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Federal Register / Vol. 86, No. 184 / Monday, September 27, 2021 / Rules and Regulations shown not to result in a hazardous engine effect.
FAA Response: Special Condition no.
16 Continued rotation corresponds to 14 CFR 33.74, which precludes hazardous engine effects from continued rotation of engine main rotating systems after the engine is shut down for any reason while in flight. This includes the effects of vibration from failures that result in a rotor unbalance. Therefore, Special Condition no. 16 addresses the failure effects TCCA identified in their comment. The FAA did not change these special conditions as a result of this comment.
Comment Summary: TCCA
recommended requiring an evaluation of vibration effects that result from excitation forces caused by fault conditions or to address these effects by reference to experience with engine failures that did not result in a hazardous engine effect. TCCA also recommended addressing the vibration effects from sustained engine unbalance.
FAA Response: Special Condition no.
16 Continued rotation precludes hazardous engine effects from continued rotation after the engine is shut down for any reason while in flight, including fault conditions. These special conditions are applicable to the magniX
engines, which are new to aviation.
Therefore, engine experience is not relevant to the magniX engine certification project. The FAA did not change this special condition as a result of this comment.

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Special Condition No. 21, Overtorque The FAA proposed that Special Condition no. 21 would require magniX
to demonstrate that the engine is capable of continuous operation without the need for maintenance if it experiences a certain amount of overtorque.
Comment Summary: TCCA suggested that the FAA add the teardown inspection requirement of Special Condition no. 29 for each engine part or individual groups of components after conducting the overtorque test.
FAA Response: The additional requirement suggested by TCCA
corresponds to 14 CFR 33.84a2, Engine overtorque test. The engines proposed by magniX may require a transient maximum overtorque rating.
The FAA has changed final Special Condition no. 21 to require compliance to Special Condition no. 29 Teardown inspection after conducting an overtorque test.

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Special Condition No. 22, Calibration Assurance The FAA received no comments for Special Condition no. 22, and it is adopted as proposed. It requires magniX
to subject the engine to calibration tests, to establish its power characteristics and the conditions both before and after the endurance and durability demonstrations specified in proposed Special Condition nos. 23 and 26. The calibration test requirements specified in 33.85 only apply to the endurance test specified in 33.87, which is applicable only to turbine engines. The methods used for accomplishing those tests for turbine engines are not the best approach for electric engines. The calibration tests in 33.85 have provisions applicable to ratings that are not relevant to the magniX magni350
and magni650 model engines. Special Condition no. 22 allows magniX to demonstrate the endurance and durability of the electric engine either together or independently, whichever is most appropriate for the engine qualities being assessed. Consequently, this special condition applies the calibration requirement to both the endurance and durability tests.
Special Condition No. 23, Endurance Demonstration The FAA proposed that Special Condition no. 23 would require magniX
to subject the engine to an endurance demonstration test, acceptable to the Administrator, to demonstrate the engine capabilities at the declared limits.
The FAA proposed to evaluate the extent to which the test exposes the engine to failures that could occur when the engine is operated at its rated values, to determine if the test is sufficient to show that the engine design will not exhibit unacceptable effects inservice, such as significant performance deterioration, operability restrictions, and engine power loss or instability, when run for sustained periods at extreme operating conditions.
Comment Summary: Rolls-Royce stated that the second sentence of the proposed special condition contained a typographical error and suggested that it should read, The endurance demonstration elevates and increases the engines power settings, and dwells at the power settings for durations that produce the extreme physical conditions. . . . Rolls-Royce recommended replacing decreases with increases in the special condition.
FAA Response: Final Special Condition no. 23 has been changed. The
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FAA considered the change proposed by Rolls-Royce and changed the term elevates to increases.
Comment Summary: TCCA
recommended that the FAA add the following three sentences to Special Condition no. 23: 1 The severity of the demonstration should consider the design and intended use of the engine, and include the demonstration of safe operation under all operational limits to be applied during service operation of the engine. 2 When approval is sought for Normal Transient engine exceedances, it must be substantiated that the engine is capable of operation at the maximum engine transient condition of the affected engine parameters without maintenance action. 3 When approval is sought for Inadvertent Transient engine exceedances, it must be substantiated that the engine is capable of operation at the maximum engine transient condition of the affected engine parameters without maintenance action other than to correct any failure that led to the exceedances.
FAA Response: The FAA does not agree to include the additions recommended by TCCA. Regarding TCCA sentence 1, adding a definition for severity in this special condition is unnecessary because this special condition is intended to achieve the same objectives as 14 CFR 33.87, Endurance test, but for the magniX
electric engines. The test will be different for the magniX engines because those engines use electrical technology for propulsion. Whether the engine is turbine or electric, the endurance test achieves a severity that demonstrates the engine is safe to operate at its certificated limits.
Regarding TCCA sentence 2, Special Condition no. 32 requires the engine and its components to be within serviceable limits, safe for continued operation, and capable of operating at declared ratings while remaining within limits upon completing all demonstrations and testing specified in these special conditions. If the magniX
engine ratings include maximum transients, the engines must demonstrate that they operate safely during the maximum transients and meet the post-test engine requirements specified in these special conditions.
Regarding TCCA sentence 3, Special Condition no. 23 is intended to assess the magniX engines capabilities. It is not intended to show the engine can accommodate failures and malfunctions that lead to inadvertent transients that exceed the engines certificated limits.
Special Condition no. 17 Safety analysis addresses potential effects
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