On July 20, 2018, about 1215 central daylight time, a Bell 206B, N325CT, sustained substantial damage when it was involved in an accident near Todd Mission, Texas. The private pilot and one passenger sustained minor injuries and two passengers sustained no injury. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. After flying in the local area and refueling, the pilot landed on a grass field to facilitate the passengers switching their seat positions in the helicopter. During the seat-switching process, the pilot reduced the throttle to the flight idle position. After the passengers switched seats and secured their restraint systems, with one passenger stationed in the front left seat, and two passengers stationed in the cabin, the pilot increased the throttle to 100 percent and lifted the helicopter off from the field. A review of accident sequence video footage shows that the helicopter began to rotate right during the takeoff. The pilot reported that about 10 ft above ground level with about 5 kts of forward airspeed and a heading of about 270°, the helicopter spun four 360° revolutions to the right. The pilot reported she applied full left pedal with no response from the helicopter. During the loss of control sequence, the pilot observed the torque gauge "jump" and she heard a "whining" noise emit from the engine. Prior to the impact with terrain, the pilot reduced the throttle to the flight idle position. The left skid impacted the ground, the helicopter rolled to the left, and came to rest on the left side of the fuselage. The pilot executed an emergency shutdown and the occupants egressed from the helicopter without further incident. The helicopter sustained substantial damage to the main rotor system, the fuselage, the tailboom, and the tail rotor system. A postaccident examination of the airframe and engine revealed no preimpact mechanical malfunctions or failures that would have precluded normal operation. The helicopter had the cyclic, collective, and the two tail rotor pedals installed in the left side of the helicopter. The pilot reported that she briefed all of the passengers about not touching any of the flight controls. The passenger in the front left seat was asked if he had his feet on top of the tail rotor pedals as a footrest. He stated "that or on the floor," and then stated that he was not sure. The passenger further reported that the pilot did give a passenger safety briefing about not touching any of the flight controls. Postaccident testing was conducted in a Bell 206B flight training device. Wind conditions were replicated for the accident site. The National Transportation Safety Board (NTSB) investigator-in-charge (IIC) rested his feet on top of the tail rotor pedals for two flight iterations with no force applied and with medium force applied. When the Bell chief training pilot (CTP) attempted to takeoff for both iterations, the helicopter started to immediately rotate to the right. The CTP had a hard time maintaining directional control due to the interference of the feet on the tail rotor pedals. The NTSB IIC also placed the tips of his feet on the floorboards up against the tail rotor pedals. When the CTP attempted to takeoff for the third iteration, the helicopter started to immediately rotate to the right. The CTP had a hard time maintaining directional control due to the interference of the feet up against the tail rotor pedals. A review of the Bell 206B rotorcraft flight manual found no guidance regarding the carrying of passengers in the cockpit and the interference of flight controls. The Federal Aviation Administration Helicopter Flying Handbook (FAA-H-8083-21B) discusses operations when carrying passengers in the cockpit and states, "If possible, remove front passenger flight controls and ensure all passenger personal items, such as cameras and mobile phones are secure."