What happened
On February 18, 2024, a Guimbal Cabri G2 helicopter, registration I-CAEF, was performing a VFR flight from Trento Mattarello Airport toward Bolzano. During the flight, the pilot initiated a low-speed approach maneuver near their residence in the southern outskirts of Laives. During this phase, the aircraft entered a rapid leftward rotation around its vertical axis, leading to an impact with the ground at an altitude of approximately 145 feet. The aircraft struck vegetation and the terrain, subsequently overturning on its side. The pilot and one passenger sustained minor injuries and were able to exit the wreckage.
The investigation
The ANSV investigation examined wreckage, flight data from the Garmin GDU 700L PFD, and video footage recorded by the passenger. The analysis of the video and ADSB data confirmed that the aircraft was executing a descending turn at low speed and low altitude. The investigation also reviewed Guimbal Service Letter 12-001 A, which addresses yaw control characteristics specific to the Cabri G2's fenestron tail rotor. Technical inspections of the engine, transmission, and flight controls revealed no mechanical failures or anomalies; the engine was producing full power at the time of the incident.
Findings
- The primary cause of the accident was the loss of control during a critical aerodynamic condition characterized by low airspeed, low altitude, and a crosswind from the right.
- The presence of a 5-knot wind from the east acted as a contributing factor, complicating the maintenance of directional control during the low-speed approach.
- The pilot failed to provide sufficiently decisive and timely pedal input to counteract the developing yaw, a phenomenon specifically warned against in the manufacturer's service letter regarding fenestron tail rotors.
- The low altitude at the moment the rotation began prevented the pilot from recovering controlled flight before ground impact.