Renewal of EASA rating
By the definition of Part FCL Renewal (of, e.g. a rating or certificate) means the administrative action taken after a rating or certificate has lapsed for the purpose of renewing the privileges of the rating or certificate for a further specified period consequent upon the fulfilment of specified requirements.
Once obtained you become a holder of the rating and the rating is attached to your EASA license. It is quite common that pilots are afraid of loosing the rating by not revalidating it. This is not true, because once you obtain the rating, you are holder of rating. However the costs involved into renewal of the privileges of the rating might highly overcome the costs required for keeping the rating valid by annual revalidation means.
Nevertheless, if your rating is outside of the validity period it requires renewal procedure in order to re-gain the proficiecncy required for that rating. For that reason, the flight school has to be involved into the process. Based on the complexity of the rating it is either ATO or DTO which is involved into the renewal process.
The renewal procedure is upon discretion of the flight school and they have to decide what exactly is required for you to re-gain the necessary proficiency. In some cases it might be just a checkride recommendation without attending any training. However in some cases the flight school may prescribe to fly the required training all-over This procedure is solely in the hands of the flight school.
Upon successful renewal procedure and by recommendation from the flight school you will have to attend the renewal proficiency check. The scope is exactly the same like the revalidation proficiency check.
Revalidation of EASA instructor certificate
Besides the ratings, an EASA establishes also certificate as an flight crew license endorsement. Talking about certificates it always refers to instructor or examiner privileges.
Same like an EASA ratings also EASA certificates are subject of limited validity period. Once obtained, you become a holder of particular certificate. However you have to keep your competency to provide the particular training. Once the certificate is expireed, EASA mandates the applicant to seek flight school for support.
For that reason, the flight school has to be involved into the process. Based on the complexity of the rating it is either ATO or DTO which is involved into the renewal process. Same like rating, also the instructor renewal procedure is upon discretion of the flight school and they have to decide what exactly is required for you to re-gain the necessary instructor competences. In any case, EASA requires to attend the so-called refresher training which will at least contain the refresher seminar. Also in case of instructor certificates, flight school has to assure that the necessary competences were re-gain. Upon successful completion of the refresher training, flight school has to recommend the candidate of the checkride with an EASA examiner - FIE(A).
Unlike the proficiency check - name required for the checkride to renew particular rating, renewal of instructor certificate is called assessment of competence.
It is also important to mention, there is no difference between initial assessment of competence, revalidation assessment of competence, nor the renewal assessment of competence.
So unlike the ratings where there is different content and scope for skill test and proficiency check, the scope and content of instructor assessment of competence remains the same for all three occasions.