# Travel >> Transportation >> Small Aircraft

How to Get Cold Air Into the Intake System

Many older, single-piston small aircraft use something called "carburetor heat" to avoid icing in the carburetor and help maintain healthy engine performance. The carb heat control regulates airflow into the carburetor to prevent icing or malfunctions. This adjustment is also used to close out the heat and allow the ambient cold air to flow into the engine's intake system. Learning how to adjust the carb heat for particular conditions and situations requires skill and training; however, the process to use the carb heat adjuster is straightforward and simple.

Instructions

- 1
  Run through the pre-flight procedures for your aircraft. Refer to the Pilot Operator Handbook (POH) for your particular aircraft. Taxi the aircraft to the run-out zone.
- 2
  Test the aircraft magnetos following the POH procedures. Magnetos are an integral part of the engine that help modulate electricity into the aircraft systems. Test the carb heat function after testing the magnetos. Rev the engine up to 1,800 RPM and pull the carb heat lever all the way out. The carb heat lever is either next to the throttle on the aircraft dash or on the left-hand side in most tail-dragger aircraft. Watch the RPM indicator and look for a drop of approximately 10 RPMs, indicating it is working properly.
- 3
  Push the carb heat lever all the way back into the dash to allow cold air to circulate through the intake system. Take off.
- 4
  Monitor the RPMs and aircraft gauges. Listen to the engine and be aware of any clouds or moisture in the air. Keep the carb heat lever pushed all the way in to allow cold air to flow through the aircraft engine's intake system.
- 5
  Open the carb heat all the way by pulling the lever out to bring heat into the intake system during landings and at low RPMs. For example, in a Cessna 172, open the carb heat at 1,000 AGL (Above Ground Level) and when the RPMs go under 1,800. This heats the engine, during descent, when the engine and carburetor are most at risk of icing.