Abstract: What follows is a description of a system for detecting rotor system related vibration in a helicopter. The vibration detecting system comprises three essential units: a sensing unit or device; a control unit; and a model module. Actually, any number of sensing units can be utilized depending upon the number of locations at which the vibration is to be monitored. The sensing unit generates a signal indicative of the rotor system related vibration and delivers this signal to the control unit which operates on the generated signal and produces an output signal within a selected frequency and amplitude range. The output signal is then displayed, for example, on a scale meter. The model module is adaptable for compatibility with the dynamic rotor system of a given helicopter model and is utilized as such to set the limits of the selected frequency and amplitude range of the control unit. The model module is readily connected to and removed from the housing of the control unit.