On July 17, 2013, about 0800 central daylight time, a Cessna 208B, N732MD, was substantially damaged on the ramp at Chicago O'Hare International Airport (KORD), Chicago, Illinois. The pilot in command, second in command, and nine passengers were not injured. The airplane was registered to and operated by Multi-Aero Inc., doing business as Air Choice One under the provisions of 14 Code of Federal Regulations Part 135 as a scheduled domestic passenger flight. Visual meteorological conditions prevailed for the flight, which operated on an instrument flight rules flight plan. The flight was originating at the time of the accident.The Director of Operations at Air Choice One reported that the pilot in command and 9 passengers were on board the airplane, and the second in command was outside on the right side of the airplane; adjacent to the passenger door and ventral stairs. A passenger in the last row of the airplane asked the second in command to assist her with her seatbelt, at which time the second in command climbed up the stairs into the airplane. At the same time, the gate agent removed the tail stand from the airplane, without communicating with the flight crew. A passenger in row 3 then stood up to hand a carry-on bag to the second in command so that it could be stowed in the cargo compartment. As the passenger stood up and stepped towards the back of the airplane, the airplane titled backwards and the tail struck the tarmac. The pilot in command ensured that everyone was okay and then asked passengers to move forward in the airplane in an effort to bring the nose of the airplane back down. The pilot in command, second in command, and passengers disembarked from the airplane without further incident. An examination of the airplane revealed substantial damage to the bulkhead in the tail section of the airplane. An examination of the airplane and remaining systems revealed no anomalies.