[Federal Register Volume 85, Number 224 (Thursday, November 19, 2020)]
[Proposed Rules]
[Pages 73644-73655]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-23434]


=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 33

[Docket No. FAA-2020-0894; Notice No. 33-19-01-SC]


Special Conditions: magniX USA, Inc., magni250 and magni500 Model 
Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

-----------------------------------------------------------------------

SUMMARY: This action proposes special conditions for magniX USA, Inc. 
(magniX), magni250 and magni500 model engines that operate using 
electrical technology installed on the aircraft for use as an aircraft 
engine. These engines have a novel or unusual design feature when 
compared to the state of technology envisioned in the airworthiness 
standards applicable to aircraft engines. The design feature is the use 
of an electric motor, controller, and high-voltage systems as the 
primary source of propulsion for an aircraft. The applicable 
airworthiness regulations do not contain adequate or appropriate safety 
standards for this design feature. These proposed special conditions

[[Page 73645]]

contain the additional safety standards that the Administrator 
considers necessary to establish a level of safety equivalent to that 
established by the existing airworthiness standards.

DATES: Send comments on or before December 21, 2020.

ADDRESSES: Send comments identified by Docket No. FAA-2020-0894 using 
any of the following methods:
     Federal eRegulations Portal: Go to http://www.regulations.gov/ and follow the online instructions for sending 
your comments electronically.
     Mail: Send comments to Docket Operations, M-30, U.S. 
Department of Transportation (DOT), 1200 New Jersey Avenue SE, Room 
W12-140, West Building Ground Floor, Washington, DC, 20590-0001.
     Hand Delivery or Courier: Take comments to Docket 
Operations in Room W12-140 of the West Building Ground Floor at 1200 
New Jersey Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday 
through Friday, except Federal holidays.
     Fax: Fax comments to Docket Operations at 202-493-2251.
    Privacy: Except for Confidential Business Information (CBI) as 
described in the following paragraph, and other information as 
described in 14 CFR 11.35, the FAA will post all comments received, 
without change, to http://www.regulations.gov/, including any personal 
information you provide. The FAA will also post a report summarizing 
each substantive verbal contact we received about this proposal.

Confidential Business Information

    Confidential Business Information (CBI) is commercial or financial 
information that is both customarily and actually treated as private by 
its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552), 
CBI is exempt from public disclosure. If your comments responsive to 
this Notice contain commercial or financial information that is 
customarily treated as private, that you actually treat as private, and 
that is relevant or responsive to this Notice, it is important that you 
clearly designate the submitted comments as CBI. Please mark each page 
of your submission containing CBI as ``PROPIN.'' The FAA will treat 
such marked submissions as confidential under the FOIA, and they will 
not be placed in the public docket of this Notice. Submissions 
containing CBI should be sent to Gary Horan, AIR-6A1, Engine and 
Propeller Standards Branch, Aircraft Certification Service, 1200 
District Avenue, Burlington, Massachusetts 01803; telephone (781) 238-
7164; gary.horan@faa.gov. Any commentary that the FAA receives which is 
not specifically designated as CBI will be placed in the public docket 
for this rulemaking.
    Docket: Background documents or comments received may be read at 
http://www.regulations.gov/ at any time. Follow the online instructions 
for accessing the docket or go to Docket Operations in Room W12-140 of 
the West Building Ground Floor at 1200 New Jersey Avenue SE, 
Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Gary Horan, AIR-6A1, Engine and 
Propeller Standards Branch, Aircraft Certification Service, 1200 
District Avenue, Burlington, Massachusetts 01803; telephone (781) 238-
7164; gary.horan@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites interested people to take part in this rulemaking 
by sending written comments, data, or views. The most helpful comments 
reference a specific portion of the proposed special conditions, 
explain the reason for any recommended change, and include supporting 
data.
    The FAA will consider all comments received by the closing date for 
comments. The FAA may change these proposed special conditions based on 
the comments received.

Background

    On June 4, 2019, magniX applied for a type certificate for its 
magni250 and magni500 model electric engines. The FAA has not 
previously type certificated an engine that uses electrical technology 
for propulsion of the aircraft. Electric propulsion technology is 
substantially different from the technology used in previously 
certificated turbine and reciprocating engines; therefore, these 
engines introduce new safety concerns that need to be addressed in the 
certification basis.
    There is a growing interest within the aviation industry to utilize 
electric propulsion technology. As a result, international agencies and 
industry stakeholders formed a new committee under ASTM International 
Committee F39 to identify the appropriate technical criteria for 
aircraft engines using electrical technology that has not been 
previously certificated for aircraft propulsion systems. ASTM 
International, formerly known as American Society for Testing and 
Materials, is an international standards organization that develops and 
publishes voluntary consensus technical standards for a wide range of 
materials, products, systems, and services. ASTM International 
published ASTM F3338-18, Standard Specification for Design of Electric 
Propulsion Units for General Aviation Aircraft, in December 2018.\1\ 
The FAA used the technical criteria from the ASTM standard and engine 
information from magniX to develop special conditions to establish an 
equivalent level of safety to that required by title 14, Code of 
Federal Regulations (14 CFR) part 33.
---------------------------------------------------------------------------

    \1\ https://www.astm.org/Standards/F3338.htm.
---------------------------------------------------------------------------

Type Certification Basis

    Under the provisions of 14 CFR 21.17(a)(1), generally, magniX must 
show that magni250 and magni500 model engines meet the applicable 
provisions of part 33 in effect on the date of application for a type 
certificate.
    If the Administrator finds that the applicable airworthiness 
regulations (e.g., 14 CFR part 33) do not contain adequate or 
appropriate safety standards for the magni250 and magni500 model 
engines because of a novel or unusual design feature, special 
conditions may be prescribed under the provisions of Sec.  21.16.
    Special conditions are initially applicable to the model for which 
they are issued. Should the type certificate for that model be amended 
later to include any other engine model that incorporates the same 
novel or unusual design feature, these special conditions would also 
apply to the other engine model under Sec.  21.101.
    In addition to the applicable airworthiness regulations and special 
conditions, the magni250 and magni500 model engines must comply with 
the noise certification requirements of 14 CFR part 36.
    The FAA issues special conditions, as defined in 14 CFR 11.19, in 
accordance with Sec.  11.38, and they become part of the type 
certification basis under Sec.  21.17(a)(2).

Novel or Unusual Design Features

    The magni250 and magni500 model engines will incorporate the 
following novel or unusual design features:
    An electric motor, controller, and high-voltage systems that are 
used as the primary source of propulsion for an aircraft.

