Special Conditions: Safran Electric & Power S.A. ENGINeTM US100 Series Electric Engines

<RULE> DEPARTMENT OF TRANSPORTATION <SUBAGY>Federal Aviation Administration</SUBAGY> <CFR>14 CFR Part 33</CFR> <DEPDOC>[Docket No. FAA-2023-0587; Special Conditions No. 33-030A-SC]</DEPDOC> <SUBJECT> Special Conditions: Safran Electric & Power S.A. ENGINe <SU>TM</SU> US100 Series Electric Engines </SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Federal Aviation Administration (FAA), DOT. <HD SOURCE="HED">ACTION:</HD> Final special conditions, amendment. <SUM> <HD SOURCE="HED">SUMMARY:</HD> This action amends the applicability of special conditions that were issued for the Safran Electric & Power S.A. Model ENGINe US100A1 electric engines. These engines have a novel or unusual design feature when compared to the state of technology envisioned in the airworthiness standards applicable to aircraft engines. The design feature is the use of an electric motor, motor controller, and high-voltage systems as the primary source of propulsion for an aircraft. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. This action amends the applicability of Special Conditions No. 33-23-01-SC, dated December 27, 2024, which contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards, to include the ENGINe US100 series electric engines. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> Effective January 27, 2026. </EFFDATE> <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Mark Bouyer, Engine & Propulsion Standards Section, AIR-625, Technical Policy Branch, Policy & Standards Division, Aircraft Certification Service, 1200 District Avenue, Burlington, Massachusetts 01803; telephone (781) 238-7755; <E T="03">mark.bouyer@faa.gov.</E> </FURINF> <SUPLINF> <HD SOURCE="HED">SUPPLEMENTARY INFORMATION:</HD> <HD SOURCE="HD1">Background</HD> On November 27, 2020, Safran applied for FAA validation of their pending EASA type certificate application for the Model ENGINe US100A1 electric engine. The FAA published a Notice of Proposed Special Conditions for public comment in the <E T="04">Federal Register</E> on March 20, 2024 (89 FR 19763). On December 27, 2024, the FAA issued Final Special Conditions No. 33-23-01-SC (89 FR 105432) for the US100A1 electric engine. Safran subsequently amended its EASA application to include the models US100B1 and US100B2. Similarly, on January 15, 2025, Safran amended their FAA application to include the B1 and B2 on the requested type certificate for the ENGINe US100 electric engines. This amendment to the special conditions updates the applicability of Special Conditions No. 33-23-01-SC from Safran Electric & Power S.A. “Model ENGINe US100A1 Electric Engines” to “ENGINe US100 Series Electric Engines”. The novel or unusual design of these additional models is adequately addressed by the requirements of Special Conditions No. 33-23-01-SC, and the requirements of these special conditions are substantively unchanged. However, the FAA is amending the Special Conditions number for these final special conditions from Special Conditions No. 33-23-01-SC to Special Conditions No. 33-030A-SC. <HD SOURCE="HD1">Type Certification Basis</HD> Under the provisions of 14 CFR 21.17(a)(1) Safran must show that ENGINe US100 series electric engines meet the applicable provisions of 14 CFR part 33 in effect on the date of application for a type certificate. If the Administrator finds that the applicable airworthiness regulations ( <E T="03">e.g.,</E> part 33) do not contain adequate or appropriate safety standards for the Safran ENGINe US100 series electric engines because of a novel or unusual design feature, special conditions may be prescribed under the provisions of § 21.16. Special conditions are initially applicable to the model for which they are issued. Should the type certificate for that model be amended later to include any other engine model that incorporates the same novel or unusual design feature, these special conditions would also apply to the other engine model under § 21.101. The FAA issues special conditions, as defined in § 11.19, in accordance with § 11.38, and they become part of the type certification basis under § 21.17(a)(2). In addition to the applicable airworthiness regulations and special conditions, the Safran ENGINe US100 series electric engines must comply with the noise certification requirements of 14 CFR part 36. <HD SOURCE="HD1">Novel or Unusual Design Feature</HD> The Safran ENGINe US100 series electric engines will incorporate the following novel or unusual design feature: An electric motor, motor controller, and high-voltage electrical systems that are used as the primary source of propulsion for an aircraft. <HD SOURCE="HD1">Discussion</HD> Electric propulsion technology is substantially different from the technology used in previously certificated turbine and reciprocating engines. Therefore, these engines introduce new safety