FlightControl Computer Actuator Controller Command Electric (Low) Power Motor Controller Torque Motor Electric (High) Power Secondary Supply Power Electronics Spool Valve Feedback Hydraulic Actuator Flight Surface EHSV EngineDriven Generator Motor Pump Hydraulic Manifold EngineDriven Pump Hydraulic (High) Power Primary Supply FlightControl Computer Electric (Low) Power EngineDriven Generator Electric (High) Power Command Figure 3. The simplified block diagram architecture of an EBHA. Actuator Controller Feedback Motor Controller Power Electronics Motor Pump Hydraulic Actuator Flight Surface Figure 4. The simplified block diagram architecture of EHAs. source as opposed to hydraulic power. EHAs have hydraulic cylinders similar to a conventional hydraulic actuator but use a local pump for the hydraulic power source. This allows the benefits of electrical power transmission coupled with the benefits of hydraulic actuation. The high-level block diagram architecture of an EHA is shown in Figure 4. 42 I E E E E l e c t r i f i cati o n M a gaz ine / DECEMBER 2017 The A380 system engineers chose to stay with hydraulics as the transmission media over EMAs for the following reasons (van den Bossche 2006): xx The jamming of a hydraulic cylinder is accepted as extremely improbable based on experience. The probability of an EMA jamming is difficult to substantiate based on the lack of service experience.