What happened
On May 19, 2023, at approximately 14:30 local time, a private helicopter pilot was conducting simulated emergency procedures at La Hacienda Aerodrome (SCHL) in Lampa, Chile. The flight involved practicing autorotations, a maneuver where the pilot descends without engine power to prepare for an emergency landing. The pilot had planned to initiate the maneuver at 4,50 and conclude it at 3,000 feet altitude to resume level flight.
During the recovery phase of the maneuver, the pilot inadvertently manipulated the throttle, which caused a significant drop in engine RPM. This loss of power prevented the pilot from maintaining sufficient rotor energy. Consequently, the aircraft continued an uncontrolled descent, striking the runway surface with heavy force. The helicopter slid approximately 42 meters across the ground, causing the tail cone and skids to detach, and eventually came to rest on its right side. The pilot was uninjured, but the Robinson R44 II sustained major structural damage.
The investigation
DGAC Chile examined the flight logs, maintenance records, and the physical wreckage of the aircraft. The investigation confirmed that the pilot held a valid private helicopter license and that the aircraft's maintenance was up to date, with no mechanical failures identified as a cause for the incident. Meteorological conditions at the time were favorable, with clear skies and light winds, ruling out weather as a contributing factor.
Investigators analyzed the pilot's actions during the critical phase of the maneuver. The investigation focused on the interaction between the pilot and the aircraft's controls, specifically noting that the pilot failed to apply the necessary throttle correction to recover engine RPM as required by the Pilot's Operating Handbook (POH).
Findings
- The primary cause of the accident was the loss of aircraft control during the execution of an autorotation maneuver.
- The pilot inadvertently manipulated the throttle, leading to a loss of engine RPM and insufficient rotor energy for a controlled landing.
- The pilot performed a critical emergency maneuver without the supervision of an instructor.
- High workload and a loss of situational awareness during the maneuver contributed to the improper control input.
- The aircraft's POH specifically advises that such practices should be conducted under instructor supervision to prevent similar accidents.