Joby Aviation’s Suppliers: The Ecosystem Behind the eVTOL
How system-level requirements from a prime contractor are reshaping suppliers who have never worked under aviation certification discipline
There are two ways to think about Joby Aviation. The first is as an aircraft manufacturer, which it is. The second is as the apex of a supply chain that did not exist five years ago and that is being built under the dual pressure of FAA type certification and commercial production ramp. The second framing is more useful for understanding where the program risk actually lives.
Joby’s S4 is a six-tilting-rotor, five-seat eVTOL with a published cruise speed of 200 mph and a range of approximately 100 miles. The aircraft has accumulated thousands of test flight hours. Type certification under FAA Part 23 with special conditions for powered-lift is the critical path item, and Joby has been more transparent than most eVTOL developers about its certification progress and supplier relationships. That transparency makes the program a useful case study—not in how one company is doing, but in how an entirely new aerospace supply tier is being formed.
The Supplier Base Joby Is Drawing From
Joby builds its electric motors in-house. This was a deliberate architectural decision: the motors are a novel axial-flux design, and no existing aerospace supplier had a qualified part that could meet the power density, weight, and reliability requirements the system spec imposed. Vertical integration at the motor level is common among eVTOL developers for exactly this reason. The physics of efficient electric propulsion at this scale pushes designers toward custom geometries that existing aerospace motor catalogs don’t cover.
The battery system is where the supply chain picture gets more complex. Joby has publicly named Toyota as a key partner, a relationship that goes beyond investment. Toyota’s battery manufacturing expertise—developed for hybrid and EV programs at scale—is being applied to cell and pack development for the S4. The Toyota partnership matters for two reasons: first, it brings genuine manufacturing scale capability; second, it brings automotive-grade quality systems (specifically IATF 16949) that are rigorous but structured around different failure mode categories than AS9100 aerospace quality management.
Power electronics—the inverters, converters, and motor controllers that sit between the battery pack and the motors—represent the third major supplier challenge. High-voltage, high-frequency switching behavior in an aircraft environment creates electromagnetic compatibility requirements that are substantially more demanding than automotive equivalents. Several of the companies supplying power electronics to eVTOL developers are semiconductor and power module manufacturers who have excellent automotive and industrial track records and no prior experience writing the documentation that FAA-qualified avionics requires.
Avionics and flight control integration pull from a different supplier tier. Garmin has been identified in public reporting as involved in avionics integration for the S4’s cockpit and pilot interface systems. Garmin has deep Part 23 experience and understands FAA DO-178C software certification and DO-254 hardware certification. That supplier relationship carries significantly less certification risk than the propulsion supply chain, precisely because Garmin has navigated the same approval process many times.
What the System Specification Actually Demands of Suppliers
The challenge isn’t that Joby’s suppliers are building inferior components. The challenge is that a system-level specification for a novel aircraft imposes derived requirements on suppliers in ways that those suppliers haven’t previously had to manage.
Consider a battery cell supplier. The system specification for the S4 defines energy density targets, thermal runaway propagation limits, charge/discharge cycle life, and operational temperature ranges. These are translated into cell-level requirements. But the cell supplier also receives requirements that flow from the aircraft’s failure mode and effects analysis (FMEA): specific failure modes that must remain below defined probability thresholds per flight hour. Those requirements are expressed in the language of FAA Advisory Circular 23.1309, which governs equipment, systems, and installations. A cell chemistry engineer who has spent a career optimizing for EV range and cycle life has to reorient around a different requirement hierarchy—one where a single failure mode occurring at more than 10⁻⁷ per flight hour can block certification.
Power electronics suppliers face a parallel translation problem. The inverter might meet every performance specification at the component level. But the system specification also requires that the inverter’s failure modes be bounded, documented, and traceable to a system-level safety assessment. This means the supplier’s internal engineering documentation—schematic reviews, design verification tests, analysis reports—has to be structured so that Joby can incorporate it into a certification deliverable that will be reviewed by the FAA Aircraft Certification Office. Suppliers who have never written a System Safety Assessment or a Hardware Accomplishment Summary are encountering this requirement for the first time and often underestimate how much organizational infrastructure it demands.
The motor supply chain—since Joby builds in-house—avoids this particular problem at Tier 1. But the winding wire, lamination steel, and bearing suppliers feeding into Joby’s own motor production are Tier 2 and Tier 3 players who face similar documentation demands. The aerospace supply chain’s quality discipline is not limited to the immediate system integrator.
The Certification Discipline Gap
Aviation certification is not primarily a technical problem. It is a documentation and process problem layered on top of a technical problem. An engineer who correctly designs a safe component is only partway to certification. The remaining work—demonstrating, to a regulator’s satisfaction, that the component is safe and that you know why it is safe—requires a quality management apparatus, a configuration control process, and a requirements traceability discipline that most non-aerospace suppliers have not developed.
The FAA’s powered-lift special conditions for eVTOL aircraft, as applied to programs like Joby’s, extend traditional airworthiness requirements to entirely new system architectures. There is no prior type certificate for a six-tilt-rotor aircraft. The means of compliance for many requirements are being negotiated between Joby’s certification team and the FAA in real time. This means that the requirements flowing down to suppliers are sometimes still maturing—a supplier may be building to a specification that is revised as the certification basis is clarified.
