On October 5, 2015, about 0805 central daylight time, a Bell 47G-3B helicopter, N160CS, sustained substantial damage when it impacted terrain during an aerial application pass near Huntsville, Texas. The pilot sustained minor injuries. The helicopter was registered and operated by Custom Air LLC under the provisions of 14 Code of Federal Regulations Part 137 as an agricultural application flight. Day visual meteorological conditions prevailed for the flight, which was not operated on a flight plan. The local flight originated from a temporary landing site near the application field shortly before the accident.The pilot reported that the helicopter felt "awkward" shortly before the event, but thought it was due to an uncoordinated turn. During the next spray pass, the helicopter developed a right rolling tendency, which the pilot was initially able to counter with left cyclic control. He entered a "gentle" right turn with the intention of returning to the fuel truck for a precautionary landing. However, full left cyclic control input was ultimately ineffective in countering the right rolling tendency. The right turn continued for about 150 degrees of heading change. The helicopter began to lose altitude during the turn and subsequently impacted the ground in a slight right bank, traveling about 40 yards before coming to rest. The pilot stated that he did not feel any abnormal vibrations or hear any "pops" before the loss of control authority. He commented that the flight went from routine to out of control in a matter of "seconds." The helicopter came to rest in an open field covered with low vegetation. A postaccident examination was conducted by Federal Aviation Administration inspectors. The windshield/canopy had separated from the fuselage, with plexiglass fragments observed at the accident site. The forward fuselage structure exhibited minor deformations and distortions; however, the integrity of the fuselage was intact. The main rotor blades remained attached to the hub; however, the rotor blades were deformed over the span of the blades. The rotor hub remained attached to the mast and transmission. The transmission and supporting structure were dislocated from the aft fuselage/forward tailboom truss structure. The fuel tanks were separated and located with the main wreckage. The tailboom was deformed. The tail rotor transmission had separated from tail boom and was located at the accident site. The tail rotor blades remained attached to the hub. The blades exhibited tip damage but appeared otherwise intact. The flight control system components were deformed and fragmented consistent with the overall impact damage. The postaccident examination did not reveal any anomalies consistent with a preimpact failure or malfunction; however, the examination was hindered by the extent of the damage.