a320 top wing frost
 

could anyone give me any information concerning frost that is formed on
top of airbus 320 wing during longer flights and how can this be avoided ? Most of airbuses have the same problem as i heard. Any information is appreciated thanks

the longer the flight, the longer the a/c is experiencing upto -56 degrees c. So one way of removing the frost as such is descending to lower altitudes.

c24

Hi Ori, as far as I am aware there is not problem with frost forming on the top surface of the wing during flight. Extended flight at high Flight levels can cause the fuel in the outer tanks to cool to Jet A1 limits, larger Airbus allow for the transfer of fuel from outer to inner tanks, options then are to increase Mach and or reduce flight level.
You do however find frost forming on the underside of the wings under the fuel tanks after flight with cold soaked fuel. If the transit is long enough you will also get the formation of clear ice on the top side of the fuel tanks dependent on atmospheric conditions. There are limitations for the frost underneath and no ice is allowed on the top. Avoided by reduced fuel load on transit and by uploading warmer fuel. Ultimately de-ice prior to departure.
hope that helps.

Something to consider when tankering. If you land with more than ~6T the cold fuel can cool the upper surface forming frost, the cost of deicing this if no warm fuel is available will be much more than what is saved by tankering.

Absolutely correct! Can't remember the 320, what we do on A300 is to x-fer fuel of the outer tanks into inner/ctr and refuel outer with warmer fuel. In most cases no deicing required. All on grd of course:ouch:

Have had this very issue on an A320 tankering fuel 3.5 hours to a destination with very limited, and sometimes no fuel availability - a perfect imprint of the fuel tanks in frost above the main and tip tanks on arrival. With an OAT of +13C on the ground and half empty main tanks, the frost soon dispersed above the mains. To remove the frost from the tip tanks which were of course still full of fuel at a chilly -15, we manually opened the fuel transfer valves allowing the fuel into the mains, and then having closed the transfer valves, uplifted warm fuel into the tip tanks. The frost cleared within around 10 minutes.

While operations with any type of frost on the upper wing is obviously absolutely no-go, the following study by Airbus makes interesting reading

SmartCockpit - Airline training guides, Aviation, Operations, Safety

It really depends how much time you have got.
I meet an A319 here that has flown for over 6 hours and the fuel temp is usually around M15degC. We have a long turn round time (3-4hrs) and a departure fuel of over 17tons. So the first thing I do on arrival is transfer all the fuel into the centre tank which fills the tanks with air at around zero deg nowadays. Then we refuel with fuel at around P3degC and depending on the conditions, manage to not deice many times.
To transfer 4 tons of fuel into the centre tank takes about 15 mins. So I suppose it could be a good idea to do this even on a one hour turnround. Just pumping it into the centre tank and out again would raise its temp quite a bit, especially if the OAT is well above zero, so the tanks are full of warm air for a while.
Transferring fuel to the centre tank is simple on an A320. Select the refuel switch to defuel (an orange lamp lights), switch the centre tank refuel switch to ON., open the crossfeed in the flight deck, and turn on the wing pumps. You will get ECAM cautions for centre tank auto feed, and wing tank low level, but just ignore them, but remember to turn off the wing pumps when before the low px lights come on.
If your dep fuel figure is below 12600 + arrival fuel, you will have to pump it back again to fill the wings for departure, but this can be done after refuelling.

a320 top wing frost
 

Thanks for the replies wold you think having the feul pumps running earlier would help the situation?

CX had a A330 diversion due to a sick passenger to Darwin ended up with ice/frost on the upper surface of the wing (lots of cold fuel with high humidity) resulted in a considerable delay. Not much de-icing in Darwin. :}

This is not only an A320-family problem. Happens on most airliners.

The A320 is somewhat less affected by this very phenomen because it heats up it's fuel a little (return fuel from the engine nacelles).

There is a widespread theory around that pumping the fuel around on the ground would ease the problem, but to my knowledge there is not much truth to it. Generally all fuel in one tank has more or less the same temperature, and the pumps themselves do not heat up the fuel.

hth,
Dani

@Dani

It's not about pumping fuel "around". The point is to get the cold fuel out of the critical tanks and replace it with warmer fuel out of the truck/fueling system. On A300 it works and we are doing it since decades.

regards