Robinson Helicopter R44 N4528T accident near Wingate, North Carolina

Probable cause

The pilot’s failure to maintain clearance from a power line during a low-level aerial application flight, resulting in tail rotor impact with the power line, a loss of control, and subsequent impact with the ground.

NTSB 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.

Text from the NTSB. Open the NTSB docket for ERA21FA200 for the full record.