This is a very simple way to check wether your power will be sufficient for a landing.....
1. Approach the area and bring the helicopter down to the obstacles.
2. Before reaching your area, reduce airspeed as much as possible, but keep it above translational lift-airspeed (mostly 18-25 knots)
3. Keep the heli with that speed straight and level (Vario=0) when flying over the are.
4. Check Torque/Power.
If your power leaves a minimum of 10% to max torque available, you can safely land (regarding to the wind...) and climb out of the area again....