Definition
A cabin heating system that warms outside air by routing it through a shroud (a metal jacket) wrapped around the engine's exhaust manifold or muffler, then ducts that heated air into the cabin. The exhaust gases themselves never enter the cabin; only fresh outside air that has been warmed by passing over the hot exhaust components is delivered to the occupants.
Plain English
A simple cabin heater that uses the heat of the engine's exhaust pipes. Fresh outside air is blown across a metal cover wrapped around the exhaust, picks up the heat, and is then piped into the cabin to keep the pilot and passengers warm.
Context Anchor
Seen in piston-engine aircraft when discussing cabin heat, preflight checks, and carbon monoxide risk.
Derivation
“Exhaust” comes from an older word meaning “to draw out” or “use up.” In aviation, it means the hot gases drawn out of the engine after combustion, which explains why those gases can be used as a heat source while still needing to stay sealed away from the cabin.
Why Pilots Care
Provides essential cabin warmth in cold conditions while carrying the risk of carbon monoxide poisoning if the heat exchanger cracks or leaks.
Grounding Statement
On a cold flight, clean outside air is warmed by passing near hot exhaust parts, then sent into the cabin for heat.
Intuition Check
Do not assume the cabin is heated by exhaust gas itself. The system should heat clean air with exhaust heat, while keeping exhaust fumes separate.
Example Sentence 1
During preflight, the pilot inspected the exhaust heating system for cracks, knowing a leak could send carbon monoxide into the cabin once the heat was turned on.
Example Sentence 2
During preflight the instructor pointed out signs of exhaust heating system wear that could allow carbon monoxide to enter the cabin.