On July 15, 2005, approximately 1345 central daylight time, a single-engine Bell 47G-4A turbine powered helicopter, N4087L, was substantially damaged when it impacted terrain while maneuvering near Black Oak, Arkansas. The commercial pilot, sole occupant of the helicopter, was not injured. The helicopter was registered to and operated by Custom Air LLC, of Louisville, Mississippi. Visual meteorological conditions prevailed, and a flight plan was not filed for the 14 Code of Federal Regulations Part 137 aerial application flight. The local flight originated from a private heliport near Manila, Arkansas, approximately 1330. The 10,370-hour pilot reported in the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) that he was spraying the south end of a cotton field on a easterly heading. While spraying at approximately 10 feet above the ground, he reported hearing, the "engine [make] a surge in power." The pilot then scanned his engine instruments to see if he was having a problem; however, all instrument indications were normal. The pilot added, he increased collective pitch when the helicopter began to lose altitude; however, the helicopter "could not gain altitude." The helicopter impacted the ground in a level attitude, bounced into the air and began turning to the left. The pilot then added left cyclic and thought he had the helicopter under control, when "the left spray boom hit the cotton [plants] and started pulling [the helicopter] into the cotton." The helicopter subsequently "snapped" to the right and "started to tumble." The helicopter impacted terrain and came to rest on its right side Examination of the helicopter by the pilot revealed that the tail boom was severed, the main rotor blades were damaged, and both landing skids separated from the airframe. The reason for the reported engine power surge could not be determined. At 1353, the automated observing system at the Blytheville Municipal Airport, near Blytheville, Arkansas, located approximately 23 miles west of the accident site reported wind from 330 degrees at 8 knots, visibility 10 statute miles, few clouds at 4,100 feet, scattered clouds at 4,800 feet, and a broken cloud layer at 6,000 feet, temperature 81 degrees Fahrenheit, dew point 72 degrees Fahrenheit, and a barometric pressure of 29.91 inches of Mercury.