The Federal Aviation Administration issued an amendment to special conditions for Safran Electric & Power S.A.'s ENGINe US100 series electric engines on January 27, 2026, as published in the Federal Register Volume 91, Number 17. This action expands the scope of earlier special conditions from the single model US100A1 to the entire US100 series, including models US100B1 and US100B2. Safran, a French aerospace company, applied for this change following amendments to its European Union Aviation Safety Agency application. The FAA's decision ensures that these innovative electric engines, which use electric motors and high-voltage systems for propulsion, maintain airworthiness standards comparable to those for conventional reciprocating and turbine engines. This development is significant as it facilitates the certification of electric propulsion in aircraft, addressing gaps in existing regulations under 14 CFR Part 33 that were not designed for such technology.
Background and Key Players
Safran initially applied for FAA validation of its ENGINe US100A1 electric engine in November 2020, based on a pending type certificate from the European Union Aviation Safety Agency. The FAA responded by issuing Special Conditions No. 33-23-01-SC on December 27, 2024, after a notice of proposed special conditions published on March 20, 2024. These conditions were necessary because the engines incorporate novel features like electric motors, controllers, and high-voltage systems, which differ from the combustion-based technologies envisioned in Part 33.
On January 15, 2025, Safran amended its FAA application to include the US100B1 and US100B2 models. The FAA determined that the novel design elements of these additional models are adequately covered by the existing special conditions, leading to the amendment renumbered as Special Conditions No. 33-030A-SC. Key players include Safran as the applicant, the FAA's Aircraft Certification Service, and Mark Bouyer, the contact for further information. The Government Publishing Office facilitated the Federal Register publication.
Legal and Regulatory Framework
Under 14 CFR 21.16, the FAA prescribes special conditions when existing airworthiness standards in Part 33 do not adequately address novel or unusual design features. Part 33 primarily covers reciprocating and turbine engines, leaving gaps for electric propulsion. The amendment applies these special conditions to the US100 series, requiring compliance with most of Part 33 except provisions explicitly for traditional engines. It also mandates adherence to noise certification under 14 CFR Part 36.
Relevant precedents include the original special conditions for the US100A1, which drew from Part 33 subparts while introducing tailored requirements. For instance, the FAA references RTCA DO-160G for environmental testing and RTCA DO-254 for electronic hardware assurance. Advisory Circular 33.28-3 provides guidance on engine control systems, adapted here for electric engines. This framework ensures a level of safety equivalent to established standards, as stated in the Federal Register: 'the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards.'
Key Aspects of the Special Conditions
The special conditions address several critical areas. Engine ratings and operating limits now include shaft power, torque, speed, temperature, duty cycles, cooling fluid specifications, and power supply requirements, as outlined in special condition no. 2. Fire protection extends Part 33.17 requirements to high-voltage wiring, mandating protection against arc faults that could lead to hazardous effects.
Durability and endurance demonstrations are emphasized, with special condition no. 23 requiring tests to simulate extreme conditions, and no. 26 focusing on minimizing unsafe conditions between maintenance intervals. The safety analysis under no. 17 classifies engine effects into minor, major, and hazardous categories, expanding hazardous effects to include electrocution and cooling system blockages. Quotes from the document highlight this: 'Hazardous engine effects are defined in special condition no. 17(d)(2) of these special conditions.'
Electrical systems receive detailed treatment in no. 33, covering power distribution, protection, and fault tolerance to prevent loss of power control events. The amendment notes that electric engines differ fundamentally from turbine engines, necessitating these adaptations: 'Electric propulsion technology is substantially different from the technology used in previously certificated turbine and reciprocating engines.'
Perspectives and Implications
From a regulatory perspective, the FAA balances innovation with safety, avoiding overly prescriptive rules while ensuring robustness. Safran's view, implicit in its application, prioritizes efficient certification for electric aviation advancements. Industry stakeholders, such as aircraft manufacturers, benefit from clearer installation guidelines, as the conditions require documenting interfaces and characteristics in manuals per 14 CFR 33.5.
Short-term implications include streamlined certification for the US100 series, potentially accelerating electric aircraft development. Long-term, this could influence broader adoption of electric propulsion, reducing emissions and noise in aviation. However, challenges arise in verifying novel features like rotor overspeed and vibration through tests or analysis, as required in nos. 9 and 20.
The forward-looking conclusion summarizes that this amendment paves the way for safer electric engines, with potential next steps involving aircraft-level integrations and ongoing debates on environmental impacts and global harmonization of standards.
