This SAE Aerospace Information Report (AIR) has been written for individuals associated with the ground-level testing of large and small gas turbine engines and particularly for those who might be interested in upgrading their existing or acquiring new test cell facilities.There are several purposes served by this document: a. to provide guidelines for the design of state-of-the-art ground-level enclosed test facilities for turbofan and turbojet engine testing applications; b. to address the major test cell/engine aerodynamic and acoustic characteristics which can influence the operation of a gas turbine engine and its performance stability in a test cell; and c. to consider acoustic environmental impact and methods to control it.