FAA MOSAIC Rule Fully Implemented

For twenty-one years, the homebuilding community has lived inside a set of numbers that never quite fit us. Thirteen hundred and twenty pounds. Two seats. A hundred and twenty knots. Forty-five knots clean at the stall. Those figures, written into the 2004 Sport Pilot and Light Sport Aircraft rule, defined a category that was supposed to lower the barrier into aviation. Instead, for a generation of builders, they became a fence—a line drawn just below the airplanes most of us actually wanted to build and fly.

That fence is coming down. By the time you read this, the second and final phase of the FAA’s Modernization of Special Airworthiness Certification rule—MOSAIC, the acronym we’ve all learned to say without thinking—will have taken full effect. The first phase arrived last October. The second arrives July 24. Together they amount to the most consequential reshaping of recreational aviation since the category we’re talking about was invented.

This is an overview. It is not the last word, and it is not meant to be. In the coming months KITPLANES will dig into the specifics—the maintenance privileges, the qualifying-model lists, the manufacturer-by-manufacturer market shifts, the gross-weight stories already unfolding. Consider this the map. The detailed surveys come later.

What Changed

The simplest way to understand MOSAIC is to understand the thing it broke apart. For two decades, the airplane a Sport Pilot could fly and the airplane a manufacturer could certify as a Light Sport Aircraft were defined by the same set of limits. They were welded together. MOSAIC took a torch to that weld.

On one side now sits the question of what a Sport Pilot may operate. On the other sits the question of what a manufacturer may build and certify. The FAA has set separate limits for each, and that single act of separation is what makes everything else possible.

On the pilot side—live since October 22, 2025—the old prescriptive limits are gone. In their place is a performance standard. A Sport Pilot, or anyone exercising Sport Pilot privileges, may now fly a single-engine aircraft with a clean stall speed of 59 knots calibrated or less, with as many as four seats, and a maximum level-flight speed of 250 knots. The two-occupant limit remains—you can sit in a four-seat airplane, but you may carry only one other person. With the proper endorsements, that pilot can also operate retractable gear and a controllable-pitch propeller, and fly at night if they hold a medical or BasicMed.

On the manufacturing side—effective July 24, 2026—the FAA has built an entirely new regulatory house. A new Part 22 now governs the design, production, and airworthiness of these aircraft, replacing the prescriptive weight ceiling with performance criteria. The defining number is no longer pounds; it is a stall speed. Factory-built Light Sport Aircraft may now carry up to four seats, cruise as fast as 250 knots, and—critically—be designed without an explicit maximum weight, with the stall-speed requirement acting as the practical limit. The old definition of “light-sport aircraft” has been struck from the regulations entirely, which is the bureaucratic equivalent of demolishing the fence rather than moving it.

The headline most people will repeat is “the 1,320-pound limit is gone.” That is true, and it is not nothing. But it undersells the real change. MOSAIC didn’t raise the ceiling. It replaced the architecture.

The Community Half

For most of our readers, the change that landed first is also the one that lands closest. The pilot privileges went live last fall, and they reach directly into hangars that have been full of capable airplanes their owners’ certificates couldn’t legally cover.

Consider Van’s. Among the current kit lineup, every variation of the RV-7, RV-8, and RV-9 carries a clean stall speed under the 59-knot threshold—which means a Sport Pilot can now fly them. That is an enormous swath of the most-built kit fleet in the world, brought inside the envelope overnight. The RV-6, with its 58-knot clean stall, sneaks in too. The faster, heavier types sit outside, as they should. But the practical effect is that a builder facing a medical question no longer faces a flying question with it.

This is where MOSAIC’s effect on the community gets interesting, because it cuts in two directions at once.

The first direction is retention. We have an aging population of builders and pilots, and for years the medical has been the quiet exit door—the moment a builder hangs it up not because they stopped loving the work but because the paperwork stopped cooperating. MOSAIC props that door open. A builder who can no longer hold, or no longer wants to chase, a third-class medical can keep flying a substantial portion of the experimental fleet under Sport Pilot privileges. People stay in the community longer. That matters more than any performance number.

The second direction is harder to talk about, which is exactly why we should. If a Sport Pilot can now fly far more capable airplanes—and if, after July 24, manufacturers can sell far more capable airplanes built to consensus standards—then one of the historical reasons people built their own airplane gets quietly weaker. The builder who reached for the toolbox primarily because building was the only affordable path to a capable airplane now has another path. It runs through a showroom.

I don’t think that shrinks our community. I think it clarifies it. More on that shortly.

The Industry Half

The certification side is where MOSAIC stops being a pilot story and becomes an industry story.

