Definition
A cleaning process in which a part is submerged in a liquid solvent inside a tank, and high-frequency sound waves are passed through the liquid. The vibrations create rapid microscopic pressure changes in the solvent that dislodge dirt, oil, and debris from the surface and from inside small passages of the part.
Plain English
A way of cleaning small parts by putting them in a liquid bath and running sound waves through the liquid. The sound waves shake the dirt loose, even from places a brush could never reach.
Context Anchor
Seen in aircraft maintenance when cleaning small engine, fuel-system, or instrument parts before inspection or reassembly.
Derivation
Sonic' comes from the Latin sonus, meaning sound. The cleaning is done using sound waves -- usually at frequencies higher than human hearing -- so the name simply describes the method.
Why Pilots Care
Removes microscopic debris that could otherwise cause wear, blockage, or failure in critical engine and fuel-system parts.
Intuition Check
Sonic does not mean the part is moving at the speed of sound. Here it means sound waves are being used in a liquid to help clean the part.
Example Sentence 1
The shop used sonic cleaning to remove varnish deposits from the fuel injector nozzles before reinstalling them.
Example Sentence 2
After sonic cleaning, the bearings were rinsed and inspected before reinstallation.