21L.A.252 Design of markings

It is not the intent of point 21L.A.252(b)(2) to introduce an obligation for an approved production organisation, declared production organisation or a natural or legal person who produce under subpart R to mark new parts with information which is not identified by the design approval holder or declarant. Therefore, the physical marking of parts is only required when established by the design approval (TC, STC, repair, change) holder or declarant.

PARTS TO BE MARKED For the purposes of point 21L.A.252(b)(2)(iii), a part that requires individual traceability for the management of its continued airworthiness, as identified by the design approval holder or declarant, should be permanently marked with a part number and a serial number. The need for the design approval holder or declarant to identify and mark parts may be related to specific requirements for critical parts included in a certification specification. For instance, according to point (c) of CS-E 110 Drawings and Marking of Parts — Assembly of Parts: ‘Certain parts (including Engine Critical Parts; see CS-E 515) as may be required by the Agency must be marked and the constructor must maintain records related to this marking such that it is possible to establish the relevant manufacturing history of the parts.’ Another typical case is for any part subject to an individually specified life limit or inspection requirement when it is also possible for that part to be removed from one serial number of the associated product during maintenance and installed on another serial number of the same product. In this case, the traceability of the part, which is necessary for continued airworthiness management purposes, is not assured through the serial number of the product alone, and it is necessary to maintain records for the part through its serial number.

The intent of point 21L.A.252(c) is to prevent a part produced for a declared aircraft and produced under Subpart R from being installed on a type-certified aircraft particularly after a part has been maintained and subsequently released on an EASA Form 1. To achieve this, the letter ‘R’ is added to the part number. The ICAs and parts catalogue should include an ‘R’ at the end of the part number that is assigned to the part. If a part is similar to a part that is normally installed on a type-certified aircraft, it is expected that the ICAs and parts catalogue for the type-certified aircraft will include a part number that does not contain an ‘R’ at the end. Therefore, an installer would be prevented from installing a part with a part number ending in ‘R’ because the part number would not match the ICAs and parts catalogue for the type-certified aircraft.