Discussion

Part 33 Developed for Gas-Powered Turbine and Reciprocating Engines

    Aircraft engines make use of an energy source to drive mechanical 
systems that provide propulsion for the

[[Page 73646]]

aircraft. Energy can be generated from various sources such as 
petroleum and natural gas. The turbine and reciprocating aircraft 
engines certified under part 33 use aviation fuel for an energy source. 
The reciprocating and turbine engine technology that was anticipated in 
the development of part 33 converts air and fuel to energy using an 
internal combustion system, which generates heat and mass flow of 
combustion products for turning shafts that are attached to propulsion 
devices such as propellers and ducted fans. Part 33 regulations set 
forth standards for these engines and mitigate potential hazards 
resulting from failures and malfunctions. The nature, progression, and 
severity of engine failures are tied closely to the technology that is 
used to design and manufacture aircraft engines. These technologies 
involve chemical, thermal, and mechanical systems. Therefore, the 
existing engine regulations in part 33 address certain chemical, 
thermal, and mechanically induced failures that are specific to air and 
fuel combustion systems operating with cyclically loaded high-speed, 
high-temperature, and highly-stressed components.

magniX's Proposed Electric Engines Are Novel or Unusual

    The existing part 33 airworthiness standards for aircraft engines 
date back to 1965. These airworthiness standards are based on fuel-
burning reciprocating and turbine engine technology. The magni250 and 
magni500 model engines are not turbine or reciprocating engines. These 
engines have a novel or unusual design feature, which is the use of 
electrical sources of energy instead of fuel to drive the mechanical 
systems that provide propulsion for aircraft. The aircraft engine is 
also exposed to chemical, thermal, and mechanical operating conditions, 
unlike those observed in internal combustion systems. Therefore, part 
33 does not contain adequate or appropriate safety standards for the 
magni250 and magni500 model engine's novel design feature.
    magniX's proposed aircraft engines will operate using electrical 
power instead of air and fuel combustion to propel the aircraft. These 
electric engines will be designed, manufactured, and controlled 
differently than turbine or reciprocating aircraft engines. They will 
be built with an electric motor, controller, and high-voltage systems 
that draw energy from electrical storage or generating systems. The 
electric motor is a device that converts electrical energy into 
mechanical energy by electric current flowing through wire coils in the 
motor producing a magnetic field that interacts with the magnets on the 
rotating shaft. The controller is a system that consists of two main 
functional elements: The motor controller and an electric power 
inverter to drive the motor.\2\ The high voltage system is a 
combination of wires and the connectors that couple the motor and the 
controller.
---------------------------------------------------------------------------

    \2\ Sometimes this entire system is referred to as an inverter. 
Throughout this document, it will be referred to as the controller.
---------------------------------------------------------------------------

    In addition, the technology required to produce these high-voltage 
and high-current electronic components introduces potential hazards 
that do not exist in turbine and reciprocating aircraft engines. For 
example, high-voltage transmission lines, electromagnetic shields, 
magnetic materials, and high-speed electrical switches are necessary to 
use the physical properties essential to the electric engine. However, 
this technology also exposes the aircraft to potential failures that 
are not common to gas-powered turbine and reciprocating engines, which 
could adversely affect safety.

magniX's Electric Engines Require a Mix of Part 33 Standards and 
Special Conditions

    Although the electric aircraft engines proposed by magniX use novel 
or unusual design features that are not addressed in the existing part 
33 airworthiness standards, there are some basic similarities in 
configuration and function that require similar provisions to prevent 
hazards that are common to aircraft engines using air and fuel 
combustion (e.g., fire, uncontained high-energy debris, and loss of 
thrust control). However, the primary failure concerns and the 
probability of exposure to common hazards are different for the 
proposed electric aircraft engines. This creates a need to develop 
special conditions to ensure the engine's safety and reliability.
    The requirements in part 33 ensure the design and construction of 
aircraft engines, including the engine control systems, are proper for 
the engine type design and operating limits. However, part 33 does not 
fully address the use of aircraft engines like magniX's, which operate 
using electrical technology as the primary means of propelling the 
aircraft. This necessitates the development of special conditions to 
provide adequate airworthiness standards for these aircraft engines.
    The requirements in part 33, subpart B, are applicable to 
reciprocating and turbine aircraft engines. Subparts C and D are 
applicable to reciprocating aircraft engines. Subparts E through G are 
applicable to turbine aircraft engines. As such, subparts B through G 
do not adequately address the use of aircraft engines that operate 
using electrical technology. This necessitates the development of 
special conditions to ensure a level of safety commensurate with these 
subparts, as those regulatory requirements do not contain adequate or 
appropriate safety standards for aircraft engines that operate using 
electrical technology to propel the aircraft.
    The special conditions that the FAA proposes for magniX's engine 
design include:
    Applicability: Proposed special condition no. 1 would require 
magniX to comply with 14 CFR part 33, except for those airworthiness 
standards specifically and explicitly applicable only to reciprocating 
and turbine aircraft engines.
    Engine Ratings and Operating Limitations: Proposed special 
condition no. 2 would require magniX, in addition to compliance with 14 
CFR 33.7(a), to establish engine operating limits related to the power, 
torque, speed, and duty cycles specific to the magni250 and magni500 
model engines. The duty or duty cycle is a statement of the load(s) to 
which the engine is subjected, including, if applicable, starting, no-
load and rest, and de-energized periods, including their durations or 
cycles and sequence in time.
    Materials: Proposed special condition no. 3 would require magniX to 
comply with 14 CFR 33.15, which sets requirements for the suitability 
and durability of materials used in the engine, and which would 
otherwise be applicable only to reciprocating and turbine aircraft 
engines.
    Fire Protection: Proposed special condition no. 4 would require 
magniX to comply with 14 CFR 33.17, which sets requirements to protect 
the engine and certain parts and components of the airplane against 
fire, and which would otherwise be applicable only to reciprocating and 
turbine aircraft engines. Additionally, this proposed special condition 
would require magniX to ensure the high-voltage electrical wiring 
interconnect systems that connect the controller to the motor are 
protected against arc-faults. An arc-fault is a high power discharge of 
electricity between two or more conductors. This discharge generates 
heat, which can break down the wire's insulation and trigger an 
electrical fire. Arc-faults can range in power from a few amps up to 
thousands of amps and are highly variable in strength and duration.

[[Page 73647]]

    Durability: Proposed special condition no. 5 would require the 
proposed engine design and construction to ensure safe engine operation 
between maintenance intervals, overhaul periods, and mandatory actions. 
This proposed condition would also require magniX to develop 
maintenance instructions and scheduling information.
    Engine Cooling: Proposed special condition no. 6 would require 
magniX to comply with 14 CFR 33.21, which requires the engine design 
and construction to provide necessary cooling, and which would 
otherwise be applicable only to reciprocating and turbine aircraft 
engines. Additionally, this proposed special condition would require 
magniX to document the cooling system monitoring features and usage in 
the engine installation manual, in accordance with Sec.  33.5, if 
cooling is required to satisfy the safety analysis described in 
proposed special condition no. 17. Loss of adequate cooling to an 
engine that operates using electrical technology can result in rapid 
overheating and abrupt engine failure with critical consequences to 
safety.
    Engine Mounting Attachments and Structure: Proposed special 
condition no. 7 would require magniX and the proposed design to comply 
with 14 CFR 33.23, which requires the applicant to define, and the 
proposed design to withstand, certain load limits for the engine 
mounting attachments and related engine structure. These requirements 
would otherwise be applicable only to reciprocating and turbine 
aircraft engines.
    Accessory Attachments: Proposed special condition no. 8 would 
require the proposed design to comply with 14 CFR 33.25, which sets 
certain design, operational, and maintenance requirements for the 
engine's accessory drive and mounting attachments, and which would 
otherwise be applicable only to reciprocating and turbine aircraft 
engines.
    Overspeed: Proposed special condition no. 9 would require magniX to 
establish by test, validated analysis, or a combination of both, that--
(1) the rotor overspeed must not result in a burst, rotor growth, or 
damage that results in a hazardous engine effect; (2) rotors must 
possess sufficient strength margin to prevent burst; and (3) operating 
limits must not be exceeded in-service. The proposed special condition 
associated with rotor overspeed is necessary because of the differences 
between turbine engine technology and the technology of these electric 
engines. Turbine speed is driven by hot air expansion and is impacted 
by the aerodynamic loads on the rotor blades. Therefore, the speed or 
overspeed is not directly controlled in turbine engines. The speed of 
an electric engine is directly controlled by the electric field created 
by the controller. The failure modes that can lead to overspeed between 
turbine engines and these engines are vastly different, and therefore 
this special condition is necessary.
    Engine Control Systems: Proposed special condition no. 10(b) would 
require magniX to ensure that these engines do not experience any 
unacceptable operating characteristics (such as unstable speed or 
torque control) or exceed any of their operating limitations.
    The FAA originally issued Sec.  33.28 at amendment 33-15 to address 
the evolution of the means of controlling the fuel supplied to the 
engine, from carburetors and hydro-mechanical controls to electronic 
control systems. These electronic control systems grew in complexity 
over the years, and as a result, the FAA amended Sec.  33.28 at 
amendment 33-26 to address these increasing complexities. The 
controller that forms the controlling system for these electric engines 
is significantly simpler than the complex control systems used in 
modern turbine engines. The current regulations for engine control are 
inappropriate for electric engine control systems; therefore, the 
proposed special condition no. 10(b) associated with controlling these 
engines is necessary.
    Proposed special condition no. 10(c) would require magniX to 
develop and verify the software and complex electronic hardware used in 
programmable logic devices, using proven methods that ensure it can 
provide the accuracy, precision, functionality, and reliability 
commensurate with the hazard that is being mitigated by the logic. RTCA 
DO-254, Design Assurance Guidance for Airborne Electronic Hardware, 
dated April 19, 2000,\3\ distinguish between complex and simple 
electronic hardware.
---------------------------------------------------------------------------

