Williams International Tests SAF On FJ44


Engine manufacturer Williams International announced on Wednesday that it has completed a successful flight test using 100 percent sustainable aviation fuel (SAF) in its FJ44-4 engine. The test flight lasted 3.5 hours with a maximum cruising altitude of FL450. It was conducted out of Williams’ flight operations center in Pontiac, Michigan, using the company’s experimental flying testbed.

“We have shown that Williams’ engines can utilize 100% SAF to decarbonize business aviation,” said Williams International CEO Gregg Williams, who also acted as copilot for the flight test. “The next critical step is to accelerate the production of SAF to make it more widely available and affordable.”

According to the company, it conducted “extensive material compatibility and endurance testing” prior to the test flight, which was captained by Williams’ chief test pilot Robert Lambert. The Williams FJ44-4 turbofan engine weighs 658 pounds and delivers 3,600 lbf thrust. It powers aircraft including the Cessna CitationJet and Pilatus PC-24.

Kate O’Connor works as AVweb's Editor-in-Chief. She is a private pilot, certificated aircraft dispatcher, and graduate of Embry-Riddle Aeronautical University.

Other AVwebflash Articles


  1. Really? So what? Try doing an energy balance evaluation on producing “sustainable fuels” . With the rush to power most vehicles using electricity no matter what, and the short and long term reductions in the use of petroleum of which the world will never run out, does this make any real world sense other than woke virtue signaling?

    • “reductions in the use of petroleum of which the world will never run out”: the Stone Age did not end because the world ran out of stone, it ended because humans came up with a better way of doing things. And the crucial thing with the word “better” is, better for whom? better to achieve what goals? To which my answers are, “better for most if not all humans”, and “to continue human civilization without large-scale conflict and suffering”. As for “energy balance evaluations”, start by putting a credible carbon tax on energy, and in other ways bring externalities into the price, and let free enterprise sort it out.

  2. Now, now calm down – how are we supposedly saving the plane ti f we cant use smoke and mirrors to prove it? No one wants to hear about energy density, input cost, renewables that cannot be recovered. That is opposite of the kool aid the eco scientists have been propagating. The important point is someone was able to burn some $20.00 a gallon bio goo in a jet engine at altitude, pay no attention to the realities of how it got produced.

  3. Fossil fuel remains relatively cheap and plentiful. The United States produces a lot of it, and almost unlimited reserves remain yet to be tapped. This represents much economic power for our country and efforts to ignore this are bad for our economy and security. I agree with Yars. This is an answer to a question that shouldn’t even be asked.

    The day will come, long after I’ve left this rock, when fuel may become more scarce and at that point people can find an alternative. At that point technology would have advanced to the point where there are practical options. That day is not today, and it’s not any time soon either.

  4. Worse for the poor people you want to take affordable portable energy away from.

    Worse for people who believe in rational thinking, objectivity, and humans.

    Data points:
    – it was warmer in the Medieval Warm Period, when Vikings farmed southwest Greenland, and in the Roman Warm Period’
    – the small amount of temperature rise is more in night lows than daytime highs, which is good because cold kills us and our food (plants, whether direct or via converters called animals)
    – rate of rise in sea level is not increasing significantly, has been steady since the end of the cold era circa 1750 AD, the era that was a reason Vikings left Greenland (see PSMSL.org)
    – rate if temperature rise has not changed either, according to accurate sensors such as weather balloons and satellites (other thermometer databases are not reliable due undocumented corrections and urban heating effect)

    Even the IPCC agrees that CO2 can only cause a small increase in average climate temperature, most of which has already been realized, but they theorize a positive feedback cycle involving evaporation and precipitation, which is not happening.

    Pilots should do homework not follow psychologically negative people’s anti-human fantasies.