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Federal Register / Vol. 86, No. 184 / Monday, September 27, 2021 / Rules and Regulations
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consequence of accidental rotor locking while the aircraft is in-flight and classifies the failure as either hazardous or major. The magniX engine will need to meet the requirements of this special condition and those of the safety analysis, which provide protection from inadvertent rotor locking.
The FAA clarified the terms hazardous and hazardous engine effects as they are used in Special Condition no. 28 by adding a reference to Special Condition no. 17d2. The FAA changed final Special Condition no. 28 as a result of this comment.
Comment Summary: Textron requested that Special Condition no. 28
require magniX to consider the potential hazards from an automatic rotor locking system. Textron stated that if the engine is shut down during flight, and the locking device is automatic, the flight crew needs to have a means to remove the locking device and restart the engine without creating a hazard. The commenter recommended adding the following to Special Condition no. 28:
b When the locking device is in place, an indication shall be provided so that the crew will be able to retract the device while in flight.
FAA Response: The FAA does not agree with the comment. magniX
verifies rotor lock performance and reliability using the tests required by Special Condition no. 28. Typically, only rotorcraft have cockpit indications for locking devices. Those rotorcraft cockpit indications for locking devices are for main rotor transmissions, which are aircraft-level components. If an engine lock position indication is required to meet the aircraft safety objectives, the devices that notify the crew are part of the aircraft safety system. The FAA did not change these special conditions as a result of this comment.
Comment Summary: TCCA
commented that this special condition should allow additional techniques to verify rotor locking performance. TCCA
also suggested that the special condition requires a demonstration of reliable rotor unlocking performance.
FAA Response: Final Special Condition no. 28 has been changed to add rotor unlocking performance to the demonstration. However, allowing the use of a validated analysis would render the demonstration optional.
Special Condition No. 29, Teardown Inspection The FAA proposed that Special Condition no. 29 would require magniX
to perform either a teardown evaluation or a non-teardown evaluation based on
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the criteria of Special Condition no.
29a or b.
The FAA proposed that Special Condition no. 29a would require that the engine be disassembled after the endurance and durability demonstrations to verify each component remained within its service limits and in a condition for continued operation in accordance with 33.4, Instructions for Continued Airworthiness.
The FAA proposed that Special Condition no. 29b would require magniX, for non-teardown evaluations, to establish life limits based on endurance and durability demonstrations.
In final Special Condition no. 29b, magniX is required, for non-teardown evaluations, to account for engines, subassemblies, and components that cannot be disassembled without destroying the components. If teardown and inspection are not accomplished for components or assemblies after testing, the maintenance requirements for the engine are contingent on the demonstrated capabilities exhibited during the certification tests.
Comment Summary: GE
recommended that the FAA clarify how life limits will be established if magniX
cannot complete the teardown inspection of parts or components after the endurance and durability demonstrations. GE stated that the life limits should be documented in the engines airworthiness limitations or the engines ICA. TCCA also requested clarification about how life limits are established for parts and components that are not torn down after testing.
FAA Response: Special Condition no.
29 can have an effect on life limits. In the foregoing discussion of this condition, the FAA provided additional information to clarify how maintenance such as life limits is established for parts and components that are not torn down and inspected after testing. Also, the FAA changed final Special Condition no. 29 to require life limits resulting from this special condition to be documented in the ICA, in accordance with 14 CFR 33.4.
Comment Summary: Textron recommended that the FAA require inspections of electrical components in the controller after the endurance and durability demonstrations. Textron stated that, at a minimum, the FAA
should require inspection of the controllers fasteners, heat transfer components, dissimilar metallic junctions, and age or use affected electrical components.
FAA Response: The preamble of these special conditions explains that the
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magniX engine consists of an electric motor, controller, and high-voltage systems. Special Condition no. 29a requires the engine to be completely torn down and inspected. Special Condition no. 29b contains provisions for engine components that are not disassembled for inspection. The FAA
did not change these special conditions as a result of this comment.
Comment Summary: An individual commenter suggested potential longterm issues with main bearing lubrication related to grease life. The commenter stated that these issues might not be evident after completing a certification program.
FAA Response: In response to this comment, the FAA has changed final Special Condition no. 29b to require a life limit for the bearing lubricant if the bearing is not disassembled after testing.
The FAA has changed the special condition as a result of this comment.
Comment Summary: TCCA
recommended that the FAA mandate additional tests if the teardown inspection shows that part replacement is necessary.
FAA Response: The FAA does not concur with the comment. Special Condition nos. 32b and b4 General conduct of tests already have the requested provisions for additional testing of parts that require replacement during a test or based on their condition at teardown inspection. The FAA made no changes to the special condition as a result of the comment.
Comment Summary: EASA
commented that this Special Condition no. 29b was proposed to define the life limits of the tested components based on the endurance and durability tests.
EASA stated this special condition was not aligned with ASTM F333818 and asked the FAA to elaborate on whether the selected limit is the highest or lowest one and how limits are compared if they are based on different test conditions.
FAA Response: ASTM F333818, section 5.22.1.5 establishes life limits for an electric engine based on the length of an endurance test if the engine is not torn down for inspection after the test. These special conditions require individual life limits to be established, based on endurance and durability demonstrations if individual components are not torn down and inspected after the tests. This special condition is consistent with the ASTM
document EASA referenced in their comment. Because these special conditions apply to the magniX engine, the life limits will be based on the test conditions magniX uses to assess their engines. The FAA made no changes to
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