Avgas

AVGAS, or Aviation Gasoline, is a specialized petroleum-based fuel used primarily in spark-ignition piston-engined aircraft. It is different from aviation turbine fuels such as Jet A or Jet A-1, which power jet engines and turboprops.

The most common current grade is 100LL, where LL stands for low lead. This grade provides high octane to prevent knocking in high-compression engines. Older high-octane grades such as 100/130 have largely been superseded, but historical references remain in the literature.

AVGAS is a high-octane, leaded gasoline. The lead content typically comes from tetraethyl lead, added to resist pre-ignition and to maintain octane performance. Some formulations and programs aim to reduce lead or move to unleaded alternatives; 100UL and other unleaded designs are under development and testing, with adoption varying by region.

The fuel is designed for aircraft with spark-ignition engines and is not interchangeable with Jet fuel or automotive gasoline. Using the wrong fuel can cause severe engine damage, and airworthiness directives specify the correct grade for each airframe.

At airports worldwide, AVGAS is stored and dispensed in dedicated tanks, hydrants, and drums, with handling procedures to manage vapors, spills, and lead exposure. Environmental and public-health concerns about lead emissions have spurred research toward unleaded options and phased approaches in some regions.

See also: Aviation gasoline; Piston-engine aircraft; Aviation turbine fuel.