Definition
An audible metallic knocking sound produced inside a piston engine's cylinders when the fuel-air mixture ignites uncontrollably ahead of the spark plug's normal flame front, rather than burning smoothly. It is a symptom of detonation and indicates abnormal combustion that can damage the engine.
Plain English
A metallic knocking or rattling noise from the engine that means the fuel is exploding inside the cylinders instead of burning smoothly. It is a warning sign that something is wrong with how the engine is running.
Context Anchor
Seen in fuel and oil discussions, especially when learning why the correct fuel grade matters for piston aircraft engines.
Derivation
From the sound itself -- a sharp metallic 'ping' or 'pinging' noise. The word imitates what the pilot or mechanic actually hears when uncontrolled combustion strikes the inside of the cylinder.
Why Pilots Care
Pinging indicates detonation that can quickly overheat and damage pistons, rings, and valves, leading to power loss or engine failure if power is not reduced or the correct fuel grade is not used.
Intuition Check
Pinging does not mean just any small sound from the airplane. In this engine context, it means a sharp knocking sound that points to abnormal burning inside a piston engine.
Example Sentence 1
After leaning the mixture too aggressively in the climb, the pilot heard pinging from the engine and quickly enriched the mixture to stop the detonation.
Example Sentence 2
Using fuel with an octane rating below the engine's requirement often produces pinging at high manifold pressure settings.