Airworthiness Criteria: Special Class Airworthiness Criteria for the Joby Aero, Inc. Model JAS4-1 Powered-Lift, 67399-67413 [2022-23962]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 87, Number 215 (Tuesday, November 8, 2022)]
[Proposed Rules]
[Pages 67399-67413]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-23962]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 21

[Docket No. FAA-2021-0638]


Airworthiness Criteria: Special Class Airworthiness Criteria for 
the Joby Aero, Inc. Model JAS4-1 Powered-Lift

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed airworthiness criteria.

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SUMMARY: The FAA announces the availability of, and requests comments 
on, the proposed airworthiness criteria for the Joby Aero, Inc. (Joby) 
Model JAS4-1 powered-lift. This document proposes airworthiness 
criteria the FAA finds to be appropriate and applicable for the 
powered-lift design.

DATES: The FAA must receive comments by December 8, 2022.

ADDRESSES: Send comments identified by docket number FAA-2021-0638 
using any of the following methods:
     Federal eRegulations Portal: Go to https://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 of 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 8 a.m., and 5 p.m., 
Monday through Friday, except Federal holidays.
     Fax: Fax comments to Docket Operations at 202-493-2251.

[[Page 67400]]

    Privacy: The FAA will post all comments it receives, without 
change, to https://www.regulations.gov, including any personal 
information the commenter provides. Using the search function of the 
docket website, anyone can find and read the electronic form of all 
comments received into any FAA docket, including the name of the 
individual sending the comment (or signing the comment for an 
association, business, labor union, etc.). DOT's complete Privacy Act 
Statement can be found in the Federal Register published on April 11, 
2000 (65 FR 19477-19478), as well as at https://DocketsInfo.dot.gov.
    Docket: Background documents or comments received may be read at 
https://www.regulations.gov at any time. Follow the online instructions 
for accessing the docket or go to the 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: William Penzes, Jr., Center for 
Emerging Technology and Innovation (CETI) Branch, AIR-650, Policy and 
Innovation Division, Aircraft Certification Service, Federal Aviation 
Administration, 950 L'Enfant Plaza SW, Washington, DC 20591; telephone 
and fax 202-267-1588; email [email protected].

SUPPLEMENTARY INFORMATION: 

Comments Invited

    The FAA invites interested people to take part in the development 
of proposed airworthiness criteria for the Joby Model JAS4-1 powered-
lift by sending written comments, data, or views. Please identify the 
Joby Model JAS4-1 and Docket No. FAA-2021-0638 on all submitted 
correspondence. The most helpful comments reference a specific portion 
of the airworthiness criteria, explain the reason for a recommended 
change, and include supporting data.
    Except for Confidential Business Information as described in the 
following paragraph, and other information as described in 14 CFR 
11.35, the FAA will file in the docket all comments received, as well 
as a report summarizing each substantive public contact with FAA 
personnel concerning these proposed airworthiness criteria. Before 
acting on this proposal, the FAA will consider all comments received on 
or before the closing date for comments. The FAA will consider comments 
filed late if it is possible to do so without incurring delay. The FAA 
may change these airworthiness criteria based on received comments.

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 the individual listed under ``For 
Further Information Contact.'' Any commentary that the FAA receives 
that is not specifically designated as CBI will be placed in the public 
docket for this notice.

Background

    The Joby Model JAS4-1 powered-lift has a maximum gross takeoff 
weight of 4,800 lbs and is capable of carrying a pilot and four 
passengers. The aircraft uses six tilting electric engines with 5-blade 
propellers attached to a conventional wing and V-tail.\1\ The aircraft 
structure and propellers are constructed of composite materials. As a 
powered-lift, the Joby Model JAS4-1 has the characteristics of both a 
helicopter and an airplane. The Model JAS4-1 is intended to be used for 
part 91 and part 135 operations, with a single pilot onboard, under 
visual flight rules.
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    \1\ A V-Tail aircraft design incorporates two slanted tail 
surfaces instead of the horizontal and vertical fins of a 
conventional aircraft empennage. The two fixed tail surfaces of a V-
Tail act as both horizontal and vertical stabilizers and each has a 
moveable flight-control surface referred to as a ruddervator.
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    On November 2, 2018, Joby applied for a type certificate for the 
Model JAS4-1 powered-lift. Under 14 CFR 21.17(c), Joby's application 
for type certification is effective for three years. Section 21.17(d) 
provides that, where a type certificate has not been issued within that 
three-year time limit, the applicant may file for an extension and 
update the designated applicable regulations in the type certification 
basis. Because the project was not certificated within three years 
after the application date above, the FAA approved the applicant's 
request to extend the application for type certification. As a result, 
the date of the updated type certification basis is June 14, 2022.

