Accident Overview
On June 14, 2024, at 1827 eastern daylight time, an experimental amateur-built Rotorway Exec 162F helicopter, registration N99TE, was substantially damaged when it struck the ground during a landing attempt near Alva, Florida. The airline transport pilot and a pilot-rated passenger were not injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
Flight Narrative
According to the pilot, a preflight inspection was performed, during which the tail rotor drive belt tension was checked with a spring scale and found to be within limits at 10 pounds. Shortly after departing from the pilot's residence, while flying at an altitude between 200 and 300 feet mean sea level, the pilot transferred control of the helicopter to the passenger. The passenger flew a high reconnaissance pass in an easterly direction toward a small grass airstrip. During the approach, at an altitude of about 150 feet above ground level and an airspeed of 20 to 30 miles per hour, the passenger made a cyclic correction to keep the helicopter aligned with the runway centerline. Following this correction, the rotor rpm dropped below 100 percent, and the passenger increased throttle. As the helicopter passed through effective translational lift, it began to yaw to the left despite full right pedal input. The pilot assumed control and applied forward cyclic with additional right anti-torque pedal to counter the yaw. The helicopter descended in a sweeping left turn with full right anti-torque pedal applied, and the pilot was unable to regain directional control before the helicopter contacted the edge of an irrigation ditch. The helicopter rolled over and came to rest on its right side. The pilot reported that the engine operated as expected throughout the flight, with no abnormal vibrations or sounds, and all flight controls functioned normally until the unanticipated yaw began.
Post-Accident Examination
An inspector from the Federal Aviation Administration examined the helicopter after the accident and discovered that the tail rotor bolt tensioner assembly was not secured. Specifically, the right-side tail rotor drive belt jam nut and self-locking nylon nut were loose. These nuts, when properly torqued, are designed to maintain tension on the tail rotor drive belt. The inspector noted that there was no means to visually inspect these critical nuts during a preflight check.
The helicopter sustained substantial damage, including damage to the rotor blades and a large crease in the tail boom.