Two Ways to Obtain an FAA PMA: Identicality vs. Test & Computations

Last month we discussed what exactly a PMA ( Parts Manufacturer Approval) is, but let’s start going down the path of how a company can obtain one. There are primarily two ways, Identicality and Test and Computations. A company can decide which is most beneficial to them based on the information they have on-hand or can obtain by the time of submission to DER (Designated Engineering Representative) or FAA (Federal Aviation Administration). So, lets dive into some details about the options.

Test and Computations:

This is what most companies would simply refer to as reverse engineering. An applicant company would research the OEM part they want to duplicate, make their business case, and begin the process of FULLY understanding it and its mating components. Two of the most important aspects of reverse engineering are dimensional and material analysis. Dimensional Analysis is typically performed via CMM (Coordinate Measuring Machine) on 3-5 OEM parts and it provides precise measurements and a tolerance range. Once dimensions and tolerances are understood, new PMA drawings can be created. Material Analysis is simply providing an OEM part to an accredited laboratory where they analyze the part to understand the base material, surface treatments, physical properties, and any special processes.

Identicality:

There are two forms of identicality — with a licensing agreement and without one. This post focuses on identicality without a licensing agreement, as it's the more common of the two.

The key to understanding this path is the FAA's role in it. The FAA's job is to determine whether an article is airworthy and meets the applicable regulations. It does not adjudicate intellectual property questions or investigate how an applicant obtained its design data — that's outside the agency's scope. What that means in practice is that an identicality showing rests entirely on the applicant: you must provide evidence to the FAA that your PMA part will be identical to the OEM part. Typically, that means demonstrating that your part and its drawings match the original OEM design.

It's worth being clear-eyed about what this path requires. Because the FAA doesn't referee data rights, the responsibility for sourcing design data lawfully — and for being able to stand behind how it was obtained — sits with the applicant. Companies pursuing identicality should be confident in the provenance of their data before going down this road. A DER can help you assess whether identicality is a realistic path for your part, or whether test and computations is the cleaner route given what you have available.

Which Path Is Right for You?

The choice between identicality and test and computations usually comes down to what you can get your hands on. If you have access to the OEM drawings, identicality is often the more direct route. If you don't, test and computations lets you build the case from the part itself through reverse engineering — it's more work, but it doesn't depend on having proprietary data in hand.

In practice, that decision is one of the first things a DER helps you make, because choosing the wrong path costs time you can't get back. Our in-house DER has guided manufacturers through both routes and can help you scope which one fits your part, your data, and your timeline before you commit engineering resources to it.

If your company needs assistance obtaining a PMA, or you just have questions about which path makes sense, contact us — we're happy to help. You can also read our Ultimate Guide to FAA PMA Certification for a step-by-step look at the full process.

Prime Propulsion delivers expert FAA certification solutions for small to medium-sized aerospace firms. Our DER-led team specializes in PMA, STC, Test Cell Correlations, and Repair Specification support.