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

Correct Answer: Option D — Borescope

Borescopes are specialized optical instruments designed for internal engine inspections without disassembly. They allow technicians to examine turbine blades, combustion liners, and compressor stages for signs of thermal distress, cracking, or erosion, ensuring compliance with maintenance schedules and preventing in-service failures of critical high-temperature gas turbine components.