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 reflecting internal stress, and ignoring high CHTs can lead to severe engine damage, including piston, ring, and cylinder head failure.
Pilots must actively manage CHT using controls such as cowl flaps (opening for high power/low airspeed, closing for cruise), mixture settings (rich or correctly lean-of-peak), and adjusting airspeed or engine power.
Effective CHT management requires continuous monitoring, ideally with multi-probe engine instruments, and strict adherence to aircraft operating limitations and manufacturer guidelines to prevent both overheating and abrupt "shock cooling."

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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.