CEN13LA436

The pilot of the helicopter reported that he was completing a turn to re-enter a field for an aerial application pass when he heard a loud "pop" and felt a vibration and noted with a decay in rotor speed. He applied aft cyclic and reduced the collective, initiating an autorotation. He stated that the helicopter rolled to the left and that he applied right cyclic with no response. He was able to raise the nose of the helicopter before impacting corn in a 15-degree left bank. The helicopter came to rest 120 degrees from the direction of flight with the engine running. A postaccident examination of the helicopter and a metallurgical examination of the fractured main rotor system components did not reveal any failure or malfunction that would have resulted in the loss of control as described by the pilot.

On July 24, 2013, about 1130 central daylight time, a Texas Helicopter OH-13E, N176MR, collided with the terrain following what the pilot described as a loss of main rotor effectiveness during an aerial application flight near Champaign, Illinois. The airline transport pilot was not injured. The helicopter received substantial damage to the airframe. The helicopter was registered to and operated by Reynolds Aerial Service LLC as a 14 Code of Federal Regulations Part 137 aerial application flight. Visual flight rules prevailed for the flight, which was not operated on a flight plan. The local flight originated about 1120. The pilot reported he was completing a turn to re-enter a field for an aerial application pass when he heard a loud "pop" and experienced a "1 to 1" vibration along with decay in rotor speed. He applied aft cyclic and reduced the collective, initiating an autorotation. He stated the helicopter rolled to the left and he applied right cyclic with no response. He was able to raise the nose of the helicopter prior to impacting the corn in a 15 degree left bank. The helicopter came to rest 120 degrees from the direction of flight. The pilot reported the engine was running when the helicopter came to rest. The helicopter was relocated to Scott's Helicopters in LeSueur, Minnesota, where it was examined by the National Transportation Safety Board (NTSB). The upper pitch change link, the equalizer beam rod end, the lower pitch change link, and the lateral cyclic torque tube assembly were fractured. These components were removed for further examination by the NTSB metallurgical laboratory. The examination revealed the fractures were a result of overstress with no evidence of any preexisting cracks. The examination of the helicopter did not reveal any failure/malfunction that would have resulted in the loss of control as described by the pilot.