CEN18FA244

The pilot of the helicopter was approaching to land on a trailer following a short local flight. A witness saw the pilot abort the landing approach and stated that the helicopter backed away from the trailer, began to climb, then entered a "violent" counterclockwise spin as it climbed to about 20 to 25 ft above the ground. The helicopter spun 4 or 5 times, then the witness heard a loud noise like an engine backfire and the helicopter "fell" to the ground and came to rest on its right side. Examination of the airframe, drive systems, flight controls, and engine did not reveal any pre-impact mechanical anomalies that would have resulted in a loss of control. The helicopter was configured with a single set of flight controls (pedals, collective, and cyclic) on the right side; the left side controls were not installed, and the cover plate for the removed left pedal assembly was not installed. Three metal ammunition boxes containing tools and loose shotgun shells were recovered from the debris field. During postaccident examination, the boxes were placed on the left side floor to determine whether they may have interfered with pedal movement. The edge of the most-forward box covered the top of the left side pedal receiver when the right pedal was positioned aft of neutral. Shotgun shells were recovered from the left floor area, the belly area, and in the debris field. One shell had a dent in the plastic shell; however, the origin of the dent could not be confirmed. Due to impact damage to the floor and pedal assemblies, whether any of these items may have interfered with pedal movement during the flight could not be determined. The pilot had over 20,000 hours in the type of helicopter. No mechanical anomalies were found that could have precluded normal operations. It is possible that the counterclockwise spin could have been a result of pedal control interference from the ammo cans or shotgun shells on the uncovered left pedal assembly; however, control interference could not be determined conclusively.

The helicopter was configured with a single set of flight controls (pedals, collective, and cyclic) at the right seat. The left seat pilot controls were not installed, and the cover plate for the removed left pedal assembly was not installed. The operator stated that the helicopter was routinely used in cattle roundup and predator mitigation operations. The helicopter had flown a previous flight of about 3.7 hours on the morning of the accident. The pilot who conducted that flight did not report any anomalies with the helicopter. On June 29, 2018, about 2010 central daylight time, a Robinson R22B, N787SH, was destroyed when it was involved in an accident near Sterling, Texas. The pilot was fatally injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 work use flight. The purpose of the flight was to inspect a nearby stock water tank and inoperative water pump. The pilot had completed the flight and was returning to land on the helicopter's trailer when the accident occurred. A witness, who was located at the home base, stated that she saw the helicopter make an approach to land on the trailer, but the pilot aborted the landing, and the helicopter backed away from the trailer and climbed. The helicopter then began "a violent spin" as it climbed to 20 to 25 ft above the ground. The helicopter spun 4 or 5 times, then the witness heard a loud noise like an engine backfire and the helicopter "fell" to the ground. She could not recall whether she heard the engine producing power following the backfire noise. The witness stated that she thought the spin was in the counterclockwise direction but was not positive. She did not see the impact because of building obstructions. The engine was not running when she reached the helicopter. South Plains Forensic Pathology, Lubbock, Texas, performed an autopsy of the pilot. The pilot's cause of death was multiple blunt force injuries. The FAA's Forensic Sciences Laboratory performed toxicology testing on the pilot's tissue samples. The toxicology tests were negative for drugs and ethanol. Small amounts of over-the-counter medicine for hay fever and allergies were present. A company pilot reported that the wind was about 10-12 knots from the south about the time of the accident. The accident site was located about 200 ft from its intended landing site on the transport trailer. The helicopter impacted level terrain and came to rest on its right side. There was no evidence of contact with obstructions during the approach. The fuselage sustained impact damage to its lower right side. Both pilot and passenger doors were not installed. Three ammunition cans containing tools and several loose shotgun shells (discharged and undischarged) were present within the wreckage area. Several shotgun shells were recovered from the left floor area, the belly area, and in the debris field. One shotgun shell had a dent in the plastic shell. Examination of the airframe and engine did not reveal anypre-impact mechanical anomalies. Flight control continuity was confirmed from the cockpit to the flight control surfaces. The ammunition boxes were placed on the left side cockpit floor to observe the geometry of the boxes in relation to the removed left pedal assembly. The edge of the most-forward box covered the top of the left side pedal receiver when the right pedal was positioned aft of neutral. Due to impact damage the position of the ammunition boxes and dented shotgun shell during the flight could not be determined. Detailed airframe and engine examination findings are included in the public docket for this accident.