    \3\ https://my.rtca.org/NC__Product?id=a1B36000001IcjTEAS.
---------------------------------------------------------------------------

    Proposed special condition no. 10(d) would require data from 
assessments of all functional aspects of the control system to prevent 
errors that could exist in software programs that are not readily 
observable by inspection of the code. Also, magniX must use methods 
that will result in the expected quality that ensures the engine 
control system performs the intended functions throughout the declared 
operational envelope.
    The environmental limits referred to in proposed special condition 
no. 10(e) include temperature, vibration, high-intensity radiated 
fields (HIRF), and others addressed in RTCA DO-160G, Environmental 
Conditions and Test Procedures for Airborne Electronic/Electrical 
Equipment and Instruments.\4\ Accordingly, proposed special condition 
10(e) would require magniX to document the environmental limits to 
which the system has been qualified in the engine installation 
instructions.
---------------------------------------------------------------------------

    \4\ https://my.rtca.org/NC__Product?id=a1B36000001IcnSEAS.
---------------------------------------------------------------------------

    Proposed special condition no. 10(f) would require magniX to 
evaluate various control system failures to assure that these failures 
will not lead to unsafe conditions. The FAA issued Advisory Circular, 
AC 33.28-3, Guidance Material For 14 CFR 33.28, Engine Control Systems, 
on May 23, 2014.\5\ Paragraph 6-2 of this AC provides applicants with 
guidance on defining an engine control system failure when showing 
compliance with the requirements of 14 CFR 33.28. AC 33.28-3 also 
includes objectives for the integrity requirements, criteria for a loss 
of thrust (or power) control (LOTC/LOPC) event, and an acceptable LOTC/
LOPC rate. As with other topics within these proposed special 
conditions, the failure rates that apply to electric engines were not 
established when the FAA issued this AC.
---------------------------------------------------------------------------

    \5\ https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_33_28-3.pdf.
---------------------------------------------------------------------------

    The phrase ``in the full-up configuration'' used in proposed 
special condition no. 10(f)(2) refers to a system without any fault 
conditions present. The electronic control system must, when in the 
full-up configuration, be single fault-tolerant, as determined by the 
Administrator, for electrical, electrically detectable, and electronic 
failures involving LOPC events.
    The term ``local'' in the context of ``local events'' used in 
proposed special condition no. 10(f)(4) means failures or malfunctions 
leading to events in the intended aircraft installation such as fire, 
overheat, or failures leading to damage to engine control system 
components. These local events must not result in a hazardous engine 
effect due to engine control system failures or malfunctions.
    Proposed special condition no. 10(g) would require magniX to 
conduct a safety assessment of the control system to support the safety 
analysis in special condition no. 17. This control safety assessment 
provides failures and rates

[[Page 73648]]

of these failures that can be used at the aircraft safety assessment 
level.
    Proposed special condition no. 10(h) requires magniX to provide 
appropriate protection devices or systems to ensure that engine 
operating limitations will not be exceeded in-service.
    Proposed special condition no. 10(i) is necessary to ensure the 
controllers are self-sufficient and isolated from other aircraft 
systems. The aircraft-supplied data supports the analysis at the 
aircraft level to protect the aircraft from common mode failures that 
could lead to major propulsion power loss. The exception ``other than 
power command signals from the aircraft'' noted in proposed special 
condition no. 10(i) is based on the FAA's determination that there are 
no reasonable means for the engine controller to determine the validity 
of any in-range signals from this system. In many cases, the engine 
control system can detect a faulty signal from the aircraft. The engine 
control system typically accepts the power command signal as a valid 
value.
    The term ``independent'' in the context of ``fully independent 
engine systems'' referenced in proposed special condition no. 10(i) 
means the controllers should be self-sufficient and isolated from other 
aircraft systems or provide redundancy that enables it to accommodate 
aircraft data system failures. In the case of loss, interruption, or 
corruption of aircraft-supplied data, the engine must continue to 
function in a safe and acceptable manner without unacceptable effects 
on thrust or power, hazardous engine effects, or inability to comply 
with the operation demonstrations in proposed special condition no. 25.
    The term ``accommodated'' in the context of ``detected and 
accommodated'' referenced in proposed special condition 10(i)(2) is to 
assure that once a fault has been detected, that the system continues 
to function safely.
    Proposed special condition no. 10(j) would require magniX to show 
that the loss of electric power from the aircraft will not cause the 
electric engine to malfunction in a manner hazardous to the aircraft. 
The total loss of electric power to the electric engine may result in 
an engine shutdown.
    Instrument Connection: Proposed special condition no. 11 would 
require magniX to comply with 14 CFR 33.29(a), (e), (f), and (g), which 
set certain requirements for the connection and installation of 
instruments to monitor engine performance. The remaining requirements 
in section 33.29 apply only to technologies used in reciprocating and 
turbine aircraft engines.
    Instrument connections (wires, wire insulation, potting, grounding, 
connector designs) present opportunities for unsafe features to be 
present on the aircraft. Proposed special condition no. 11 would 
require the safety analysis to include potential hazardous effects from 
failure of instrument connections to function properly. The outcome of 
this analysis might identify the need for design enhancements or 
additional Instructions for Continued Airworthiness (ICA) to ensure 
safety.
    Stress Analysis: Section 33.62 requires applicants to perform a 
stress analysis on each turbine engine. This regulation is explicitly 
applicable only to turbine engines and turbine engine components, and 
not appropriate for the magniX magni250 and magni500 model engines. 
However, the FAA proposes that a stress analysis particular to these 
electric engines is necessary.
    Proposed special condition no. 12 would require a mechanical, 
thermal, and electrical stress analysis to show there is a sufficient 
design margin to prevent unacceptable operating characteristics. Also, 
the applicant must determine the maximum stresses in the engine by 
tests, validated analysis, or a combination thereof, and show that they 
do not exceed minimum material properties.
    Critical and Life-Limited Parts: Proposed special condition no. 13 
would require magniX to show whether rotating or moving components, 
bearings, shafts, 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 engineering plan referenced in proposed special condition no. 
13(b)(1) would require magniX to establish activities for managing 
documents, practices, and procedures that govern key design criteria 
essential to part airworthiness. The engineering plan would be required 
to contain methods for verifying the characteristics and qualities 
assumed in the design data using methods that are suitable for the part 
criticality. The engineering plan flows information from engineering to 
manufacturing about the criticality of key attributes that affect the 
airworthiness of the part. The plan also includes a reporting system 
that flows problematic issues that develop in engines while they 
operate in service so the design process can address them. For example, 
the effect of environmental influences on engine performance might not 
be consistent with the assumptions used to design the part. The impact 
of ice slab ingestion on engine parts might not be fully understood 
until the engine ingests the specific ice quantities and shapes that 
the airplane sheds. During the pre-certification activities, magniX 
must ensure the engineering plan is complete, available, and acceptable 
to the Administrator before the engine is certified.
    The term ``low-cycle fatigue'' referenced in proposed special 
condition no. 13(a)(2) is a decline in material strength from exposure 
to cyclic stress at levels beyond the stress threshold the material can 
sustain indefinitely. This threshold is known as the material endurance 
limit. Low-cycle fatigue typically causes a part to sustain plastic or 
permanent deformation during the cyclic loading and can lead to cracks, 
crack growth, and fracture. Engine parts that operate at high 
temperatures and high-mechanical stresses simultaneously can experience 
low-cycle fatigue coupled with creep. Creep is the tendency of a 
metallic material to permanently move or deform when it is exposed to 
the extreme thermal conditions created by hot combustion gasses and 
substantial physical loads such as high rotational speeds and maximum 
thrust. Conversely, high-cycle fatigue is caused by elastic 
deformation, small strains caused by alternating stress, and a much 
higher number of load cycles compared to the number of cycles that 
cause low-cycle fatigue.
    The term ``manufacturing definition'' referenced in proposed 
special condition no. 13(b)(2) is the collection of data required to 
translate documented engineering design criteria into physical parts 
and verify that the parts comply with the properties established by the 
design data. Since engines are not intentionally tested to failure 
during a certification program, there are inherent expectations for 
performance and durability guaranteed by the documents and processes 
used to execute production and quality systems required by Sec.  
21.137. These systems limit the potential manufacturing outcomes to 
parts that are consistently produced within design constraints.
    The manufacturing plan and service management plan ensure essential 
information from the engineering plan, such as the design 
characteristics that ensure the integrity of critical and life-limited 
parts, is consistently produced and preserved over the lifetime of 
those parts. The manufacturing plan includes special processes and 
production controls to prevent inclusion of manufacturing-induced 
anomalies, which can degrade the part's structural integrity. Examples 
of manufacturing-induced anomalies are material

