If, apart from this regulation, there would be more than one maintenance schedule for an aircraft, the maintenance schedule for the aircraft is:
(a) if:
(i) CASA has approved a system of maintenance for the aircraft under regulation 42M; and
(ii) the system was submitted for approval because of a direction by CASA; and
(iii) the approval is still in force;
that approved system of maintenance; and
(b) in any other case--the maintenance schedule that the holder of the certificate of registration for the aircraft has most recently elected to use, or that CASA has most recently approved, as the case may be.