What is borescope inspection and what is it used for in GSM maintenance?

• A. A visual inspection of external surfaces for damage.
• B. Measure turbine blade vibrations.
• C. Test fuel flow rate.
• D. A visual inspection of internal engine components using a flexible camera; check for cracks, wear, deposits, and FOD.

Answer: (D)

Borescope inspection is a nondestructive way to look inside a gas turbine engine without taking it apart. A thin, flexible camera on a long probe is inserted through access ports to illuminate and image internal components, allowing technicians to see areas that can’t be viewed from the outside.

In GSM maintenance, this method is used to examine critical interior areas such as the compressor and turbine sections, combustor, and bearing chambers. It helps identify cracks, wear, deposits (like ash or carbon buildup), and foreign object damage that could affect performance or safety. By visualizing these internal surfaces, technicians can assess whether components are still within spec, need cleaning, repair, or replacement, or require a more extensive disassembly and overhaul.

The procedure relies on proper lighting, clean equipment, and skilled interpretation of the images or video captured. While other inspections might focus on external surfaces or dynamic measurements (like vibration or fuel flow), borescope inspection specifically targets the interior where many hidden issues originate.