Question about Flight Control Power Control Units
 

Hello,

I am doing some study of the CRJ and my systems study guide mentions that the rudder and elevators use power control units connected to a hydraulic system. However, the explanation is a bit unclear. So, can someone please give me a simple breakdown in plain english?

What is a power control unit in detail?

For example, moving the control column back, moves the control cables, which does what to the power control unit and what does the power control unit do to the rudder???

Thank you.

Moving the control column back, moves the control cable that controls the control valve (or servo valve) in the PCU porting hydraulic fluid under pressure to the actuator. The PCU actuator moves the rudder. In simple words.

Ever see a door cylinder on a self-closing door? A PCU looks a lot like that.

A powered flying control unit (pfcu) is a hydraulic actuator (A jack).

Moving the cockpit controls moves a selector valve in the pfcu. This controls the flow of pressurised hydraulic fluid to move the pfcu. This in turn moves the control surfaces.

If you do an internet search for powered flying control unit you hold find lots of links, many with good clear illustration.