As part of the certification testing of the R22, they did some drop tests. RHC have a video which, as has been mentioned, is shown on their course. Its quite impressive to see how much the skids deflect, and then return.
From experience doing instruction, the R22 skids are pretty good at resisting damage from "drops": much more so than many other apparently stronger helicopters. However, helicopters can be dropped in various ways. Sometimes, even when the drop is not large, it can be awkward. If the drop is not just straight down, but has a lateral element, you can get damage. Not necessarily the skids, but damage to the MR gearbox and/or its fairing.