INVESTIGATION OF AUTOMATED ROTOR SMOOTHING USING CONTINUOUS VIBRATION MEASUREMENTS

Traditionally, rotor smoothing has been performed by acquiring vibration phase and amplitude at a few locations in the fixed-frame during dedicated maintenance test flights, in which the flight crew acquires the data at several known ground, hover and forward flight conditions. Although this process works, it is time consuming and expensive. A method to reduce or eliminate special maintenance test flights is highly desirable. In this paper, the use of vibration data acquired continuously through the flight for rotor smoothing is studied. Vibration data for one UH-60L Blackhawk and two AH-64A Apaches were acquired both continuously and manually. The vibration characteristics and recommended adjustments for each method are compared. It was determined that there was scatter in the vibration data, but a composite solution could be calculated that would reduce the average vibrations. This method may be effective to allow for small adjustments between maintenance flights on aircraft that do not have a regime based rotor smoothing data acquisition capability.