Special Conditions: BETA Technologies Inc. Model H500A Electric Engines

<RULE> DEPARTMENT OF TRANSPORTATION <SUBAGY>Federal Aviation Administration</SUBAGY> <CFR>14 CFR Part 33</CFR> <DEPDOC>[Docket No. FAA-2022-1641; Special Conditions No. 33-028-SC]</DEPDOC> <SUBJECT>Special Conditions: BETA Technologies Inc. Model H500A 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 BETA Technologies Inc. (BETA) Model H500A 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 16, 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 January 27, 2022, BETA applied for a type certificate for its Model H500A electric engines. The BETA Model H500A electric engine initially will be used as a “pusher” electric engine in a single-engine airplane that will be certified separately from the engine. A typical normal category general aviation aircraft locates the engine at the front of the fuselage. In this configuration, the propeller attached to the engine pulls the airplane along its flightpath. A pusher engine is located at the rear of the fuselage, so the propeller attached to the engine pushes the aircraft instead of pulling the aircraft. The BETA Model H500A 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. The magnets are arranged in a Halbach magnet array, and the stator is a concentrated, tooth-wound configuration. A stator is the stationary component in the electric engine that surrounds the rotating hardware; for example: the BETA propeller shaft, which consists of a bonded core with coils of insulated wire, known as the windings. When alternating current is applied to the coils of insulated wire in a stator, a rotating magnetic field is created, which provides the motive force for the rotating components. <HD SOURCE="HD1">Type Certification Basis</HD> Under the provisions of 14 CFR 21.17(a)(1), generally, BETA must show that Model H500A 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 BETA Model H500A 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 BETA Model H500A 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. <HD SOURCE="HD2">BETA's Electric Engines Are Novel or Unusual</HD> The BETA Model H500A electric 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. Therefore, part 33 does not contain adequate or appropriate safety standards for the BETA Model H500A electric engine's novel or unusual design feature. BETA'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>1</SU> <FTREF/> The high-voltage electrical system is a combination of wires and connectors that integrate the motor and controller. <FTNT> <SU>1</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. <HD SOURCE="HD2">BETA's Electric Engines Require a Mix of Part 33 Standards and Special Conditions</HD> 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 BETA Model H500A, which operates using electrical technology as the primary means of propelling the aircraft. 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. The FAA proposed special conditions and received comments from many commenters. Some comments resulted in changes to the special conditions. These changes are explained in the Discussion of Comments. <HD SOURCE="HD1">FAA Special Conditions for the BETA Engine Design</HD> <E T="03">Applicability:</E> Special condition no. 1 requires BETA 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 BETA to establish engine operating limits related to the power, torque, speed, and duty cycles specific to BETA Model H500A 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 BETA to declare cooling fluid grade or specification, power supply requirements, and to establish any additional ratings that are necessary to define the BETA Model H500A electric engine capabilities required for safe operation of the engine. <E T="03">Materials:</E> Special condition no. 3 requires BETA 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 BETA 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 BETA to ensure that the high-voltage electrical wiring interconnect system ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Preview showing 10k of 118k characters. Full document text is stored and available for version comparison. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━