A Certificate of Airworthiness is in force ... the aircraft must not fly unless a Certificate of Release to Service has been issued in accordance with the Order if the aircraft or any part of the aircraft or such of its equipment as is necessary for the airworthiness of the aircraft has been overhauled, repaired, replaced, modified, maintained, or has been inspected as provided in the Order, as the case may be.
Certificates of Release to Service will certify that the overhaul, repair,replacement, modification or maintenance, as the case may be, has been carried out in a manner and with material of a type approved for a class of aircraft or the particular aircraft. The Certificate must identify the task to which it relates and must include particulars of the work done. The inspection must be specified in an Approved Maintenance Schedule and Mandatory Inspections.
The Certifying Person is entitled to accept aircraft components which have been either manufactured, overhauled, repaired, modified or inspected by approved organisations.
The Certifying Person must ensure that the component is to the required design and modification standard for fitment. This may be determined by reference to the aircraft, engine or propeller manufacturers parts catalogue as appropriate. Care must also be exercised in ensuring compliance with applicable Airworthiness Directives and the status of any life limited parts fitted to the aircraft component. The Certifying Person is responsible for ensuring that the component is in a satisfactory condition for fitting and that all required functional and installation checks are carried out to ensure the particular system serviceability or structural integrity.
An aircraft component must be dismantled sufficiently to establish satisfactory condition and any necessary replacement of life limited parts, and that the component is to the required design modification standard. Only parts listed in the Equipment Maintenance Manual parts list may be fitted. The issue of a component Certificate of Release to Service is after all certification requirements have been completed on reassembly by an organisation
Aircraft Component Distributors provide an essential service in the supply of aircraft components and whilst the Certifying Person remains responsible for acceptance of the aircraft component, the Distributor can provide good support to the Certifying Person.
Aircraft Component Distributors themselves are not required to be approved, and when acting in the Distributor role are not required to possess the necessary technical expertise to establish the status of aircraft components. It is acceptable for Distributor documentation to be endorsed:'The aircraft components identified above have been obtained from or maintained by a suitable source.
Aircraft components obtained from another Operator or Maintenance Organisation when an aircraft is grounded at a location other than the main line station or main maintenance base due to the non-availability of an aircraft component with the appropriate release certificate, it is permissible to temporarily fit an aircraft component without the appropriate release certificate for a maximum of 30 flight hours or until the aircraft first returns to the main line station or main maintenance base, whichever is the sooner, subject to the aircraft operator agreement and said component having a suitable serviceable tag.
Aircraft components must be removed by the specified time unless an appropriate release certificate has been obtained in the meantime. Aircraft components from the above sources which are then sold surplus to requirements must be accompanied by the original Certification Documentation and maintenance records, as appropriate.
A Supplemental Type Certificate (STC) is a means by which Airworthiness Authorities, including the CAA, indicate that an aircraft modification is approved.
Prior to 28 September 2003 the CAA issued STCs in its capacity as a member of the Joint Aviation Authorities (JAA). The CAA also issued Airworthiness Approval Notes (AANs) for the approval of aircraft modifications.
Since 28 September 2003 all the STCs issued by the CAA have been European Aviation Safety Agency (EASA) approved STCs issued by the CAA on behalf of EASA.
To identify all modifications approved through the CAA the AAN Database should be interrogated in addition to the CAA's own list of STCs.