What happened
The accident occurred during the initial phase of flight when the helicopter was climbing. The pilot reported that at approximately 300 feet above ground level (AGL), the rotor RPM decreased by about 500 revolutions per minute. In an effort to recover, the pilot attempted to regain normal rotor RPM until the aircraft descended to approximately 100 feet AGL. Unable to restore sufficient rotational speed, the pilot initiated an autorotation maneuver.
The helicopter landed hard during this emergency procedure. Upon impact with the ground, the aircraft rolled over. There were no reports of mechanical failures or system malfunctions prior to the event from the pilot's perspective, though the specific cause of the RPM loss was not detailed in the narrative beyond the initial drop.
The investigation
A post-accident examination of the helicopter was conducted to determine if any mechanical issues contributed to the incident. Investigators inspected the airframe and its systems for discrepancies. The inspection revealed no mechanical discrepancies with the aircraft. This finding suggests that the loss of rotor RPM was likely due to operational factors or an external cause rather than a pre-existing mechanical failure within the helicopter itself.
Findings
The sequence of events indicates a sudden loss of rotor RPM during climb-out. The pilot's response involved attempting to correct the RPM followed by an autorotation when recovery failed. The hard landing and subsequent rollover were direct consequences of the emergency descent. The absence of mechanical discrepancies points toward the event being driven by factors outside of equipment failure, such as power management or environmental conditions, although specific details on those factors are not provided in the source text.