Guys
You need to find the balance really between a high hourly rate (which has the potential to put you off flying) or a low rate with "cash calls" when surprises crop up.
Unfortunately, there is no perfect solution as some people prefer the lower hourly rate whilst other prefer a higher rate which leaves a contribution to unforeseen maintenance accruing in the pot.
Either way, helicopter ownership costs and which ever way you slice and dice the numbers, the cost will be the same.
Joel