Discussion

    Because the FAA has not yet established powered-lift airworthiness 
standards in title 14 CFR, the FAA type certificates powered-lift as 
special class aircraft. Under the procedures in 14 CFR 21.17(b), the 
airworthiness requirements for special class aircraft are the portions 
of the requirements in 14 CFR parts 23, 25, 27, 29, 31, 33, and 35 
found by the FAA to be appropriate and applicable to the specific type 
design and any other airworthiness criteria found by the FAA to provide 
an equivalent level of safety to the existing standards. This notice 
announces the applicable regulations and other airworthiness criteria 
developed, under Sec.  21.17(b), for type certification of the Joby 
Model JAS4-1 powered-lift.
    The Model JAS4-1 powered-lift has characteristics of both a 
rotorcraft and an airplane. It is designed to function as a helicopter 
for takeoff and landing and as an airplane cruising at higher speeds 
than a helicopter during the en-route portion of flight operations. The 
electric engines on the Joby Model JAS4-1 powered-lift will use 
electrical power instead of air and fuel combustion to propel the 
aircraft through six 5-bladed composite variable-pitch propellers. The 
propeller blade pitch is electronically controlled and the blades are 
asymmetrically spaced around the hub for acoustic noise reduction. 
Accordingly, the Joby Model JAS4-1 powered-lift proposed airworthiness 
criteria contain standards from parts 23, 33, and 35 as well as other 
proposed airworthiness criteria specific for a powered-lift.
    For the existing regulations that are included without 
modification, these proposed airworthiness criteria include all 
amendments to the existing part 23, 33, and 35 airworthiness standards 
in effect as of the application date of June 14, 2022. These are part 
23, amendment 23-64, part 33, amendment 33-34, and part 35, amendment 
35-10.
    The Joby Model JAS4-1 powered-lift proposed airworthiness criteria 
also include new performance-based criteria consisting of part 23 
standards as modified by amendment 23-64. The FAA developed these 
criteria because no existing standard captures the powered-lift's 
transitional flight modes. The proposed criteria also contain 
definitions specific for a powered-lift, such as flight modes, 
configurations, speeds, and terminology. Additionally, electric-engine 
and related propeller airworthiness criteria are proposed. The

[[Page 67401]]

new requirements specific to the Joby Model JAS4-1 use a ``JS4.xxxx'' 
section-numbering scheme.
    The FAA selected and designed the particular airworthiness criteria 
proposed in this notice for the following reasons:

Aircraft-Level Requirements

    The proposed installation requirements for cockpit voice and flight 
data recorders remain unchanged from the normal category airplane 
airworthiness standards in part 23. The proposed requirement to prepare 
Instructions for Continued Airworthiness accounts for the applicant's 
option to install type certificated engines and propellers or to seek 
approval of the engines and propellers under the aircraft type 
certificate.

General

    The proposed airworthiness criteria include new or modified 
definitions to explain the unique capabilities and flight phases of the 
Joby Model JAS4-1 and the meaning of certain terms used in regulations 
that have been incorporated by reference. In the event of a loss of 
engine power, airplanes and rotorcraft inherently have the ability to 
glide or autorotate, respectively. Although the aircraft may sustain 
damage, the ability to glide or autorotate allows the aircraft to 
reasonably protect the occupants. However, not all powered-lift have 
these capabilities. To address this, the FAA proposes a definition for 
``continued safe flight and landing,'' unique for the Model JAS4-1, 
that modifies language from the existing definition in Sec.  23.2000; 
the FAA also proposes a new definition for ``controlled emergency 
landing'' to capture the level of performance the Model JAS4-1 must 
meet, equivalent to a glide or autorotation.
    In addition, because many of the proposed airworthiness criteria 
are performance-based, like the regulations found in part 23, the FAA 
has proposed to adopt Sec.  23.2010 by reference, which would require 
that the means of compliance used to comply with these proposed 
airworthiness criteria be accepted by the Administrator. Because no 
powered-lift consensus standards are currently accepted by the 
Administrator, the means of compliance for the Joby Model JAS4-1 
aircraft will be accepted through the issue paper process.\2\
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    \2\ See Order 8110.112A, Standardized Procedures for Usage of 
Issue Papers and Development of Equivalent Levels of Safety 
Memorandums.
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Flight

    Although part 23 (amendment 23-64) replaced prescriptive design 
requirements with performance-based rules that are more easily 
adaptable to new and novel technology, these performance-based rules 
were written for conventionally configured airplanes equipped with 
reversible flight controls for fixed-wing takeoff and landing 
operations. To accommodate Joby's ability to engage in vertical takeoff 
and landing operations, these proposed airworthiness criteria adopt 
language from parts 27 and 29, where appropriate, with changes to allow 
for safe operation of the powered-lift below the stall speed of the 
wing. The FAA developed proposed criteria to address the integration of 
alternating sources of lift: thrust-borne, semi-thrust-borne, and wing-
borne. While the FAA has experience certifying indirect flight-control 
systems such as fly-by-wire systems, Joby's design uses a unique, 
integrated flight- and propulsion-control system that requires new 
airworthiness criteria.
    In addition, the FAA proposes a new JS4.2105, which incorporates 
all of Sec.  23.2105 and adds criteria in new paragraphs (f) and (g). 
Proposed JS4.2105(f) and (g) would ensure the pilot is capable of 
executing a controlled emergency landing in the event of a loss of 
power or thrust, whether by the aircraft's ability to glide or 
autorotate, or through an equivalent means that reasonably protects 
occupants.

