Hi, thx for your answer! Today new try, checklists as everytime. Normal start, normal autopilot flight. LNAV auto, VS "by hand" 1500ft/min. Normal pressure on the hydraulics display. 23min after departure:"beep beep beep"- alarm: yellow system out. "out" and "on" pressed, yaw damper on again: normal flight till the approach and landing. May be my fault is to use the electric hydraulic pumps and both PTU's? all three green lamps "on" like I know it from the XPlane-11 A320...thx for your help!