[[Page 73649]]

contamination, unacceptable grain growth, heat affected areas, and 
residual stresses. The service management plan has provisions for 
enhanced detection and reporting of service-induced anomalies that can 
cause the part to fail before it reaches its life limit or service 
limit. Anomalies can develop in service from improper handling, 
unforeseen operating conditions, and long-term environmental effects. 
The service management plan ensures important information that might 
affect the assumptions used to design a part is incorporated into the 
design process to remove unforeseen potential unsafe features from the 
engine.
    Lubrication System: Proposed special condition no. 14 would require 
magniX to ensure the lubrication system is designed to function 
properly between scheduled maintenance intervals and prevent 
contamination of the engine bearings. This proposed condition would 
also require magniX to demonstrate the unique lubrication attributes 
and functional capability of the magni250 and magni500 model engine 
design.
    The corresponding part 33 regulations include provisions for 
lubrication systems used in reciprocating and turbine engines. The part 
33 requirements account for safety issues associated with specific 
reciprocating and turbine engine system configurations. These 
regulations are not appropriate for the magniX magni250 and magni500 
model engines. For example, these engines do not have a crankcase or 
lubrication oil sump. The bearings are sealed, so they do not require 
an oil circulation system. The lubrication system in these engines is 
also independent of the propeller pitch control system. Therefore, 
proposed special condition no. 14 incorporates only certain 
requirements from the part 33 regulations.
    Power Response: Proposed special condition no. 15 would require the 
design and construction of the magni250 and magni500 model engines to 
enable an increase (1) from the minimum power setting to the highest-
rated power without detrimental engine effects, and (2) from the 
minimum obtainable power while in-flight and on the ground to the 
highest-rated power within a time interval for safe operation of the 
aircraft.
    The engine control system governs the increase or decrease in power 
in combustion engines to prevent too much (or too little) fuel from 
being mixed with air before combustion. Due to the lag in rotor 
response time, improper fuel/air mixtures can result in engine surges, 
stalls, and exceedances above rated limits and durations. Failure of 
the engine to provide thrust, maintain rotor speeds below burst 
thresholds, and temperatures below limits have the potential for 
detrimental effects to the aircraft. Similar detrimental effects are 
possible in the magni250 and magni500 model engines, but the causes are 
different. Electric engines with reduced power response time can 
experience insufficient thrust to the aircraft, shaft over-torque, and 
over-stressed rotating components, propellers, and critical propeller 
parts. Therefore, this special condition is necessary.
    Continued Rotation: Proposed special condition no. 16 would require 
magniX to design the magni250 and magni500 model engines such that, if 
the main rotating systems continue to rotate after the engine is shut 
down while in-flight, this continued rotation will not result in any 
hazardous engine effects.
    The main rotating system of the magniX magni250 and magni500 model 
engines consists of the rotors, shafts, magnets, bearings, and wire 
windings that convert electrical energy to shaft torque. This rotating 
system must continue to rotate after the power source to the engine is 
shut down. The safety concerns associated with this proposed special 
condition are substantial asymmetric aerodynamic drag that can cause 
aircraft instability, loss of control, and reduced efficiency, and 
result in a forced landing or inability to continue safe flight.
    Safety Analysis: Proposed special condition no. 17 would require 
magniX to comply with 14 CFR 33.75(a)(1), (a)(2), and (a)(3), which 
require the applicant to conduct a safety analysis of the engine, and 
which would otherwise be applicable only to turbine aircraft engines. 
Additionally, this proposed special condition would require magniX to 
assess its engine design to determine the likely consequences of 
failures that can reasonably be expected to occur. The failure of such 
elements and associated prescribed integrity requirements must be 
stated in the safety analysis.
    A primary failure mode is the manner in which a part is most likely 
going to fail. Engine parts that have a primary failure mode, a 
predictable life to the failure and a failure consequence that results 
in a hazardous effect are life-limited or critical parts. Some life-
limited or critical engine parts can fail suddenly in their primary 
failure mode from prolonged exposure to normal engine environments such 
as temperature, vibration, and stress. Due to the consequence of 
failure, these parts are not allowed to be managed by on-condition or 
probabilistic means because the probability of failure cannot be 
sensibly estimated in numerical terms. Therefore, the parts are managed 
by compliance with integrity requirements such as mandatory maintenance 
(life limits, inspections, inspection techniques) to ensure the 
qualities, features, and other attributes that prevent the part from 
failing in its primary failure mode are preserved throughout its 
service life. For example, if the number of engine cycles to failure 
are predictable and can be associated with specific design 
characteristics, such as material properties, then the applicant can 
manage the engine part with life limits.
    Ingestion: Proposed special condition no. 18 would require magniX 
to ensure that these engines will not experience unacceptable power 
loss or hazardous engine effects from ingestion. The associated 
regulation for turbine engines, 14 CFR 33.76, is based on potential 
damage from birds being ingested into the turbine engine that has an 
inlet duct, which directs air into the engine for combustion, cooling, 
and thrust. In contrast, these electric engines do not use an inlet for 
those purposes.
    An ``unacceptable'' power loss, as used in proposed special 
condition no. 18(a), is one in which the power or thrust required for 
safe flight of the aircraft becomes unavailable to the pilot. The 
specific amount of power loss that is required for 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 safe operation of the aircraft.
    Liquid Systems: Proposed special condition no. 19 would require 
magniX to ensure that liquid systems used for lubrication or cooling of 
engine components are designed and constructed to function properly. 
Also, if a liquid system is not self-contained, the interfaces to that 
system would be required to be defined in the engine installation 
manual. Liquid systems for the lubrication or cooling of engine 
components can include heat exchangers, pumps, fluids, tubing, 
connectors, electronic devices, temperature sensors and pressure 
switches, fasteners and brackets, bypass valves, and metallic chip 
detectors. These systems allow the electric engine to perform at 
extreme speeds and temperatures for durations up to the maintenance 
intervals without exceeding temperature limits or predicted 
deterioration rates.
    Vibration Demonstration: Proposed special condition no. 20 would 
require

