getting to grips with COLD WEATHER OPERATIONS 寒冷天气运行(66)

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. An extended environmental envelope has been approved only for A300-600 and A310 aircraft fitted with the fuel temperature indication system (figure D3).
However, the full benefit of this extended envelope may be limited by the tank fuel temperature limitation.

D3.3 A319/A320/A321
A fuel temperature sensor is installed in each outer and inner cell on the A319 and A320, and in each wing tank on the A321.
Different means are provided to avoid flying below minimum allowed fuel temperature:
.
The Flight Manual mentions: .When using JET A: If TAT reaches -34°C, call ECAM fuel page and monitor that fuel temperature remains higher than -36°C..

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An ECAM advisory is activated as soon as fuel temperature in any tank reaches -40°C

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An ECAM warning .FUEL OUTER / INNER (FUEL WING on A321) TK LO TEMP. is activated when fuel temperature in any tank reaches -45°C. On ground before takeoff, this warning is associated with .DELAY T.O. message.

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D3.4 A330/A340
A fuel temperature sensor is installed in each inner tank, in the trim tank and in the LH outer tank.
The ECAM displays the appropriate information according to the actual fuel temperature.
.
 If INR TK fuel temperature < -35°C (-37°C on A330) (-40°C for OUTR TK or TRIM TK) the message .IF JET A. appears together with the appropriate procedure (delay takeoff if on ground or transfer fuel in flight).

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This caution is automatically recalled if INR TK fuel temperature < -42°C (-44°C on A330) (-47°C for OUTR TK or TRIM TK). In this case .IF JET A. is not displayed.

.
For both cases occurring in flight the ECAM also displays the following message:

.IF NECESSARY:
TAT ........................................ INCREASE.

The first occurrence copes with JET A fuel which may have a freezing point up to -40°C. It complies with the 5°C margin requested for CFM engine on A340, and consequently with the 3°C (GE) and 0°C (PW and RR) on A330.
The second occurrence deals with JET A1 fuel freezing point (-47°C) and all other fuels having a lower freezing point and also complies with all engine manufacturers margins.

D4 MAXIMUM ACCEPTABLE FUEL FREEZING POINT

D4.1 Wish expressed for JET A1 freezing point relaxation
The limit on freezing point in the jet fuel specification is one of the major constraining
factors as to how much jet fuel can be made from a particular crude oil.
In other words, the lower the freezing point, the lower the yield of fuel obtainable
from the crude oil.

This was highlighted during the second .oil shock. in 1979 when, to increase fuel
availability, a relaxation of the JET A1 specification freezing point from the (then) limit of
-50°C maximum was proposed.
Analysis of in-flight fuel temperatures by airlines concluded that a freezing point of -47°C
　
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