Which option correctly describes the role of borescopes in VT?

• A. Use of a borescope to inspect interiors or hard-to-reach surfaces.
• B. Direct measurement of thickness using calipers.
• C. A device to calibrate lighting.
• D. A type of coating to improve visibility.

Answer: (D)

Borescopes in visual testing are about seeing what’s hidden. They let you look inside hollow parts or around tight corners without taking the assembly apart, using a slim, lighted probe to bring a live image to the inspector. This capability is crucial for spotting cracks, corrosion, deposits, or misalignments in interiors of engines, turbines, pipes, and other hard‑to‑reach areas. Because the device is for viewing, it doesn’t directly measure thickness—thickness checks use calipers, micrometers, or ultrasonic gauges. It also isn’t used to calibrate lighting, nor is it a coating to improve visibility. The real strength of a borescope is providing access and visualization to areas that would otherwise be unavailable for inspection.