[[Page 73650]]

magniX to ensure (1) the engine is designed and constructed to function 
throughout its normal operating range of rotor speeds and engine output 
power without inducing excessive stress caused by engine vibration, and 
(2) the engine design undergoes a vibration survey.
    The vibration demonstration is a survey that characterizes the 
vibratory attributes of the engine and verifies the stresses from 
vibration do not impose excessive force or result in natural frequency 
responses on the aircraft structure. The vibration demonstration also 
ensures internal vibrations will not cause engine components to fail. 
Excessive vibration force occurs at magnitudes and forcing functions or 
frequencies, which may result in damage to the aircraft. Stress margins 
to failure add conservatism to the highest values predicted by analysis 
for additional protection from failure caused by influences beyond 
those quantified in the analysis. The result of the additional design 
margin is improved engine reliability that meets prescribed thresholds 
based on the failure classification. The amount of margin needed to 
achieve the prescribed reliability rates depends on an applicant's 
experience with a product. The FAA considers the reliability rates when 
deciding how much vibration is ``excessive.''
    Overtorque: Proposed special condition no. 21 would require magniX 
to demonstrate that the engine is capable of continued operation 
without the need for maintenance if it experiences a certain amount of 
overtorque.
    The electric engine proposed by magniX converts electrical energy 
to shaft torque, which is used for propulsion. The electric motor, 
controller, and high-voltage systems control the engine torque. When 
the pilot commands power or thrust, the engine responds to the command 
and adjusts the shaft torque to meet the demand. During the transition 
from one power or thrust setting to another, there is a small delay, or 
latency, in the engine response time. While the engine dwells in this 
time interval, it can continue to apply torque until the command to 
reduce the torque is applied by the engine control. The amount of 
overtorque the FAA permits during operation depends on how well the 
applicant demonstrates the engine's capability to remain operational 
without the need for maintenance action. Therefore, this special 
condition is necessary.
    Calibration Assurance: Proposed special condition no. 22 would 
require 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 Sec.  33.85 only apply to the endurance test specified in Sec.  
33.87, which is applicable only to turbine engines. The FAA proposes 
that the methods used for accomplishing those tests for turbine engines 
is not the best approach for electric engines. The calibration tests in 
Sec.  33.85 have provisions applicable to ratings that are not relevant 
to the magniX magni250 and magni500 model engines. Proposed special 
condition no. 22 would allow 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, the proposed special condition applies the calibration 
requirement to both the endurance and durability tests.
    Endurance Demonstration: Proposed special condition no. 23 would 
require magniX to perform an endurance demonstration test that is 
acceptable to the Administrator. The Administrator will evaluate the 
extent to which the test exposes the engine to failures that could 
occur when the engine is operated at up to its rated values, to 
determine if the test is sufficient to show the engine design will not 
exhibit unacceptable effects in-service, such as significant 
performance deterioration, operability restrictions, engine power loss 
or instability, when it is run for sustained periods at extreme 
operating conditions.
    Temperature Limit: Proposed special condition no. 24 would require 
magniX to ensure the engine can endure operation at its temperature 
limits plus an acceptable margin. An ``acceptable margin,'' as used in 
the proposed special condition, is the amount of temperature above that 
required to prevent the least-capable engine allowed by the type design 
from failing due to temperature-related causes when operating at the 
most extreme thermal conditions.
    Operation Demonstration: Proposed special condition no. 25 would 
require the engine to demonstrate safe operating characteristics 
throughout its declared flight envelope and operating range. Engine 
operating characteristics define the range of functional and 
performance values the magniX magni250 and magni500 model engines can 
achieve without incurring hazardous effects. They are requisite 
capabilities of the type design that qualify the engine for 
installation into aircraft and determine aircraft installation 
requirements. The primary engine operating characteristics are assessed 
by the tests and demonstrations that would be required by these special 
conditions. Some of these characteristics are shaft output torque, 
rotor speed, power consumption, and engine thrust response. The engine 
performance data magniX will use to certify the engine must account for 
installation loads and effects. These are aircraft-level effects that 
could affect the engine characteristics that are measured in a test 
cell. These effects could result from elevated inlet cowl temperatures, 
extreme aircraft maneuvers, flowstream distortion, and hard landings. 
An engine that is run in a test facility could demonstrate more 
capability for some operating characteristics than it will when 
operating on an aircraft and potentially decrease the engine ratings 
and operating limits. Therefore, the installed performance defines the 
engine performance capabilities.
    Durability Demonstration: Proposed special condition no. 26 would 
require magniX to subject the engine to a durability demonstration. The 
durability demonstration must show that each part of the engine is 
designed and constructed to minimize the development of any unsafe 
condition of the system between overhaul periods or between engine 
replacement intervals if overhaul is not defined. Durability is the 
ability of an engine, in the fully deteriorated state, to continue 
generating rated power or thrust, retain adequate operating margins, 
and retain sufficient efficiency that enables the aircraft to reach its 
destination. The amount of deterioration an engine can experience is 
restricted by operating limitations and managed by the ICA. Section 
33.90 specifies how maintenance intervals are established; it does not 
include provisions for an engine replacement. Electric engines and 
turbine engines deteriorate differently; therefore, magniX will use 
different test effects to establish overhaul periods or engine 
replacement intervals if no maintenance is specified.
    System and Component Tests: Proposed special condition no. 27 would 
require magniX to show that the systems and components of the engine 
would perform their intended functions in all declared engine 
environments and operating conditions.
    Sections 33.87 and 33.91, which are specifically applicable to 
turbine engines, have conditional criteria to decide if additional 
tests will be required after the engine tests. The criteria are not 
suitable for electric

