Hoverbover: apologies for getting overheated about snow!!
Tiercel: There are very few, if any 'current' civilian helos that are allowed to fly in icing, and the definition of icing is: flight in visible moisture below 0 degrees celcius (in the UK anyway). This includes snow. That's why I said "do not fly".
CTD: I was based at Shearwater on exchange to 423 sqdn for 3 years in early 80's. Did a couple of cross country's to nanaimo (if I remember the spelling) and stopped en route to do glacier and snow flying. Also flying off frigates from St Johns harbour because the ship was stuck solid in sea ice!!
Were you a mil pilot with the air force too?
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Thermal runaway.