This paper will discuss the effects of flow and pressure transients on axial flow fans. A brief review of the basic aerodynamic principles which underlie the operation of axial flow fans is made. Using these principles, an estimate of the effect of flow and pressure transients is discussed. Since it is desirable to verify experimentally the nature and magnitude of these effects, a method of simulating flow and pressure tubes is described. Description of the actual test hardware, the instrumentation and the test technique is given. Results of tests performed on a 7-ft diameter vaneaxial fan are presented and discussed. Comparison between the experimental results and those expected from theoretical consideration is made.