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Whilst taxiing out at Beijing the TAT was -6°C , and
the fuel temperature, measured in the left main fuel tank, was -2°C.
The aircraft took off at 0209 hrs.
The aircraft climbed to a pressure altitude of 10,590 m, where, at 0232 hrs, it levelled off into the cruise portion of the flight.
The TAT had reduced to -25°C with the fuel temperature remaining at -2°C at this time.
Two hours into the cruise (0432 hrs) the TAT had progressively reduced to -33°C and the left main tank fuel temperature was about -22°C.
During the next three and a half hours (0800 hrs) the fuel temperature reduced further from -22°C to -32°C , in line with further reductions in TAT.
At 0842 hrs the aircraft made the first of two cruise step climbs, climbing from 10,590 m to 11,610 m.
Prior to the second step climb, the aircraft made a minor flight level change to FL380 as it crossed international air traffic control boundaries.
At 0931 hrs, fuel temperature reduced to its lowest recorded value of -34°C . It remained there for about 80 minutes during which the lowest value of TAT of -45°C was recorded.
0232 hrs, 34750 ft, TAT -25 °C, Fuel -02 °C
0432 hrs, 34750 ft, TAT -33 °C, Fuel -22 °C
0800 hrs, 34750 ft, TAT -xx °C, Fuel -32 °C
0842 hrs, 38100 ft, TAT -xx °C, Fuel -xx °C
0931 hrs, StepCL#2, TAT - xx °C, Fuel -xx °C
1051 hrs, xxxxx ft, TAT - 45°C, Fuel -34 °C
Entre 0432 hrs et 1051 hrs, soit une durée de 06h19', la TAT est passée de -33 à -45 °C.
En 03h30 de croisière, la température du fuel passe de - 22°C à - 32°C soit une diminition de 10 °C .
Je me demande bien pourquoi la température de fuel passe seulement de - 32°C à -34° C pendant les 02 h 50' suivante.
Je ne pense pas que le 777 soit équipé d'un Fuel heating system (heat exchanger).
Suivant le descriptif du B777 Fuel System, la limite "température minimum" du fuel est de - 37° C.
http://www.smartcockpit.com/pdf/plane/b ... tems/0008/
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