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LOW FUEL TEMPERATURE
Fuel temperature changes relative to total air temperature. For example, extended operation at high cruise altitudes tends to reduce fuel temperature. In some cases the fuel temperature may approach the minimum fuel temperature limit.
Fuel freezing point should not be confused with fuel ice formation caused by frozen particles. The fuel freezing point is the temperature at which the formation of wax crystals appears in the fuel. The Het A fuel spesification limits thee freezing point to -40C maximum, while the Jet A-1 limit is -47C maximum. In the Commonwealth of Independent States (CIS), the fuel is TS-1 or RT, which has a maximum freezing point of -50C, which can be lower in some geographical regions. The actual uplifted freezing point for jet fuels varies by the geographical region in which the fuel is refined.
Unless the operator measures the actual freezing point of the loaded fuel at the dispatch station, the maximum specification freezing point must be used. At the most airports, the measured fuel freezing point can yield a lower freezing point than the specification maximum freezing point. The actual delivered freezing temperature can be used if it is known. Pilots should keep in mind that some airports store fuel above ground and, in extremely low temperature conditions, the fuel may already be close to the minimum allowable temperature before being loaded.

For blends of fuels, use the most conservative freezing point of the fuel on board as the freezing point of the fuel mixture. This procedure should be used until 3 consecutive refuelings with a lower freezing point fuel have been completed. Then the lower freezing point may be used. If fuel freezing point is projected to be critical for the next flight segment, wing tank fuel should be transferred to the center wing tank before refueling. The freezing point of the fuel being loaded can then be used for that flight segment.

Fuel temperature should be maintained within AFM limitations as specified in the Limitations chapter of the FCOM.

Maintaining a minimum fuel temperature should not be a concern unless the fuel temperature approaches the minimum temperature limit. The rate of cooling of the fuel is approximately 3C per hour, with a maximum of 12C per hour possible under most extreme conditions.

Total air temperature can be raised in the following three ways, used individually or in combination:
- climb or descend to a warmer air mass
- deviate to a warmer air mass
- increase Mach number.
Note: In most situations, warmer air can be reached by descending but there have been reports of warmer air at higher flight levels. Air temperature forecasts should be carefully evaluated when colder than normal temperatures are anticipated.

It takes from 15 minutes to one hour to stabilize the fuel temperature. In most cases, the required descend would be 3000ft to 5000 feet below optimum altitude. In more severe cases, descend to altitudes of 25000ft to 30000 ft might be required. An increase of 0.01 Mach results in an increase of 0.5C to 0.7C total air temperature.
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LIMITATIONS - Fuel System
Maximum tank fuel temperature: 49C
Minimum inflight tank fuel temperature: 3C above the freezing point of the fuel being used or -43C, whichever is higher.
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BOEING FCTM ve FCOM dan alıntılar.
Ne kadar zamanda bir olduğu konusunda saatte bir gibi bir fikir edindim; yukarıdaki yazıdan. Ama regülasyon olarak bir kuralı var mı bilemiyorum. Ben bulamadım.

Yukarıdaki yazıda biraz durumlardan bahsetmiş sadece ama yakıtın sıcaklığını ne nasıl düşürür neler etki eder? Biraz RAŞİT EGE yine olaya dahil oluyor burada sanırım detaylı bilgi için Smile

not: bir de bunu buldum güzel bişey http://www.iasa.com.au/folders/Safety_Issues/RiskManagement/cold_fuel.htm

not2: http://www.aaib.gov.uk/cms_resources.cfm?file=/1-2010%20G-YMMM.pdf Londra'da düşen tek 777 kazası, sebebi fuel temperature idi, raporu incelenebilir aynı zamanda...
GORKEM ACIKGOZ2012-09-09 13:25:07

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HAKAN SAHIN

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GORKEM ACIKGOZ

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HAKAN SAHIN

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RASIT EGE

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