The counterbalances are huge on the elevators and there is a great stress concentration right where your last hinge ends. During 3D like waterfalls with huge elevator throws and lots of power the propwash hits the counterbalance and wants to tear it off (due to the deflection the elevator presents a big cross section to the airflow and the elevator wants to bend back right where the last hinge stops). My first elevators were built entirely stock and did not last long because of this. My elevators now have less counterbalance and more corner gussets at this weakpoint and hold up fine.