The 4 bladed Bell 430 is designed for our turbine mechanics Ord.No. 1002/67, alternatively the PHT3-L mechanics can be used from JetCat. The important point is the choice of turbine: the max permissible speed of the four-blade head is 850 rpm, the 4 rotor blades generate such high torque that it is not feasible to use all the available turbine reduction ratios. If you wish to use a higher rpm, the only option is a 2 blade rotor head.