Thanks for the responses.
This is, as Kevin surmises, to do with UK tax allowances. We have a new rule which restricts the value of capital allowances if the asset has an economic life over a certain period. HMRC say they have agreed with the Aviation Industry" that aircraft have a life over this limit and therefore they get only very small tax allowances.
But this agreement was brokered with owners / operators of large tin tubes - not GA and light commercial helicopters.
HMRC try to apply this "Aviation Agreement" to everyone and I have helped one Robinson owner to resist and to get a more sensible deal. I want to see if there is a way to analyse by make / model what a sensible life expectency is in practice - i.e. not simply what the maker says.
For that reason, I don't need operator costs or the capital depreciation included in financial models (eg for leasing).
Could I go to (for example) the CAA for date of first registration of all Schweizer 300's? Is there a database available (free) online?
Thanks for any help