Cold Fuel

[Brian Abraham]

A question to you high flying types from a bottom feeder (<5,000). Does fuel approaching its freeze point at high altitude an occurence which requires remedial action very often, or is it something only of consideration on polar routes?

Blue Skies,
Brian

[Intruder]

In the past 7 years on the 747, it has been of concern about 3 times.

[alatriste]

It usually takes a lot of time to reach the freezing point ( FP)when conditions outside are severe. When this point is reached do not think that the whole fuel will became solid, the queroxene will be still a fluid, first problems will arise at FP-10ºC know as Pouring Point.
If the FP is reached you have to "heat" your fuel, descending to warmer FL or speeding up. None of these remedies are very effective because it take a lot of time to warm up the fuel as well. If speed is increasd 0.01M, Rat will increase 0.5ºC after ONE HOUR depending on aircraft type, tanks considered and fuel quantity.

FP for JET A-1 -47ºC, and fuel is not usually served below 5ºC even in the most severe weather conditions.

If you want to know more check "Polar Route Operations". www.boeing.com/commercial/aeromagazine/aero_16/polar_story.html.

[OverRun]

The dreaded hyperlink truncation struck again - try this for the Boeing story

[Brian Abraham]

Thanks guys. It was from reading the Boeing URL that I raised the question.

[Confabulous]

Because a lot of aircraft now have 'wet wings', would turning on WAI have any effect on fuel temperatures? I'm guessing it could, but since WAI is not generally required at high alt it would never be used.

Any opinions?

Confab