Special Conditions: Safran Electric & Power S.A. Model ENGINeUS 100A1 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. 33-23-01-SC]</DEPDOC> <SUBJECT>Special Conditions: Safran Electric & Power S.A. Model ENGINeUS 100A1 Electric Engines</SUBJECT> <HD SOURCE="HED">AGENCY:</HD> Federal Aviation Administration (FAA), DOT. <HD SOURCE="HED">ACTION:</HD> Final special conditions. <SUM> <HD SOURCE="HED">SUMMARY:</HD> These special conditions are issued for the Safran Electric & Power S.A. (Safran) Model ENGINeUS 100A1 electric engines that operate using electrical technology installed on the aircraft for use as an aircraft engine. These engines will have a novel or unusual design feature when compared to the state of technology envisioned in the airworthiness standards applicable to aircraft engines. This 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. These special conditions 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. </SUM> <EFFDATE> <HD SOURCE="HED">DATES:</HD> Effective January 27, 2025. </EFFDATE> <FURINF> <HD SOURCE="HED">FOR FURTHER INFORMATION CONTACT:</HD> Mark Bouyer, Engine and Propulsion Standards Section, AIR-625, Technical Policy Branch, Policy and 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 for a type certificate for their Model ENGINeUS 100A1 electric engine. The Safran Model ENGINeUS 100A1 electric engine will be used in a single-engine airplane that will be certified separately from the engine. The Safran Model ENGINeUS 100A1 electric engine is comprised of a direct-drive, radial-flux, permanent magnet motor, divided in two sections, each section having a three-phase motor, and one electric power inverter controlling each three-phase motor. <HD SOURCE="HD1">Type Certification Basis</HD> Under the provisions of 14 CFR 21.17(a)(1), generally, Safran must show that Model ENGINeUS 100A1 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 Model ENGINeUS 100A1 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). <HD SOURCE="HD1">Novel or Unusual Design Features</HD> The Safran Model ENGINeUS 100A1 electric engines will incorporate the following novel or unusual design features: 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. A growing interest within the aviation industry involves electric propulsion technology. As a result, international agencies and industry stakeholders formed Committee F39 under ASTM International, formerly known as American Society for Testing and Materials, to identify the appropriate technical criteria for aircraft engines using electrical technology that has not been previously type certificated for aircraft propulsion systems. ASTM International is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services. ASTM International published ASTM F3338-18, “Standard Specification for Design of Electric Propulsion Units for General Aviation Aircraft,” in December 2018. <SU>1</SU> <FTREF/> The FAA used the technical criteria from the ASTM F3338-18, the published Special Conditions No. 33-022-SC for the magniX USA, Inc. Model magni350 and magni650 engines, and information from the Safran Model ENGINeUS 100A1 electric engine design to develop special conditions. <FTNT> <SU>1</SU>   <E T="03">https://www.astm.org/Standards/F3338.html.</E> </FTNT> <HD SOURCE="HD2">Part 33 Was Developed for Gas-Powered Turbine and Reciprocating Engines</HD> Aircraft engines make use of an energy source to drive mechanical systems that provide propulsion for the aircraft. Energy can be generated from various sources such as petroleum and natural gas. The turbine and reciprocating aircraft engines certificated under part 33 use aviation fuel for an energy source. The reciprocating and turbine engine technology that was anticipated in the development of part 33 converts oxygen and fuel to energy using an internal combustion system, which generates heat and mass flow of combustion products for turning shafts that are attached to propulsion devices such as propellers and ducted fans. Part 33 regulations set forth standards for these engines and mitigate potential hazards resulting from failures and malfunctions. The nature, progression, and severity of engine failures are tied closely to the technology that is used in the design and manufacture of aircraft engines. These technologies involve chemical, thermal, and mechanical systems. Therefore, the existing engine regulations in part 33 address certain chemical, thermal, and mechanically induced failures that are specific to air and fuel combustion systems operating with cyclically loaded, high-speed, high-temperature, and highly stressed components. <HD SOURCE="HD2">Safran's Electric Engines Are Novel or Unusual</HD> The existing part 33 airworthiness standards for aircraft engines date back to 1965. As discussed in the previous paragraphs, these airworthiness standards are based on fuel-burning reciprocating and turbine engine technology. The Safran Model ENGINeUS 100A1 electric engines are neither turbine nor reciprocating engines. These engines have a novel or unusual design feature, which is the use of electrical sources of energy instead of fuel to drive the mechanical systems that provide propulsion for aircraft. The Safran aircraft engine is subject to operating conditions produced by chemical, thermal, and mechanical components working together, but the operating conditions are unlike those observed in internal combustion engine systems. Therefore, part 33 does not contain adequate or appropriate safety standards for the Safran Model ENGINeUS 100A1 electric engine's novel or unusual design feature. Safran's aircraft engines will operate using electrical power instead of air and fuel combustion to propel the aircraft. These electric engines will be designed, manufactured, and controlled differently than turbine or reciprocating aircraft engines. 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. The electric motor is a device that converts electrical energy into mechanical energy by electric current flowing through windings (wire coils) in the motor, producing a magnetic field that interacts with permanent magnets mounted on the engine's main rotor. The controller is a system that consists of two main functional elements: the motor controller and an electric power inverter to drive the motor. <SU>2</SU> <FTREF/> The high-voltage electrical system is a combination of wires and connectors that integrate the motor and controller. <FTNT> <SU>2</SU>  Sometimes the entire system is referred to as an inverter. Throughout this document, it is referred to as the controller. </FTNT> In addition, the technology comprising these high-voltage and high-current electronic components introduces potential hazards that do not exist in turbine and reciprocating aircraft engines. For example, high-voltage transmission lines, electromagnetic shields, magnetic materials, and high-speed electrical switches are necessary to use the physical properties of an electric engine for propelling an aircraft. However, this technology also exposes the aircraft to potential failures that are not common to gas-powered turbine and reciprocating engines, technological differences which could adversely affect safety if not addressed through these special conditions. <HD SOURCE="HD2">Safran's Electric Engines Require a Mix of Part 33 Standards and Special Conditions</HD> Although Safran's electric aircraft engines 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 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 106k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━