Prist or no Prist . . . that is the question

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Diamondskip
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Prist or no Prist . . . that is the question

Post by Diamondskip »

I am going back and forth between the AFM and the Austro engine webpage.
The manual tells be that we should not use Prist and the Austro engine webpage tells be that can use 1500ppm of Print.
Scratching my head now :shock:
Problem is, that some FBOs provide only pre-mixed Jet-A.
Can anyone point me please to the proper answer?
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Re: Prist or no Prist . . . that is the question

Post by Soareyes »

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Re: Prist or no Prist . . . that is the question

Post by Boatguy »

Assuming you're buying Jet-A, as the manual says, you can use Prist. I've used it when, as you say, it's the only Jet-A available (usually at self serve). I've never had any problems.
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Re: Prist or no Prist . . . that is the question

Post by CFIDave »

You don't need Prist in an Austro/Continental diesel engine, but if it's already pre-mixed in with the JetA fuel you're buying, there's no problem with using it.
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Mjwatlanta
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Re: Prist or no Prist . . . that is the question

Post by Mjwatlanta »

Jet A1 has a freezing point of -47 degrees Celsius, and Jet A slightly higher at -40 degrees Unlikely we will see anything that cold. But we do have unavailable dissolved water in our fuel, and prist will protect us by somehow keeping it from becoming dangerous free water. From this article, https://aip.scitation.org/doi/pdf/10.1063/1.4977286, we see water % goes up with temperature but it comes out as temp goes down. The question to me is whether the temps at at our relevant altitudes are low enough enough to cause water to separate to the extent necessary to be a problem, See this article too: https://www.sciencedirect.com/science/a ... 6122027740.

FAA publication https://www.faa.gov/documentLibrary/med ... 20-125.pdf

Here is what a bunch of jet pilots have to say: https://jetcareers.com/forums/threads/w ... st.129714/

Bottom line, I can’t imagine ever needing prist for the flying im doing.
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Re: Prist or no Prist . . . that is the question

Post by MackAttack »

Good question and at least here in the Southeast US, fuel temperature exceedances on the low side would be very rare below FL180. In my Piper M600, Prist is required. Interestingly, the fuel heat system in the 600 is different than in the Meridian, so the fuel stays warmer in the 600 and I haven’t encountered a low fuel temp issue even when I fly at 290 and 300 in the winter. And most smaller FBOs I have been to with the Piper, it’s premixed. But good to know that I can get it with or without depending on what’s available.
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