getting to grips with COLD WEATHER OPERATIONS 寒冷天气运行(63)

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End point or final point is the fuel temperature at which all of the liquid will distill over into vapor.

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.JET A1. is by far the most frequently used fuel in civil aviation, (except in the USA and Russia), and has a maximum freezing point of -47°C and a mandatory requirement for a static dissipator additive. .JET A. is similar to JET A1 but has a higher maximum freezing point of -40°C, with an option for a static dissipator additive. It is primarily available in the USA. JP8 is similar to JET A1. It contains additives required by military users. TS1 is a Russian fuel similar to JET A1. RT (Russian) and TH (Romanian) are other commonly available kerosenes in Eastern Europe. These three fuels can be used if the individual fuel batches are re-qualified to JET A1 or JET A fuel specification. Alternatively, specific flight test or in-service evaluation before approval on Airbus aircraft can be considered.
● Wide-cut:
These are obtained by mixing kerosene and aviation gasoline. They have a low flash
point.
JET B is not widely used. It can be available in Canada and Alaska.
JP4 has not been produced since 1992 but can be found in military stock piles. It is being
replaced by JP8 that provides more safety.

● High flash point:
JP5, which is obtained by direct distillation, has a flash point higher than 60(C and very
low volatility characteristics.
It is almost exclusively used for naval operation aboard aircraft carriers.
This fuel is generally not found at civil airports.

D3 MINIMUM ALLOWED FUEL TEMPERATURE
D3.1 Published minimum fuel temperature
The minimum fuel temperature, published in the operational documentation, may be more restrictive than the certified aircraft environmental envelope. It includes two different limitations both linked to engine operation: Fuel freezing point limitation, and Fuel heat management system limitation.
a) Fuel freezing point limitation
This limitation provides an operating margin to prohibit operations under fuel temperature conditions that could result in the precipitation of waxy products in the fuel. The presence of wax crystals in the fuel is undesirable because of the risk of fuel lines and filters becoming blocked, with consequential effects on engine operation (instability, power loss or flame-out).

The resulting limitation varies with the freezing point of the fuel being used.
Aside from this, engines have a fuel warming (oil cooling) system at their inlet.
Because of the architecture of this system and the fact that the fuel inlet hardware varies
from one engine type to another, the specification of what fuel temperature is acceptable
at the inlet of the engine varies from one engine type to the other.

Therefore, engine manufacturers sometime require a temperature margin to fuel freezing
point to guarantee correct operation.

The engine manufacturer’s margins relative to the fuel freezing point are as follows:
　
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