Managing CHTs

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

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Key Takeaways:

Cylinder Head Temperature (CHT) is a critical, often neglected, engine parameter whose prolonged elevation causes significant thermal stress and severe damage to general aviation aircraft engines.
CHT serves as the best proxy for internal cylinder pressure and engine stress, requiring active pilot management through external airflow (e.g., cowl flaps, airspeed) and fuel mixture settings (rich or lean-of-peak).
Modern multi-probe engine monitors provide essential real-time CHT and Exhaust Gas Temperature (EGT) data for each cylinder, enabling pilots to accurately monitor engine health, diagnose abnormalities, and make informed adjustments to prevent engine failure.

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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.