Definition
A low point or reservoir in an aircraft engine or fuel system designed to collect liquid — typically oil, fuel, or water — by gravity. In a wet-sump engine, the sump is the pan at the bottom of the crankcase that holds the engine's oil supply. In fuel tanks, a sump is the lowest point where water and sediment settle so they can be drained off during preflight.
Plain English
The lowest part of a tank or engine, where liquid naturally collects so it can either be used (engine oil) or drained out (water and dirt in fuel).
Context Anchor
Seen in engine lubrication discussions, oil servicing, and maintenance inspections.
Derivation
From Middle English 'sompe', meaning a marsh or boggy low spot. The idea carries through directly: the sump is the low place where liquid pools.
Why Pilots Care
Oil level is checked here; a damaged or contaminated sump can lead to oil loss, engine wear, or failure.
Analogy
Functions like the oil pan underneath a car engine.
Intuition Check
Do not think of a sump as just any container. In this context, it is specifically the low collection area where engine oil drains and gathers.
Example Sentence 1
During preflight, the pilot drained a small amount of fuel from each sump to check for water and contamination.
Example Sentence 2
Metal particles found in the sump during an oil change indicated possible internal engine wear.