Plenty of light singles run out of power trying to come to an OGE hover.....
Sudden onset of excess gravity affects all sizes of helicopters.
Explaining the various causes of such sudden onsets is where it gets complicated.
SWP, IVRS,VRS, Excess Weight, Density Altitiude, Wind Direction and Velocity, Turbine Lag, Mechanical Failure, Pilot Technique.....and combinations of several factors will find you making an interesting arrival at your final landing spot.
Prevention is the key....perferably learned in a classroom or training environment and not by Trial and Error.
Some video can begin to show what the most likely cause of such landings might be....but a full analysis should be the basis for accurate assessment.