One reportedly flew home after losing of main rotor blade to a tree. Controls vary the pitch of the main rotor blades cyclically throughout rotation. One modification for the S-61 is the Carson Composite Main Rotor Blade. The effect was to swap those letters before and after the main rotor scrambling unit. Witnesses of the crash cite seeing "something wrong with the main rotor". It directly led to a mid-air seizure of the main rotor blades. This version incorporates active noise suppression, vibration dampers and a composite main rotor. Longbow Fire Control Radar dome installed over the main rotor. AH-6S cockpit and main rotor composite blades are to be based the AH-64D Block III. This creates a force which cancels out the main rotor torque and provides directional control. The main rotor may be driven by tip jets. The H160 is the first rotorcraft to feature the Blue Edge five-bladed main rotor. UH-72 Lakota is a twin-engine helicopter with a single, four-bladed main rotor. The main rotor is also equipped with two coning hinges. The main rotor blades' material was changed to a titanium-fiberglass composite.