Definition
A fuel system icing inhibitor additive, blended into aviation gasoline or jet fuel in small, specified concentrations to prevent water dissolved or suspended in the fuel from freezing into ice crystals that could block fuel filters or fuel lines at low temperatures.
Plain English
A chemical you can add to fuel in tiny amounts to stop water in the fuel from freezing and clogging the fuel system when the aircraft is flying in very cold conditions.
Context Anchor
Seen in fuel-system icing and cold-weather prevention procedures, especially when discussing approved fuel additives.
Derivation
The chemical name describes its structure: 'ethylene glycol' is a common antifreeze base, and 'monomethyl ether' indicates one methyl group attached through an oxygen. Knowing it is an antifreeze-family compound helps explain why it works — it lowers the freezing point of any water present in the fuel.
Why Pilots Care
Uninhibited water in fuel can freeze, restricting fuel flow and risking engine failure during flight in cold conditions.
Grounding Statement
If there is a little water in the fuel and the temperature is low enough, EGME helps keep that water from becoming ice inside the fuel system.
Intuition Check
Do not assume EGME can be added to any aircraft fuel whenever it is cold. It must be used only if the aircraft and fuel instructions allow it, and only in the approved amount.
Example Sentence 1
Before the long high-altitude leg, the line crew added EGME to the fuel at the concentration listed in the POH.
Example Sentence 2
Mechanics checked the fuel sample to confirm the EGME concentration met the manufacturer’s specification.