This SAE Aerospace Information Report (AIR) has been written for individuals associated with ground level testing of turbofan and turbojet engines and particularly for those who might be interested in investigating the performance characteristics of a new test cell design or of proposed modifications to an existing test cell by means of a scale model test. The purpose of this information report is two-fold: One of the primary purposes of this report is to provide guidelines for performing a scale model test of new configurations of and/or proposed modifications to a ground level enclosed test facility for turbofan and turbojet engine applications@ i.e.@ a jet engine test cell. Another important purpose is to address the major considerations when performing such a model test in the two main areas of the engine test cell model and the simulation of the engine. Requirements for the scale model test cell hardware and the associated instrumentation are presented and discussed. The requirements and considerations for the simulation of the engine are given@ along with some of the special considerations which should be made when air ejector systems are the motive power for the simulator.