I think I am going to have to agree to disagree with you on this one, but that's not the issue. I think that the gearbox has recently been overhauled or the oil for some reason was maybe missing and like winnie says in Canada a few years ago a similar event occurred but the helicopter was sitting on the ground when it happened and this was due to an error made by the overhaul shop fitting a gasket the wrong way round and a critical oil port was covered! I also had this happen to me, on running up the helicopter after the gearbox had just come back from the overhaul shop the engineer spotted the oil pouring out from the seal and I shut down immediately. When talking to the overhaulers they came down that evening worked through the night and amend their error and they couldn't apologise enough. It's only really now that I can appreciate the consequences of what might have happened.
It seems this helicopter had managed to take off before they lost their rotor system, probably got just a couple of meters high....very very lucky to be alive. Thank god they are and hope they make a speedy recovery.