[[Page 73651]]

engines. Part 33 associates the need for additional testing with the 
outcome of the Sec.  33.87 endurance test because it is designed to 
address safety concerns in combustion engines. For example, Sec.  
33.91(b) establishes a need for temperature limits and additional 
testing where the endurance test does not fully expose internal 
components to thermal conditions that verify the desired operating 
limits. A safety concern for electric engines is extreme temperatures. 
The FAA proposes that the Sec.  33.87 endurance test might not be the 
best way to achieve the highest thermal conditions for all the 
electronic components of electric engines because heat is generated 
differently in electronic systems than it is in turbine engines. There 
are also additional safety considerations that need to be addressed in 
the test. Therefore, proposed special condition no. 27 would be a 
performance-based requirement that allows magniX to determine how to 
challenge the electric engine and to determine the appropriate 
limitations that correspond to the technology.
    Rotor Locking Demonstration: Proposed special condition no. 28 
would require the engine to demonstrate reliable rotor locking 
performance and that no hazardous effects will occur if the engine uses 
a rotor locking device to prevent shaft rotation.
    Some engine designs enable the pilot to prevent a propeller shaft 
or main rotor shaft from turning while the engine is running or the 
aircraft is in-flight. This capability is needed for some installations 
that require the pilot to confirm functionality of certain flight 
systems before takeoff. The proposed magniX engine installations are 
not limited to vehicles that will not require rotor locking. Section 
33.92 prescribes a test that may not include the appropriate criteria 
to demonstrate sufficient rotor locking capability for these engines; 
therefore, this special condition is necessary.
    The proposed special condition does not define ``reliable'' rotor 
locking, but would allow magniX to classify the hazard (major/minor) 
and assign the appropriate quantitative criteria that meet the safety 
objectives required by Sec.  33.75.
    Teardown Inspection: Proposed special condition no. 29 would 
require magniX to perform either a teardown evaluation or a non-
teardown evaluation based on the criteria provided in proposed special 
condition no. 29(a) or (b).
    Proposed special condition no. 29(b) includes restrictive criteria 
for ``non-teardown evaluations'' to account for electric engines, sub-
assemblies, and components that cannot be disassembled without 
destroying them. Some electrical and electronic components like 
magniX's are constructed in an integrated fashion that precludes the 
possibility of tearing them down without destroying them. Sections 
33.55 and 33.93 do not contain similar requirements because 
reciprocating and turbine engines can be disassembled for inspection.
    Containment: Proposed special condition no. 30 would require the 
engine to provide containment features that protect against likely 
hazards from rotating components unless magniX can show, by test or 
validated analysis, that the margin to rotor burst does not justify the 
need for containment features. Rotating components in electric engines 
are typically disks, shafts, bearings, seals, orbiting magnetic 
components, and the assembled rotor core. However, if the margin to 
rotor burst does not unconditionally rule out the possibility of a 
rotor burst, then the condition would require magniX to assume a rotor 
burst could occur and provide case features that will contain the 
failed rotors. In addition, magniX must also determine the effects of 
subsequent damage precipitated by the main rotor failure and 
characterize any fragments that are released forward or aft of the 
containment features. The fragment energy levels, trajectories, and 
size must be documented in the installation manual because the aircraft 
will need to account for the effects of a rotor failure in the aircraft 
design. The intent of this special condition is to prevent hazardous 
engine effects from structural failure of rotating components and the 
rotating parts that are built into them.
    Operation with a Variable Pitch Propeller or Fan: Proposed special 
condition no. 31 would require magniX to conduct functional 
demonstrations, including feathering, negative torque, negative thrust, 
and reverse thrust operations, as applicable, based on the propeller or 
fan's variable pitch functions that are planned for use on these 
electric engines, with a representative propeller. The tests prescribed 
in Sec.  33.95, for engines operating with variable pitch propellers, 
are based on the operating characteristics of turbine engines, which 
include thrust response times, engine stall, propeller shaft overload, 
loss of thrust control, and hardware fatigue. The electric engines 
proposed by magniX have different operating characteristics that 
substantially affect their susceptibility to these and other potential 
failures. Since magniX's proposed electric engines may be installed 
with a variable pitch propeller, the proposed special condition 
associated with the operation with a variable pitch propeller or fan is 
necessary.
    General Conduct of Tests: Proposed special condition no. 32 would 
require magniX to (1) include scheduled maintenance in the engine ICA 
before certification; (2) include any maintenance, in addition to the 
scheduled maintenance, that was needed during the test to satisfy the 
requirement; and (3) conduct any additional tests that the 
Administrator finds necessary warranted by the test results.
    For example, certification endurance test shortfalls might be 
caused by omitting some prescribed engine test conditions or from 
accelerated deterioration of individual parts arising from the need to 
force the engine to operating conditions that drive the engine above 
the engine cycle values of the type design. If an engine part fails 
during a certification test, the entire engine might be subjected to 
penalty runs with a replacement or newer part design installed on the 
engine to meet the test requirements. Also, the maintenance performed 
to replace the part so that the engine could complete the test would be 
included in the engine ICA. In another example, if the applicant 
replaces a part before completing an engine certification test because 
of a test facility failure and can substantiate the part to the 
Administrator through bench testing, they might not need to 
substantiate the part design using penalty runs with the entire engine.
    The term ``excessive'' is used to describe the frequency of 
unplanned engine maintenance and the frequency unplanned test stoppages 
to address engine issues that prevent the engine from completing the 
tests in proposed special condition nos. 32(b)(1) and (2), 
respectively. Excessive frequency is an objective assessment from the 
FAA's analysis of the amount of unplanned maintenance needed for an 
engine to complete a certification test. The FAA's assessment may 
include the reasons for the unplanned maintenance, such as the effects 
test facility equipment may have on the engine, the inability to 
simulate a realistic engine operating environment, and the extent to 
which an engine requires modifications to complete a certification the 
test. In some cases, the applicant may be able to show that unplanned 
maintenance has no effect on the certification test results, or they 
might be able to attribute the problem to the facility or test-enabling 
equipment that is not part of the type design. In these cases, the ICA 
will not

[[Page 73652]]

be affected. However, if magniX cannot reconcile the amount of 
unplanned service, then the FAA may consider the unplanned maintenance 
required during the certification test to be ``excessive,'' prompting 
the need to add the unplanned maintenance to mandatory ICA in order to 
comply with the certification requirements.
    These proposed special conditions contain the additional safety 
standards that the Administrator considers necessary to establish a 
level of safety equivalent to that established by the existing 
airworthiness standards for reciprocating and turbine aircraft engines.

Applicability

    As discussed above, these proposed special conditions are 
applicable to the magniX magni250 and magni500 model engines. Should 
magniX apply at a later date for a change to the type certificate to 
include another model on the same type certificate incorporating the 
same novel or unusual design feature, these special conditions would 
apply to that model as well.

Conclusion

    This action affects only magniX magni250 and magni500 model 
engines. It is not a rule of general applicability.

List of Subjects in 14 CFR Part 33

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

Authority Citation

    The authority citation for these special conditions is as follows:

    Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701, 44702, 44704.

The Proposed Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for magniX USA, Inc., magni250 and magni500 model engines. The 
applicant must also comply with the certification procedures set forth 
in 14 CFR part 21.

1. Applicability

    Unless otherwise noted in these special conditions, the design must 
comply with the airworthiness standards for aircraft engines set forth 
in 14 CFR part 33, except those airworthiness standards specifically 
and explicitly applicable only to reciprocating and turbine aircraft 
engines.

2. Engine Ratings and Operating Limits

    In addition to Sec.  33.7(a), the design must comply with the 
following:
    Ratings and operating limitations must be established and included 
in the type certificate data sheet based on:
    (a) Power, torque, speed, and time for:
    (1) Rated maximum continuous power; and
    (2) Rated maximum temporary power and associated time limit.
    (b) The duty cycle and the rating at that duty cycle. The 
manufacturer must declare the duty cycle or cycles in the engine 
certificate data sheet.

3. Materials

    The engine design must comply with 14 CFR 33.15.

4. Fire Protection

    The engine design must comply with 14 CFR 33.17.
    In addition, high-voltage electrical wiring interconnect systems 
must be protected against arc-faults. Any non-protected electrical 
wiring interconnects must be analyzed to show that arc-faults do not 
cause a hazardous engine effect.

