TULSA, Oklahoma - You may have noticed a large helicopter hovering over downtown Sunday morning.

Crews took to the sky for several hours--all to replace the window-washing equipment on top of the 52-story BOK Tower.

Access to some areas, including parking lots around the BOK Tower, was restricted while they used a Sikorsky S-58t helicopter, capable of lifting loads up to 4,500 lbs., to lift the equipment to the top of the tower.