😬 Is it possible to freeze your fuel lines on airplanes?!?!?
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I don't the original source for this, but this says 737-6/900 can go down to -43C before fuel freezes... so they are not far from there for sure. 🤯 Brrrrrr
https://www.scribd.com/document/834566484/Boeing-737-Limitations
@ai6yr
What I really want to know is there is why the 737-1/500 can tolerate -45C, but the 6/900 can only go to -43C
@PaulWermer @ai6yr The 737 Next Gen models had heat exchangers to take heat from the hydraulic systems and dump it into the fuel. The Jurassic 737s used pumps and engine heat, which could get more energy into the fuel but was inefficient and not as reliable.
Small decrease in capability in the interest of efficiency, which is not surprising in an airliner.
GFS says air at 40,000ft (they are at 39,000ft, flight level 390) is -65C.
To get down to warmer than 37C, they have to descend to somewhere slightly above 23,000ft, it appears.
So that must mean airplanes in polar vortexes/Canada/etc. must have to fly much lower in winter? (interesting)
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If ACARS Drama Jumpseat is correct, they immediately descended to 33,000 ft, which apparently was warm enough for the fuel, and then did a gradual descent to their destination and arrived safely. 🤷
@ai6yr huzzah!
Thermodynamics wins again!
@ai6yr BA38 accident at Heathrow a few years ago comes to mind, it was caused by ice in the fuel oil heat exchanger https://en.wikipedia.org/wiki/British_Airways_Flight_38
@ai6yr they would likely use Jet B, or an additive package to ensure the fuel flows at the expected temperature
Socializing with a B-52 fuels guy in North Dakota for 8 years has its trivia hazards
@ai6yr The fuel can gel, but it’s more likely condensed water freezing in the lines. They usually add a fuel additive called “Prist” which is like “Heet” for gasoline engines.
Water condensing in fuel tanks has been a very common issue in planes forever. There’s frequently a low point(s) in the system where water is regularly drained off.
https://www.univarsolutions.com/suppliers/pristaerospace/prist-anti-icing-fuel-additive
@LabSpokane @ai6yr I remember sampling fuel from a Cessna 172 tank and holding it up to look for water before takeoff. Of course, that particular plane also was carburated and had a “carb ice” lever to open and close the engine cowling a bit to thaw out the carburetor.
from the time i froze my radiator solid going 80 on the expressway, even with only "radiator fluid" in it.
guessing that there is probably still enough water in the fuel to freeze and clog the fuel line if it's cold enough...
@ai6yr it gets cold up there, insanely cold!
@ai6yr if I'm not mistaken jet fuel is more or less kerosene. And at right around -40 some of the distillates in it start to turn solid. Not all of them, bit enough that it can become a problem.