Definition
A clear container installed at the low point of an aircraft fuel system that collects water and sediment drained from fuel tanks during preflight inspection. The pilot opens a small drain valve, captures the fuel sample in the sump jar, and visually checks it for water, debris, or contamination before flight.
Plain English
A see-through cup used to catch a small sample of fuel from the aircraft so the pilot can look for water or dirt mixed in with the fuel.
Context Anchor
Used during preflight inspection and maintenance checks when sampling fuel from the aircraft's drain points.
Derivation
Sump' comes from the Middle English word for a swamp or low pool, and refers to any low point where liquid collects. In aviation, it names the part of the fuel system where water and sediment naturally settle out, since both are heavier than fuel.
Why Pilots Care
Detecting contaminants prevents engine failure due to fuel starvation or blockage.
Grounding Statement
Picture holding a clear jar under a fuel drain and looking for a water layer or small specks before you fly.
Intuition Check
A sump jar is not the aircraft sump itself. It is the clear container used to catch and inspect the fuel that comes out of the sump or drain point.
Example Sentence 1
During preflight, she drained a sample from each tank into the sump jar and held it up to the light to check for water.
Example Sentence 2
After refueling, always sump the tanks into the jar to ensure no moisture was introduced.