Plain English Meaning

A simple system that heats the cabin by passing fresh outside air around the hot exhaust muffler. The air picks up heat from the muffler and is then sent into the cockpit and to the windshield defroster vents.

Full Definition

In small piston-engine aircraft, a heating system that supplies warm air to the cabin and to the windshield defrost outlets by routing outside air through a shroud surrounding the engine exhaust muffler, where the air is warmed by contact with the hot muffler surface before being ducted into the cockpit.

Context Anchor

Seen in aircraft systems discussions, cold-weather flying, preflight checks, and use of the .