On July 18, 2026, about 1440 central daylight time, a Robinson Helicopter Company R44, N484AT, was substantially damaged when it was involved in an accident near Adair, Iowa. The pilot was not injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 137 aerial application flight. The pilot stated that he was recently hired by the owner to complete agricultural spraying operations. He spoke with the pilot who flew the helicopter on the previous day and reported that the engine governor was slow to respond and that he should watch it during subsequent flights. The accident pilot decided to load the helicopter with water and complete a test flight to ensure normal operations and no governor malfunctions. The test flight was completed with no anomalies noted, and the governor was working normally. The pilot completed about 5 hours of flight time and sprayed about 600 acres without incident. Shortly before the accident, the pilot landed the helicopter on the refueler truck and added 1 quart of oil to the engine, then continued to spray another field. The pilot had completed 2 to 3 spray passes and climbed out of the field to turn around for another pass. During the turn, the low rotor rpm horn sounded so the pilot lowered the collective and increased the throttle, which increased the rotor rpm and the horn turned off. The pilot continued another spray pass and the low rotor rpm horn sounded again. He attempted to increase the throttle beyond the governor limitation, but the horn continued. The helicopter was flying about 60 mph and was about 15 to 20 ft above the field, so he executed an autorotation and landed in the mature corn. The helicopter slid in the field and rolled left, then came to rest upright. The responding FAA inspector reported that the helicopter sustained substantial damage to the main rotor blades, fuselage, and tailcone. Postaccident examination revealed that the governor control unit was not secured to its mounting location but was still connected to the airframe main wiring harness. The owner and company mechanic stated that the helicopter was recently purchased for the agricultural business and discovered that the previous owner had removed the governor control unit. They acquired another governor control unit and helicopter underwent an overhaul. When the helicopter was put back into service, the governor control unit was not secured to its mounting location. The helicopter was retained for further examination.