Hi R88, just because you were in icing conditions for some time before it appeared significant, doesn’t mean it can’t happen in something less than a minute. I had an engine stop on a 365C because I allowed myself to be descended into an icing layer (that took about a minute) and I’m aware of two EC135s and an S61 that ended up descending at Vy and MCP in ‘uncontrolled fashion’ after a very short time in sub-zero temperature cloud. It can happen quickly!
Cheers
TeeS