European Implementing rules for continuing airworthiness (EU) 2014/1321 do not apply to European NCC operators for third-country registered aircraft unless the regulatory oversight has been delegated to an EU Member State.
In particular, tasks related to the continuing airworthiness management do not need to be implemented by a CAMO in the sense of Regulation (EU) No 1321/2014. However, the essential requirements established in Annex V of Regulation UEU) 2018/1139 (the “Basic Regulation”) must be complied with. For airworthiness, the elements required in Annex V point 6 must be ensured by an organisation as required in point 8.8.
In short, European NCC operators of third-country registered aircraft need to ensure that an organisation is managing the continuing airworthiness of their aircraft and that this organisation is able to demonstrate that the aircraft comply with the continuing airworthiness requirements contained in Annex V of Regulation (EU) 2018/1139. This organisation does not need to be a CAMO; it can be the operator itself or any other organisation or natural person under the responsibility of the operator.
Please also see FAQ 47404: Where can I find the continuing airworthiness requirements for third-country registered aircraft used by EU operator/owner?