What happened
On May 12, 2016, at approximately 10:55 local time, a Bell 20 and 6 Jet Ranger B3 was conducting a flight from the EPWL Wielkie Lniska airport near Grudziądz. The flight was being performed by a professional helicopter pilot accompanied by a Civil Aviation Authority (ULC) examiner for the purpose of flight competency extension.
During the approach to landing, the aircraft encountered heavy turbulence. The crew experienced a sudden, violent oscillation of the main rotor followed by significant vibrations throughout the helicopter. In response to the instability, the crew adjusted flight parameters, which successfully stabilized the aircraft. The crew subsequently completed the landing safely at the airport.
The investigation
Following the incident, the pilot notified the Maintenance Organization Manager, and the aircraft was immediately grounded. Technical personnel conducted a comprehensive inspection of the main rotor blades, the swashplate assembly, the tail boom, the tail rotor drive shaft, and the tail rotor itself. No mechanical irregularities or defects were discovered during this inspection, and the aircraft was subsequently returned to service.
Findings
- The primary cause of the incident was improper use of flight controls while operating in conditions of heavy turbulence.