Airbus towing: is it necessary to switch on the Y HYD pump? So, somehow our operations came up with a new requirement: if one of our A320 or A340 is being towed, we are supposed to switch on the Y ELEC pump (if the engines are off). This shall prevent inadvertent retraction of the nose gear caused by the towing force.

Is this even mechanically possible for A320/A340 airplanes? I highly doubt it...
Please read fully the answer to understand the matter. 

Please be careful, with respect to the 320 it depends on the aircraft generation, as I remember if not all, some A320 landing gears are green operated. Nevertheless, by switching on the yellow electrical pump, the green circuit will be pressurized via the PTU, thus preventing the towing force to cause inadvertent retraction of the nose gear. 

This is just an explanation, not a procedure to be followed.