The 2556 pneumatic control heads were designed for controllable pitch (CP) propeller and engine speed functions. The longer handle will actuate 2 pressure regulating valves, providing "0" pressure for "0" pitch, and in case of failure, the CP actuator will return to "0" pitch position.
The 2556 is available with illuminated side scales and has a maximum supply pressure of 150 PSI (10.3 BAR) and 1/8" NPT.