Borescopes are used for visual inspection work where the area to be inspected is inaccessible by other means. Similar devices for use inside the human body are referred to as endoscopes. Borescopes are mostly used in non destructive testing techniques for recognizing defects or imperfections.
Borescopes are commonly used in the visual inspection of boilers, aircraft engines, aero derivative industrial gas turbines, steam turbines, diesel engines, exchanger tubes and automotive and truck engines. Gas and steam turbines require particular attention because of safety and maintenance requirements. Borescope inspection of engines can be used to prevent unnecessary maintenance, which can become extremely costly for large turbines. They are also used in manufacturing of machined or cast parts to inspect critical interior surfaces for burrs, surface finish or complete through-holes.