It’s easier to catch a neutrino in a jar than come across a fundamental change in general aviation, but it appears we just caught a drum-full.
GAMI, the balanced fuel injector people who are also Tornado Alley Turbo and who have been doing the heavy lifting of developing an unleaded, drop-in replacement for 100LL avgas for over a decade, just announced the FAA has approved an STC for burning GAMI’s G100UL fuel in a range of Lycoming-powered Cessnas.
This is the camel’s fuel nozzle snuggling under the hangar door. Once those few Cessnas provide some real-world data the all-but guaranteed expectation is soon any piston engine will be included in the STC. GAMI expects the STC’s Approved Model List to expand rapidly in the next nine to twelve months.
Avfuel of Ann Arbor, Michigan, will distribute the new gasoline “as fast as production can be ramped and delivered to airports.” And to answer the number one question, G100UL is expected to cost 60 to 85 cents a gallon more than 100LL. So, now you can put a price on your environmental consciousness.
Viable unleaded avgas is a game changer if only because it deflects legal entanglements from environmentalists, such as attempts to outright ban leaded fuels. But there are many other advantages to unleaded avgas both on the supply side and for the consumer.
For those in the fuel business an unleaded fuel eliminates costs and difficulties imposed by lead, which is seen as a contaminant to all other fuels. This is especially the case in refinery-to-airport transportation.
For those of us burning the stuff, getting the lead out means greatly reduced oil and spark plug contamination. That pasty gray goo won’t build up inside higher time engines and there are fundamental implications for increased oil life; GAMI figures oil change intervals could double. Superior, full-synthetic oils could also become a reality in aircraft engines. Spark plugs, valves and guides don’t build up lead deposits, either, so those components should last longer.
Downsides are contained to the increased cost, says GAMI. The detonation resistance of G100LL is at least equal to 100LL in GAMI testing. The turbocharged big-bore Continental test engine bumped as high as 380 hp does not detonate on the new fuel and GAMI postulates highly-supercharged WWII-era V-12 and radial engines can return to their original take-off power ratings. There are no new toxicity concerns. Mixing G100UL and 100LL in any ratio poses no issues, and, if anything, there is a negligible 1 percent increase in range with G100UL as the new fuel apparently has a tick more energy density compared to 100LL. Fuel weight does go up from 6 pounds per gallon for 100LL to 6.3 pounds per gallon for G100UL.
How rapidly pilots line up to pay extra for unleaded fuel remains to be seen, but as the benefits and possibilities of the fuel are realized we’ll be able to say the unleaded avgas era was announced at AirVenture 2021.