What happened
On November 16, 2017, at approximately 13:12 LMT, a Dynali H3 ultralight helicopter, registration SP-HELI, was performing a flight demonstration at Modlin Airport (EPM/PMO). The flight was intended to showcase the aircraft's capabilities to a prospective trainee.
After completing several take-offs and landings, the pilot began demonstrating lateral movements and turns at an altitude of approximately 1.5 to 2 meters above the grass. During a left turn, the pilot lost control of the cyclic control stick. The aircraft pitched forward and tilted to the right while descending. The right skid struck the ground, causing the helicopter to tilt further until the main rotor blades made contact with the earth. The impact destroyed the rotor blades and caused the aircraft to capsize onto its right side. The pilot and passenger were able to exit the cabin uninjured.
The investigation
The PKBWL investigation examined the aircraft's maintenance records, weight and balance, and the pilot's credentials. The investigation established that the aircraft was being operated in violation of the Pilot Operating Handbook (POH) limitations. Specifically, the investigation found that the aircraft's maintenance status was undocumented for certain periodic inspections, rendering it technically unairworthy. Furthermore, the investigation scrutinized the regulatory oversight regarding the approval of the aircraft's technical documentation by the civil aviation authority.
Findings
- The primary cause of the accident was the loss of control over the helicopter during low-altitude maneuvers.
- The aircraft exceeded its maximum takeoff weight by 40 kg (8.93%).
- The maximum cabin weight limit was exceeded by 22 kg (14.67%).
- The center of gravity was outside of approved limits, specifically exceeding the forward limit by 17 mm (12.5%).
- The lateral balance requirements for the helicopter were not maintained.
- The aircraft was being operated in a manner inconsistent with the approved flight manual.
- Wind conditions at the time of the event contributed to the rightward tilt of the aircraft.
Safety action
- The President of the Civil Aviation Authority (ULC) is recommended to verify the quality of documentation approved for aviation entities and implement measures to prevent future irregularities.