5. Durability

    The engine design and construction must minimize the development of 
an unsafe condition of the engine between maintenance intervals, 
overhaul periods, or mandatory actions described in the applicable 
Instructions for Continued Airworthiness (ICA).

6. Engine Cooling

    The engine design and construction must comply with 14 CFR 33.21. 
In addition, if cooling is required to satisfy the safety analysis as 
described in special condition no. 17, the cooling system monitoring 
features and usage must be documented in the engine installation 
manual.

7. Engine Mounting Attachments and Structure

    The engine mounting attachments and related engine structure must 
comply with 14 CFR 33.23.

8. Accessory Attachments

    The engine must comply with 14 CFR 33.25.

9. Overspeed

    (a) A rotor overspeed must not result in a burst, rotor growth, or 
damage that results in a hazardous engine effect, as defined in special 
condition no. 17(d)(2). Compliance with this paragraph must be shown by 
test, validated analysis, or a combination of both. Applicable assumed 
speeds must be declared and justified.
    (b) Rotors must possess sufficient strength with a margin to burst 
above certified operating conditions and above failure conditions 
leading to rotor overspeed. The margin to burst must be shown by tests, 
validated analysis, or a combination of both.
    (c) The engine must not exceed the speed operational limitations 
that could affect rotor structural integrity.

10. Engine Control Systems

    (a) Applicability.
    The requirements of this paragraph apply to any system or device 
that controls, limits, monitors, or protects engine operation and is 
necessary for the continued airworthiness of the engine.
    (b) Engine control.
    The engine control system must ensure the engine does not 
experience any unacceptable operating characteristics or exceed any of 
its operating limitations.
    (c) Design assurance.
    The software and complex electronic hardware, including 
programmable logic devices, must be--
    (1) Designed and developed using a structured and systematic 
approach that provides a level of assurance for the logic commensurate 
with the hazard associated with the failure or malfunction of the 
systems in which the devices are located; and
    (2) Substantiated by a verification methodology acceptable to the 
Administrator.
    (d) Validation.
    All functional aspects of the control system must be substantiated 
by tests, analysis, or a combination thereof, to show that the engine 
control system performs the intended functions throughout the declared 
operational envelope.
    (e) Environmental limits.
    Environmental limits that cannot be adequately substantiated by 
endurance demonstrations, validated analysis, or a combination thereof, 
must be demonstrated by the system and component tests in special 
condition no. 27.
    (f) Engine control system failures.
    The engine control system must--
    (1) Have a maximum rate of Loss of Power Control (LOPC) that is 
suitable for the intended application;
    (2) When in the full-up configuration, be single-fault tolerant, as 
determined by the Administrator, for electrical, electrically 
detectable, and electronic failures involving LOPC events;
    (3) Not have any single failure that result in hazardous engine 
effects; and
    (4) Not have any likely failure or malfunction that lead to local 
events in the intended aircraft installation.
    (g) System safety assessment.
    This assessment must identify faults or failures that affect normal 
operation,

[[Page 73653]]

together with the predicted frequency of occurrence of these faults or 
failures.
    (h) Protection systems.
    The design and function of the engine control devices and systems, 
together with engine instruments, operating instructions and 
maintenance instructions, must ensure that engine operating limitations 
will not be exceeded in-service.
    (i) Aircraft-supplied data.
    Any single failure leading to loss, interruption, or corruption of 
aircraft-supplied data (other than power command signals from the 
aircraft), or aircraft-supplied data shared between engine systems 
within a single engine or between fully independent engine systems 
must--
    (1) Not result in a hazardous engine effect, as defined in special 
condition no. 17(d)(2), for any engine installed on the aircraft; and
    (2) Be able to be detected and accommodated by the control system.
    (j) Engine control system electrical power.
    The engine control system must be designed such that the loss, 
malfunction, or interruption of the control system electrical power 
source will not result in a hazardous engine effect, as defined in 
special condition no. 17(d)(2), the unacceptable transmission of 
erroneous data, or continued engine operation in the absence of the 
control function.

11. Instrument Connection

    The applicant must comply with 14 CFR 33.29(a), (e), (f), and (g). 
In addition, as part of the system safety assessment of special 
condition no. 10(g), the applicant must assess the possibility and 
subsequent effect of incorrect fit of instruments, sensors, or 
connectors. Where practicable, the applicant must take design 
precautions to prevent incorrect configuration of the system.

12. Stress Analysis

    (a) A mechanical, thermal, and electrical stress analysis must show 
there is a sufficient design margin to prevent unacceptable operating 
characteristics.
    (b) Maximum stresses in the engine must be determined by tests, 
validated analysis, or a combination thereof, and must be shown not to 
exceed minimum material properties.

13. Critical and Life-Limited Parts

    (a) The applicant must show by a safety analysis or means 
acceptable to the Administrator, whether rotating or moving components, 
bearings, shafts, static parts, and non-redundant mount components 
should be classified, designed, manufactured, and managed throughout 
their service life as critical or life-limited parts.
    (1) Critical part means a part that must meet prescribed integrity 
specifications to avoid its primary failure, which is likely to result 
in a hazardous engine effect, as defined in special condition no. 
17(d)(2) of these special conditions.
    (2) Life-limited part means a rotor and major structural static 
part whose failure can result in a hazardous engine effect due to a 
low-cycle fatigue (LCF) mechanism or any LCF driven mechanism coupled 
with creep. A life limit is an operational limitation that specifies 
the maximum allowable number of flight cycles that a part can endure 
before the applicant must remove it from the engine.
    (b) The applicant must establish the integrity of each critical 
part or life-limited part by providing the following three plans to the 
Administrator for approval:
    (1) An engineering plan that establishes and maintains that the 
combination of loads, material properties, environmental influences, 
and operating conditions, including the effects of engine parts 
influencing these parameters, are sufficiently well-known and 
predictable by validated analysis, test, or service experience. The 
engineering plan must ensure each critical part or life-limited part is 
withdrawn from service at an approved life before hazardous engine 
effects can occur. The engineering plan must establish activities to be 
executed both pre- and post-certification. magniX must perform 
appropriate damage tolerance assessments to address the potential for 
failure from material, manufacturing, and service-induced anomalies 
within the approved life of the part. The approved life must be 
published in the mandatory ICA.
    (2) A manufacturing plan that identifies the specific manufacturing 
definition (drawings, procedures, specifications, etc.) necessary to 
consistently produce critical or life-limited parts with the attributes 
required by the engineering plan.
    (3) A service management plan that defines in-service processes for 
maintenance and repair of critical or life-limited parts that maintain 
attributes consistent with those required by the engineering plan. 
These processes must become part of the mandatory ICA.

14. Lubrication System

    (a) The lubrication system must be designed and constructed to 
function properly between scheduled maintenance intervals in all flight 
attitudes and atmospheric conditions in which the engine is expected to 
operate.
    (b) The lubrication system must be designed to prevent 
contamination of the engine bearings by particle debris.
    (c) The applicant must demonstrate by test, validated analysis, or 
a combination thereof, the unique lubrication attributes and functional 
capability of (a) and (b).

15. Power Response

    The design and construction of the engine must enable an increase--
    (a) From the minimum power setting to the highest-rated power 
without detrimental engine effects; and
    (b) From the minimum obtainable power while in-flight and while on 
the ground to the highest-rated power within a time interval for safe 
operation of the aircraft.