Powerplant

    Part 23 (amendment 23-64) addresses electric propulsion, but only 
for conventionally configured airplanes that use propulsion for forward 
thrust. Joby's new and novel design uses a distributed propulsion 
system to provide forward thrust, lift, and control. While some of 
these design features can be addressed by existing airworthiness 
standards in parts 23 and 27, other features require the development of 
new airworthiness criteria. The proposed airworthiness criteria address 
the following unique and novel powerplant installation features:
     multi-engine isolation in a distributed propulsion system,
     simplified control of distributed propulsion,
     integration of a propulsion system into aircraft flight 
controls, and
     energy-system crashworthiness associated with vertical 
takeoff and landing capability.
    The proposed airworthiness criteria in JS4.2405 combine engine and 
propeller control functions from Sec.  23.2405 and Sec.  23.2425 and 
revise the application to capture all powerplant control functions 
including engine control, propeller control, and nacelle rotation. 
Energy system airworthiness criteria in proposed JS4.2430 would include 
a requirement to address energy system crashworthiness to capture the 
intent of Sec.  27.952 and would delete requirements specific to liquid 
fuel systems. The powerplant fire-protection airworthiness criteria in 
proposed JS4.2440 would replace prescriptive language from Sec.  
23.2440 for designated fire zones, with generalized fire-zone language 
to address all powerplant-related fire threats. Electric propulsion 
systems introduce new fire threats from high-voltage electrical power 
and battery systems. Designated fire zones assume a kerosene-based fire 
threat, which is inconsistent with fire threats from electric 
powerplant installations. These proposed criteria are intended to allow 
for safe operation of the powered-lift using an all-electric 
distributed propulsion system for thrust-borne, semi-thrust-borne, and 
wing-borne flight.

Structures

    The flight and ground loads for powered-lift are generally 
comprised of three types of flight configurations: vertical, 
transition, and forward. The proposed airworthiness criteria are not 
taken solely from the forward-flight requirements of part 23 (for 
airplanes) or the vertical-flight requirements of part 27 (for 
rotorcraft). Powered-lift also rely on a transitional type of lift, 
which may include a combination of forward and vertical flight loads. 
The aerodynamic flow field around the powered-lift during transitional 
type of lift can be considerably different from what is traditionally 
observed during forward and vertical flight. In some flight 
configurations, the powered-lift may experience a combination of 
forward and vertical flight loads (forces). In other configurations, 
the aircraft may undergo a completely new type of aerodynamic flow 
field, not experienced during strictly forward or vertical flight. 
Traditional existing airworthiness standards do not adequately 
represent the aerodynamic loads, used for structural design, of a 
powered-lift. Therefore, the FAA finds that additional airworthiness 
criteria are necessary for structural design. The FAA created JS4.2200 
and JS4.2225 by revising Sec. Sec.  23.2200 and 23.2225 to address the 
powered-lift structural design envelope. The FAA created JS4.2240 by 
revising Sec.  23.2240 to remove level 4 airplane requirements, because 
the Joby Model JAS-4 aircraft is not a level 4 airplane.

[[Page 67402]]

    In addition, the FAA proposes a new JS4.2320, which incorporates 
all of Sec.  23.2320 except for Sec.  23.2320(b). Proposed JS4.2320(b) 
contains a new bird strike requirement specific for the applicant's 
design. The FAA recognizes the threat from bird strike in the 
environment in which these aircraft are intended to operate is more 
severe than the environment that rotorcraft or part 23 fixed wing 
aircraft operate in today. The Model JAS4-1 has inherent design 
features and expected operations that potentially expose the aircraft 
to a higher probability of impact with birds.
    The Model JAS4-1 will operate at altitudes similar to rotorcraft, 
and the FAA expects it will cruise at airspeeds that are the same as or 
greater than rotorcraft. However, the FAA expects the Model JAS4-1 will 
spend less time in hover compared to rotorcraft, increasing high-speed 
flight time. The FAA also recognizes that the JAS4-1 will be much 
quieter than conventional helicopter turboshaft engines and rotors. As 
a result, birds will have fewer cues to the existence of the vehicle 
due to quiet approach environments.
    All of these factors combined increase the aircraft's exposure to 
birds. Accordingly, the FAA proposes a more comprehensive bird strike 
requirement for the Model JAS4-1. As cited in the Aviation Rulemaking 
Advisory Committee (ARAC) Rotorcraft Bird Strike Working Group (RBSWG) 
report,\3\ an analysis of bird strike threats against rotorcraft showed 
the median bird size for birds involved in damaging strikes was 1.125 
kg (2.5 lb). Based on that research, the FAA proposes a bird impact 
size of 1.0 kg (2.2-lb), consistent with rotorcraft industry testing. 
The applicant must perform an evaluation at the aircraft level to 
determine what parts of the aircraft are exposed to potential bird 
strikes.
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    \3\ ARAC RBSWG Report, Rev. B, May 8, 2019, page 15, Section 
``Bird Mass'' (ARAC RBSWG Report), https://www.faa.gov/regulations_policies/rulemaking/committees/documents/index.cfm/document/information?documentID=3964.
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    The FAA also proposes a requirement for bird deterrence devices to 
reduce the potential for bird strikes. Research, testing, and use of 
bird-deterrence technology has shown to be effective in reducing bird 
strikes.\4\ Alerting birds to the presence of the aircraft allows birds 
to avoid striking the aircraft. Bird deterrence systems may include, 
for example, light technology to aid birds in detecting and avoiding 
the aircraft.
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    \4\ ARAC RBSWG Report, page 48-50.
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Electric Engines

