The FAA has temporarily halted flight testing for its Piston Aviation Fuels Initiative (PAFI) unleaded 100LL replacement fuels program while issues related to the differences between the two PAFI fuels and 100LL are being assessed, according to a progress update issued by the FAA on Monday. “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,” said the FAA.
Some engine testing of PAFI fuels has also been stopped and the FAA has said it is interested in pursuing alternative high-octane unleaded fuels developed outside of the PAFI program while the assessment is taking place. If other potentially workable 100LL replacement fuels are found, the FAA will invite developers “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.”
The flight testing part of the PAFI program is currently about one-third complete and the engine testing is about halfway done, according to the update. With the additional evaluations needed, the end date for the PAFI program has been pushed from December 2018 to December 2019. “The overall goal of the PAFI initiative remains to authorize a fleetwide replacement fuel, and the best and brightest are working to realize that goal,” said AOPA’s David Oord, who is part of the PAFI steering group.
PAFI began in 2014, with the Shell and Swift fuels being selected for Phase Two testing in March 2016. Before this most recent development, the FAA’s last program update was issued at AirVenture 2017.