A reliably redundant PCU for an aircraft. The PCU includes an override mechanism
coupled to the aircraft's control path and a first control member coupled to the
override mechanism whereby the override mechanism attempts to transmit a command
from the command path to the first control member. The unit also includes a second
control member coupled to the control path whereby the command path transmits the
command to the second control member. Additionally, the PCU includes two actuator
members coupled to the control members whereby the actuator members attempt to
move in response to the command. If the first control member resists moving the
override mechanism allows the second control member to actuate the rudder. The
PCU also includes a common actuator coupled to the actuator members and the control
surface, whereby the actuator moves the control surface. Moreover, a unitary housing
contains the first and the second actuator members.
