CFM RISE Test, FAA eVTOL Rule, NASA X‑59 Taxi: Breakthroughs Stack Up Across Aviation

In a span of weeks, propulsion, regulation, and flight‑test campaigns advanced in lockstep: CFM’s open‑fan engine ran on a test stand, the FAA finalized its powered‑lift rule, and NASA’s X‑59 moved onto the runway. Airlines and startups sealed fresh SAF and hydrogen milestones that pull decarbonization and new airframes closer to service.

Published: December 8, 2025 By James Park, AI & Emerging Tech Reporter Category: Aviation

James covers AI, agentic AI systems, gaming innovation, smart farming, telecommunications, and AI in film production. Technology analyst focused on startup ecosystems.

CFM RISE Test, FAA eVTOL Rule, NASA X‑59 Taxi: Breakthroughs Stack Up Across Aviation
Executive Summary
  • CFM’s open‑fan RISE demonstrator achieved its first test‑stand run in mid‑November, targeting a 20% fuel‑burn cut versus today’s single‑aisle engines, according to program partners GE Aerospace and Safran.
  • The FAA issued its final rule for powered‑lift pilot certification and operations on November 18, unlocking a clearer certification path for eVTOL makers like Joby Aviation and Archer Aviation, per the FAA.
  • NASA’s quiet‑supersonic X‑59 advanced to runway taxi tests in late November, a key pre‑first‑flight step in the Quesst program, NASA said.
  • Hydrogen and SAF momentum accelerated: Rolls‑Royce and easyJet reported phase‑two hydrogen combustion tests, while United Airlines signed a new eSAF offtake agreement, and ZeroAvia announced FAA certification‑basis progress.
Propulsion Breakthroughs Move From Concept To Test Stand CFM’s open‑fan RISE demonstrator, a collaborative effort of GE Aerospace and Safran, completed its first instrumented run on a ground test stand in the U.S. in mid‑November, a pivotal event on the path to a next‑generation single‑aisle powerplant promising roughly 20% lower fuel burn and CO2 emissions relative to current CFM LEAP engines, according to the partners and industry reporting from Reuters and program briefs from CFM. The test kick‑starts a multi‑year validation campaign that also includes open‑rotor acoustics work aimed at meeting stringent community noise limits. In parallel, hydrogen propulsion edged forward. Rolls‑Royce and easyJet disclosed phase‑two results of ground testing of a hydrogen‑fueled aero engine under altitude and thermal conditions representative of flight, expanding on earlier ambient runs and showing stable combustion characteristics across a broader envelope, per the companies’ recent updates. Hydrogen fuel‑cell hybrid systems are also advancing: ZeroAvia said in early December that the FAA agreed the certification basis for its ZA600 engine would align to Part 33 standards with supplementary means of compliance, an administrative milestone toward regional entry‑into‑service in the latter part of the decade as outlined in its program roadmap. Regulators Clear The Runway For eVTOL Operations On November 18, the Federal Aviation Administration finalized its rule establishing pilot certification, training, and operating requirements for powered‑lift aircraft, creating a uniform framework for type certificated eVTOLs entering service, the agency announced here. The rule synchronizes with existing parts for air carrier operations and maintenance, providing a clearer path for urban air mobility underpinned by certification and operating approvals. The move immediately impacts timelines at Joby Aviation and Archer Aviation, which each reported stepped‑up engagement with the FAA’s certification teams and production oversight. Archer said it secured a key production milestone for its Georgia facility in late November, with additional conformance inspections underway as it targets initial commercial operations with Delta Air Lines in select U.S. markets, according to Reuters and its company updates. These developments build on related Aviation developments around vertiport infrastructure and state‑level incentives that are helping de‑risk early service launches. Quiet Supersonic And Autonomy Enter The Test Phase NASA’s X‑59 quiet‑supersonic demonstrator advanced to runway taxi tests at the agency’s Armstrong Flight Research Center in late November, a precursor to first flight and community overflight campaigns meant to gather data that could inform future supersonic noise standards, NASA said in a program update here. The Quesst team is sequencing low‑speed and high‑speed taxi checks, systems verification, and range coordination to set up an initial envelope‑expansion flight profile. Autonomous flight also notched progress. Reliable Robotics reported additional FAA approvals to expand its certification program for remotely operated cargo flights in late November, citing successful system safety reviews and test flights with a modified Cessna Caravan under observation, as detailed in its newsroom. Together with eVTOL operational rules and ongoing detect‑and‑avoid standardization, these steps signal regulatory momentum that aligns with a wave of flight‑test activity across advanced air mobility and high‑speed flight, reinforcing broader Aviation trends toward automation and new airspace integration. Decarbonization: SAF, eSAF And Hydrogen Hit New Markers On December 2, United Airlines announced an additional eSAF offtake agreement with a power‑to‑liquids supplier, part of its strategy to secure several hundred million gallons of cleaner fuel this decade, building on its United Airlines Ventures SAF portfolio, per the carrier’s newsroom. The International Civil Aviation Organization said in early December that its member states endorsed expanded work programs under the Long‑Term Global Aspirational Goal, including scaling sustainable aviation fuel, with updated guidance to be published in 2026, according to an ICAO briefing. Industry groups expect SAF supply to rise meaningfully through 2026 as new e‑fuel and HEFA capacity comes online, with IATA’s latest update indicating a path to multi‑million‑ton annual output mid‑decade as supportive policies and purchase agreements proliferate (IATA press resources). For more on [related ai chips developments](/ai-chips-talent-reset-nvidia-tsmc-and-aws-rework-roles-as-packaging-and-in-house-silicon-surge-07-12-2025). Airlines including Lufthansa and Air France‑KLM have reiterated incremental SAF commitments in recent weeks at industry events and investor briefings, citing price premiums but noting contracting structures such as book‑and‑claim and offtake pre‑payments to manage cost, as reported by Bloomberg and company IR updates. Key Q4 Milestones Across Programs The pace of announcements suggests 2026 will be defined by parallel advances in propulsion, certification, and early operational pilots. For investors, the signal is that capital is now attaching to programs with tangible test data and firm regulatory calendars, while policy steps are narrowing uncertainty around operations and fuel adoption. Programs And Milestones: Late 2025 Snapshot
Program/EntityMilestone (Date)Claimed/Targeted BenefitSource
CFM RISE (GE Aerospace/Safran)First test‑stand run (Nov 2025)~20% lower fuel burn vs. current single‑aisle enginesReuters
FAA Powered‑Lift RuleFinal rule published (Nov 18, 2025)Defines pilot cert and ops for eVTOLFAA
NASA X‑59 QuesstRunway taxi tests (late Nov 2025)Pre‑first‑flight system validationNASA
Rolls‑Royce/easyJet HydrogenPhase‑two ground tests disclosed (Nov–Dec 2025)Hydrogen combustion stability across wider envelopeRolls‑Royce
ZeroAvia ZA600FAA certification‑basis update (Dec 2025)Alignment to Part 33 with extra compliance meansZeroAvia
United Airlines eSAFNew offtake announced (Dec 2, 2025)Scaled eSAF procurement toward 2030United
Grouped bar and milestone chart showing CFM RISE 20% efficiency target, FAA powered-lift rule timeline, X-59 taxi-to-first-flight steps, and recent eSAF offtake volumes.
Sources: Reuters; FAA; NASA; United Airlines, Nov–Dec 2025
Conclusion Three tracks—new engines, new rules, and new fuels—are converging. The open‑fan’s first spin gives airlines and lessors a tangible decarbonization lever beyond airframe tweaks; the FAA’s powered‑lift rule stabilizes the eVTOL business case for Joby and Archer; and NASA’s X‑59 edges toward flight, with potential implications for future supersonic standards. Combined with fresh eSAF deals from carriers like United and hydrogen trials from Rolls‑Royce, late‑2025 signals a decisive pivot from powerpoint to hardware across the sector. References

