On October 11, 2024, about 1650 eastern daylight time, a Rotorway Executive 90, N314AC, was substantially damaged when it was involved in an accident near Plymouth, Indiana. The two pilots sustained minor injuries. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The owner and his flight instructor were flying the helicopter so the owner could gain proficiency. While preparing to practice an autorotation in the traffic pattern, the flight instructor told the owner that he heard a noise. Shortly thereafter, the nose of the helicopter started to yaw to the left. Airspeed began to slow, and the left yaw accelerated. The flight instructor took control of the helicopter and autorotated into a cornfield. The right skid caught the ground; the helicopter rolled onto its side, and came to rest on its right side. The main rotor and fuselage were substantially damaged. A postaccident examination revealed that the forward tail rotor drive belt was broken. The belt was frayed at the separation point. According to the owner, who is also an airframe and powerplant mechanic, the helicopter was in storage for several years before he purchased it in September 2024. A review of the tail rotor maintenance records revealed that after purchase, the owner inspected the tail rotor pulleys, bearings, bolts, and belt tension. He also greased the tail rotor slider. The annual condition inspection was signed off on the day of the accident. The maintenance manual for the helicopter recommends that the tail rotor belts be replaced every 250 hours, every 2 years, or as needed upon condition inspections, whichever comes first. All three tail rotor belts were replaced in January 2006 and the center tail rotor belt was replaced in September 2006. There is no indication in the tail rotor maintenance records that any of the tail rotor belts were replaced after 2006. The operator reported that before the accident the belts appeared to be in satisfactory condition but acknowledged they were beyond the 2-year service life and should have been replaced.