What is the minimum fuel temperature for Jet 1A?

[TO/GA]

On my last ferry flight at FL 410 OAT was -70 Celsius. B737-800 fuel temperature gage indicated – 35 Celsius. I was trying to find the minimum fuel temp. for the fuel but the AOM /vol 1/limitations gives you this brief:

“Minimum inflight tank fuel temperature: 3C above the freezing point of the fuel being used or -43C, whichever is higher.”

So what is the freezing point for Jet 1A?

[Scando]

Ops Info 1.1, Jet A-1: -47 degrees Celsius.

[Prof2MDA]

Actually, the freeze temp listed for the various fuel types (JetA = -40, JetA1= -47, JetB=-50, etc) is the most conservative fuel freeze point. Some carriers to measure the actual freeze point of the fuel pumped for that flight to prevent unnecessary diversion due to cold fuel.

[SuperRanger]

TOGA,

i am guessing that you must have flown rather close to the pole to get such cold temp? here's a good article by boeing about polar route operations. our company ferried a 777 back from seattle over the pole beginning of this year (and i mean OVER the pole). in fact they did a couple of orbit over the pole.

<a href="http://www.boeing.com/commercial/aeromagazine/aero_16/polar_story.html" target="_blank">http://www.boeing.com/commercial/aeromagazine/aero_16/polar_story.html</a>

SR

[Sick]

More likely a tropical routing for that temperature at that level, I think.

[Bellerophon]

Sick

Strange how many people assume it's colder (at altitude) over the poles than the equator.

A quick glance at the tropopause height should convince any doubters.

[TO/GA]

My route of flight was from Malaga to Stockholm. Lowest OAT temperatures were indicated after climb from FL390 to FL 410, between Paris and Amsterdam. Temperature started to climb after AMS and was highest at top of descent.

[Back Seat Driver]

If a varience of fuel types is used ie. Jet A1 from here, and Jet A from there, then it may take a few (2) fuel tank refills before the higher freeze point Jet A is considered to have all been used, thereby requiring the adhereance to a higher minimum fuel temp restriction in flight.

[GlueBall]

Are C130s landing at Antarctica (down to -60) using any fuel additive to keep from freezing? Anybody who knows?

[wondering]

What is the `normal` water content of Jet A-1? Since its density is closer to water, than let´s say 100LL, more water could be dissolved in it. Therefore, wouldn´t freezing water be a greater concern than freezing Jet A-1? If that is not the case then why are so many bizjet manufactures requiring to add Prist to the fuel?

[sparnell]

In reply to "wonderings" query:
There is no "normal" water content level for Jet A-1. Ideally it should have no water in it at all. When attending each aircraft, fuel company staff should do a water check (this is in addition to water checks carried out at the fuel storage facilities)at the commencement of refuelling. This is done by inserting a water sensitive cartridge into a fuel sample which then changes colour if water is present. The exact figure escapes me but I seem to remember from my apprentice days that water content should be no more than six parts per million. Can anyone offer the exact figure? Obviously water can still find its way into fuel through mishandling or condensation in the tanks and this is why fuel tank sumps are drained on a regular basis during routine maintenance(water being denser than fuel will sink to the lowest point in the tank). Large transport aircraft also have fuel scavenging systems which draw fuel from low points in the tanks and feed it to the inlets of the booster pumps thereby removing any water that may be present before it freezes. I don't have experience of biz-jets, but if they do not have such systems, this may be why they have to add anti freezing fluids to the fuel.

[LeadSled]

As will probably come as no surprise to anybody, certain major suppliers of JET A/JetA-1 ensure that the maximum water content allowed by the Mil. Spec/ASTM standard for the fuel is the water content.
Mind you, given the price people pay for water at the local supermarket, who is to say that somebody is being ripped off paying kero. prices for water.
The real problem comes with long delivery times, as the water comes out of solution. Beware ex-SIN fuel in YPDN or anywhere round that part of the world, as but one example.
Tootle pip!

[machone]

When the fuel filter bypass light comes on the fuel temp is too low. It does not need to be north of 56N for the fuel to cause the cabin temperature to rise!!!!!! <img src="confused.gif" border="0"> <img src="confused.gif" border="0"> <img src="confused.gif" border="0"> <img src="wink.gif" border="0">