M.A.304
A person or organisation repairing an aircraft or a component, shall assess any damage. Modifications and repairs shall be carried out using, as appropriate, the following data:
(a) approved by the Agency;
(b) approved by a design organisation complying with Annex I (Part-21) to Regulation (EU) No 748/2012;
(c) contained in the requirements referred to in point 21.A.90B or 21.A.431B of Annex I (Part-21) to Regulation (EU) No 748/2012.
AMC M.A.304 Damage assessment
A person or organisation repairing an aircraft or component should assess the damage against published approved repair data and the action to be taken if the damage is beyond the limits or outside the scope of such data. This could involve any one or more of the following options; repair by replacement of damaged parts, requesting technical support from the type certificate holder or from an organisation approved in accordance with Part-21 and finally Agency approval of the particular repair data.