Helicopters must take off and land in suitable places. There must be a helipad, significant clearing (30-40 metre radius), away from buildings, away from roads, etc.
Helicopters RDM will result in ban.
Terrorist attacks using helicopter are forbidden.
Abusing helicopters to avoid RP is forbidden.
Helicopters cannot be stolen in RP - you are not certified to fly this vehicle.
Committing crimes and breaking rules can risk your aviation licence, which costs $200k to replace and potential confiscation of the aircraft.
Staff can determine whether your behavior in a helicopter is acceptable.