Which of the following instruments is designed to help you when performing an internal inspection of the GTE?

Correct Answer: Option D — Borescope

A borescope is an essential optical instrument used for non-destructive internal inspections of gas turbine components. It allows technicians to examine compressor blades, combustion liners, and turbine nozzles for damage, erosion, or foreign object debris without requiring the complete disassembly of the engine, significantly reducing maintenance downtime and costs.