A fun thing that Rust has is a patrol helicopter that roams around the map. To damage it you can either shoot the entire thing anywhere which deals minimal damage, or the rotors to deal alot of damage. I thought it would be cool that if you shot the thrusters on the VTOL, or the back ones near the back end (I think there's thrusters there too) then it will deal more damage.
TL;DR: VTOL Takes more damage from the thrusters being shot.