Definition
In a reciprocating aircraft engine, the cylinders are the chambers in which fuel and air are compressed, ignited, and burned to drive the pistons. Each cylinder houses a piston that moves up and down inside it, along with intake and exhaust valves and one or more spark plugs. The cylinders are arranged around the crankcase in patterns such as opposed, in-line, V-type, or radial.
Plain English
Cylinders are the metal tubes inside an aircraft engine where fuel burns and pushes the pistons. The pistons sliding up and down inside them is what makes the engine produce power.
Context Anchor
Seen in aircraft engine descriptions, preflight inspection discussions, engine cooling, compression checks, and powerplant maintenance.
Derivation
From the Greek 'kylindros,' meaning a roller or rolling object — referring to the round, tube-like shape. The aviation meaning keeps that shape: a smooth round chamber that a piston slides inside.
Why Pilots Care
Each cylinder contributes to total engine power; a failing cylinder reduces performance and can lead to roughness or in-flight shutdown if not addressed during preflight and run-up checks.
Intuition Check
Do not think of cylinders only as simple geometric shapes. In an aircraft engine, cylinders are working engine parts where power is actually made.
Example Sentence 1
The Cessna 172's engine has four cylinders arranged horizontally opposed, two on each side of the crankcase.
Example Sentence 2
A drop in RPM during the magneto check often indicates a problem with one or more cylinders.