foreign objects

In aviation and aerospace, foreign object debris (FOD), is any particle or substance, alien to an aircraft or system, which could potentially cause damage.External FOD hazards include bird strikes, hail, ice, sandstorms, ash-clouds or objects left on the runway. Internal FOD hazards include items left in the cockpit that interfere with flight safety by getting tangled in control cables, jam moving parts or short-out electrical connections.
The term FOD is used to describe both the foreign objects themselves, and any damage attributed to them.

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