Definition
Flexible rubber tubes that carry liquid coolant between the engine and the radiator on liquid-cooled aircraft engines. They route hot coolant away from the engine to be cooled, and return cooler fluid back to absorb more heat.
Plain English
The rubber pipes that carry the engine's cooling fluid back and forth between the engine and the radiator.
Context Anchor
Seen during the outside-airplane preflight inspection, especially when checking the engine area for leaks, cracks, loose fittings, or damaged hoses.
Derivation
Coolant comes from cool plus the suffix -ant, meaning a substance that performs an action — in this case, the fluid that does the cooling. Hose comes from Old English and Dutch words for a tube or stocking-like covering. Together: the tubes that carry the cooling fluid.
Why Pilots Care
Damaged or leaking coolant hoses can cause rapid engine overheating and possible power loss in flight.
Analogy
Coolant hoses work much like the hoses in a car’s cooling system: they carry hot liquid away from the engine and return cooler liquid back to it.
Intuition Check
Do not assume every hose near the engine is a coolant hose. Coolant hoses specifically carry engine cooling liquid, not fuel, oil, or air.
Example Sentence 1
During preflight, the pilot inspected the coolant hoses for any signs of cracking or leaks before the first flight of the day.
Example Sentence 2
A small leak in a coolant hose caused the engine temperature to climb steadily during the climb-out.