Hot spots found during borescope inspection indicate malfunction in which system?

• A. Combustion chamber liner
• B. Turbine blades
• C. Fuel pump
• D. Fuel nozzle or other fuel system malfunctions

Answer: (D)

Hot spots seen in a borescope mean the flame in the combustor isn’t burning uniformly. When the fuel isn’t delivered or atomized correctly by the fuel nozzle or other fuel-system components, certain pockets burn hotter, creating localized high-temperature areas on the combustor liner. That pattern points to fuel-system malfunctions—such as nozzle problems, dirty passages, or improper fuel flow—rather than a primary issue with the liner or turbine blades. A damaged liner would show cracks or scorching from overall heat exposure, and turbine blades would exhibit blade-specific heating or damage, not just localized combustor hot spots. So the presence of hot spots during inspection most strongly indicates a fuel nozzle or fuel-system issue.