Engine Induction, Exhaust and Cooling

Engines are air pumps. The induction system brings filtered air in, and the alternate-air or carburettor-heat door is the backup that lets the engine breathe when the filter ices or becomes blocked. Any induction leak leans the mixture and roughens the engine, so seals, gaskets and duct security are inspected rather than assumed.

The exhaust system carries burnt gas out through mufflers and shrouds that often supply cabin heating air. A cracked muffler or exhaust stub near a heater shroud can feed carbon monoxide into the cabin, which makes exhaust inspection a life-or-critical item. The engine is often run rich or with the mixture off-lean specifically to clear a blockage, so a hot exhaust is normal on the ground.

Air-cooled cylinders shed heat through external fins. Baffles and seals force cooling air across every fin, and cowl flaps meter the flow. Missing or perished baffle seals overheat the rear cylinders first, which is why cylinder-head temperature spread is checked during run-up. Liquid-cooled engines instead rely on a coolant circulation system, pump, radiator and expansion tank with their own inspection and servicing requirements.

Superchargers and turbochargers compress the intake air to restore sea-level power at altitude, adding heat and complexity and giving the exhaust system an exhaust-driven turbine. A leak anywhere in the induction or exhaust path produces an overtemperature, a rough engine or a power loss, and none of them may be flown until repaired.