    The electric engines proposed for installation on the Joby Model 
JAS4-1 powered-lift use electric power instead of air-and-fuel 
combustion to propel the aircraft. These electric engines are designed, 
manufactured, and controlled differently than aircraft engines that 
operate using aviation fuel. These engines are built with an electric 
motor, a controller, and a high-voltage system that draws energy from 
electrical storage or generating systems. The engines in the Joby Model 
JAS4-1 aircraft are devices that convert electrical energy into 
mechanical energy; electric current flowing through wire coils in the 
motor produces a magnetic field that interacts with magnets on the 
rotating armature shaft. The controller is a system that consists of 
two main functional elements: the motor controller and an electric-
power quad inverter to drive the four motors associated with an 
electric engine. The four motors include the drive motor, functioning 
as the electric engine; the position motor for adjusting propeller 
pitch; the position motor for the engine-tilt function; and the motor 
for cooling-system operation. The high-voltage system is a combination 
of wires, power-conditioning components, and connectors that couple an 
energy source to an electric engine, associated motors, and a 
controller.
    The technology required to provide energy through these high-
voltage and high-current electronic components introduces potential 
hazards that do not exist in aircraft engines that operate using 
aviation fuel. For example, high-voltage transmission lines, 
electromagnetic fields, magnetic materials, and high-speed electrical 
switches form the electric engine's physical properties. Operating at 
these high power levels also exposes the electric engines to potential 
failures, which could adversely affect safety, and that are not common 
to aircraft engines that operate using aviation fuel.

Propellers

    Part 35 contains airworthiness standards to ensure that uninstalled 
propellers meet the minimum level of safety that the FAA deems 
acceptable. Part 35 requirements are appropriate for propellers that 
are installed on conventional airplanes, type certificated under part 
23 or part 25, that have construction and blade-pitch actuation methods 
typically found on such airplanes.
    Emerging electric-powered and hybrid electric-powered aircraft, 
especially electric powered-lift that are intended for ``air taxi'' 
type operations in and near urban areas and capable of vertical and 
short takeoff and landing, often feature propellers designed for both 
horizontal thrust and vertical lift. In addition, propeller blade-pitch 
actuation for such aircraft typically is performed electrically, and is 
more extensively integrated into the aircraft's propulsion and flight-
control system compared to conventional airplanes type certificated 
under part 23 or part 25.
    Propellers are integral parts of a variety of airplane propulsion 
systems and, until the advent of electric engines, have been subjected 
to the forces of fossil-fuel-powered reciprocating and turbine 
combustion engines. Electric engines present different considerations 
due to the increased torque and potentially higher revolutions per 
minute.
    The most basic requirement, for all conventional part 23 and 25 
aircraft as well as the Joby JAS4-1 aircraft, is to reduce the risk of 
propeller failure or release of debris to the occupants and critical 
aircraft structures and components to an acceptable level. Features and 
characteristics of propellers must ensure that they are safe for the 
certification application requested.
    These proposed airworthiness criteria would require functional 
engine demonstrations, including feathering, negative torque, negative 
thrust, and reverse-thrust operations, as appropriate, using a 
representative propeller. The applicant may conduct these 
demonstrations as part of the endurance and durability demonstrations.

Applicability

    These airworthiness criteria, established under the provisions of 
Sec.  21.17(b), are applicable to the Joby Model JAS4-1 powered-lift. 
Should Joby wish to apply these airworthiness criteria to other 
powered-lift models, it must submit a new application for a type 
certificate.

Proposed Airworthiness Criteria

    The FAA proposes to establish the following airworthiness criteria 
for type certification of the Joby Model JAS4-1 powered-lift. The FAA 
proposes that compliance with the following criteria will provide an 
equivalent level of safety to existing rules.

Aircraft-Level Requirements

Sec. 23.1457 Cockpit Voice Recorders

    (a) through (g) [Applicable to JAS4-1]

Sec. 23.1459 Flight Data Recorders

    (a) through (e) [Applicable to JAS4-1]

[[Page 67403]]

JS4.1529 Instructions for Continued Airworthiness

    The applicant must prepare Instructions for Continued Airworthiness 
(ICA), in accordance with Appendices A, A1, and A2, that are acceptable 
to the Administrator. ICA for the aircraft, engines, and propellers may 
be shown in a single aircraft ICA manual if the engine and propeller 
approvals are sought through the aircraft certification program. 
Alternatively, the applicant may provide individual ICA for the 
aircraft, engines, and propellers. The instructions may be incomplete 
at the time of type certification if a program exists to ensure their 
completion prior to delivery of the first aircraft, or issuance of a 
standard certificate of airworthiness, whichever occurs later.

