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Federal Register / Vol. 86, No. 184 / Monday, September 27, 2021 / Rules and Regulations 17d2ii to prevent hazardous engine effects from cooling blockage.
Comment Summary: EASA
commented that the special condition has no proposed safety objectives for major failure conditions. EASA
recommended that the FAA use the approach of EASA SC E19 10 that requires the propulsion system to have a level of safety that allows the intended aircraft to meet its safety objectives defined in the aircraft type certification basis.
FAA Response: There are many possible outcomes to the magniX engine safety analysis, including the failure classifications. Failure classification and probabilities for the engine and certain electronic components are needed, but the failure classifications and reliability thresholds will account for aircraft capabilities. The FAA has changed final Special Condition no. 10g and added Special Condition no. 17e to require magniX to account for the intended aircraft application.
The additions to Special Condition nos. 10g and 17e allow for the aircraft safety objectives to be considered when establishing the engine failure classifications and failure rates.
Comment Summary: EASA noted the reference to Special Condition no. 9 in Special Condition no. 17b: If the failure of such elements is likely to result in hazardous engine effects, then the applicant may show compliance by reliance on the prescribed integrity requirements of 14 CFR 33.15, Special Condition no. 9, or Special Condition no. 13, as determined by analysis.
EASA stated that proposed Special Condition no. 9 is insufficient for hazardous failure conditions. EASA said that a rotor growth margin is a design margin, but it does not preclude any other failure root cause of a failure, such as a production issue. EASA suggested that the FAA change these special conditions to remove this possibility.
FAA Response: The FAA agrees with the comment. There might be a need to consider additional integrity requirements to account for the potential root causes for failures of the magniX electric engine parts. The FAA
has changed final Special Condition 17b to add such as before the list of integrity requirements.

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Special Condition No. 18, Ingestion The FAA proposed that Special Condition no. 18 would require magniX
to ensure that these engines will not experience unacceptable power loss or 10 https www.easa.europa.eu/document-library/
product-certification-consultations/final-specialcondition-sc-e-19-electric.

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hazardous engine effects from ingestion.
For example, the current bird-ingestion airworthiness regulation for turbine engines, 14 CFR 33.76, is based on potential damage from birds entering a turbine engine with an inlet duct that directs air into the engine for combustion, cooling, and thrust. In contrast, these electric engines do not use an inlet duct for those purposes.
Instead, the electric engine inlet duct is primarily used to streamline the air entering the inlet for efficient cooling of internal engine components.
An unacceptable power loss, as stated in Special Condition no. 18a, refers to a situation in which the power or thrust required for safe flight of the aircraft becomes unavailable to the pilot. The specific amount of power loss necessary for a safe flight depends on the aircraft configuration, speed, altitude, attitude, atmospheric conditions, phase of flight, and other circumstances, where the demand for thrust is critical to the aircrafts safe operation.
This special condition also requires magniX to declare the ingestion sources that are not evaluated in the engine installation manual.
Comment Summary: Textron recommended that this special condition quantify the ingestion threats in a manner similar to the way they are quantified for turbine engines in 14 CFR
33.76, Bird ingestion, 33.77, Foreign object ingestionice, and 33.78, Rain and hail ingestion. The commenter suggested that bird numbers and sizes, ice, rain, and hail concentrations should be provided.
FAA Response: The FAA does not agree with Textrons recommendation.
A special condition is not required to quantify ingestion threats. The FAA did not change this special condition as a result of this comment.
Comment Summary: Airbus stated that while detailed means of compliance test, analysis, etc. need not be part of this special condition, the FAA should specify the ingestion conditions, such as icing environments, that magniX must consider in showing compliance.
FAA Response: The FAA has changed final Special Condition no. 18 to require ingestion sources, that are not evaluated by magniX, to be declared in the engine installation manual.
Comment Summary: Textron recommended that this special condition include a provision to prevent the accumulation of ferromagnetic material in the air-cooled passages, and to prevent blockages and short circuits between the rotor and the stator for nonsealed engines.

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FAA Response: The FAA does not agree with this comment. The special condition requires magniX to consider ingestion of material originating from outside the engine, not from within it.
The potential for ferromagnetic contamination of engine bearings from sources within the engine would not likely meet the requirements established in these special conditions, such as Special Condition nos. 5 Durability and 7 Safety Analysis. The contamination is more likely a consequence of an engine failure or inadequate maintenance. The FAA
made no changes to these special conditions as a result of this comment.
Comment Summary: EASA stated rain conditions are a normal flight condition, even in VFR, and should be distinguished from other ingestion phenomena. EASA recommended incorporating EASA Special Condition E18 issue 2: operation under rain conditions must not result in any abnormal operation i.e., shutdown, power loss, erratic operation, power oscillations, failures . . . throughout the EPU operating range.
FAA Response: The FAA has modified Special Condition no. 18 in response to this comment to require the magniX engine to operate safely in rain environments. The word rain was removed from Special Condition no.
18a. The following special conditions were added: Special Condition no.
18b, which provides that rain ingestion must not result in an abnormal operation such as shutdown, power loss, erratic operation, or power oscillations throughout the engine operating range, and Special Condition no. 18d, which requires the applicant to declare, in the engine installation manual, ingestion sources that are not evaluated.
Comment Summary: EASA asked the FAA to verify the proposed Special Condition no. 18 might result in a limitation that could be established at the aircraft-level for operation in icing conditions.
FAA Response: These special conditions are not intended for all electric engine certification projects.
They are intended for the magni350 and magni650 electric engines. magniX
intends to pursue a type certificate for their electric engine. If magniX elects to omit likely sources of ingestion foreign objects, birds, ice, hail from their evaluations, Special Condition no. 18d requires magniX to declare ingestion sources that are not evaluated in the engine installation manual, except for rain. Special Condition no. 18b was added as a result of EASAs comment to implement performance requirements in
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