Variable clearance control for a gas turbine engine

In a gas turbine engine having an engine case and a rotating machinery section rotatably supported therein, seal means circumferentially surrounding the rotating machinery section and attached to said engine case, and a clearance control comprising means for directing cooling air on said engine case for cooling thereof, thereby controlling clearance between said rotating machinery and said seal means, an improvement comprising:

• cooling air control means for varying the amount of cooling air directed on said engine case, said cooling air control means comprising a bypass line in flow communication with a case cooling line for directing a portion of said cooling air from said case cooling line for the purpose of varying the amount of air provided to said clearance control, said bypass line being provided with a bypass line valve that is opened during appropriate engine operations to allow cooling airflow to enter said bypass line, said bypass line valve being controlled by fluid pressure;
• a pressurized fire extinguishing source incorporated into said engine;
• and
• a pressure line connecting said pressurized fire extinguishing source to said bypass line valve for the purpose of closing said bypass line during release of fire extinguishing material.