Most commonly used aviation gasoline for piston engines: 100LL
Dye used in 100LL: 1,4-dialkylaminoanthraquinone (also called C.I. Solvent Blue 98)
Dye color: Blue
Average cost of 100LL in the U.S., April 2017: $4.75/gal.
Average cost of avgas in the U.S., 1980: $1.95
Density of avgas (all grades) at 15° C: 6.01 lbs./U.S. gal.
Density of avgas (all grades) at -40° C: 6.41 lbs./U.S. gal.
Freezing point of avgas: -58°C
Emission coefficient of avgas: 18.4 lbs. CO2 per U.S. gal.
Octane rating: measures how much the fuel can be compressed before it spontaneously ignites (knock/detonation)
Determining factor for minimum octane rating needed in an engine: compression ratio
Benefits of higher compression ratio: more power for a given fuel burn
Tetraethyl Lead (TEL): additive mixed with gasoline to allow increased engine compression without detonation
Chemical formula of TEL: C8H20Pb
Amount of TEL per 1 gal. 100LL: 1.2-2 grams
Chemist credited with discovery of effectiveness of TEL as an antiknock additive: Thomas Midgley Jr.
Year of Midgley’s discovery: 1921
Also discovered by Midgley: use of ethylene bromide to expel lead in exhaust to help prevent buildup in engine
Harmful effects of TEL in humans: lead poisoning; many harmful effects including neurological, cellular and immunological damage
Exposure risk: TEL can be absorbed through skin contact with fuel or inhalation of exhaust (GA pilots most at risk due to cumulative effects of regular exposure)
Problems with TEL in engines: spark plug fouling, lead deposits in engine (especially if fuel octane rating is too high for the engine)
Amount of lead (Pb) in 1 gram TEL: 640.6 milligrams
Only non-Chinese company producing TEL: Innospec Specialty Chemicals, headquartered in Englewood, Colorado
Use of TEL: banned for automotive use in many countries, including the U.S.
Reason TEL is still used in avgas: no operationally safe alternative is available yet
Most commonly used aviation gasoline for turbine engines: Jet A-1
Freezing point of Jet A-1: -47°C (-53°F) or below
Primary difference between Jet A and Jet A-1: Jet A-1 is required to have an anti-static additive
Density of Jet A-1 at 15°C: 6.71 lbs./U.S. gal.
Type of fuel, Jet A and A-1: kerosene-based (unleaded)
Emission coefficient of jet fuel: 21.1 lbs. CO2 per U.S. gal.
Average cost of 1 gallon Jet A, April 2017: $4.17
Average cost of 1 gallon Jet A, 1980: $0.87
Amount of aviation gasoline produced in the U.S., 2016: 4,080,000 barrels
Amount of kerosene-type jet fuel (commercial) produced in the U.S., 2016: 576,317,000 barrels
Number of U.S. gallons per barrel: 42
Alternatives to traditional jet fuel: biofuel and biofuel blends
Some biofuel components: municipal solid waste, used cooking oil, jatropha, camelina and sugarcane
Alternatives to 100LL: unleaded substitutes under development via the FAA’s Piston Aviation Fuels Initiative (PAFI)
PAFI goal: finding and qualifying unleaded avgas substitutes that will safely work fleet-wide
Members of PAFI Steering Group: AOPA, EAA, GAMA, NATA, NBAA, FAA
Date PAFI began: June 2013
Original PAFI entrants: 17 formulations from 6 companies
Number of formulas that made it to Phase 1 testing: 4
Current status of PAFI: engine and aircraft testing of selected formulas (Phase 2 testing)
Number of formulas in Phase 2: 2
Date Phase 2 began: Summer 2016
Date Phase 2 is scheduled to conclude: 2018
Phase 2 Formulas: Shell UL100 and Swift UL102
Only unleaded high-octane avgas to have an ASTM Production Specification approval: Swift UL102 (ASTM D7719)
Number of U.S. GA aircraft that rely on 100LL for safe operation: Approximately 167,000