The CAR 21 | Certification of Aircraft Subpart C details the requirements for the approval of design changes.
Design changes that are classified as Major or Minor require the applicant to obtain approval of the design change to an aircraft and provide evidence to the satisfaction of the CAA before the aircraft or aircraft part is modified.
It is strongly recommended that applicants liaise with the CAA before considering the embodiment of a design change so that it is clearly understood by both parties what is involved in terms of the certification basis, evidential documentation required and what must be accomplished to successfully gain CAA approval.
A Certificate of Release (CRS) cannot be made unless the modification is approved by the CAA.
An application for a minor or major modification approval for an aircraft registered in San Marino can be made using FORM SM 45.
Reference should also be made to CAP 02 Section 18 for further guidance.