OS Engine MAX 55HZ-RThe latest engine in the 600 50 helicopter class borrows much of its technology from the fabulous Max 91HZ R, to provide class leading power under the most demanding of 3D manouevres. The latest DRS system (Demand Regulator System) uses a crankcase pressure tap off to pressurise the fuel tank via a one way valve. The pressurised fuel is then carfully regulated at the carburettor to provide the optimum mixture no matter what demands are placed on it.