Definition
Damage to a turbine engine caused by external objects being ingested into the intake during ground or flight operations. Common sources include stones, runway debris, loose hardware, ice, birds, and even tools or rags left near the aircraft. Because turbine engines draw in large volumes of air at high velocity, even small objects can strike the rotating compressor blades and cause nicks, dents, cracks, or catastrophic blade failure.
Plain English
Damage caused when something gets sucked into a jet engine and hits the spinning parts inside. It can be anything from a small stone on the runway to a bird or a forgotten tool — and even small items can do serious harm.
Context Anchor
Seen during preflight inspections, ramp operations, taxi, takeoff, and turbine engine discussions, especially when checking for loose items near the aircraft or engine inlet.
Derivation
‘Foreign’ comes from the Latin foras, meaning ‘outside.’ A foreign object is simply something that doesn’t belong inside the engine — anything from outside the system that ends up where it shouldn’t.
Why Pilots Care
FOD can destroy turbine engines, trigger emergencies, ground aircraft, and create high repair costs and safety risks.
Grounding Statement
A small stone on the pavement can become a real aircraft hazard if it is thrown into a tire or pulled into an engine.
Intuition Check
Do not read foreign as meaning from another country. Here, foreign means out of place or not part of the aircraft or operating surface.
Example Sentence 1
After spotting a loose bolt on the ramp near the intake, the pilot stopped the engine start to prevent FOD.
Example Sentence 2
A single rivet left on the runway led to foreign object damage during the next takeoff.