I've been aware of this possibility for some time. Now, this test report. Have any of you read it (all
181 pages)?
http://www.tc.faa.gov/its/worldpac/techrpt/ar0853.pdf
Allegedly, a lot cheaper to produce than 100LL.
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HR
A couple points that popped out at me.
16. Abstract
As of this writing, the Environmental Protection Agency (EPA) exemption for general aviation from compliance with the 1990 Clean Air Act Amendments regarding the use of leaded fuel is still in effect. Recent petitions to the EPA call for either a ban or the study of the health effects of lead in aviation gasoline. It is likely that environmental and cost pressures of using leaded fuels will continue to increase for the general aviation community. Past extensive testing by the Federal Aviation Administration (FAA) William J. Hughes Technical Center on an unleaded replacement for the current leaded 100 low-lead (100LL) aviation gasoline centered on the petroleum industry’s use of specialty chemicals. Significant engine modifications may also be required on the high-compression, legacy fleet for operation on a lower-octane, unleaded fuel, which would likely result in changes to engine and aircraft performance and pilot-operating procedures. FAA testing has confirmed that significant detonation performance differences exist between unleaded and leaded fuels of the same octane.
The FAA William J. Hughes Technical Center entered into a Cooperative Research and Development Agreement (CRDA) with Swift Enterprises of Indiana. Under the CRDA, Swift developed a high-octane, high-heat-content, bio-renewable aviation fuel that has the potential for significant reduction in life-cycle CO2 emissions and has the potential to be produced inexpensively on a mass scale.
The Swift 702 fuel contains no alcohols or oxygenates.FAA William J. Hughes Technical Center researchers performed detonation and power performance tests on the Swift 702 fuel as compared to a locally purchased 100LL in two of the highest octane requirement engines in the fleet. A Lycoming TIO-540-J2BD and a Lycoming IO-540-K were evaluated on both fuels. A power baseline and detonation test was run in the IO-540-K engine, comparing the performance of the Swift 702 fuel to 100LL fuel, and a detonation performance test was run in a Lycoming TIO-540-J2BD engine. A full laboratory analysis was performed on the Swift 702 fuel to compare its results to the current leaded aviation gasoline specification ASTM D 910. The 100LL was also evaluated for octane and lead content.
The engines produced more than 98% of the peak power on the Swift 702 fuel as they did on 100LL. The Swift 702 fuel contained 96.3% of the energy content per unit mass as the 100LL. On a volume basis, the Swift 702 fuel contained 13% more energy than the 100LL. Operation on the Swift 702 fuel resulted in an average decrease in volumetric fuel consumption of approximately 8%.
The Swift 702 fuel met most of the current leaded aviation gasoline specification and outperformed the 100LL in detonation testing. Average exhaust gas temperatures were 50°F higher for the Swift 702 fuel. Further extensive endurance tests on the Swift 702 fuel are planned.
Table 1 shows that the Swift 702 fuel met almost all of the current ASTM D 910 leaded aviation gasoline specifications. The gas chromatography analysis showed that the fuel consists of two primary components, with all the other components comprising less than 1% by mass.
The fuel had a very high MON (104.4) and a very high performance number (159.6), which were well above the current required minimums. The Swift fuel heat content was 96.3% of the 100LL minimum specification. This would probably result in a slight drop in power. The T50, T90, and end distillation points were above the current specification limits. However, it should be noted that the high end of the distillation curve is where the high-octane components will lie. It will be very difficult to attain the same detonation performance of the current 100LL aviation gasoline without lead if the higher distillation points, typically expected with an aviation alkylate, are not increased. Previous FAA tests, in conjunction with the Coordinating Research Council (CRC), showed that equivalent detonation performance to the leaded 100LL was only attainable at least 10% volume-to-volume aromatic amine, or with a very high aromatic hydrocarbon-content fuel. It is unlikely that such a fuel will meet the distillation curve parameters chosen for the current performance of an aviation alkylate with lead.
Future full-scale engine endurance tests will verify whether there will be issues with oil dilution, nozzle and fuel system deposits, bearing failure, induction varnish buildup, or cylinder and valve deposits from using Swift 702 fuel.
