Beyond the Surface: Non-Destructive Testing with Computed Tomography
Joining forces with the Technical University of Munich to complement our propeller maintenance capabilities
To reliably assess the condition of a propeller blade, a visual inspection alone is not always enough — especially when damage is more complex or continues beneath the surface.
A recent project is a good example of how we use modern analysis methods to continuously strengthen and expand our maintenance capabilities: as part of an unscheduled maintenance case, we analyzed hovercraft propeller blades with a few cracks.
In hovercraft applications, propeller blades are exposed to particularly demanding operating conditions: high mechanical loads combined with operation in saltwater environments can put significant stress on both the material and the structure.
“Hovercraft propellers operate in a very demanding environment and face high rotational forces, vibration, and salt-laden marine air”, says Ashley Tate, Non-Destructive Testing Technician at Hoffmann Propeller. “Imagine rough sea waters with waves constantly striking from different directions — this subjects the propellers to highly dynamic and often unpredictable forces. Over time, these repeated stress cycles can lead to microscopic fatigue damage.”
After leaving our service workshops, we want our customers' blades to withstand many more operating hour reliably before the next inspection. To determine the most appropriate repair approach, it is essential to fully understand the extent of the damage.
Narrowing down potential root causes can also help prevent recurring damage over the blades’ operational lifetime.
To examine the blades as gently as possible and support potential continued use, we partnered with the Technical University of Munich and applied advanced non-destructive testing methods. Using special thermography and computed tomography (CT), the propeller blades were analyzed in detail without introducing additional stress to the material.
CT scans reveal internal structures and make corrosion damage and material irregularities far easier to identify than with conventional inspection methods alone.
“During the CT scan, X-rays capture hundreds of cross-sectional images from different angles, which specialized software then combines into a detailed 3D model of the propeller blade’s internal structure,” explains Ashley.
This allowed us to assess the actual condition of the blades more accurately and define targeted overhaul measures — helping to avoid unnecessary scrap, reduce service time and cost, and return the blades to operation as efficiently as possible.
For us, this project demonstrates how maintenance is evolving beyond repair. Combining hands-on experience with advanced inspection technology and data-driven analysis enables us to make informed maintenance decisions and provide appropriate, sustainable, and cost-efficient solutions for our customers.
Projects like this are part of Hoffmann Propeller’s ongoing transformation, helping us lay important groundwork through the integration of advanced technologies and the continuous development of technical expertise.