NTSB Final Report: Wingate, NC

Analysis

The pilot of the helicopter was conducting an aerial application when the accident occurred. Data recovered from an onboard GPS device showed that the helicopter took off, flew to the field, made two full passes and had turned back to begin a third. During the first two passes, the track showed a climb and descent near a power line that spanned the field; however, on the third and final pass, the climb and descent occurred immediately after the final turn and before the power line. The track also showed that, before the data ended, the helicopter was descending toward the power lines in the vicinity of where the wreckage ultimately came to rest.

Postaccident examination of the wreckage revealed that the tip portion of one of the fractured tail rotor blades exhibited impact scars consistent with a wire strike as well as impact with the tail rotor guard. One tail rotor blade tip was not found. Examination of the wreckage revealed no evidence of preimpact failures or damage that would have precluded normal operation of the helicopter. It is likely that the helicopter’s tail rotor struck the power line, separating a portion of the tail rotor blades. The tail rotor imbalance resulted in the separation of the tail rotor gearbox and empennage, and a nose-down tendency from the forward center of gravity shift, consistent with the cockpit crushing at ground impact. Given the lack of powered impact signatures on the main rotor blades, it is possible that the pilot reduced the throttle and collective control, resulting in reduced main rotor power, when he experienced a reduced or complete loss of directional control authority after the tail rotor struck the power line.

The sun’s elevation at the time of the accident was high enough that it would likely not have been a factor in the pilot’s ability to detect the power line in the field. Given the available information, the pilot likely prematurely descended the helicopter while overflying the power line, which resulted in the subsequent wire strike.

Findings

History of Flight

On May 2, 2021, at 1318 eastern daylight time, a Robinson R-44 helicopter, N4528T, was substantially damaged when it was involved in an accident near Wingate, North Carolina. The pilot was fatally injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 137 aerial application flight.

The commercial pilot was spraying fungicide on a wheat field when the accident occurred. According to several witnesses, this was the first time they had observed the northwest portion of the field, which contained multiple power lines, being sprayed via aerial application. The helicopter had been applying fungicide all morning, operating about 15 ft above the 3-ft-tall wheat during the spraying operation. The pilot’s wife reported that, after landing, having lunch and loading more fungicide, the pilot departed to begin spraying where he left off. Images of the flight track recovered from an onboard GPS device showed that the helicopter completed its first pass on a northerly heading. The helicopter then turned and flew over the field on a southerly heading, and the track ended in the vicinity of where the main wreckage came to rest.

 Witnesses in a nearby home reported that they heard a loud noise and simultaneously lost electricity to their home. They looked out their window and saw the helicopter as it descended in a nose-down attitude before it impacted the field in the vicinity of the power lines. One of the witnesses stated that it appeared as though the helicopter became entangled in the wires before it descended nose-first into the ground.

 The helicopter impacted and severed an energized wire, also known as a primary wire, that was oriented about 228° magnetic and measured about 29 ft above ground level at its lowest point over the wheat field. The wire spanned about 345 ft between two utility poles, 264 ft of that span over the wheat field. After the accident occurred, the severed wire was repaired the same day by the utility company. An additional power line spanned another portion of the northwesterly part of the field.

Aircraft and Owner/Operator Information

Charlotte-Monroe Executive Airport (EQY) was located about 12 miles northwest of the accident site. At 1253, the reported weather included scattered clouds at 3,800 ft. A review of astronomical data from the National Oceanic and Atmospheric Administration revealed that, at the time of the accident, the sun was located at an azimuth of about 180° and an elevation of about 71° from the accident site.

Wreckage and Impact Information

Accident Site Examination

The helicopter came to rest on its left side. The cockpit and cabin portion of the fuselage was crushed and deformed aft. The tail boom remained attached to the main fuselage; however, the empennage, composed of the upper and lower vertical stabilizers, horizontal stabilizer, the tail rotor and its gearbox, were separated from the tail boom. The windscreen and door windows were separated from the fuselage and fragmented. Both main rotor blades remained attached to the hub and were whole from root to the fractured tips. One main rotor blade was bent downwards about 2 ft outboard of the blade grip, and the other was bent downward and in a “U” shape. The agricultural hopper remained partially attached to the fuselage; it was breached, and its lower side was crushed from impact. The engine compartment and engine remained intact.

All major components of the helicopter were located in the vicinity of the accident site. Examination of the airframe and main rotor system revealed no evidence of preimpact failures. The main drive sheave (pulley) belts were intact and exhibited no evidence of anomalous damage or excessive wear. The clutch (freewheeling unit) functioned normally and continuity of drive from the sheave to the main rotor and tail rotor drive shaft was confirmed. The tail rotor gearbox mounts were fractured and exhibited signatures consistent with overload. Impact deformation to the lower vertical fin was consistent with tail rotor blade contact. The leading edge of the tail rotor blade tip end fractures was deformed in the direction opposite of normal rotation.