Greene Tweed believes it has solved one of the biggest hurdles in the widespread adoption of 100% sustainable aviation fuel (SAF): gasket and seal leakage. This problem arises due to the lack of aromatic compounds in neat SAF, which are necessary in legacy aircraft fuel systems for the proper function of synthetic rubber (nitrile) gaskets and seals in preventing leakage.
“Since there may be nitrile seals in both the legacy aircraft fuel systems (and in the refueling systems) that have been exposed to aromatic-containing jet fuel, any ‘drop-in’ SAF will still need to be blended with aromatic containing fuels,” said Ronald Campbell, senior technical advisor for Pennsylvania-based materials developer Greene Tweed.
According to the company, a recent study proves its elastomer seals made from FKM—a fluorinated, carbon-based synthetic rubber first developed in the 1950s for its ability to withstand high temperatures—could address that situation. Testing protocol simulated extreme aerospace environments, with temperatures up to 248 degrees F (120 degrees C) and prolonged exposure to SAF, both neat and blended.
“All three of our FKM compounds show consistent and acceptable swell and hardness change in the three straight 100% [SAF] fuels tested,” Campbell told AIN, citing the results of a recent test study. “Our findings therefore suggest that these compounds—and FKM compounds in general—do not require the fuel to contain an aromatic content.”