Refer to figure.
According to CAT.POL.H.215 (PC1) En-route – critical engine inoperative:

• The mass of the helicopter and flight path at all points along the route, with the critical engine inoperative and the meteorological conditions expected for the flight, should such that when it is intended that the flight will be conducted at any time out of sight of the surface, the mass of the helicopter permits a rate of climb of at least 50 ft/minute with the critical engine inoperative at an altitude of at least 300 m (1000 ft), or 600 m (2000 ft) in areas of mountainous terrain, above all terrain and obstacles along the route within 9.3 km (5 NM) on either side of the intended track.

Thus, the Figure 3.12 must be used with the following manner:

1. Enter with RoC 50 ft/min from the bottom left of the graph and draw a horizontal line to the right crossing all the mass curves.
2. Enter with the Pressure Altitude 10 000 ft from the top left of the graph (8000 ft terrain + 2000 ft safety margin = 10 000 ft PA).
3. Move horizontally to the right and intersect the temperature at +10°C.
4. Continue vertically down until intersecting the initial horizontal line emanating from the RoC 50 ft/min.
5. The intersection between the vertical and horizontal lines gives the Maximum Allowed Take-Off Mass so as to meet the Performance Class 1 requirements: 7100 kg.