31 July 2011 C1 CIVIL AVIATION DEPARTMENT HONG KONG ...

electrical components. For items used as 'Aircraft Components' as definedhere, the known or probable use will determine the approval category and, forControlled Items, the requirements of paragraph 5 of HKAR-1 Sub-section 1.4-8 will need to be followed as appropriate. The term 'Uncontrolled' relatessolely to the status of items in their functional role in an aircraft and does notimply that such components may be ignored. Paragraph 2 of BCAR ChapterD6-1 requires those designing installations to consider the suitability of'Unclassified parts and Equipment' and, where necessary, these 'shall becontrolled ... to a standard to ensure compliance with the relevant requirementsof ... Section D'. Thus the design and build standard of the 'Uncontrolled Item'may still be subject to a measure of control under the CAD proceduresprescribed in this Notice to ensure that no new unassessed failure modes areintroduced.3.3 The selection and use of Aircraft Components is normally the responsibility ofan Approved Organisation with appropriate Terms of Approval under HKAR-1procedure. Such organisations need to satisfy themselves, and ultimately theDirector-General, as to the suitability of an equipment in a given application.This is most conveniently done by obtaining a Declaration of Design andPerformance (DDP) to a format based upon that given in HKAR-1 Sub-section1.4-8 paragraph 6, BS 3G100 Part 1 or ISOR224. The authorisation of theDDP by an Approved Signatory within an Approved Organisation and itsacceptance by the user constitutes Approval under Component Procedures. Ifthe design authority for an equipment additionally obtains approval for theirproduct from the Director-General then the equipment is said to be 'AccessoryApproved'. It is important to note, however, that 'Accessory Approval' doesnot absolve the user from ensuring that the item to be used as an AircraftComponent is suitable for the particular application.3.4 The assurance that the products obtained are as declared on the DDP is afunction of a clearly defined purchase order requiring 'CAD Release'. (Seeparagraph 5) In the context of this Notice it is essential that users appreciatethat generalised claims that an item is 'approved' can only relate to theconformity with specifications, compliance with which may, or may not, havebeen validated by a third party. Approval for aircraft use is a function ofselection by an authorised Design Authority who will, in effect, approve theapplication of the item.4 Component Parts - Selection4.1 The designer of a piece of equipment which utilises individual component partshas freedom of choice in the matter of selection provided that the equipmenttaken as a whole meets its design specification and the relevant AirworthinessRequirements. The Requirements of HKAR-1 have to be satisfied and thisestablishes the need for control of the identification, reliability and modificationstandard of component parts. Users and overhaulers of equipment need to beable to procure component parts which will maintain the established andaccepted reliability of the total equipment. It follows that all necessaryinformation regarding special testing, selection or condition of component parts31 January 2002 AN-39 P.2