Managing CHTs

Monday, September 20, 2021 at 10:22 AM ET

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Key Takeaways:

Cylinder Head Temperature (CHT) is a critical engine parameter often overlooked by pilots, serving as the best proxy for internal cylinder pressure and overall engine stress.
Maintaining CHT within proper operating ranges is essential to prevent severe engine damage, such as piston/cylinder failure, detonation, and reduced longevity.
Pilots manage CHT through various interventions, including proper use of cowl flaps, adjusting mixture (e.g., lean-of-peak operation), and controlling airspeed and power settings to optimize cooling airflow.
Modern multi-probe engine monitors are crucial for providing real-time CHT and Exhaust Gas Temperature (EGT) data for each cylinder, enabling timely intervention and diagnosis of potential engine abnormalities.

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After 20 years as a flight instructor, I’ve observed that too many general aviation pilots do not monitor nor understand the significance of maintaining cylinder head temperature (CHT) within the proper operating range. Thanks to aircraft system ignorance, failure to maintain engine situational awareness, laziness, apathy or combinations thereof, many pilots are remiss at monitoring CHT, an essential engine parameter. Why should pilots be concerned about maintaining CHT within the proper operating range?

In his book Proficient Pilot (Vol. 2), Captain Barry Schiff states: “Heat is one nemesis of a piston engine airplane. Its cumulative effects can lead to piston, ring and cylinder head failure, as well as placing thermal stress on other engine components.” Abnormally high CHTs in normal operation weaken the aluminum alloy from which cylinder heads are manufactured. High CHTs over protracted periods can result in serious engine damage and failure.