Definition
Describes a fuel, typically automotive gasoline (autogas), that contains ethanol mixed in with the gasoline. Ethanol-blended fuels are not approved for use in most aircraft and can damage composite structures, fuel system seals, and certain fiberglass fuel tanks on contact.
Plain English
Fuel that has alcohol mixed into it. Most car gas sold today has some alcohol added, which is why it is generally not safe to use in aircraft or to spill on aircraft parts made from composite materials.
Context Anchor
Seen in fuel discussions and in warnings about fluid spills on composite aircraft parts.
Derivation
Ethanol is the chemical name for the type of alcohol found in alcoholic drinks and many fuels. 'Blended' simply means mixed in. So 'ethanol blended' means the gasoline has alcohol mixed into it, usually at 10% (E10) or higher.
Why Pilots Care
Ethanol-blended fluids can swell or weaken composite structures, creating hidden damage that affects airworthiness.
Intuition Check
Do not assume ethanol blended means upgraded, cleaner, or automatically safe for aircraft. Here it means alcohol has been mixed into the fuel, and that mixture may not be approved for the airplane.
Example Sentence 1
The owner's manual warned that ethanol-blended automotive fuel must never be used in the aircraft, even though the engine was approved for autogas.
Example Sentence 2
Spilled ethanol blended fuel was wiped up immediately to prevent damage to the fuselage composites.