On July 16, 2021, about 1330 eastern daylight time, a Robinson R44, N512RT, was substantially damaged when it was involved in an accident near Princeton, Kentucky. The commercial pilot received serious injuries, and the pilot-rated passenger received minor injuries. The helicopter was operated as a Title 14 Code of Federal Regulations Part 137 aerial application flight. According to the pilot, the purpose of the flight was to spray a nearby cornfield. He reported that they were having a problem with the agricultural mapping and navigation system installed in the helicopter, so the passenger, who was also an aerial application pilot, was onboard to assist with the operation of the system. They had flown two loads without incident. The pilot reported that they took off on the third load, and “after about a couple of hundred yards,” the low rotor rpm warning light illuminated. Prior to takeoff, the helicopter was filled with about 50 gallons of spraying solution. They knew it was barely overweight but felt it would be fine. After the accident, the pilot told his wife that “the helicopter just wouldn't fly, and he was getting a low rotor rpm light.” As the pilot maneuvered the helicopter for landing, the left spray boom contacted trees, and the helicopter landed hard, bounced, and rolled onto its left side. The passenger exited the helicopter and assisted the pilot in getting out. According to the pilot’s wife, after the accident, the pilot told her that before takeoff, the helicopter was filled with about 50 gallons of spraying solution. She stated that the pilot told her he “knew it was barely overweight but felt it would be fine.” She further stated that the pilot told her that “the helicopter just wouldn't fly.” Examination of the helicopter by a Federal Aviation Administration inspector revealed substantial damage to the airframe and partial separation of the tail boom. An examination was conducted on the engine and its components. No anomalies were noted during the examination. The maximum gross weight for the helicopter was 2,500 lbs. A weight and balance calculation revealed that the helicopter’s estimated weight at the time of the accident was 2,641.4 lbs.