Environmental control system including humidity sensor

An environmental control system of an aircraft, comprising:

• a primary heat exchanger;
• a secondary heat exchanger;
• and
• an air cycle machine including:
• a compressor fluidly coupled to an outlet of the primary heat exchanger and an inlet of the secondary heat exchanger;
• a dehumidification system arranged in fluid communication with an outlet of the secondary heat exchanger;
• a first turbine fluidly coupled to an outlet of the secondary heat exchanger;
• a second turbine disposed downstream of the first turbine that receives air from the first turbine in a normal mode;
• and
• a first humidity sensor disposed fluidly between the first turbine and the second turbine that measures humidity of air that has left the first turbine as the air enters the second turbine in the normal mode;
• wherein the first humidity sensor includes an inlet and an exhaust;
• wherein the second turbine receives the air via a second turbine inlet;
• wherein the inlet is connected to the second turbine inlet such that air is directed from the second turbine inlet through the first humidity sensor to the exhaust.