Dual pressure control for a rotor brake actuator for vertical lift aircraft

A rotor blade rotation control master cylinder assembly for vertical lift aircraft, the assembly comprising:

• a master cylinder configured to be activated by movement of a rotor blade rotation control handle of a vertical lift aircraft to move pressurized hydraulic fluid through one or more conduits;
• a rotor brake actuator connected to the master cylinder and configured to engage a rotor brake of the vertical lift aircraft in response to receiving hydraulic fluid at a hydraulic fluid pressure from the master cylinder;
• a low pressure relief valve fluidly connected in parallel to the master cylinder and the rotor brake actuator, and configured to transmit pressurized hydraulic fluid away from the rotor brake actuator in response to the hydraulic fluid pressure exceeding a first pressure threshold of the low pressure relief valve;
• a high pressure relief valve connected in parallel to the master cylinder, the rotor brake actuator and the low pressure relief valve, and configured to transmit pressurized hydraulic fluid away from the rotor brake actuator in response to the hydraulic fluid pressure exceeding a second pressure threshold of the high pressure relief valve, the second pressure threshold higher than the first pressure threshold, wherein the low pressure relief valve can be isolated from the high pressure relief valve;
• and
• an isolation valve connected in series to the master cylinder and the low pressure relief valve, the master cylinder configured to push the hydraulic fluid at a first pressure to the rotor brake actuator in response to the isolation valve being open and to push the hydraulic fluid at a second pressure that is lower than the first pressure in response to the isolation valve being closed.