View Full Version : A320 Low Outer Tanks Fuel Temperatures
Hi,
would manual opening of the Transfer Valves be an option to avoid fuel burn after a neccessary descent and/or speed increase ?
Yes, I read about " structural integrity " and " reduction of wing tip flutter at some high Mach Nos. & FL's ", apart of the applicability of SOP`s.
Cheers RvB.
TopBunk
12th Feb 2010, 16:29
The BA guys flying the A318 JFK-LCY have been experiencing the outer tanks approaching fuel freeze point (with the lower -40deg C Jet A fuel ex-USA and very cold temps in the last couple of months).
As I understand it, there is no approved Airbus procedure to facilitate early fuel transfer and as such it is not permitted.
Endeavour
12th Feb 2010, 16:57
On the A320 the fuel used for IDG cooling is returned to the outer tanks, so the fuel temp is usually warmer in the outer tanks than it is in the inner tanks.
TopBunk
12th Feb 2010, 18:02
On the A320 the fuel used for IDG cooling is returned to the outer tanks
Yes, but if the outer tank is already full, the fuel overflows to the inner tank.
That leaves it a bit vague as to whether some or all off the IDG cooling returns to the inner wing tanks if the outers are full.
Getting back to my point, I am reporting what the actual experience on the A318 has been - forget theory.
rooaaiast
12th Feb 2010, 18:41
On the 320, outer to inner transfers automatically when inners go below 750kgs, no pilot input.
Personally as a rule of thumb, when the FL+30 is close to the OAT, it's time to get out FCOM3 & see if its time to drop down.:8
Endeavour
12th Feb 2010, 19:06
I am reporting what the actual experience on the A318 has been - forget theory
I've been flying the A320 series since 1999, so my statement is not based simply on what is written in FCOM 1.
FCOM 1.28.10
FUEL RECIRCULATION SYSTEM
Some of the fuel supplied to each engine goes from the high-pressure fuel line in that
engine, through the integrated drive generator (IDG) heat exchanger (where it absorbs
heat), to the fuel return valve, and to the outer fuel tank.
This operation ensures the IDG cooling when the oil temperature is high or when at low
engine power.
The FADEC controls the fuel return valve.
If the outer tank is already full, the fuel overflows to the inner tank through a spill pipe.
I don't ever recall seeing outer tank temeratures less than inner tank temperatures in flight.
PappyJ
13th Feb 2010, 06:14
I don't ever recall seeing outer tank temperatures less than inner tank temperatures in flight.
Been flying A320's and A330's since 1992, and can recall that on the A320 temperature differences between the outer and inner tanks are quite common. However, it's not a series issue even for the type of extended operations that are being discussed here, Reason, that outer tank fuel remains in the outer tanks until the inner fuel is down to a predetermined level. Then, it is basically dumped into the inner tank where it is mixed with fuel that is much warmer.
A321's are different, as they do not have an inner and outer. A330's are significantly different, as the fuel moves around all over the place.
With a SAT of -73°C on a four and a half hour flight I saw -28°C in an inner tank and -40°C in an outer Tank.
-73 is outside the enviromental envelope of our Airbus aircraft - shouldn't be planned or operate in those temps - aircraft isn't certified for it.
kijangnim
13th Feb 2010, 08:26
LYKA :ok::ok::ok:
Just a note for anyone using JetA from the States. I have been operating out of there for many years and we pay to have the actual fuel freeze temperatures checked. This involves taking three samples, one at the start, one during and one at the end of refueling. The worse case of the three is the declared as the fuel freeze temperature for fuel loaded. I have never come across any JetA fuel that would freeze below -45C and it is often much better than that.
Wingswinger
14th Feb 2010, 18:55
Outer fuel temperatures much cooler than inner is normal on A319/320. When in the descent, the outer usually warms up possibly due to spill-back from the IDG cooling circuit.
There are two CBs on VU49 overhead for the FUEL TXFER VALVES. Pull them and, BINGO, the valves open and the outer fuel transfers. We used to do it in the company I worked for when I first converted to the A320 (11 years ago) because some old lags didn't trust the auto system! It's not an approved technique of course but the knowledge just might get someone out of a sticky situation sometime.