Which NDT method is described as suitable for simple parts such as turbine and compressor blades?

• A. Magnetic Particle Inspection
• B. Dye Penetrant
• C. Radiographic Method
• D. Eddy Current Method

Answer: (D)

Eddy current testing is ideal for quick, non-contact inspection of simple, conductive parts with straightforward geometry. It uses an alternating magnetic field to induce currents in the metal; cracks or defects disturb these currents, causing changes in the measured impedance. Because turbine and compressor blades are metallic and typically thin, you can scan their surfaces rapidly to detect surface and near-surface cracks or flaws without disassembly or radiation exposure. The method is fast, easy to automate, and well suited to parts where geometry is simple and access is direct, making it a practical choice for blades.

Magnetic particle inspection requires ferromagnetic materials, which isn’t always the case for blades. Dye penetrant inspection detects surface-breaking cracks but needs surface preparation and post-cleanup and is less efficient for rapid, routine checks on moving or numerous blades. Radiographic testing reveals internal features but is more time-consuming, involves radiation safety considerations, and is less convenient for quick blade inspections.