(1) Subject to subsections (2) and (6), heavy oil which has not been taxed at the rate specified in Schedule 2 for heavy oil used for air navigation, may be used for private pleasure flying.

(2) Where subsection (1) applies, the person who has used the heavy oil concerned shall, not later than the first day of March following the calendar year in which the heavy oil was so used, deliver to an officer -

(a) a return, in such form as the Commissioners may require, of the quantity in litres of such heavy oil purchased for private pleasure flying in that calendar year, and

(b) payment of the mineral oil tax, calculated at the rate set down in Schedule 2 for heavy oil used for air navigation, on such quantity.