Helicopter giant Sikorsky Aerospace has opened what it claims is one of the world's most powerful structures to dynamically balance helicopter main rotor blades at Dallas Fort Worth International Airport.
Designed by Sikorsky to test main rotor blades that rotate either clockwise or counter-clockwise, the US$15 million bi-directional whirl tower will enable helicopter operators and manufacturers to rebalance their rotor blades in the US regardless of the aircraft’s country of origin.
“The addition of a high-powered bi-directional balance stand offers our customers reliable, accurate measurements for main rotor blades flown by helicopter operators across all categories, from lights up to heavy lift,” Sikorsky Aerospace Services President David Adler said.
The whirl tower features two 3000 shaft horsepower (shp) variable frequency drive induction motors for rotation of three blades (a precision-balanced master blade and two test blades) in either direction at a peak rating of 6000 shp. The tower’s 6000-lb rotor head will enable Sikorsky to spin blades weighing up to 500 pounds each, meaning it can accommodate anything up to the blades used US Marine Corps CH-53 heavy lift helicopters.
The whirl tower measures imbalance by spinning two test blades against a precision-balanced master blade of the same configuration. As the three blades rotate about the rotor head, a laser tracking system measures where the blades fly relative to one another. Adjustment of weights at a blade’s tip and trailing edge enable correction for tip deflection, and for any rotational twist along a blade’s length.