THS in the Airbus A320/21/19...
Sorry for the question that in as far as operating an Airbus goes comes from a plain simmer mindset here :-)
I have 3 different behaviour of the THS as operated manually using the trim wheels...
1) It requires at least the Hyd Elec Pump to be on in order to be able to set it, even being able to move the wheels, for setting the proper trim for takeoff;
2) With the APU running, it is also possible to use the trim wheels;
3) It's only possible to use the trim wheels if either the Hyd Elc Pump OR the engines are running;
What is the typical flow ? Will the crew set the trim while still at the gate with engines stopped, and even before APU start, or is this unusual ? And in this case, for instance for when there are problems with the APU and they don't want to start it, they have to switch on the Elec Hyd Pump in order to be able to set takeoff trim ?
Or, will it be possible and actually done only after APU is running ?
Thx for any enlightenment :-)