Subpart A--General

JS4.2000 Applicability and Definitions

    (a) These airworthiness criteria prescribe airworthiness standards 
for the issuance of a type certificate, and changes to that type 
certificate, for the Joby Aero, Inc. Model JAS4-1 powered-lift.
    (b) For purposes of these airworthiness criteria, the following 
definitions apply:
    (1) Continued safe flight and landing means an aircraft is capable 
of continued controlled flight and landing, possibly using emergency 
procedures, without requiring exceptional pilot skill or strength.
    (2) Phases of flight means ground operations, takeoff, climb, 
cruise, descent, approach, hover, and landing.
    (3) Source of lift means one of three sources of lift: thrust-
borne, wing-borne, and semi-thrust-borne. Thrust-borne is defined as 
when the powered-lift is maneuvering in the vertical plane and lift is 
predominately from downward thrust. Wing-borne is defined as when the 
powered-lift is maneuvering in the horizontal plane and lift is 
predominately from fixed airfoil surfaces. Semi-thrust-borne is the 
combination of thrust-borne and wing-borne, where both forms of lift 
are applied.
    (4) Loss of power/thrust means a condition when the aircraft can no 
longer provide the commanded power or thrust required for continued 
safe flight and landing.
    (5) Controlled emergency landing means the pilot is capable of 
choosing the direction and area of touchdown, and the aircraft is 
capable of reasonably protecting occupants. Upon landing, some damage 
to the aircraft may be acceptable.
    (c) Terms used in the part 23 provisions that are adopted in these 
airworthiness criteria are interpreted as follows:
    ``Airplane'' means ``aircraft.''
    ``This part'' means ``these airworthiness criteria.''

Sec. 23.2010 Accepted Means of Compliance

    (a) through (b) [Applicable to JAS4-1]

Subpart B--Flight

Performance

Sec. 23.2100 Weight and Center of Gravity

    (a) through (c) [Applicable to JAS4-1]

JS4.2105 Performance Data

    (a) Unless otherwise prescribed, an aircraft must meet the 
performance requirements of this subpart in still air and standard 
atmospheric conditions.
    (b) Unless otherwise prescribed, the applicant must develop the 
performance data required by this subpart for the following conditions:
    (1) Airport altitudes from sea level to 10,000 feet (3,048 meters); 
and
    (2) Temperatures above and below standard day temperature that are 
within the range of operating limitations, if those temperatures could 
have a negative effect on performance.
    (c) The procedures used for determining takeoff and landing 
performance must be executable consistently by pilots of average skill 
in atmospheric conditions expected to be encountered in service.
    (d) Performance data determined in accordance with paragraph (b) of 
this section must account for losses due to atmospheric conditions, 
cooling needs, installation losses, downwash considerations, and other 
demands on power sources.
    (e) The hovering ceiling, in and out of ground effect, must be 
determined over the ranges of weight, altitude, and temperature, if 
applicable.
    (f) Continued safe flight and landing must be possible from any 
point within the flight envelope following a critical loss of thrust 
not shown to be extremely improbable.
    (g) The aircraft must be capable of a controlled emergency landing, 
after loss of power or thrust, by gliding or autorotation, or an 
equivalent means, to mitigate the risk of loss of power or thrust.

JS4.2110 Minimum Safe Speed

    The applicant must determine the aircraft minimum safe speed for 
each flight condition encountered in normal operations, including 
applicable sources of lift and phases of flight, to maintain controlled 
safe flight. The minimum safe speed determination must account for the 
most adverse conditions for each flight configuration.

JS4.2115 Takeoff Performance

    (a) The applicant must determine takeoff performance accounting for 
flight envelope and obstacle safety margins.
    (b) The applicant must determine takeoff performance accounting for 
any loss of thrust not shown to be extremely improbable.

JS4.2120 Climb Requirements

    (a) The applicant must demonstrate minimum climb performance at 
each weight, altitude, and ambient temperature within the operating 
limitations using the procedures published in the flight manual.
    (b) The applicant must demonstrate minimum climb performance 
accounting for any loss of thrust not shown to be extremely improbable.

JS4.2125 Climb Information

    (a) The applicant must determine climb performance at each weight, 
altitude, and ambient temperature within the operating limitations 
using the procedures published in the flight manual.
    (b) The applicant must determine climb performance accounting for 
any loss of thrust not shown to be extremely improbable.

JS4.2130 Landing

    The applicant must determine the following, for standard 
temperatures at critical combinations of weight and altitude within the 
operational limits:
    (a) The landing performance, assuming approach paths applicable to 
the aircraft.
    (b) The approach, transition if applicable, and landing speeds, 
configurations, and procedures, which allow a pilot of average skill to 
land within the published landing performance consistently and without 
causing damage or injury, and which allow for a safe transition to the 
balked landing conditions of these airworthiness criteria, accounting 
for the minimum safe speed.

Flight Characteristics

JS4.2135 Controllability

    (a) The aircraft must be controllable and maneuverable, without 
requiring exceptional piloting skill, alertness, or strength, within 
the operating envelope--
    (1) At all loading conditions for which certification is requested;

[[Page 67404]]

    (2) During all phases of flight while using applicable sources of 
lift;
    (3) With likely flight-control or propulsion-system failure;
    (4) During configuration changes;
    (5) In all degraded flight-control-system operating modes not shown 
to be extremely improbable; and
    (6) In thrust-borne operation, and must be able to land safely in 
wind velocities from zero to a wind limit appropriate for the aircraft 
from any azimuth angle.
    (b) The applicant must determine critical control parameters, such 
as limited-control power margins, and if applicable, account for those 
parameters in developing operating limitations.
    (c) It must be possible to make a smooth change from one flight 
condition to another (changes in configuration, and in source of lift 
and phase of flight) without exceeding the approved flight envelope.