This creates a specific traceability problem. If the system specification changes—say, a thermal runaway propagation requirement is tightened based on new test data—every derived requirement downstream of that change needs to be identified, assessed for impact, and potentially re-verified. For a supplier with a mature requirements management process and bidirectional traceability, this is a manageable change control event. For a supplier using a shared spreadsheet and a folder of PDFs, it is a program crisis.
The gap between those two states is not a technology problem. It is a process maturity problem. And it is the single most consistent source of schedule risk in eVTOL supply chain industrialization, across every major program that has been publicly discussed by FAA officials and industry working groups.
What’s Actually Happening vs. the Hype
Public reporting on eVTOL supply chains tends to emphasize the technology—novel cell chemistries, high-efficiency inverters, distributed propulsion architectures. The engineering is genuinely interesting. But the more consequential story is organizational.
Joby’s supply chain organization has been visibly investing in supplier development activities: working with partners to build quality systems that can support certification deliverables, conducting supplier audits, and in some cases co-locating engineering resources at supplier facilities to accelerate the documentation build. This is expensive and slow. It is also unavoidable. The alternative—accepting supplier deliverables that cannot be incorporated into a type certificate submission—is not actually an alternative.
Toyota’s involvement is illustrative of how a sophisticated industrial partner navigates this. Toyota’s quality system is among the most mature in manufacturing. Its engineers understand process documentation, variation control, and failure mode analysis at a level that most automotive suppliers don’t match. But automotive quality management is still not aviation quality management. The investment Toyota is making in understanding FAA requirements and adapting its processes is real, and it is one of the reasons the Joby-Toyota relationship is more substantive than a typical investment announcement.
On the avionics side, the certification path is comparatively well-understood. DO-178C for software and DO-254 for complex electronics are established frameworks. Garmin’s participation in the S4 program means that at least one critical supply relationship is between Joby and a partner who speaks FAA fluently. The propulsion supply chain does not yet have an equivalent—a set of fully qualified, certification-experienced suppliers who can deliver battery cells and power electronics with the same documentation maturity that Garmin brings to avionics.
The Requirements Flow Problem at Scale
When Joby certifies a single prototype aircraft, the requirements management challenge is tractable with skilled engineers and disciplined tooling. When the program scales to production—Joby has publicly discussed manufacturing ambitions in the hundreds of aircraft per year—the requirements flow problem scales with it.
Each production aircraft involves the same certification-grade documentation chain. Supplier conformity, configuration control records, and test data packages don’t become easier to manage at volume; they become harder, because the volume of data grows while the tolerance for errors remains at zero. The suppliers who will succeed in the eVTOL supply chain long-term are those who build requirements management and configuration control as organizational capabilities, not as one-time certification efforts.
This is an area where the tooling conversation becomes relevant. Requirements management platforms designed for aerospace—where bidirectional traceability, change impact analysis, and structured document generation are native capabilities—exist. Tools like IBM DOORS have been the traditional choice for exactly this workflow, and many Tier 1 aerospace suppliers have years of DOORS investment. The challenge for new entrants is that DOORS’s complexity and licensing costs create a barrier for suppliers who are implementing requirements management for the first time. Newer platforms, including Flow Engineering, are being evaluated by some eVTOL-adjacent teams precisely because they offer graph-based traceability and AI-assisted requirements analysis without the implementation overhead of legacy tools—which matters when a battery supplier is trying to stand up a compliant requirements process in 18 months rather than three years.
The practical implication is that primes like Joby have a direct interest in what requirements management tooling their suppliers adopt. A supplier using tooling that can export structured traceability data compatible with Joby’s own systems reduces the integration burden at the prime level. This is starting to show up in supplier development discussions across the eVTOL sector—not as a mandated tool selection, but as a preference for structured, machine-readable requirements artifacts over document-based deliverables.
Honest Assessment
The Joby supply chain story is a test case for whether the aviation industry can absorb a wave of non-aerospace suppliers quickly enough to support eVTOL certification timelines. The technology is not the primary constraint. The constraint is organizational: whether suppliers who have never operated under FAA certification discipline can build the process infrastructure that certification requires, and whether primes like Joby can transmit not just specification numbers but certification intent down the supply chain.
Joby is better positioned than most eVTOL developers to navigate this, partly because of the Toyota partnership’s manufacturing depth, partly because of its direct motor manufacturing capability, and partly because the program’s transparency suggests a management team that has been honest with itself about where the risks are. That self-awareness doesn’t eliminate the supply chain risk. It means the program is running toward the problem rather than away from it.
The broader lesson for the eVTOL industry is that supply chain readiness for certification is not something that can be purchased at the end of a development program. It has to be built in parallel with the aircraft, starting from the first supplier selection. The programs that treat requirements flow and supplier documentation maturity as a design activity—not a procurement activity—will have a structural advantage as they approach type certificate.
The programs that don’t will find out why aerospace has always been hard.