An Overview of Aviation Standard Parts and its Types

Aircraft standard parts are designed, manufactured, and showcase an approved uniform identification established by either the U.S. Government or an industry-accepted specification. Some examples of industry-accepted specifications include National Aerospace Standard (NAS) parts, Military Standard (MS) parts or Aerospace Standard (AS) parts created by SAE International. These standards were implemented to protect against counterfeit and unsafe aerospace components, materials and aircraft instrument parts. Manufacturers are required to adhere to complete compliance of these guidelines to ensure every part in the aerospace industry is safe, airworthy and reliable. In addition to published specifications establishing design, materials, manufacture, and uniform identification requirements, the FAA has also issued a performance based criteria. This second category will aim to regulate longevity and performance of only certain approved parts such as more discrete electrical and electronic parts. 

For all types of Aviation Standard Components, parts, and materials, a Certificate of Conformity is to be provided by the producer of the part. This serves as proof that the part meets published FAA specifications and criteria outlined above. In addition, the part must carry a mark identifying it as a standard part. Blueprints of the exact design must also be included in part documentation showing visual evidence the design meets approved specifications. It is important that all information of a standard part be published so that any party may manufacture the part. Approved Standard Parts will have met one of the following requirements: they are produced in accordance with a Parts Manufacturer Approval (PMA) or Technical Standard Order Authorization (TSOA), they are produced during the Type Certificate (TC) application process, or under a Production Certificate (PC). Also parts may be approved if they are produced under a bilateral airworthiness agreement, or produced in any other manner acceptable to the FAA.

When a type design calls for the installation of a standard part, FAA surveillance of the Manufacturer and Supplier may be carried out and regulatory oversight enforced. Because standard parts are not required to be produced under an FAA approved production inspection system, it is also up to the installer and the producer to determine both that a part meets specifications and specific type design installation is approved. The FAA published an Advisory Circular on the subject of detecting and reporting suspected unapproved parts in early 2000, which provides updated information and guidance to the aviation community for detecting suspected unapproved parts (SUP) and means of reporting such violations. The Aviation Safety Hotline serves as its main form of anonymously reporting SUP and other unsafe practices in direct violation. 

It became apparent after the FAA initiated Standard Part guidelines and regulations that many specialized fasteners, seals, and bearings fell outside of the criteria for standard parts since their specifications are not published. To provide approval for these groups of parts, the FAA issued the following Technical Standard Orders (TSO): TSO-C148, Aircraft Fasteners; TSO-C149, Aircraft Bearings; and TSO-C150, Aircraft Seals. These orders, unlike standard parts such as nuts, bolts, etc., follow TSO minimum performance, marking, and installation approval requirements specifically for fasteners, bearings, and seals. The Fastener Quality Act (FQA) was enacted in 1990 to ensure the quality of billions of fasteners used in America and serves as an added safe-guard to assist Standard Part regulations in ensuring only safe and airworthy parts are produced and sold. The Aircraft Safety Act of 1999 followed suit to help stop the manufacturing, distribution and installation of fraudulent, nonconforming aircraft parts.

Parts that have been rebuilt, altered or overhauled may be approved to return to service after inspection and testing by an authorized person. This screening process will determine FAA-approved design data and acceptable installation conformity is re-established. Military surplus parts fall under this distinction, defined as parts originally released as surplus by the military, even if subsequently resold by manufacturers, repair facilities, owners/operators, or any other suppliers of parts. Ordinance AC 20-62, eligibility, quality, and identification of aeronautical replacement parts, provides further information regarding eligibility and traceability of such replacement parts and can be found in the Advisory Circular.