The FAA has re-evaluated its Piston Aviation Fuels Initiative schedule, reaffirming its commitment to develop a replacement for leaded avgas but delaying expected testing completion from December 2018 to mid-2020.

The new timeline focuses on testing of an unleaded fuel being developed by Shell—now the lone participant in PAFI following the elimination of Swift Fuels’ candidate fuel.

The FAA had halted testing last spring, calling for Shell and Swift to address concerns that emerged in data gathered in early phase tests.

In August, following a meeting of the PAFI Steering Group at AOPA Headquarters, AOPA reported on PAFI’s continued progress and plans going forward.

Before flight testing under PAFI resumes, preliminary work “will include clearing material compatibility, durability, detonation, and performance issues,” the FAA said.

Addressing the extension of testing into 2020, the FAA reiterated that “the PAFI mission endures,” noting, “although it will take additional time to realize this goal, it is essential to ensure a viable, safe, and economical fuel is ultimately authorized.”

“AOPA is encouraged to see Shell’s continued commitment and efforts to work on issues and come up with mitigations,” said David Oord, AOPA senior director of regulatory affairs. “We and the other members of the PAFI steering group were pleased to see that early results from their efforts look promising.”

Oord reiterated continued support of the government-industry efforts to identify, test, and authorize a general aviation fleetwide unleaded replacement for 100LL avgas, noting AOPA’s longstanding position that the resulting fuel must not require extensive changes to engines, aircraft systems, or fuel delivery systems.

“Ultimately, we are looking for the best fuel, whether it results from PAFI or other means.The goal is the same, regardless of the path we take to get there.”