If it helps, these numbers served me well in Canada:
For a quick and dirty power check in the Bell 206, if you approach at 60 kts and 250 fpm ROD, the torque reading will approximate what will be needed in the hover. This is because 250 fpm reduces the thrust required to transition into the hover by about 15%, which is much the same as for ground effect and there should be minimal collective movement at the end as the machine will stop by itself anyway if you have ground effect.
More formally, you need to find the distance between the bucket speed at the bottom of the power curve and the power available. At a safe height near the landing site, fly straight and level into wind at the best rate of climb speed. Note the power used.
Then apply maximum power to see what is available. Subtract 10% and remain within the resulting value.
Here are the figures for a Bell 206:
Departure. Note the N1 in a 2-foot hover and increase the power until a 5-minute takeoff power limit is reached (Torque, N1 or TOT). The difference is your power margin.
N1 Margin (%) Takeoff
1 Cushion Creep*
2 Shallow Climb
3 Steep Climb
4 Towering
5 Vertical
*Not allowed under EASA Operations rules.
N1 is used because it provides a steadier reading.
With a 206, 10% is more than enough to clear a confined area.
Arrival. From straight & level at 200 feet above the site at 40 kts, note the N1 and increase the power until a 5-minute takeoff power limit is reached. The difference is the margin.
N1 Margin (%) Approach/Landing
4-5 Running Landing
6 Zero Speed
7 Normal to low hover
8 Normal to high hover
9 Steep to high hover
10 Vertical Approach