Redundant valve system

A redundant valve system to provide a regulated fluid flow, comprising:

• a housing having an inlet at an inlet end which receives a pressurized fluid from a turbine engine, and an outlet at an outlet end which provides the regulated fluid flow of the pressurized fluid from the turbine engine;
• a first piston assembly arranged in the housing having a first cavity, the first piston assembly configured to regulate the fluid flow;
• a first fluid connection connected to the first cavity and to a point along the housing at the outlet end;
• a second piston assembly arranged in the housing downstream of the first piston assembly having a second cavity, the second cavity having a second fluid connection to a vent, the second piston assembly configured to regulate the fluid flow when the first piston assembly fails;
• an upstream valve to control the first fluid connection and control a position of the first piston assembly;
• and
• a downstream valve to control the second fluid connection and control a position of the second piston assembly,
• wherein the upstream valve is configured to close the first fluid connection, and
• wherein the downstream valve is configured to close the second fluid connection.