At 1756 Central time, the helicopter was force-landed during a post-maintenance test flight. Day visual conditions prevailed. The solo airline transport pilot was not injured. The helicopter sustained substantial damage to the tailboom section just aft of the cabin. According to the pilot, the engine governor was replaced earlier in the day and the test flight was to confirm proper inflight settings. While turning to the base leg of the traffic pattern, at approximately 500 feet agl and at 40 to 50 knots, the pilot reported hearing a “loud bang and the airframe lurched.” He entered an autorotation and located a vacant parking garage deck within gliding range. The pilot landed the helicopter, which skidded approximately 15 feet.
