Definition
An organophosphate chemical compound (chemical formula (CH3C6H4O)3PO) used as an anti-wear and anti-knock additive in aviation turbine engine oils and certain piston engine fuels. It forms a protective film on hot metal surfaces, reducing wear on heavily loaded components such as gears and bearings.
Plain English
A chemical added to aviation oils and some fuels that coats hot metal parts inside the engine, helping protect them from wear and damage.
Context Anchor
You may see this term in aircraft oil specifications, maintenance manuals, or safety data sheets for lubricants and fluids.
Derivation
From 'tri-' (three), 'cresyl' (referring to cresol, a coal-tar compound), and 'phosphate' (a salt of phosphoric acid). The name describes the chemical structure: three cresyl groups attached to a phosphate. Knowing it is a phosphate-based compound helps explain why it forms protective films on metal under heat and pressure.
Why Pilots Care
Oil leaks containing this additive can contaminate cabin air and create health risks during flight.
Intuition Check
Do not assume “phosphate” means harmless or fertilizer-like here. Tricresyl phosphate is an industrial chemical additive, and some forms are toxic.
Example Sentence 1
Tricresyl phosphate is one of the additives that gives turbine engine oil its anti-wear properties.
Example Sentence 2
Maintenance crews wear gloves when handling oils that contain tricresyl phosphate.