What happened
On December 13, 2019, at approximately 21:40 UTC, a Robinson R44-II helicopter, registration PR-TOS, was performing agricultural spraying operations in a rural area of São Manoel do Paraná, Brazil. The aircraft had departed from a nearby dirt road to execute a local flight for pesticide application.
During the application process, the pilot was navigating a flight strip when the aircraft struck an electrical power line. The pilot reported being aware of a power line running parallel to the application strip; however, a perpendicular line, spanning approximately 150 meters without intermediate poles, went undetected. Upon impact, the pilot felt a fluctuation in the aircraft and heard the sound of a cable striking the helicopter. This caused the aircraft to enter a high-rate clockwise rotation, leading to a loss of control and a subsequent impact with the ground. The collision resulted in the separation of the tail cone and damage to the main rotor blades and transmission shaft. The pilot sustained minor injuries, and the aircraft suffered substantial damage.
The investigation
CENIPA investigators examined the flight planning and safety management protocols of the operator, Aereo Agrícal Fornagieri Ltda. The investigation focused on the effectiveness of the company's Operational Risk Management (GRO) process. While the operator maintained a Safety Management System (SMS), investigators found that the risk assessment form for the specific area was completed the day before the accident and contained geographical coordinates that were offset by 3.9 NM from the actual site.
Although the risk assessment identified the presence of low-voltage networks in the area, the description was noted as being too vague. The documentation lacked a detailed sketch or map identifying specific obstacles such as trees or power lines. Furthermore, while the pilot had performed a reconnaissance flight earlier that day, this flight was insufficient to identify the perpendicular cable.
Findings
- The pilot was qualified, experienced, and held valid medical and aeronautical certifications.
- The aircraft was airworthy, within weight and balance limits, and properly maintained.
- Meteorological conditions were favorable, with clear skies and good visibility.
- The lack of a detailed area study and a detailed flight plan prevented the identification of all hazards.
- The company's risk management documentation failed to provide precise locations for electrical obstacles.
- The reconnaissance flight failed to detect the perpendicular power line.