Over the past few months, I have encountered a number of PMA exporters, and European PMA importers, who have asked for clear guidance on how to distinguish a “critical” PMA parts from a “non-critical” PMA part.
This is an important distinction because under the Bilateral Airworthiness Safety Agreement (BASA) that was signed between the United States and the European Union, there are three types of PMA parts that are accepted in the European Union (for installation on products certified or validated by EASA) without further showing. Those three “acceptable” situations, as described in the BASA Technical Implementation Procedures (TIP) are:
(1) The PMA part is not a “critical component”; or
(2) The PMA part conforms to design data obtained under a licensing agreement from the TC or STC holder according to 14 CFR §21.303; or
(3) The PMA holder is the holder of an EASA STC which incorporates the PMA part.
Thus, non-critical PMA parts are directly acceptable (and they should have text on their export 8130-3 tag that states “This PMA part is not a critical component”). So there is a significant advantage to having a clear understanding of when a PMA part is critical and when it is not critical.
This can be a little confusing if you don’t know where to look. The FAA has used the term “criticality” to define different categories of parts for approval purposes, and to set differnt levels of FAA involvement in the approval process. The distinct use of the term means that we need to look in the right place for the definition of “critical” that applies to our export/import transactions.
For purposes of US exports of PMA parts that are imported into the European Union, the controlling guidance is found in the BASA’s Technical Implementation Procedures for Airworthiness And Environmental Certification (BASA TIP). The definition of critical component for purposes of that document is found in Section 1.6(i) of the BASA TIP:
“Critical Component” means a part identified as critical by the design approval holder during the product type validation process, or otherwise by the exporting authority. Typically, such components include parts for which a replacement time, inspection interval, or related procedure is specified in the Airworthiness Limitations section or certification maintenance requirements of the manufacturer’s maintenance manual or Instructions for Continued Airworthiness.
Don’t fall for the temptation draw a semantic difference between a “critical component” and a “critical part.” The PMA acceptance procedures found in section 2.8.2(a)(1) of the BASA TIP explicitly cross reference the definition in section 1.6(i).
In light of this definition found in the BASA TIP, the question of whether a PMA part is “critical” will be based on the decision of the FAA (the exporting authority) about whether it was critical at the time of approval.
The regulatory guidance for critical parts is found in the marking requirements discussion in section 45.15(c) of the FAA’s regulations. That section makes it clear that an article is “critical” if it has a hard time specified in the Airworthiness Limitations section of the manual (instructions for continued airworthiness), like a life limit, then it is a critical part (or critical component).
Under normal circumstances, there are two methods for specifying such a limit on a PMA part. The first is during the FAA approval process (usually as an airworthiness limitation published in the instructions for continuous airworthiness), when the airworthiness limitation section associated with the part would be approved. The second is by an FAA airworthiness directive issued after initial approval in response to an identified safety issue.
Thus the best source for identifying whether a PMA article is “critical” is the PMA manufacturer, who should be able to tell customers whether there were any such hard times associated with the article as part of the approval process (or review of the PMA manufacturer’s instructions for continuous airworthiness). If the FAA did not establish that the part was critical at the time of approval, and if they did not subsequently issue an airworthiness limit (such as through an airworthiness directive), then the part is not critical.