Foreign Object Damage (FOD) refers to:

• A. Damage to a gas turbine engine caused by an object being sucked into the engine while it is running.
• B. A weather phenomenon causing icing.
• C. A type of fuel leak resulting in engine damage.
• D. A radio navigation error.

Answer: (A)

Foreign Object Damage means damage that occurs when a foreign object enters a running engine or other aircraft system and causes harm. In a gas turbine engine, objects like gravel, bolts, ice, or birds can be sucked into the intake and strike or damage the compressor blades or other components. The highly stressed and precise gear inside blades can be chipped, bent, or unbalanced by even small items, which can reduce performance, cause vibration, or lead to engine failure. That’s why FOD prevention is emphasized—keeping the ramp and cockpit areas clear, inspecting for debris after maintenance, and performing thorough walk-arounds and preflight checks. The other options describe icing, a fuel leak, or navigation errors, which are not what FOD refers to.