Your MRO Already Has the Hard Part Done. Here's How to Turn It Into a FAA PMA.

Most MROs don't realize they're sitting on a PMA opportunity. If your facility has developed a proprietary repair process — one that your engineers figured out, your technicians perfected, and your quality system has been executing consistently for years — you've already done the heaviest lifting in the certification process. The engineering knowledge exists. The process works. The safety case has been validated in the field, sometimes thousands of times over.

What you don't have yet is the FAA's approval to sell that capability as a marketable part. That's where the MRO repair-to-PMA conversion comes in — and it's a more accessible path than most operators assume.

What Does "MRO Repair to PMA" Actually Mean?

Let's be precise about what we're talking about. A Repair Specification (RS) authorizes a specific facility to perform a specific repair on a specific part. It's facility-bound, process-bound, and doesn't create a product you can sell or a part number anyone else can order. It keeps your aircraft flying — but the value stays locked inside your four walls.

A Parts Manufacturer Approval is different. Once you hold a PMA, you are an FAA-approved manufacturer. You can produce and sell that article — whether it's a repaired component returned to serviceable condition or an entirely new replacement part — to any operator, any MRO, any airline in the world that needs it. The repair process you've already proven becomes a product. The knowledge you've accumulated becomes a revenue stream.

That's the MRO-to-PMA conversion. And the regulatory path is more straightforward than most people expect, because the foundational engineering work is largely already done.

Why MRO Repair Data Is the Ideal PMA Starting Point

When an MRO develops a proprietary repair, it typically goes through several steps that map almost directly onto FAA PMA requirements under 14 CFR §21.303. Think about what that process usually involves:

You've reverse-engineered or thoroughly characterized the part — you know the dimensions, the materials, the tolerances. You've developed a process that restores the part to airworthy condition, which means you've already established a technical baseline for what the part needs to look like and perform like. You have inspection criteria. You have quality records. You likely have field data on how the repaired parts perform over time.

A PMA application requires design data, substantiation, and a quality system. The repair process you've been running is, in essence, all three. The gap between where you are and where you need to be for PMA is real — but it's far narrower than starting from scratch.

The 3 Gaps That Need to Be Closed for MRO Repair-to-PMA Conversion

In our experience working with MROs through this conversion, the challenges are almost always the same three things:

1. Drawing formalization. Repair processes often live in work instructions, traveler documents, and tribal knowledge. FAA PMA requires formal engineering drawings with revision control, full material callouts, part marking per 14 CFR §45.15, and DER sign-off. Translating what your team does instinctively into an auditable, FAA-ready drawing package is typically the most labor-intensive part of the conversion — but it's documentation work, not discovery work. The underlying data already exists.

2. Substantiation framing. A Repair Specification approval is focused on the repair process. An FAA PMA requires substantiating the design of the article itself — showing that the part, as produced under your process, meets the applicable airworthiness standards. For many MRO-derived PMAs, this follows the test and computations via comparative analysis path: demonstrating that the article produced by your process is equivalent to the approved design through direct comparison against the OEM part. In some cases, particularly where your process produces a part that improves on the original, a broader test and computations approach may be the stronger argument. A DER helps you make that call correctly.

3. Quality system scoping. Most MROs already operate under FAA-approved quality systems. However, a repair station quality system and a Part 21.137 production approval quality system are not identical in scope. The production side adds requirements around supplier controls, first article inspection, and ongoing conformity that may not yet be captured in your existing procedures. Closing this gap is usually the fastest of the three — it's typically an expansion of what you already have, not a rebuild.

None of these are insurmountable. In most MRO-to-PMA conversions we've worked through, the timeline from engagement to PMA submission is meaningfully shorter than a greenfield certification project, precisely because the engineering foundation is already solid.

The Business Case for Converting MRO Repairs to PMA Products

MROs that make this conversion don't just gain a new FAA approval. They fundamentally change their market position.

Before the conversion, your repair capability generates revenue only when a customer brings you their part. You're reactive. Your market is limited to operators in your network who know you can do the job.

After the FAA PMA approval, you're proactive. You can market an approved article. Distributors can stock it. Airlines can order it for their parts catalog. Other MROs can source it. The same technical capability that was generating one-at-a-time repair revenue can scale into a production business.

This is particularly compelling for MROs that specialize in components with known OEM supply chain problems — parts where lead times are long, prices are high, or the OEM has reduced support. Those are precisely the parts where a PMA alternative has immediate buyer interest. If you've already been repairing them, you know the market. The conversion lets you serve it at scale.

How to Start the MRO Repair-to-PMA Process

The first step is an honest feasibility assessment. Not every proprietary repair converts cleanly into a PMA opportunity, and it's worth knowing that before committing engineering resources to the effort. The key questions to answer upfront:

• Is there genuine demand for this part beyond your current customer base?

• Do you have enough OEM part samples and field data to support substantiation?

• Does your current repair data package have sufficient engineering depth to translate into PMA-ready documentation?

• What's the competitive landscape — are other PMA holders already in this space?

If the answers point toward a viable opportunity, the next step is engaging a DER to assess your existing data and define exactly what the MRO repair-to-PMA conversion path looks like for your specific part and process. That scoping conversation typically takes a few hours and gives you a clear picture of the effort, timeline, and investment required before you commit to anything.

Conclusion: The Engineering Work Is Already Done

The path from proprietary MRO repair to FAA PMA approval is one of the most underutilized opportunities in aerospace certification. The engineering is already done. The safety record is already established. The market need is often already visible to you because you've been serving it.

What's missing is the certification step — and that's exactly what we do at Prime Propulsion. Our DER-led team has guided MROs through this conversion repeatedly, and we know where the gaps are before the FAA finds them.

If your facility has a repair process you've been relying on and you've wondered whether it could become something more, contact us to schedule a feasibility discussion. There's no cost to find out whether the opportunity is real. You can also learn more about our FAA PMA certification services and Repair Specification support.

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.