I know, the only refrence made is in
FCOM 1.27.00 Description:
"
Mechanical control from the pitch trim wheel has priority over electrical control."
and
Flight controls normal law.
Automatic pitch trim is frozen in the following cases:
– Manual trim order
- ......
I've read that during training crew is prohibited to touch the wheel,
IMO that's a shame, they should know the dangers and benefits of such action.
To be exact:
In Direct LAW it is PFD amber message "USE MAN PITCH TRIM"
in backup (Elevator not available) the message is red "MAN PITCH TRIM ONLY"