JS4.2140 Trim

    (a) The aircraft must maintain lateral and directional trim without 
further force upon, or movement of, the primary flight controls or 
corresponding trim controls by the pilot, or the flight-control system, 
under normal phases of flight while using applicable sources of lift in 
cruise.
    (b) The aircraft must maintain longitudinal trim without further 
force upon, or movement of, the primary flight controls or 
corresponding trim controls by the pilot, or the flight-control system, 
under the following conditions:
    (1) Climb.
    (2) Level flight.
    (3) Descent.
    (4) Approach.
    (c) Residual control forces must not fatigue or distract the pilot 
during normal operations of the aircraft and likely abnormal or 
emergency operations, including loss of thrust not shown to be 
extremely improbable on multi-engine aircraft.

JS4.2145 Stability

    (a) Aircraft not certified for aerobatics must exhibit stable 
characteristics in normal operations and after likely failures of the 
flight and propulsion control system.
    (b) No aircraft may exhibit any divergent longitudinal stability 
characteristic so unstable as to increase the pilot's workload or 
otherwise endanger the aircraft and its occupants.

JS4.2150 Minimum Safe Speed Flight Characteristics, Minimum Safe Speed 
Warning, and Spins

    (a) The aircraft must have controllable minimum safe speed flight 
characteristics in straight flight, turning flight, and accelerated 
turning flight with a clear and distinctive minimum safe speed warning 
that provides sufficient margin to prevent inadvertent slowing below 
minimum safe speed.
    (b) Aircraft not certified for aerobatics must not have a tendency 
to inadvertently depart controlled flight from thrust asymmetry after a 
critical loss of thrust.
    (c) Aircraft certified for aerobatics that include spins must have 
controllable stall characteristics and the ability to recover within 
one and one-half additional turns after initiation of the first control 
action from any point in a spin, not exceeding six turns or any greater 
number of turns for which certification is requested, while remaining 
within the operating limitations of the aircraft.
    (d) Spin characteristics in aircraft certified for aerobatics that 
includes spins must recover without exceeding limitations and may not 
result in unrecoverable spins--
    (1) With any typical use of the flight or engine-power controls; or
    (2) Due to pilot disorientation or incapacitation.

Sec. 23.2155 Ground and Water Handling Characteristics

    [Applicable to JAS4-1]

Sec. 23.2160 Vibration, Buffeting, and High-Speed Characteristics

    (a) [Applicable to JAS4-1]
    (b) through (d) [Not applicable to JAS4-1]

JS4.2165 Performance and Flight Characteristics Requirements for Flight 
in Atmospheric Icing Conditions

    (a) An applicant who requests certification for flight in 
atmospheric icing conditions must show the following in the icing 
conditions for which certification is requested:
    (1) Compliance with each requirement of this subpart, except those 
applicable to spins and any that must be demonstrated at speeds in 
excess of--
    (i) 250 knots calibrated airspeed (CAS);
    (ii) VMO/MMO or VNE; or
    (iii) A speed at which the applicant demonstrates the airframe will 
be free of ice accretion.
    (2) The means by which minimum safe speed warning is provided to 
the pilot for flight in icing conditions and non-icing conditions is 
the same.
    (b) The applicant must provide a means to detect icing conditions 
for which certification is not requested and show the aircraft's 
ability to avoid or exit those icing conditions.
    (c) The applicant must develop an operating limitation to prohibit 
intentional flight, including takeoff and landing, into icing 
conditions for which the aircraft is not certified to operate.

Subpart C--Structures

JS4.2200 Structural Design Envelope

    The applicant must determine the structural design envelope, which 
describes the range and limits of aircraft design and operational 
parameters for which the applicant will show compliance with the 
requirements of this subpart. The applicant must account for all 
aircraft design and operational parameters that affect structural 
loads, strength, durability, and aeroelasticity, including:
    (a) Structural design airspeeds, landing-descent speeds, and any 
other airspeed limitation at which the applicant must show compliance 
to the requirements of this subpart. The structural design airspeeds 
must--
    (1) Be sufficiently greater than the minimum safe speed of the 
aircraft to safeguard against loss of control in turbulent air; and
    (2) Provide sufficient margin for the establishment of practical 
operational limiting airspeeds.
    (b) Design maneuvering load factors not less than those, which 
service history shows, may occur within the structural design envelope.
    (c) Inertial properties including weight, center of gravity, and 
mass moments of inertia, accounting for--
    (1) Each critical weight from the aircraft empty weight to the 
maximum weight; and
    (2) The weight and distribution of occupants, payload, and fuel.
    (d) Characteristics of aircraft control systems, including range of 
motion and tolerances for control surfaces, high lift devices, or other 
moveable surfaces.
    (e) Each critical altitude up to the maximum altitude.
    (f) Engine-driven lifting-device rotational speed and ranges, and 
the maximum rearward and sideward flight speeds.

