With this spate of very cold weather ...I have always wondered about Aviation Fuel...

[michal 44]

 

 

it was the water content which was suspended in the jet fuel that turned into ice.

That's correct.

By the way, fuel quality wasn't a factor here, it didn't contain abnormal amount of water.

[AviatorMoser 353]

I've had the PMDG MD-11 fuel freeze up on a polar flight once. Makes for an interesting scenario.

[Sesquashtoo 2,846]

To put the BA accident in simple term, it wasn't the fuel which turns into ice and blocked the FOHE inlet, it was the water content which was suspended in the jet fuel that turned into ice.

 

Although the refueler always do a water check at during refueling stage, it's inevitable that some water content is suspended in the fuel. Imagine 0.1% water content of 100Tons of fuel is still a substantial volume of water (~125L of water).

 

When pure 100% jet fuel temperature approaches the fuel freezing point, it turns into a gel type of "liquid" which makes it harder for the fuel pump to pump it towards the engine, until a point where it turns into a gel completely and exceeds the fuel pump capability.

Right....not the water making its way into the fuel, per se....as I made the reference to gelled diesel fuel (like 'Vaseline' in my O.P.) that transport trucks, and diesel powered cars might have to deal with, but I thought they (commercial aircraft)would have fuel separator technology to trap any moisture and evaporate/release it to atmosphere, before it made it (any actual water content) into the lines on the fuel's way towards the engines. Obviously, modern aircraft seeming, do not at this time.  Yes, 'gelled' fuel at extremely low, frigid temperatures was the thrust of the topic. I am glad to see that there is/are standards and crew action/methods in place to deal with the physics of jet fuel, to not be at a point of temperature, to compromise the flight, the next time I board as a passenger!  It was a question that I had never asked myself, or I wonder, has other's here, themselves....

I've had the PMDG MD-11 fuel freeze up on a polar flight once. Makes for an interesting scenario.

Are you kidding me?!??!  That was coded into the PMDG plane simulation?  

[AviatorMoser 353]

Oh yeah, the fuel management on the MD-11 is simulated quite well. Realistic cooling and heating gradients applied to the fuel temperature based on the TAT.

[Sesquashtoo 2,846]

Oh yeah, the fuel management on the MD-11 is simulated quite well. Realistic cooling and heating gradients applied to the fuel temperature based on the TAT.

WOW.....wow.......

 

Mitch

[Spam3d 54]

 

 

I thought they (commercial aircraft)would have fuel separator technology to trap any moisture and evaporate/release it to atmosphere, before it made it (any actual water content) into the lines on the fuel's way towards the engines. Obviously, modern aircraft seeming, do not at this time

 

Sometimes certain designs create unique circumstances like the FOHE that RR used, The oil system is going to be nice and warm by the time its gone through each cooler, the GE90 coolers have larger fuel matrices in them, probably why its never been an issue for the 90's. The initial fuel lines into the main fuel pump is about 3" in diameter and other engine piping is around 1/2" so no problems are going to arise in there

[FormerSF3 15]

We are supposed to check the fuel temp prior to the descent.  If it's below 0 C, we are to turn on the fuel heat to clear out any ice that might have formed in the filters.  What I have heard is that you won't know there is ice until there is a large demand of thrust from the engines.

[Sesquashtoo 2,846]

We are supposed to check the fuel temp prior to the descent.  If it's below 0 C, we are to turn on the fuel heat to clear out any ice that might have formed in the filters.  What I have heard is that you won't know there is ice until there is a large demand of thrust from the engines.

....and that seemingly played out with British Airways's flight 38 on the triple 7...  The First Officer requested full throttle add-on for power...and saw only the engines spoiling down for his effort.....at less than a thousand feet above ground....