List three common nondestructive testing methods used during turbine engine overhaul and what they detect.

• A. Radiographic testing detects interior heat damage.
• B. Ultrasonic testing detects rough surface finishes.
• C. Magnetic particle inspection detects surface cracks in ferrous parts.
• D. Magnetic particle inspection detects surface cracks; liquid penetrant detects surface-breaking defects; eddy current detects near-surface cracks and material inconsistencies.

Answer: (D)

The key idea is how three common nondestructive testing methods cover surface and near-surface flaws on turbine engine parts during overhaul. Magnetic particle inspection exposes surface and near-surface cracks in ferrous components by magnetizing the part and attracting iron particles to discontinuities. Liquid penetrant testing reveals surface-breaking defects by letting a dye or fluorescent liquid seep into cracks and then showing the defect when a developer draws it out on the surface. Eddy current testing detects near-surface cracks and material inconsistencies by measuring how the part’s electromagnetic response changes with flaws, thickness loss, or changes in heat treatment.

This combination is why the best answer matches each method with its typical detections: magnetic particle inspection for surface cracks in ferrous parts, liquid penetrant for surface-breaking defects, and eddy current for near-surface cracks and material variations. The other statements either misstate what the methods detect or omit two of the three common methods, making them less accurate.