Sec. 23.2205 Interaction of Systems and Structures

    [Applicable to JAS4-1]

Structural Loads

Sec. 23.2210 Structural Design Loads

    (a) through (b) [Applicable to JAS4-1]

Sec. 23.2215 Flight Load Conditions

    (a) through (c) [Applicable to JAS4-1]

Sec. 23.2220 Ground and Water Load Conditions

    [Applicable to JAS4-1]

[[Page 67405]]

JS4.2225 Component Loading Conditions

    The applicant must determine the structural design loads acting on:
    (a) Each engine mount and its supporting structure such that both 
are designed to withstand loads resulting from--
    (1) Powerplant operation combined with flight gust and maneuver 
loads; and
    (2) For non-reciprocating powerplants, sudden powerplant stoppage.
    (b) Each flight control and high-lift surface, their associated 
system and supporting structure resulting from--
    (1) The inertia of each surface and mass balance attachment;
    (2) Flight gusts and maneuvers;
    (3) Pilot or automated system inputs;
    (4) System induced conditions, including jamming and friction; and
    (5) Taxi, takeoff, and landing operations on the applicable 
surface, including downwind taxi and gusts occurring on the applicable 
surface.
    (c) A pressurized cabin resulting from the pressurization 
differential--
    (1) From zero up to the maximum relief pressure combined with gust 
and maneuver loads;
    (2) From zero up to the maximum relief pressure combined with 
ground and water loads if the aircraft may land with the cabin 
pressurized; and
    (3) At the maximum relief pressure multiplied by 1.33, omitting all 
other loads.
    (d) Engine-driven lifting-device assemblies, considering loads 
resulting from flight and ground conditions, as well limit input torque 
at any lifting-device rotational speed.

Sec. 23.2230 Limit and Ultimate Loads

    (a) through (b) [Applicable to JAS4-1]

Structural Performance

Sec. 23.2235 Structural Strength

    (a) through (b) [Applicable to JAS4-1]

JS4.2240 Structural Durability

    (a) The applicant must develop and implement inspections or other 
procedures to prevent structural failures due to foreseeable causes of 
strength degradation, which could result in serious or fatal injuries, 
or extended periods of operation with reduced safety margins. Each of 
the inspections or other procedures developed under this section must 
be included in the Airworthiness Limitations Section of the 
Instructions for Continued Airworthiness, required by JS4.1529.
    (b) For pressurized aircraft:
    (1) The aircraft must be capable of continued safe flight and 
landing following a sudden release of cabin pressure, including sudden 
releases caused by door and window failures.
    (2) For aircraft with maximum operating altitude greater than 
41,000 feet, the procedures developed for compliance with paragraph (a) 
of this section must be capable of detecting damage to the pressurized 
cabin structure before the damage could result in rapid decompression 
that would result in serious or fatal injuries.
    (c) The aircraft must be designed to minimize hazards to the 
aircraft due to structural damage caused by high-energy fragments from 
an uncontained engine or rotating machinery failure.

Sec. 23.2245 Aeroelasticity

    (a) through (b) [Applicable to JAS4-1]

Design

Sec. 23.2250 Design and Construction Principles

    (a) through (e) [Applicable to JAS4-1]

Sec. 23.2255 Protection of Structure

    (a) through (c) [Applicable to JAS4-1]

Sec. 23.2260 Materials and Processes

    (a) through (g) [Applicable to JAS4-1]

Sec. 23.2265 Special Factors of Safety

    (a) through (c) [Applicable to JAS4-1]

Structural Occupant Protection

Sec. 23.2270 Emergency Conditions

    (a) through (e) [Applicable to JAS4-1]

Subpart D--Design and Construction

JS4.2300 Flight-Control Systems

    (a) The applicant must design flight-control systems to:
    (1) Operate easily, smoothly, and positively enough to allow proper 
performance of their functions; and
    (2) Protect against likely hazards.
    (b) The applicant must design trim systems, if installed, to:
    (1) Protect against inadvertent, incorrect, or abrupt trim 
operation; and
    (2) Provide a means to indicate--
    (i) The direction of trim control movement relative to aircraft 
motion;
    (ii) The trim position with respect to the trim range;
    (iii) The neutral position for lateral and directional trim; and
    (iv) The range for takeoff for all applicant-requested center of 
gravity ranges and configurations.
    (c) In addition to paragraph (a) and (b) of this section, for 
indirect flight-control systems:
    (1) A means must be provided to indicate to the flightcrew any 
significant changes or degradation to the handling or operational 
characteristics of the aircraft during normal and abnormal system 
operation; and
    (2) Features that protect the aircraft against loss of control, 
structural damage, or exceeding critical limits must be designed such 
that--
    (i) The onset characteristics of each protection feature is smooth 
and appropriate for the phase of flight and type of maneuver;
    (ii) There are no adverse flight characteristics in aircraft 
response to flight-control inputs, unsteady atmospheric conditions, and 
other likely conditions, including simultaneous limiting events; and
    (iii) The aircraft is capable of continued safe flight and landing 
following failures not shown to be extremely improbable throughout the 
approved flight envelope and expected operational conditions.

Sec. 23.2305 Landing Gear Systems

    (a) through (c) [Applicable to JAS4-1]

Sec. 23.2310 Buoyancy for Seaplanes and Amphibians

    (a) through (b) [Applicable to JAS4-1]

Occupant System Design Protection

Sec. 23.2315 Means of Egress and Emergency Exits

    (a) through (b) [Applicable to JAS4-1, including the ditching 
exclusion in (a)(1)]

JS4.2320 Occupant Physical Environment

    (a) The applicant must design the aircraft to:
    (1) Allow clear communication between the flightcrew and 
passengers;
    (2) Protect the pilot and flight controls from propellers; and
    (3) Protect the occupants from serious injury due to damage to 
windshields, windows, and canopies.
    (b) The aircraft must be capable of continued safe flight and 
landing after a bird strike with a 2.2-lb (1.0 kg) bird. In addition, 
the aircraft design must include bird deterrence devices to reduce the 
potential for bird strikes.
    (c) The aircraft must provide each occupant with air at a 
breathable pressure, free of hazardous concentrations of gases, vapors, 
and smoke during normal operations and likely failures.
    (d) If a pressurization system is installed in the aircraft, it 
must be designed to protect against:
    (1) Decompression to an unsafe level; and
    (2) Excessive differential pressure.
    (e) If an oxygen system is installed in the aircraft, it must--

[[Page 67406]]

    (1) Effectively provide oxygen to each user to prevent the effects 
of hypoxia; and
    (2) Be free from hazards in itself, in its method of operation, and 
its effect upon other components.