About the Author

JP

James Park

AI & Emerging Tech Reporter

James covers AI, agentic AI systems, gaming innovation, smart farming, telecommunications, and AI in film production. Technology analyst focused on startup ecosystems.

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Frequently Asked Questions

What makes the CFM RISE open‑fan test a breakthrough for commercial aviation?

The first test‑stand run of the CFM RISE demonstrator is significant because it transitions the open‑fan concept from analysis to hardware validation. GE Aerospace and Safran target around a 20% fuel‑burn reduction versus today’s single‑aisle engines, which could materially cut operating costs and emissions if noise and integration goals are met. The test initiates a multi‑year campaign to validate acoustics, efficiency, and reliability before any product launch decision, as reported by Reuters and CFM program materials.

How does the FAA’s powered‑lift rule change the timeline for eVTOL operators?

The final rule provides a standardized framework for pilot certification, training, and operations for powered‑lift aircraft, reducing regulatory uncertainty that previously slowed program planning. It enables companies like Joby Aviation and Archer Aviation to align certification test points, production conformance, and operational approvals under clearly defined parts. This supports targeted early commercial services once type certification and production approvals are secured, as outlined in the FAA’s newsroom and recent company updates.

Why are NASA’s X‑59 taxi tests important before first flight?

Taxi tests confirm systems integration, handling qualities at low speeds, braking, steering, and instrumentation ahead of high‑speed runs. For the X‑59, they also validate safety interlocks and telemetry essential for initial envelope expansion. Completing these steps de‑risks the first flight and sets up the community overflights designed to collect data on perceived noise, which could inform future supersonic standards, according to NASA’s Quesst program communications.

Where do SAF and eSAF fit alongside hydrogen in the decarbonization roadmap?

SAF, including power‑to‑liquids eSAF, is the most immediately scalable option for existing fleets, with airlines like United announcing new offtakes to build supply and experience. Hydrogen—both combustion and fuel‑cell—offers deeper long‑term cuts but requires new aircraft architectures and infrastructure. The near‑term pathway pairs SAF scale‑up with efficiency gains from engines like CFM’s RISE, while hydrogen demonstrations by Rolls‑Royce and ZeroAvia prepare for regional and eventually narrowbody segments later in the decade.

What should investors watch in early 2026 to gauge momentum?

Key signals include continued open‑fan test data releases from CFM, FAA certification progress reports from eVTOL manufacturers such as Joby and Archer, and NASA’s X‑59 initial flight results. On sustainability, look for additional long‑term eSAF contracts from network carriers, policy support mechanisms in the U.S. and EU, and hydrogen program milestones like integrated flight demonstrations. Clear movement across these fronts would indicate hardware readiness converging with regulatory and market buy‑in.