A DER recently asked a question about how to mark and identify PMA parts that are designed to interface with (or attach to) TSOed articles. His question included identifying the parts on the PMA supplement. This is a challenging issue because the current rules appear to anticipate PMA parts being installed on PC products (not on TSOA articles).
Let’s start with the basics. The FAA may issue a PMA for replacement and/or modification parts intended to be installed on type certificated articles. The FAA may issue a PMA for replacement parts for articles produced under a TSO authorization (TSOA) only when these articles are in the product’s type design. The PMA replacement part is considered to be a replacement part for the eligible product – not a replacement part for the TSOAed article.
A PMA applicant is required to identify the product on which the PMA part will be installed. The term “product” has been defined in the regulations and in advisory guidance to be limited to aircraft, engines and propellers (effective April 16, 2011, this definition will be more firmly established in the definitions section of Part 21 – this change was promulgated under the Part 21 rulemaking activity published on October 16, 2009). The applicant must identify the product by make and model, series, and serial numbers if necessary. The standard PMA supplement found in Appendix F of Order 8110.42C lists columns only for make eligibility and model eligibility.
The FAA has held that the installation of a PMA part that affects a TSOAed article may result in a minor design change in a TSOAed article yet meet the product’s airworthiness requirements. If installation of the PMA part does result in a minor design change in the TSOAed article, then the FAA requires the installer of the part to place a modifier’s nameplate on the article. But many PMA parts are not modifications to the TSOAed article! The FAA has also said that replacement parts approved under the basis of identicality (which would include licensing agreement from the TC/PC holder) do not change the article’s design and do not require a modifier’s nameplate.
Similarly, the installation eligibility markings of parts destined for installation on a TSOed article must note the name and model of each applicable type-certificated product (not the TSOAed article). FAA guidance specifies that a PMA holder should NOT list the TSO identification information on the part, unless the PMA holder also holds the TSOA, in which case the part should be marked to reflect the fact that it is manufactured under both approvals (e.g. mark the part with both PMA and TSO markings).