concerns that need to be addressed in the certification basis. Safran's proposed aircraft engines will operate using electrical power instead of air and fuel combustion to propel the aircraft. They will be built with an electric motor, motor controller, and high voltage electrical systems that draw energy from electrical storage or electrical energy generating systems. <HD SOURCE="HD2">Safran's Proposed Electric Engines Require a Mix of Part 33 Standards and Special Conditions</HD> Although the electric aircraft engines Safran proposes use novel or unusual design features that the FAA did not envisage during the development of its existing part 33 airworthiness standards, these engines share some basic similarities, in configuration and function, to engines that use the combustion of air and fuel, and therefore require similar provisions to prevent common hazards ( <E T="03">e.g.,</E> fire, uncontained high energy debris, and loss of thrust control). However, the primary failure concerns and the probability of exposure to these common hazards are different for the proposed Safran ENGINe <E T="51">TM</E> US100 series electric engines. This creates a need to develop special conditions to ensure the engine's safety and reliability. The requirements in part 33 ensure that the design and construction of aircraft engines, including the engine control systems, are proper for the type of aircraft engines considered for certification. However, part 33 does not fully address aircraft engines like the Safran Model ENGINe US100A1, which operates using electrical technology as the primary means of propelling the aircraft. This necessitates the development of special conditions that provide adequate airworthiness standards for these aircraft engines. The requirements in part 33, subpart B, are applicable to reciprocating and turbine aircraft engines. Subparts C and D are applicable to reciprocating aircraft engines. Subparts E through G are applicable to turbine aircraft engines. As such, subparts B through G do not adequately address the use of aircraft engines that operate using electrical technology. Special conditions are needed to ensure a level of safety for electric engines that is commensurate with these subparts, as those regulatory requirements do not contain adequate or appropriate safety standards for electric aircraft engines that are used to propel aircraft. <HD SOURCE="HD1">FAA Special Conditions for the Safran Engine Design</HD> <E T="03">Applicability:</E> Special condition no. 1 requires Safran to comply with part 33, except for those airworthiness standards specifically and explicitly applicable only to reciprocating and turbine aircraft engines. <E T="03">Engine Ratings and Operating Limitations:</E> Special condition no. 2 in addition to compliance with § 33.7(a), requires Safran to establish engine operating limits related to the power, torque, speed, and duty cycles specific to Safran ENGINe US100 series electric engines. The duty or duty cycle is a statement of the load(s) to which the engine is subjected, including, if applicable, starting, no-load and rest, and de-energized periods, including their durations or cycles and sequence in time. This special condition also requires Safran to declare cooling fluid grade or specification, power supply requirements, and to establish any additional ratings that are necessary to define the Safran ENGINe US100 series electric engine capabilities required for safe operation of the engine. <E T="03">Materials:</E> Special condition no. 3 requires Safran to comply with § 33.15, which sets requirements for the suitability and durability of materials used in the engine, and which would otherwise be applicable only to reciprocating and turbine aircraft engines. <E T="03">Fire Protection:</E> Special condition no. 4 requires Safran to comply with § 33.17, which sets requirements to protect the engine and certain parts and components of the airplane against fire, and which would otherwise be applicable only to reciprocating and turbine aircraft engines. Additionally, this special condition requires Safran to ensure that the high-voltage electrical wiring interconnect systems that connect the controller to the motor are protected against arc faults. An arc fault is a high power discharge of electricity between two or more conductors. This discharge generates heat, which can break down the wire's insulation and trigger an electrical fire. Arc faults can range in power from a few amps up to thousands of amps and are highly variable in strength and duration. <E T="03">Durability:</E> Special condition no. 5 requires Safran to design and construct the engines to minimize the development of an unsafe condition between maintenance intervals, overhaul periods, and mandatory actions described in the ICA t ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 85k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━