helicopters will go home when damaged - as do planes.
If an aircraft is damaged, the pilot does not
knowif the damage will bring him down eventually, or not till he gets the crate back to the mechanics at base.
Pilots do
not like the idea of falling out of the sky, so choose caution.
ANY damage that gets past an aircraft's armour protection (if any) is therefore an RTB item. (If damaged to the full extent of their survivability, it is crash in flames time.
However, Helicopters
CAN sometimes hang around for a move, before going back to base, especially if carrying troops, it gives you a chance to drop the pax on map. Depends on morale and experience, and if you can rally them. Though sometimes id rallied they will still go home. You cannot force a pilot with an unserviceable bird that may drop out of the air at any moment from returning to base.
Cheers
Andy