Definition
A clear, fast-evaporating organic solvent (chemical name 2-butanone) used in aviation maintenance to clean metal surfaces, thin certain paints and dopes, and prepare materials for bonding. It dissolves greases, oils, resins, and many adhesives, and is highly flammable.
Plain English
A strong, quick-drying liquid cleaner and thinner used in aircraft shops. It cuts through grease and old paint and dries fast, but it catches fire easily and gives off fumes that need good ventilation.
Context Anchor
Seen in aircraft maintenance manuals, cleaning procedures, surface preparation instructions, and safety warnings for powerplant work.
Derivation
From the chemistry of the molecule itself: it contains a methyl group and an ethyl group attached to a ketone. Knowing the name is just chemistry shorthand helps explain why the same solvent appears under two labels — “MEK” on a shop can and “methyl ethyl ketone” on the safety data sheet.
Why Pilots Care
Maintenance technicians use MEK regularly for cleaning and surface prep, but it is flammable and the fumes are harmful with prolonged exposure. Proper ventilation, gloves, and ignition-source control are required whenever it is used.
Intuition Check
Do not treat MEK like ordinary soap or a mild shop cleaner. It is a strong chemical solvent, so the correct procedure, ventilation, fire safety, and skin protection matter.
Example Sentence 1
The technician wiped the aluminum skin with MEK to remove oil residue before applying the primer.
Example Sentence 2
MEK evaporates quickly, leaving no residue on the cleaned turbine blades.