A propeller inspection regime requires an enhanced NDT technique that is capable of finding small as well as large defects. We do have very advanced NDT techniques but not all are created equal. Every technique has its perks and flaws, so while inspecting propellers for aviation industries inspection needed is of high quality as no defect can be permitted as these are one of the most critical equipment.

Hence to obtain comprehensive data during propeller inspection, the best NDT techniques include Eddy current array (ECA) for conductive materials and PAUT (phased array ultrasonic testing) for composite materials. The arrays can help in detection in awkward positions including miniscule aberrations, which are difficult to detect by other methods.

Finding Best Eddy Current Equipment

Eddy current techniques can help to detect discontinuities in the form of cracks, corrosion or heat damage.

It also helps in detecting surface and subsurface which is best suited for flat surfaces. ECT is applied to a conductive surface that reacts to eddy current generated by the equipment. ECA advance by using multiple probes which in turn helps provides additional details and shortens inspection times. It has been established that using array probes can reduce inspection times by 95 percent using traditional probes.

More advanced probes assist in inspection in the following ways

  • wider coverage with a single pass
  • Adaptation of curves and contours
  • ECA probes and encoders provide a greater versatility 

Equipment signal power should detect the slightest material loss. Corrosion is also one of the major challenges in propeller blades which can further compromise the integrity of the blades and degrades engine performance.

Another advantage of ECA technology being that it is portable that generally allows the analyst and technicians to move seamlessly throughout the inspection process. With other NDT procedures such as MPT a constant electrical source is required that can reduce mobility, it also requires greater prep time and is also not efficient to work in tight spaces.

ECT requires less surface prep and no hazardous chemicals are involved. This helps technicians to determine flaws rather than being engaged in rather cumbersome preparations procedures

Regardless of the mentioned benefits of ECA technologies it can only inspect propellers surfaces and can’t inspect defects on a volumetric level. It is only a viable option if the test object is conductive as ECA is not an effective tool against a composite material. Hence for composite materials and deeper inspection PAUT is the best viable option and an appropriate choice.

The Benefits of Using Advanced Ultrasonic Techniques

PAUT allows for multiple probing angles. a single probe offers only one angle of propagation and there is no room for beam customization or diverse angles during the inspection. With PAUT technicians and inspectors can achieve:

  • Multiple beams that shorten inspection time
  • Wave beam customization can cover a wide area during single probing
  • Ability to detect parallel cracking
  • Scanning can provide the best coverage

PAUT also comes with the same portability and maneuverability as ECA technique. But PAUT instrument also has (TFM) total focus method that provides the best data collection as no other equipment can offer a resolution that can highlight defects with such clarity.

Equipment with bipolar pulses can probe through thicker sections of the components and provide good signal quality. A signal can detect erosion as well as corrosion. It also enhances the detection of planer defects and corrosion cracking.

PAUT doesn’t require long setup times or not hazardous chemicals are involved, the instrumentation is simple enough to begin testing in a short span of time. Equipment is easy to use for novice or experienced personnel. PAUT equipment provides us with advanced software that helps in the assessment of data online and offline provides real-time imaging of the discontinuities.

Importance of Using Right Equipment During Propeller Inspection

As it has been established that PAUT and ECA are the best methods for propeller inspection, inspectors must have the right equipment. Equipment should have a flexible probing option that can conform to design parameters. PAUT equipment should provide beam customizations and multiple probing options to provide an inspector to find additional deviations.

ECA is by far the best option for conductive materials while PAUT is best suited for composite materials. A proper inspection and test plan for the propeller may require a technique beyond the traditional methods. Hence with either method, analysts can capture hidden defects that could comprise asset integrity and cause safety hazards.

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