Differences Between Two Fuels Under Development Are Being Evaluated

The FAA continues to be committed to evaluating suitable replacement unleaded fuels to support general aviation. Phase Two testing of unleaded avgas continues, having completed two and a half years of testing and evaluation since the FAA's selection of the two finalists in the Piston Aviation Fuels Initiative (PAFI) replacement unleaded fuels program. To date, the flight test program is approximately one-third complete, while the engine test program is about halfway complete.

In an update on the program posted on the FAA website, the agency says that differences in the two PAFI fuels as compared to 100LL are being evaluated for impacts and mitigations. While these issues are assessed, PAFI flight testing and some engine testing have been halted. Both fuel producers, Shell and Swift, are currently evaluating options to mitigate the impacts that these differences will present in fuel production, distribution, and operation in the GA fleet. These evaluations will take time and ultimately affect the schedule of the test program. Based on current projected activities and timelines, the testing completion date for the PAFI program will be December 2019 (previously December 2018).

The FAA and industry are interested in pursuing all alternatives while issues are assessed including evaluating high-octane unleaded fuels currently being developed outside of the PAFI program. The FAA invited the fuel producers currently developing high-octane unleaded fuels to bring their data to the FAA for evaluation and consideration for possible detonation, operability, and performance testing at the FAA's William J. Hughes Technical Center. Fuel producers offering alternatives determined to have potential viability as an unleaded replacement for 100LL will be invited to participate in a Cooperative Research and Development Agreement with the FAA, which will be conducted on a non-interference basis with the PAFI program.

(Source: FAA)

FMI: Program update