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Federal Register / Vol. 86, No. 184 / Monday, September 27, 2021 / Rules and Regulations demonstration. The durability demonstration must show that each part of the engine is designed and constructed to minimize any unsafe condition of the system between overhaul periods or between enginereplacement intervals if the overhaul is not defined.
Comment Summary: TCCA
commented that these special conditions do not contain a modified 14
CFR 33.4 description of ICA for the intended electric engine applications.
TCCA suggested that ICA should represent all the instructions required for the magniX engines to remain airworthy, but that instructions for offwing maintenance instructions in the ICA would not be appropriate.
FAA Response: These special conditions are not intended for all electric engine certification projects. As required by Special Condition no. 1, magniX must comply with 33.4, Instructions for Continued Airworthiness, and its appendix. These requirements are appropriate to address the maintenance requirements for these proposed engine designs. The FAA
made no changes to the special condition as a result of the comment.
Comment Summary: TCCA
recommended adding 14 CFR 33.19b, Propeller pitch control design requirements, to Special Condition no.
26, with an opt-out option if the magniX
engines do not have propeller-blade pitch control systems.
FAA Response: These special conditions apply to the magni350 and magni650 model engines. These magniX
engines do not have a propeller-blade pitch control system. The FAA made no changes to the special condition as a result of the comment.
Comment Summary: TCCA
recommended revising this special condition to state, The engine must be subjected to a durability demonstration to show that each part of the engine has been designed and constructed to minimize any unsafe condition of the system and subsystem between overhaul periods or between engine components/
parts replacement intervals. . . .
FAA Response: magniXs proposed engines must meet Special Condition no. 29 Teardown inspection requirements after completing the durability demonstration specified in this special condition. In addition, magniX must meet the requirements of Special Condition no. 32 General conduct of tests. These special conditions, in combination with the demonstration tests required by these magniX special conditions, achieve the objectives identified by this comment.
The FAA made no changes to the
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special condition as a result of the comment.
Comment Summary: TCCA suggested that the FAA modify Special Condition no. 26 in a manner that results in the following revision: This test must simulate the conditions in which the engine is expected to operate in-service, including typical start-stop cycles and scheduled maintenance actions and must be of sufficient duration in order to provide confidence in the durability of the engine.
FAA Response: The FAA does not agree with the comment. The required durability demonstration provides information for compliance to 14 CFR
33.4, Instructions for continued airworthiness, which is imposed by Special Condition no. 1. If maintenance is required to complete the test, the specific maintenance actions could become part of the mandatory ICA. The discussion for Special Condition no. 32
contains more information about maintenance conducted during a test.
Special Condition no. 32 General conduct of tests has criteria that permit some maintenance to be accomplished during the test without incurring additional mandatory ICA. The FAA
agrees that the test duration can provide confidence in the engines durability.
However, whether the test duration is long or short, magniX will develop a maintenance plan based on the test that magniX creates for their program, in accordance with 33.4. The FAA made no changes to the special condition as a result of the comment.
Special Condition No. 27, System and Component Tests The FAA proposed that Special Condition no. 27 would require magniX
to show that the engines systems and components would perform their intended functions in all declared engine environments and operating conditions.
Comment Summary: TCCA
recommended that the FAA require magniX to establish temperature limits for each component that requires temperature-controlling provisions in the aircraft installation to assure satisfactory functioning, reliability, and durability.
FAA Response: Other special conditions address TCCAs concern.
Special Condition no. 2 Engine ratings and operating limits requires magniX to establish a temperature limit that is necessary for safe operation of the engine. Whether or not a temperature limit is established for a component depends on the outcome of Special Condition no. 17 Safety analysis, which examines the consequence of
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engine failure from high-temperature. If cooling is required to satisfy Special Condition no. 17 Safety analysis, the cooling system monitoring features and usage are documented in accordance with 33.5c, Safety analysis instructions. The FAA did not change this special condition as a result of this comment.
Comment Summary: TCCA
recommended that the FAA require magniX to establish voltage and current limits for each component that requires voltage or current controlling provisions, or both, in the aircraft installation to assure satisfactory functioning, reliability, and durability.
FAA Response: Other special conditions address TCCAs concern.
Regarding voltage and current limits, Special Condition no. 2 requires magniX
to establish ratings and operating limitations based on power-supply requirements for the engine. Whether or not voltage and current limits are established for a component depends on the outcome of Special Condition no. 17
Safety analysis, which examines the consequence of the components failure from high temperature. The FAA did not change this special condition as a result of this comment.
Special Condition No. 28, Rotor Locking Demonstration The FAA proposed that Special Condition no. 28 would require the engine to demonstrate reliable rotor locking performance and that no hazardous engine effects will occur if the engine uses a rotor locking device to prevent shaft rotation.
Comment Summary: Wisk stated that this special condition does not contain a requirement that ensures the rotor lock feature cannot be enabled with a motor power set and also that its inadvertent activation is sufficiently unlikely that no major engine effect can occur. Wisk recommended that the FAA clarify if the term hazardous is being used in the context of system safety or in general terms.
Textron also requested that the FAA
clarify the definition of hazardous effects and use that term consistently and recommended the following be added to Special Condition no. 28:
. . . that no hazardous effects as specified in Special Condition no.
17d2 will occur.
FAA Response: If magniX implements a rotor locking device in their engine design, Special Condition no. 28 will ensure the device exhibits reliable rotor locking performance and will not cause hazardous engine effects to preserve system safety. Special Condition no. 17
Safety analysis examines the
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