Vibration studies are a necessity for manufacturers of rotating equipment. Propeller blades are susceptible to potential damage from a variety of sources. Most users are well aware that a blade will have some resonance frequency (or frequencies!) Different modes of oscillation can be excited if energy is introduced at these frequencies. One common source of blade failure is improper placement of structural members. That is, motor supports or belt housings may partially block the airflow from a blade. The effect can be much more drastic than increased power consumption and decreased airflow. If the blade passing frequency with respect to a misplaced structural member excites one of the fan's modes of oscillation, a premature failure will result.

By investigating the resonance properties and modal response of propeller blades, a useful operating range can be identified. In many cases, that range can be extended by careful examination of the application. Air Turbine takes a conservative approach when defining the range of operation for their blades. By avoiding known resonance frequencies, failures are minimized.