The intent of the article M.A.901(b)(i) is to define the ‘controlled environment’ by indicating that the aircraft must be managed during last 12 months by unique CAMO, which indirectly refers to a standard term of validity of the ARC. Therefore, if the aircraft has been managed by more than one CAMO since the date of issue of the last ARC or the date of issue of the ARC extension, it actually indicates that controlled environment was discontinued.
In addition in accordance with M.A.710(d) the 90 days anticipation shall be used to allow the physical review to be performed during a maintenance check. However, the intention of the rule was never to address the transfer of the aircraft within those 90 days with the purpose of avoiding the forthcoming airworthiness review. Concerning the 30 days anticipation for the ARC extension, point M.A.901(f) is intended for 2 consecutive extensions by the same CAMO managing the continuing airworthiness of the aircraft from the date of issue of the ARC, so the extended ARC could not be extended 2nd time by another organisation, because this constitutes a ‘breach’ of controlled environment.