absolute codswallop!........There may be circumstances where the Taxes Acts are ambiguous and in those circumstances, quite often a different Inspector will have a different interpretation of the legislation.
So, in other words, an agreement is made.....which is what I said. However, none of this exchange is much use to someone in Australia. But it gives "Whirls" a chance to puff-up the chest and speak out.
I speak facts. Not codswallop. You may check these facts with any R44 operator. By all means depreciate your helicopter over 5 years - but the sensible approach is to follow either the 12-year or the per flying hour approach as agreed with HMRC.