Prime Propulsion Aviation Blog: FAA Certification & Engineering Insights

14 CFR Part 43 is one of the most consequential regulations in the FAA's airworthiness framework, and one of the least discussed in the certification consulting space. Most content about FAA certification focuses on Parts 21, 23, 25, or 33 — the design approval regulations. Part 43 operates differently. It doesn't govern how you design a product. It governs how you maintain, repair, and alter it once it's in service — and what level of FAA authorization is required before tha

FAA certification is the common thread running through nearly every engineering decision an aerospace manufacturer makes. Whether you're producing a replacement part, modifying an aircraft, approving a repair process, or qualifying a test cell — you're navigating the FAA certification system. Understanding how that system works, and which approval path applies to your specific situation, is the difference between a program that moves efficiently and one that stalls in a comme

If you're a manufacturer looking at producing a replacement part for a TSO-approved article — or a component that goes inside one — the approval path is a Parts Manufacturer Approval. But the relationship between a TSO and a PMA isn't obvious, and getting it wrong can send a program down the wrong path before it starts. This post explains how TSO articles fit into the certification structure, where the PMA opportunity actually sits, and why the complexity of the article deter

14 CFR Part 29 is the regulation that establishes the airworthiness standards for transport-category rotorcraft — the larger, multi-engine helicopters used in commercial passenger transport, heavy-lift operations, offshore energy, and emergency medical services. It's the rotorcraft equivalent of Part 25 for transport-category airplanes, and like Part 27 for normal-category rotorcraft, it carries powerplant and drivetrain requirements that have no fixed-wing parallel. The same

14 CFR Part 27 is the regulation that establishes the airworthiness standards for normal-category rotorcraft — the smaller helicopters used across commercial, utility, and private operations. Like its fixed-wing counterparts Part 23 and Part 25, Part 27 covers the full aircraft. But the portion that intersects with propulsion certification work is specific to rotorcraft in a way that sets it apart from the fixed-wing regulations. In a fixed-wing aircraft, the engine turns a p

14 CFR Part 25 is the regulation that establishes the airworthiness standards for transport-category aircraft — the larger, multi-engine airplanes that carry passengers and cargo in commercial service. It's a broad regulation covering the entire aircraft: structures, flight characteristics, systems, and equipment. But there's one part of it that sits directly alongside the engine work most propulsion certification involves, and that's where this post focuses. Part 25 is where

This is a question we get asked often, and it usually comes up the same way: a repair scheme that started out clearly as a repair has grown, and somewhere along the line it started to look less like fixing the part and more like changing it. The person asking already knows what a major repair is and what an STC is. What they're not sure about is which side of the line their particular project has landed on. It's a fair question, because the line is real but it isn't always ob

An auxiliary power unit doesn't produce thrust, but the test cell that evaluates it still has to produce numbers you can trust. And just like with a turbofan or turbojet, the way you prove an APU test facility produces trustworthy data is with a correlation. We've covered test cell correlation as a general discipline — establishing that a facility's data is traceable to a known-good baseline, usually an OEM. This post focuses on what's specific about doing that for APUs, beca

Most conversations about the FAA PMA certification timeline focus on what it takes to get approved — engineering rigor, quality system documentation, DER findings, compliance matrices. All of that matters enormously. But there's a dimension of the PMA process that rarely gets discussed directly: what it actually costs when approval takes longer than it should. Not in regulatory terms. In business terms. If you're an aerospace manufacturer or MRO pursuing a Parts Manufacturer

Most conversations about the FAA PMA certification timeline focus on what it takes to get approved — engineering rigor, quality system documentation, DER findings, compliance matrices. All of that matters enormously. But there's a dimension of the PMA process that rarely gets discussed directly: what it actually costs when approval takes longer than it should. Not in regulatory terms. In business terms. If you're an aerospace manufacturer or MRO pursuing a Parts Manufacturer

The content on this post is strong — it was my voice reference for every rewrite we've done. So the output below is the existing content with minimal, surgical additions: a few internal links to posts that now exist, and confirming the boilerplate is there. I've marked where I added something with a note so you can see the changes. TITLE TAG: MRO Repair to FAA PMA Conversion: Turn Your Repair Into a Product | Prime Propulsion META DESCRIPTION: Your MRO's proprietary repair pr

Welcome to Prime Propulsion’s resource on FAA PMA certification approval. Through many years, we’ve guided dozens of manufacturers through the Parts Manufacturer Approval process, turning regulatory complexity into clear, actionable steps. Whether you’re a seasoned DER, a quality manager, or a component engineer, this guide will walk you through the high level certification path—from FAA Part 21 Subpart K requirements to advanced test & computation strategies. Every Parts Man

Need FAA PMA Certification Help? Here’s How Prime Propulsion Can Guide You Through the Process. Navigating the FAA Parts Manufacturer...

Atlanta, GA – The roar of the aerospace industry is about to reach a fever pitch at MRO Americas, and Prime Propulsion is poised to be a...

Piston Engines: The Heartbeat of General Aviation Introduction Piston engines have been the driving force behind general aviation...

Aircraft piston engines don't get the attention turbofans do, but they're the backbone of general aviation — and they've been keeping the same airframes flying for decades. That longevity is exactly what makes them interesting from a Parts Manufacturer Approval standpoint. A fleet that stays in service for forty or fifty years needs parts for forty or fifty years, and the original manufacturers aren't always there to supply them. This post is less about how a piston engine wo

The COVID-19 pandemic's impact on the aviation industry was undeniable. Grounded fleets, plummeting passenger numbers, and economic...

## Soaring High: A Look at the FAA Reauthorization Act of 2024 On May 16th, 2024, President Biden signed the FAA Reauthorization Act of...

The race for dominance in the electric vertical takeoff and landing (eVTOL) market is heating up. These futuristic vehicles promise to...

Summary of Advisory Circular 43-18: Fabrication of Aircraft Parts by Maintenance Personnel Introduction Advisory Circular (AC) 43-18, published by the Federal Aviation Administration (FAA), provides guidance for maintenance personnel involved in the fabrication of parts for aircraft. Its primary objective is to ensure that parts fabricated during maintenance or alterations achieve an equivalent level of safety compared to those produced by the original design holder. The AC o