Incident Overview
A helicopter pilot reported an accident while flying at approximately 300 feet above a ridge at an elevation of 4,900 feet, at a speed of 10 miles per hour (8.68 knots). According to the pilot, he had difficulty hearing in his headset and needed to adjust the volume. He removed his left hand from the collective and used it to hold the cyclic, freeing his right hand to adjust the headset volume. However, he forgot to increase the friction on the collective before releasing his left hand. The collective subsequently dropped, decreasing main rotor pitch and causing the engine to overspeed.
Sequence of Events
The pilot reported that the helicopter then began to spin to the right. He grabbed the collective, reduced throttle, and increased collective pitch. The helicopter experienced settling with power and spun approximately 8 to 10 times. The helicopter landed hard on top of the ridge and rolled onto its right side. The accident resulted in substantial damage to the fuselage, main rotor system, tailboom, and tail rotor system.
Aircraft and Pilot Findings
The pilot verified that there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation. The pilot sustained minor injuries and was using a 4-point restraint system. He credited the shoulder harness with preventing more serious injuries.
Pilot’s Safety Observations
As a safety recommendation, the pilot stated that he should have increased the collective friction prior to removing his left hand from the collective stick. He also noted that the situation was exacerbated by the helicopter being only 300 feet above ground level at 10 miles per hour.
Reference to Published Guidance
The Federal Aviation Administration (FAA) Helicopter Flying Handbook (FAA-H-8083-21, 2012) describes the collective friction control as a means to help prevent inadvertent collective pitch movement. The handbook also discusses recovery from settling with power, noting that increasing collective pitch can worsen the condition by increasing the stalled area of the rotor and the rate of descent. Recovery typically involves increasing airspeed and/or partially lowering collective pitch, or in a fully developed vortex ring state, entering autorotation.