Dual valve system with mechanical linkage

A gas turbine engine comprising a pneumatic system, the pneumatic system comprising:

• a first pneumatic tube configured to receive a first airflow from the gas turbine engine;
• a first valve body coupled to the first pneumatic tube;
• a first valve disc operably disposed within the first valve body, the first valve disc having a first disc geometry;
• a second pneumatic tube configured to receive a second airflow from the gas turbine engine;
• a second valve body coupled to the second pneumatic tube;
• a second valve disc operably disposed within the second valve body, the second valve disc having a second disc geometry;
• and
• a mechanical linkage operably coupled to the first valve disc and the second valve disc, wherein the second disc geometry differs from the first disc geometry such that opening of a first flow area between the first valve body and the first valve disc occurs prior to opening of a second flow area between the second valve body and the second valve disc responsive to movement of the mechanical linkage, wherein the first disc geometry comprises a uniform thickness of the first valve disc, and the second disc geometry comprises a tapered thickness increasing radially outward from a pivot point of the second valve disc, and wherein a first outer edge of the first valve disc forming the first flow area has a first thickness that is less than a second thickness of a second outer edge of the second valve disc forming the second flow area, and the second valve disc has a partially spherical outer diameter.