Jet fuel Freeze?

[jimmyw]

The other day at altitude in a lear the outside temp was in the minus 70's.Yes we have fuel heaters to avoid fuel system ice,however am wondering in the tanks is there a temp jet fuel (with no additive)tends toward freezing ?
Also how long does it take all the pressurized air to be completly replaced at altitude in a lear 31 or 35 or comprable corporate jet.

 

[TrafficInSight]

The other day at altitude in a lear the outside temp was in the minus 70's.Yes we have fuel heaters to avoid fuel system ice,however am wondering in the tanks is there a temp jet fuel (with no additive)tends toward freezing ?
Also how long does it take all the pressurized air to be completly replaced at altitude in a lear 31 or 35 or comprable corporate jet.

-40 for Jet A and -47 for A1.

 

[User546]

-40 for Jet A and -47 for A1.

That's Celcius I assume?

 

[TrafficInSight]

That's Celcius I assume?

affirmative, my physics teacher would be ashamed

"UNITS UNITS UNITS, -40 what? monkeys?."

 

[$$$4nothin]

no it is -40F. Think about it for a minute

 

[TrafficInSight]

no it is -40F. Think about it for a minute

I know -40c and -40f are the same but -47c is -53f so:smash:

 

[minitour]

I know -40c and -40f are the same but -47c is -53f so:smash:

We should all just go to Kelvin....

-mini

 

[satpak77]

http://www.csgnetwork.com/jetfuel.html

http://www.chevron.com/products/prodserv/fuels/bulletin/aviationfuel/1_at_fuel_intro.shtm

Chevron says -40 C

 

[Lead Sled]

The other day at altitude in a lear the outside temp was in the minus 70's.Yes we have fuel heaters to avoid fuel system ice,however am wondering in the tanks is there a temp jet fuel (with no additive)tends toward freezing ?
Also how long does it take all the pressurized air to be completly replaced at altitude in a lear 31 or 35 or comprable corporate jet.

Fuel heaters in a Lear 35? It's been over 10 years since I last flew a 35, but as I remember, they required the additive because they didn't have fuel heaters. I don't know about a 31 however. In the 35, you also have the fuel in the fuselauge tank which tends to stay warmer than the fuel in the wings. As that fuel is transfered, it will "warm up" the fuel in the wings.

The issue is addressed in various ways in various airplanes. In some airplanes, the fuel is constantly being recirculated; other aircraft have heat exchangers have heat exchangers in the tanks; etc. It's really not that much of a problem except on extended flights - for example, early on, BBJs had a problem with fuel temperature on some of their extreme long-range flights.

As far as how long does it take to exchange the air in the cabin of a corporate jet? I don't have the exact numbers and, of course, it would depend upon a lot of different variables. I do know that it will take longer that you might believe. We were testing our Lear for cabin leaks and one of the tests we had to perform was a cabin bleed down test. Once we found and sealed all of the leaks it actually took quite a while for the cabin to bleed down. It makes sense when you think about it - that's why one of the steps on most "Smoke and Fume Removal" checklists is to dump the cabin [open the outflow valves].

'Sled

 

[Bandit60]

To add what Sled said. The lears that I have flown with fuel heaters (Lear 60 and 31A). There is a limitation that says when it gets below -60 (I think that is the temp but Im not sure) you are restricted to 800 pounds of fuel in the wings. The rest of the fuel must be in the fuselage tank to keep it warm.

Please someone correct me if I am wrong.