What happened
The incident occurred while the pilot was conducting a practice autorotation maneuver. During the descent phase of this exercise, the pilot failed to apply engine power in time to arrest the high rate of descent. Consequently, the helicopter impacted the ground with significant force. Upon touchdown, the main rotor blades flexed downward and struck the tail boom, resulting in the severing of that structural component.
The investigation
Post-accident examination confirmed the mechanical failure mode described above. The impact forces from the hard landing caused the main rotor system to deflect sufficiently to contact and cut through the tail boom structure. No other mechanical anomalies were cited as primary contributors to the sequence of events leading to the damage.
Findings
The pilot reported that his inability to add power in time was directly attributable to fatigue. Supporting this assessment, records indicated that the pilot had flown for eight hours on the day of the accident. Additionally, the pilot noted that environmental conditions were extremely hot, which likely exacerbated physical exhaustion and impaired operational performance.
Safety message
This event highlights the critical importance of managing pilot fatigue, particularly during extended flight days in high-temperature environments. Adequate rest and awareness of physiological limits are essential for maintaining the situational awareness and reaction times required for safe helicopter operations, especially during demanding maneuvers like autorotations.