Bjorn’s Corner: Aircraft structures Part 10: Composite certification.

Bjorn Fehrm's latest installment in Leeham News' aircraft structures series turns to the certification framework underpinning composite construction, a topic with direct implications for the next generation of transport-category aircraft and the emerging eVTOL sector. The core thesis is that a composite structure cannot be certified merely by qualifying fiber and resin separately—the regulator requires an entire "material system" encompassing fiber, matrix, and fabrication process to be validated as an integrated whole. This is why Airbus and Boeing's current composite platforms, the A350 and 787, rely on tape prepreg with autoclave curing, a mature but comparatively slow and expensive process that both airframers now acknowledge is unsuitable for the 10x production rates envisioned for next-generation single-aisle aircraft. Airbus's "Wing of Tomorrow" program, which has consumed over 15 years of development and more than five years of certification work with EASA and the FAA involving over 10,000 coupon tests, illustrates just how enormous the qualification burden is when moving to dry fiber and resin-infusion techniques designed for higher throughput.

For working pilots, this deep dive into materials certification may seem far removed from the flight deck, but it explains why airframers are so cautious and slow to commit to all-composite fuselage designs for narrowbody replacements. The four-times-greater test volume required for composite material systems compared to metal alloys is a major driver of program timelines and costs, and it directly affects when—or if—a true 737 MAX/A320neo successor with a composite primary structure will reach the market. Pilots transitioning onto new equipment in the coming decade should understand that any claims of dramatically lighter, more efficient composite airframes come with an equally dramatic certification tail. The rigor described—hundreds of pages of specifications, coupon testing across multiple climate conditions, and characterization of strength, modulus, and Poisson's ratio—reflects the same conservative, data-driven approach to structural integrity that pilots rely on every day when they trust an airframe's certified limits, whether they're flying a legacy metal jet or a composite widebody.

The piece's most operationally relevant observation concerns NCAMP, the NIAA-administered public database of FAA-recognized material systems such as Hexcel's 8552/AS4 system. This shared resource allows smaller manufacturers—including business jet OEMs and general aviation companies—to access pre-qualified composite systems without bearing the full cost of independent certification, dramatically lowering the barrier to entry for composite structures in smaller programs. However, Fehrm's warning about eVTOL manufacturers is a pointed one for anyone tracking advanced air mobility as a future segment of professional aviation. Many eVTOL start-ups have built their initial prototypes and low-rate production using NCAMP-available systems, but their business plans call for scaling to hundreds or thousands of airframes annually—rates that likely exceed what current publicly available material systems can support. If these companies have not budgeted the years and tens of millions of dollars required to develop or requalify a higher-rate composite system, they face a serious and potentially program-ending bottleneck between prototype and volume production.

This matters broadly for commercial, business, and general aviation because it underscores a recurring pattern: the gap between a compelling airframe concept and a certifiable, mass-producible reality is often defined not by aerodynamics or propulsion but by materials science and regulatory process. Airlines and operators evaluating future fleet types—whether next-gen narrowbodies from Airbus and Boeing or eVTOL air taxis from well-funded start-ups—should treat certification-basis maturity for composite manufacturing as a leading indicator of program risk. Fehrm's analysis is a reminder that in aviation, the unglamorous back-office work of qualifying coupon tests and locking down cure cycles is what ultimately determines whether ambitious production targets are achievable, and it explains why legacy OEMs with decades of composite certification experience still move cautiously even as newer entrants promise faster timelines.