UNIVERSAL BALANCING EQUIPMENT FOR MAIN ROTOR BLADES

Main rotor blades at Bell Helicopter Textron Inc. have traditionally been balanced using a dedicated balance fixture for each rotor blade model. These individual fixtures use Marvel™ arbors to support a blade cradle, which includes a counterweight that is “tuned” to match the weight of a master rotor blade. Two bubble levels attached near the pivot point at the center of the balance fixture are used to indicate the blade balance in the spanwise and chordwise directions. The levels indicate when the blade is in tolerance to the master blade. A new system of balancing all rotor blade models on the same fixture was developed to increase balance accuracy, provide written documentation of balance operation, and reduce the amount of floor space required in the balance area. The new balance technology was developed using high-capacity, high-precision scales, placed on air bearings to enhance reading accuracy. The weight readings from the scales are transferred through an interface to a computer equipped with Windows 95™ and Lotus 1-2-3™. Within Lotus 1-2-3™, a balance program is written for each blade model to be balanced.