***This report was modified on 5/15/2019. Please see the docket for this accident to view the original report.*** On January 8, 2018, at 1345 central standard time, a Robinson R44 helicopter, N797JR, collided with trees and the terrain during an autorotation near Albany, Texas. The commercial pilot was not injured. The helicopter was substantially damaged. The helicopter was registered to S2 Helicopter Services and was operated by an individual as a Title 14 Code of Federal Regulations Part 91 personal flight. Day visual meteorological conditions prevailed. The flight was not operated on a flight plan. The local flight originated from a ranch in Albany, Texas, at 1310. The pilot stated he was using the helicopter to roundup cattle when the accident occurred. He reported he applied power to stabilize in a hover about 50 ft above the ground, when he heard a single loud bang and "felt it in the pedals." The helicopter spun to the right and the pilot applied full left pedal which had no effect. The pilot stated that after about 2 spins, he entered an autorotation to remove torque from the rotor system. The helicopter contacted trees as it descended to the ground. The helicopter came to rest upright with the tail boom separated. The pilot reported that he was not sure if there was a "mechanical problem" or not. His recommendation was "Conduct a better clearing turn to ensure that nothing was around including animals/birds" and to "maintain more forward airspeed in case of emergency." The helicopter was sitting upright on the skids. The fuselage was intact and the tailboom was separated just forward of the empennage. Minor crushing damage was visible on the right side of the helicopter aft of the cabin area. Crush damage was visible on the left side of the helicopter above the front and rear skid struts. The main rotor blades, main rotor blade hub, and main rotor mast were intact. One of the main rotor blades exhibited minor bending near the outboard section of the blade. The other blade had a hole in the blade near the tip and the leading edge of the blade at the tip was pulled away from the remainder of the blade. The empennage and tailrotor were separated from the tailboom. The tailrotor drive shaft separated at the aft flex plate. The drive shaft remained connected to the clutch assembly. The main rotor blades turned when the tailrotor drive shaft was rotated by hand. Ratchet marks were visible inside the tailboom near the aft flex plate. Corresponding damage was visible on the flex plate and drive shaft. The trailing edge of the lower vertical stabilizer contained impact damage to the rear edge of the surface, pushing the skin forward toward the leading edge. The tail rotor blade assembly remained attached to the tail rotor gearbox. One tail rotor blade was bent outward 90 ° at the blade root. The other blade was bent out about 20° the blade root. The blade was free to turn when rotated by hand.