Just one Helicopter report:
Rotorway Executive 162F, G-CCMU
Inadvertent hover out of ground effect, Salterford Farm, Nottinghamshire, 26 October 2017.
"Summary: The pilot was returning after a local flight and as he turned onto finals, at approximately 40 to 50 ft, the helicopter yawed to the left. He attempted to correct with right pedal but the turn sped up quickly. The pilot noticed he was losing height and raised the collective lever, but he was unable to stop the descent. The helicopter spun two or three times before striking the grass surface with skids level. It then rolled over, causing extensive damage. Both occupants were restrained by their harnesses and could exit the aircraft through the broken windscreen.The pilot commented that he had allowed his airspeed to reduce excessively during his approach and may have inadvertently entered a hover out of ground effect. This requires a collective input and a significant increase in power. If insufficient engine power is applied, the rotor speed will drop. This can reduce tail rotor effectiveness and is likely to have resulted in the spin.
The Rotorways Executive 162F pilot operating handbook prohibits out of ground effect hovers for all pilots under 150 hours.
The pilot was relatively inexperienced on helicopters and commented that he may not have identified the situation as it unfolded."