Definition
Structural failure of the upper portion of an engine cylinder, typically caused by sustained excessive temperatures that weaken the metal until it cracks, warps, or breaks. In a piston aircraft engine, this results in loss of compression in the affected cylinder, rough running, partial or complete power loss, and possible secondary damage from escaping combustion gases or oil.
Plain English
The top part of an engine cylinder breaks or cracks, usually because it got too hot for too long. The engine then runs roughly or loses power.
Context Anchor
Seen in heat management discussions, especially when high engine temperatures are allowed to continue in climb, low-speed flight, or other high-power conditions.
Derivation
The cylinder head is literally the 'head' (top, capping piece) of the cylinder, where the spark plugs and valves sit. It carries the heaviest thermal load in the engine, which is why it is the part most likely to fail when temperatures are not managed.
Why Pilots Care
A failed cylinder head can cause sudden power loss, oil leaks, or even engine fire, requiring immediate emergency procedures and possible off-field landing.
Grounding Statement
In flight, think of cylinder head failure as one engine cylinder losing the strong, sealed top it needs to make power.
Intuition Check
Do not assume cylinder head failure always means the engine instantly stops or a part breaks off completely. It can begin as a crack, leak, or heat-related damage that shows up as rough running, power loss, or abnormal engine temperature.
Example Sentence 1
After noticing the cylinder head temperature climbing into the red during the climb, the pilot reduced power and enriched the mixture to avoid cylinder head failure.
Example Sentence 2
After landing, maintenance found evidence of cylinder head failure caused by prolonged operation above red-line temperatures.