The FAA has released some details and photos as the first phase of testing draws to a close of four fuels designed to be a replacement for 100LL.
According to a report at AOPA.org, test rigs have been heated and cooled to extreme temperatures, fuel samples have been run through specially designed rigs replicating aircraft fuel systems on a bench, and ignition temperatures have been carefully measured, to name just a few of the tests designed to winnow down the candidate fuels that will be put through the second, and final, phase of testing that will begin in 2016.
That phase, which will include real-world testing in a variety of aircraft, is scheduled to conclude in 2018.
Source: http://generalaviationnews.comFAA releases details on avgas replacement testing