STANDARD PARTS
WHAT IS A STANDARD PART? Mentioning standard parts usually
brings to mind the
thought of merely “nuts or bolts” when, in fact, other types of
parts as well as materials used to produce aviation parts may fall under the
category of “standard part.” A standard part is a part or material
that conforms to an established industry or U.S. Government-published
specification. The FAA’s acceptance of a standard part as an approved
part is based on the certification that the part has been designed and produced
in accordance with an independent established set of specifications and
criteria. “Standard part” is not defined in Title 14 of the Code of
Federal Regulations. Section 21.303(b) provides four exceptions to the
requirement to hold a Parts Manufacturer Approval to produce replacement and
modification aircraft parts. Section 21.303(b)(4) provides the exception for
standard parts -- bolts and nuts -- which are parts that conform to established
industry or U.S. specifications. The FAA has published a non-regulatory
definition of “standard part” as well as interpretative information
regarding what criteria parts must meet to come under the standard part
category. Advisory Circular 21-29 (pdf), Detecting and Reporting Suspected
Unapproved Parts, provides the following definition of “standard
part”:
A part manufactured in complete compliance with an established industry or U.S.
Government specification which includes design, manufacturing, test and
acceptance criteria, and uniform identification requirements; or for a typeof
part which the Administrator has found demonstrates conformity based solely on
meeting performance criteria, is in complete compliance with an established
industry or U.S. Government specification which contains performance criteria,
test and acceptance criteria, and uniform identification requirements. The
specification must include all information necessary to produce and conform the part and be published so that any party may
manufacture the part. Examples include, but are not limited to, National
Aerospace Standard (NAS), Army-Navy Aeronautical Standard (AN), Society of
Automotive Engineers (SAE), SAE Sematec, Joint Electron Device Engineering
Council, Joint Electron Tube Engineering Council, and American National
Standards Institute (ANSI).
This definition incorporates two categories of standard part criteria.
Initially, the FAA recognized as “standard” those parts that met
published specifications that included information clearly establishing design,
materials, manufacture, and uniform identification requirements. The FAA issued
a subsequent interpretation of standard part that provided for a class of parts
conforming to a standard not based on their physical configuration but on their
meeting a specified performance criterion. The FAA stated this second category
of standard parts is best exemplified by discrete electrical and electronic
parts. See 62 Fed. Reg. 9,923 (1997). The FAA must
make a specific finding of applicability to a class of parts before the
“performance only” criterion can be used.
REGULATORY OVERSIGHT.The FAA does not certificate manufacturers of standard
parts. However, when a type design calls for the installation of a standard
part, the FAA may conduct surveillance of the manufacturer and/or supplier of
that part.
The FAA has previously noted that standard part manufacturers are subject to
continuing in-depth audits by their customers, and these audits provide an
appropriate degree of confidence that the standards are being met. A standard
part must conform to the designated part specification in order to qualify as a
standard part. Accordingly, the production of a standard part offered for sale
for installation on a type-certificated product where that part does not
conform to the standard part specification may be a violation of section
21.303(a). Recognizing that billions of fasteners are used in the American
economy each year, Congress enacted the Fastener Quality Act (FQA) (15 U.S.C.
5401). Enacted in 1990, the FQA has been subsequently amended several times.
However, the basic intent remains the same, i.e., to ensure the quality of
fasteners and to prevent mismarked, misrepresented, and counterfeit fasteners
from entering the commercial market. Numerous articles have been written about
the FQA, and several points presented in them are noteworthy. For purposes of
the FQA, “fastener” is defined as:
A metallic screw, nut, bolt, or stud having internal or external threads, with
a nominal diameter of 6 millimeters or greater, in the case of such items
described in metric terms, or ¼ inch or greater, in the case of
suchitems described in terms of the English system of measurement, or a loadindicating
washer that is through-hardened or represented as meeting a consensus standard
that calls for through-hardening, and that is grade-identification marked or
represented as meeting a consensus standard that requires grade-identification
marking…
The FQA then provides various types and configurations of fasteners that are
exempt from the Act, including fasteners specifically manufactured for use on
an aircraft if the quality and suitability of those fasteners have been
approved by the FAA or by a foreign airworthiness authority. Although the U.S.
Department of Commerce is responsible for the implementation and enforcement of
the FQA, this exemption provides for the FAA to have the regulatory oversight
and enforcement for fasteners approved for installation on aircraft.
STANDARD OR OTHERWISE. Standard parts are produced per
published specifications and
criteria. After the FAA initiated an enhanced enforcement program to bring
parts manufacturers into compliance with section 21.303, it became apparent
that many specialized fasteners, seals, and bearings were manufactured to
specifications known only to the manufacturer. It would not be practical to
obtain a Parts Manufacturer Approval for such specialized groups of fasteners,
seals, and bearings, but these groups of parts fall outside the criteria for
standard parts since their specifications are not published. To provide
approvals under which these groups of parts could be produced, the FAA issued
thefollowing Technical Standard Orders (TSO): TSO-C148, Aircraft Fasteners;
TSO-C149, Aircraft Bearings; and TSO-C150, Aircraft Seals. Authorizations for
these TSO’s are not issued for standard parts nor for parts used in
critical applications. In contrast to “standard part” nuts, bolts,
etc., these fasteners, bearings, and seals must meet the TSO minimum
performance, marking, and installation approval requirements.
CONSIDERATIONS. When purchasing and installing
standard parts, consider the
following: •
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A Certificate of Conformity (C of C) should be provided by the producer of a
standard part. A standard part should carry a mark indicating the part has been
produced in accordance with the specification requirements. A part is no longer
considered “standard” if it is used in a critical application that
imposes qualification or quality control requirements beyond the standard
specification. To facilitate traceability, commingling like fasteners from
different lots is not recommended. Section 21.303(b 4)
provides that acceptable government specifications are limited to those
published by the U.S. Government. Parts produced to a foreign standard may,
however, be acceptable for installation on foreign type-certificated aircraft
and products. Installation of a standard part must be in accordance with the
requirements of part 43. Generally, a standard part may be replaced with an
identical standard part; however, substituting standard parts would require a
demonstration of acceptability in accordance with part 43.
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