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Federal Register / Vol. 86, No. 184 / Monday, September 27, 2021 / Rules and Regulations
term Critical Parts from this special condition.
FAA Response: Section 33.70
prescribes a mandatory replacement interval for turbine engine parts that are likely to fail from fatigue if they are not removed from service. The failure can cause a hazardous engine effect. Section 33.70 does not address parts that have a different primary failure mode than fatigue but can still fail in a way that causes a hazardous engine condition.
Electric engine technology operates using electromagnetic technology and physical properties that are different than those of turbine engines. This is why the special condition has requirements for critical parts.
Therefore, there is a need for a special condition that addresses failures of parts and components caused by the properties related to the novel technology used in these proposed engines. Further, the FAA currently uses the term critical parts to describe certain parts approved under 14 CFR
part 21 subpart K, Parts Manufacturer Approval and in 14 CFR part 35, Airworthiness Standards: Propellers.
The use of the term critical parts in these special conditions is consistent with the FAAs use of the term as it applies to conventional engines. The FAA did not change these special conditions as a result of these two comments.
Comment Summary: TCCA asked that these special conditions define primary failure as failures that are not the result of a prior failure of another part or system.
FAA Response: The term primary failure is used in 14 CFR 33.70, and this special condition is based on the requirements in that section. The FAA
did not change these special conditions as a result of this comment, but the suggested clarification is adopted in the discussion to Special Condition no. 17.
Comment Summary: AIAB proposed that the FAA require the assumptions used by the applicant in the life-limited parts analysis to be declared in the engine installation manual, should the FAA certify the engine with no associated aircraft.
FAA Response: Final Special Condition nos. 10g and 17e require magniX to account for the intended aircraft application for the engine safety analysis and engine control systems safety assessment to be valid, so there will be no need to account for engines with no associated aircraft. Special Condition no. 13, Critical and lifelimited parts, requires magniX to show, by safety analysis or means acceptable to the Administrator, whether rotating or moving components, bearings, shafts,
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static parts, and non-redundant mount components should be classified, designed, manufactured, and managed throughout their service life as critical or life-limited parts. The assumptions used by magniX in the life-limited parts analysis are design data that provide information for compliance to Special Condition no. 13. The installers and operators of the magniX engines do not use these assumptions, and therefore, the assumptions do not need to be included in the installation manual. The FAA made no changes to this special condition as a result of this comment.
Special Condition No. 14, Lubrication System The FAA proposed that Special Condition no. 14 would require that the lubrication system of these engines be designed to function properly between scheduled maintenance intervals and prevent engine bearing and lubrication system contamination. The FAA also proposed to require magniX to demonstrate the unique lubrication attributes and functional capability of the magni350 and magni650 Model engines.
Comment Summary: Wisk recommended removing the reference to particle debris from Special Condition no. 14b, and replacing it with The lubrication system must be designed to prevent unacceptable contamination of the engine bearings.
FAA Response: The FAA has changed Special Condition no. 14 to specify the lubrication system must prevent any unacceptable contamination of the engine bearings. The FAA has changed the special condition as a result of this comment.
Comment Summary: TCCA
recommended that Special Condition no. 14 require magniX to declare, in the engine installation manual, any reliance upon assumed installation conditions or installation requirements.
FAA Response: Special Condition no.
1 requires magniX to comply with14
CFR 33.5, Instruction manual for installing and operating the engine.
Section 33.5a5 includes the additional requirement recommended by TCCA. The FAA made no changes to the special condition as a result of the comment.
Special Condition No. 15, Power Response The FAA proposed that Special Condition no. 15 would require the design and construction of these engines and their control systems to enable an increase 1 from the minimum power setting to the highest-rated power without detrimental engine effects and
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2 from the minimum obtainable power while in-flight and on the ground to the highest-rated power within a time interval for the safe operation of the aircraft.
Comment Summary: Wisk recommended including the engine control system as part of the engine in these requirements. They suggest adding and its control system to this special condition to read, The design and construction of the engine and its control system must enable an increase.
FAA Response: The FAA has modified Special Condition no. 15 in these final special conditions to incorporate including its control system in response to the comment.
Comment Summary: Ampaire recommended that the FAA add a requirement to these special conditions that correspond to ASTM F333818, section 5.20.9.
FAA Response: The FAA added Special Condition no. 15c in the final special condition, which incorporates criteria from ASTM F333818, section 5.20.9.
Comment Summary: Textron commented that electrical motors could produce significantly more torque than reciprocating or turbine engines.
Textron said that unregulated application of torque could be detrimental to the flight characteristics of the aircraft or the structural components of the aircraft. Textron recommended supplementing this special condition with the following requirement: c of torque without detrimental engine or aircraft effects.
Aircraft components must be designed to withstand the unregulated application of torque, or the application of torque should be controlled to ensure aircraft structural integrity or aircraft aerodynamic characteristics are not exceeded.
FAA Response: The FAA agrees that electric engines produce torque differently than turbine engines. The potential for high torque values is attributable to the novel technology used in magniXs proposed engines.
Therefore, final Special Condition no.
15 has changed to include a requirement that prevents engine torque from causing detrimental aircraft effects.
Comment Summary: TCCA
recommended that the FAA revise Special Condition no. 15b, from a time interval for the safe operation of the aircraft to a time interval that is determined to be safe for aircraft operation.
FAA Response: The FAA finds that the recommended revision would be beneficial and consistent with the
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