form of fatigue points or corrosion cracking.

PAUT doesn’t require lengthy setup times or hazardous chemicals; the instrumentation is simple enough to begin testing in a short time span. Regardless of the type, the equipment should be accessible to novice and veteran personnel alike. The accessibility of the technology stems from the powerful software that facilitates online and offline data with ease, fostering precise real-time imagery of aberrations.

The Importance of Propeller Inspection Using the Right Equipment

Even though ECT and UT are the best methods for propeller inspection, inspectors must have the right equipment. ECA equipment should have flexible probing options that can conform to the designs of the propellers. PAUT equipment should provide multiple angles and wave beam customizations that allow inspectors to find additional deviations. 

ECA is the best option for conductive materials, while PAUT technology is suited for composite materials. A proper propeller inspection plan requires array readiness that is a step above other NDT techniques such as MPT, which absorbs more time than necessary and fails to produce the same accurate data as PAUT or ECA. With either method, analysts can capture more hidden defects that could compromise asset integrity and cause safety hazards. 

Zetec is a leading provider of ECA and PAUT equipment for the aerospace industry. Contact us today to learn how you can extract the best data using ECA or PAUT method methodology.