Until now, a company wanting to bring a genuinely capable airplane to market had two unappealing options. It could pursue full Part 23 type certification—slow, expensive, and out of reach for all but the best-funded. Or it could sell a kit and let the builder shoulder the regulatory burden as an amateur-built project. MOSAIC opens a third road: series production of capable, four-seat-capacity, fast airplanes certified against ASTM consensus standards rather than Part 23. The promise—and it remains a promise until the market proves it—is meaningfully lower cost than type certification while preserving the safety discipline of a real standard.

The FAA has been candid about its reasoning here, and builders should understand it because it shapes everything downstream. The agency’s stated view is that consensus-standard aircraft, built to an accepted design and production discipline, sit higher on the safety continuum than amateur-built aircraft, which carry no mandated design or production standard at all. In plain terms: part of MOSAIC’s design intent is to make the factory LSA a more attractive alternative to the homebuilt. The rule is not neutral about where it would like the fleet to go.

That intent is the single most important thing for our community to absorb, and it is the thread we’ll be pulling on in the issues to come.

What will the industry do with it? The early signals are already here. Zenith, characteristically quick, has been first out of the gate—its CH 750 owners registered as experimental amateur-built can now take advantage of higher gross weights, and the company has been building momentum precisely because the rule expands the pool of pilots its designs can serve. Van’s has walked its customers through the implications type by type. The bigger wave—wholly new airplanes designed from a clean sheet to live inside the new Part 22 envelope—won’t fully break until manufacturers have had time to develop and certify against the standards. The first serious evidence will appear, as these things always do, on the flight line at AirVenture.

We should be clear-eyed about the open questions, too. Will a flood of more capable factory LSAs depress the resale value of the simple two-seat LSAs that defined the 2004 era? Some owners worry it will, and they aren’t wrong to ask. Will consensus-standard production actually deliver the cost savings the rule promises, or will feature creep push these airplanes toward Part 23 prices anyway? We don’t know yet. Anyone who tells you they do is selling something.

The Maintenance Change Nobody Should Overlook

Tucked inside the pilot-side provisions is a change that may, in the long run, matter as much to our community as anything else in the rule—and it is one we’ll devote proper space to in a later issue.

For years, the great asymmetry of homebuilding was the repairman certificate. Build the airplane, and you could earn the privilege to perform its annual condition inspection. Buy that same airplane secondhand, and you could not—you were tethered to an A&P for the life of the airplane. That asymmetry quietly suppressed the resale value of every used homebuilt and discouraged plenty of would-be second owners.

MOSAIC addresses it. The framework now opens a path for owners who didn’t build their airplanes to earn condition-inspection privileges through training rather than through having wielded the rivet gun themselves. The implications ripple outward: a more liquid used market, more confident second owners, and a homebuilt that holds its value better because the next buyer isn’t signing up for a lifetime of dependency. We’ll cover the mechanics—who qualifies, what training, which aircraft—in detail. For now, understand that MOSAIC didn’t just change who can fly these airplanes. It changed who can take care of them.

So Why Build?

Which brings us back to the question this rule forces, the one I’d argue every builder should sit with: if so much of what once required a homebuilt can now be bought, why build?

For some, the honest answer was always utilitarian. You built because building was the accessible path to the airplane you wanted at a price you could afford. MOSAIC diminishes that motive, and there’s no use pretending otherwise. As capable factory LSAs appear, the “I had to build it to get it” rationale gets weaker.

But I don’t read that as bad news. I read it as clarifying. Strip away the utilitarian motive and you’re left with the reasons that actually keep people in the shop at midnight. You build because you want this airplane, configured your way, to a standard and a specification no factory will match for the money. You build because the education is the point—because the person who emerges from the project understands their airplane in a way no buyer ever will. And now you build knowing that maintaining it across its whole life just got dramatically easier, for you and for whoever owns it next.

MOSAIC changes the conversation from whether you can fly something capable to why you’d build rather than buy. The builders who were only ever in it for the cheap airplane may well drift toward the showroom, and the rule was arguably designed to nudge them there. The ones who were in it for the airplane and the building won’t go anywhere—and they’ll find more company at the airport than they’ve had in years, because MOSAIC is bringing lapsed and sidelined pilots back through the gate.

The Map, Not The Territory

Twenty-one years ago, a well-meaning rule drew a fence and called it a doorway. MOSAIC is the FAA admitting the fence was in the wrong place and, to its considerable credit, doing something genuinely bold about it. The pilot privileges are live. The certification framework arrives July 24. The full consequences will take years to play out across the flight line, the classified ads, and the kit-company order books.

This has been the overview—the lay of the land as the rule reaches full effect. In the issues ahead, in both print and digital, we’ll walk the ground in detail: the maintenance privileges and exactly who qualifies, a clear-eyed accounting of which kits and certificated types fall inside the new envelope, and a hard look at how the manufacturers respond when the certification door finally opens.

The rules have caught up with us. Now we get to find out what we do with the room they’ve made. We’ll be watching which kit makers lean into customization and cost—and which ones blink. 

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This article first appeared in the 2026 August Issue of KITPLANES magazine.