16. Continued Rotation

    If the design allows any of the engine main rotating systems to 
continue to rotate after the engine is shut down while in-flight, this 
continued rotation must not result in any hazardous engine effects, as 
specified in special condition no. 17(d)(2).

17. Safety Analysis

    (a) The applicant must comply with Sec.  33.75(a)(1), (a)(2), and 
(a)(3) using the failure definitions in special condition no. 17(d).
    (b) 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 Sec.  33.15, 
special condition no. 9, or special condition no. 13, as determined by 
analysis. The failure of such elements and associated prescribed 
integrity requirements must be stated in the safety analysis.
    (c) The applicant must comply with 14 CFR 33.75(d) and (e) using 
the failure definitions in special condition no. 17(d) of this special 
condition.
    (d) Unless otherwise approved by the Administrator, the following 
definitions apply to the engine effects when showing compliance with 
this condition:
    (1) An engine failure in which the only consequence is the 
inability to dispatch the aircraft will be regarded as a minor engine 
effect.
    (2) The engine effects in Sec.  33.75(g)(2) are hazardous engine 
effects with the addition of:
    Electrocution of crew, passengers, operators, maintainers, or 
others.
    (3) Any other engine effect is a major engine effect.

[[Page 73654]]

18. Ingestion

    (a) Ingestion from likely sources (foreign objects, birds, ice, 
rain, hail) must not result in unacceptable power loss, or in hazardous 
engine effects as defined by special condition no. 17(d)(2).
    (b) If the design of the engine relies on features, attachments, or 
systems that may be supplied by the installer for the prevention of 
unacceptable power loss or hazardous engine effects following potential 
ingestion, then the features, attachments, or systems must be 
documented in the engine installation manual.

19. Liquid Systems

    (a) Each liquid system used for lubrication or cooling of engine 
components must be designed and constructed to function properly in all 
flight attitudes and atmospheric conditions in which the engine is 
expected to operate.
    (b) If a liquid system used for lubrication or cooling of engine 
components is not self-contained, the interfaces to that system must be 
defined in the engine installation manual.

20. Vibration Demonstration

    (a) The engine must be designed and constructed to function 
throughout its normal operating range of rotor speeds and engine output 
power, including defined exceedances, without inducing excessive stress 
in any of the engine parts because of vibration and without imparting 
excessive vibration forces to the aircraft structure.
    (b) Each proposed engine design must undergo a vibration survey to 
establish that the vibration characteristics of those components that 
may be subject to induced vibration are acceptable throughout the 
declared flight envelope and engine operating range for the specific 
installation configuration. The possible sources of the induced 
vibration that the survey must assess are mechanical, aerodynamic, 
acoustical, or electromagnetic. This survey must be shown by test, 
validated analysis, or a combination thereof.

21. Overtorque

    When approval is sought for a transient maximum engine overtorque, 
the applicant must demonstrate by tests, validated analysis, or a 
combination thereof, that the engine is capable of continued operation 
after operating at the maximum engine overtorque condition without 
maintenance action.

22. Calibration Assurance

    Each engine must be subjected to calibration tests to establish its 
power characteristics and the conditions both before and after the 
endurance and durability demonstrations specified in special conditions 
nos. 23 and 26.

23. Endurance Demonstration

    The applicant must subject the engine to an endurance demonstration 
acceptable to the Administrator to demonstrate the limit capabilities 
of the engine. The endurance demonstration elevates and decreases the 
engine's power settings, and dwells at the power settings for durations 
that produce the extreme physical conditions the engine experiences at 
rated performance levels, operational limits, and at any other 
conditions or power settings that are required to verify the limit 
capabilities of the engine.

24. Temperature Limit

    The engine design must demonstrate its capability to endure 
operation at its temperature limits plus an acceptable margin. The 
applicant must quantify and justify the margin at each rated condition 
to the Administrator. The demonstration must be repeated for all 
declared duty cycles and associated ratings.

25. Operation Demonstration

    The engine design must demonstrate safe operating characteristics, 
including but not limited to, power cycling, acceleration, and 
overspeeding, throughout its declared flight envelope and operating 
range. The declared engine operational characteristics must account for 
installation loads and effects.

26. Durability Demonstration

    The engine must be subjected to a durability demonstration to show 
that each part of the engine has been designed and constructed to 
minimize the development of any unsafe condition of the system between 
overhaul periods, or between engine replacement intervals if overhaul 
is not defined. This test must simulate the conditions in which the 
engine is expected to operate in-service, including typical start-stop 
cycles.

27. System and Component Tests

    The applicant must show that systems and components will perform 
their intended functions in all declared environmental and operating 
conditions.

28. Rotor Locking Demonstration

    If shaft rotation is prevented by a means to lock the rotor(s), the 
engine must demonstrate reliable rotor locking performance and that no 
hazardous effects will occur.

29. Teardown Inspection

    The applicant must comply with either (a) or (b) as follows:
    (a) Teardown evaluation.
    (1) After the endurance and durability demonstrations have been 
completed, the engine must be completely disassembled. Each engine 
component must be within service limits and eligible for continued 
operation in accordance with the information submitted for showing 
compliance with Sec.  33.4, Instructions for Continued Airworthiness.
    (2) Each engine component having an adjustment setting and a 
functioning characteristic that can be established independent of 
installation on or in the engine must retain each setting and 
functioning characteristic within the limits that were established and 
recorded at the beginning of the endurance and durability 
demonstrations.
    (b) Non-Teardown evaluation.
    If a teardown is not performed for all engine components, then the 
life limits for these components must be established based on the 
endurance and durability demonstrations.

30. Containment

    The engine must provide containment features that protect against 
likely hazards from rotating components as follows--
    (a) The design of the case surrounding rotating components must 
provide for the containment of the rotating components in the event of 
failure unless the applicant shows that the rotor has a margin to burst 
that would justify no need for containment features.
    (b) If the margin to burst shows the case must have containment 
features in the event of failure, the case must provide for the 
containment of the failed rotating components. The applicant must 
define by test, validated analysis, or combination thereof, and 
document in the installation manual the energy level, trajectory, and 
size of any fragments released from damage caused by the main rotor 
failure that pass forward or aft of the surrounding case.

31. Operation With a Variable Pitch Propeller or Fan

    The applicant must conduct functional demonstrations including 
feathering, negative torque, negative thrust, and reverse thrust 
operations, as

[[Page 73655]]

applicable, with a representative propeller. These demonstrations may 
be conducted as part of the endurance and durability demonstrations.

32. General Conduct of Tests

    (a) Maintenance of the engine may be made during the tests in 
accordance with the service and maintenance instructions contained in 
the proposed ICA.
    (b) The applicant must subject the engine or its parts to 
maintenance and additional tests that the Administrator finds necessary 
if--
    (1) The frequency of the service is excessive;
    (2) The number of stops due to engine malfunction is excessive;
    (3) Major repairs are needed; or
    (4) Replacement of a part is found necessary during the tests or as 
the result of findings from the teardown inspection.
    (c) Upon completion of all demonstrations and testing specified in 
these special conditions, the engine and its components must be--
    (1) Within serviceable limits;
    (2) Safe for continued operation; and
    (3) Capable of operating at declared ratings while remaining within 
limits.

    Issued in Burlington, Massachusetts, on October 19, 2020.
Robert J. Ganley,
Engine and Propeller Standards Branch, Policy and Innovation Division, 
Aircraft Certification Service.
[FR Doc. 2020-23434 Filed 11-18-20; 8:45 am]
BILLING CODE 4910-13-P