Fire and High Energy Protection

Sec.  23.2325 Fire Protection

    (a)(1), (a)(2), (b) through (d), (f)(1), and (g) through (h) 
[Applicable to JAS4-1]
    (a)(3), (e), and (f)(2) [Not applicable to JAS4-1]

JS4.2330 Fire Protection in Fire Zones and Adjacent Areas

    (a) Flight controls, engine mounts, and other flight structures 
within or adjacent to fire zones must be capable of withstanding the 
effects of a fire.
    (b) Engines in a fire zone must remain attached to the aircraft in 
the event of a fire.
    (c) In fire zones, terminals, equipment, and electrical cables used 
during emergency procedures must perform their intended function in the 
event of a fire.

JS4.2335 Lightning and Static Electricity Protection

    (a) The aircraft must be protected against catastrophic effects 
from lightning.
    (b) The aircraft must be protected against hazardous effects caused 
by an accumulation of electrostatic charge.

Subpart E--Powerplant

JS4.2400 Powerplant Installation

    (a) For the purpose of this subpart, the aircraft powerplant 
installation must include each component necessary for propulsion, 
which affects propulsion safety, or provides auxiliary power to the 
aircraft.
    (b) Each aircraft engine and propeller must have a type certificate 
or be approved under the aircraft type certificate using standards 
found in subparts H and I.
    (c) The applicant must construct and arrange each powerplant 
installation to account for--
    (1) Likely operating conditions, including foreign-object threats;
    (2) Sufficient clearance of moving parts to other aircraft parts 
and their surroundings;
    (3) Likely hazards in operation including hazards to ground 
personnel; and
    (4) Vibration and fatigue.
    (d) Hazardous accumulations of fluids, vapors, or gases must be 
isolated from the aircraft and personnel compartments and be safely 
contained or discharged.
    (e) Powerplant components must comply with their component 
limitations and installation instructions or be shown not to create a 
hazard.

JS4.2405 Power or Thrust Control Systems

    (a) Any power or thrust control system, reverser system, or 
powerplant control system must be designed so no unsafe condition 
results during normal operation of the system.
    (b) Any single failure or likely combination of failures or 
malfunctions of a power or thrust control system, reverser system, or 
powerplant control system must not prevent continued safe flight and 
landing of the aircraft.
    (c) Inadvertent flightcrew operation of a power or thrust control 
system, reverser system, or powerplant control system must be 
prevented, or if not prevented, must not prevent continued safe flight 
and landing of the aircraft.
    (d) Unless the failure of an automatic power or thrust control 
system is extremely remote, the system must--
    (1) Provide a means for the flightcrew to verify the system is in 
an operating condition;
    (2) Provide a means for the flightcrew to override the automatic 
function; and
    (3) Prevent inadvertent deactivation of the system.

Sec. 23.2410 Powerplant Installation Hazard Assessment

    (a) through (c) [Applicable to JAS4-1]

Sec. 23.2415 Powerplant Ice Protection

    (a) through (b) [Applicable to JAS4-1]

JS4.2425 Powerplant Operational Characteristics

    (a) Each installed powerplant must operate without any hazardous 
characteristics during normal and emergency operation within the range 
of operating limitations for the aircraft and the engine.
    (b) The design must provide for the shutdown and restart of the 
powerplant in flight within an established operational envelope.

JS4.2430 Energy Systems

    (a) Each energy system must--
    (1) Be designed and arranged to provide independence between 
multiple energy-storage and supply systems, so that failure of any one 
component in one system will not result in loss of energy storage or 
supply of another system;
    (2) Be designed to prevent catastrophic events due to lightning 
strikes, taking into account direct and indirect effects on the 
aircraft where the exposure to lightning is likely;
    (3) Provide the energy necessary to ensure each powerplant and 
auxiliary power unit functions properly in all likely operating 
conditions;
    (4) Provide the flightcrew with a means to determine the total 
useable energy available and provide uninterrupted supply of that 
energy when the system is correctly operated, accounting for likely 
energy fluctuations;
    (5) Provide a means to safely remove or isolate the energy stored 
in the system from the aircraft; and
    (6) Be designed to retain energy under all likely operating 
conditions and to minimize hazards to occupants following an emergency 
landing or otherwise survivable impact (crash landing).
    (7) [Reserved]
    (b) Each energy-storage system must--
    (1) Withstand the loads under likely operating conditions without 
failure; and
    (2) Be isolated from personnel compartments and protected from 
hazards due to unintended temperature influences.
    (3) [Reserved]
    (4) [Reserved]
    (c) Each energy-storage refilling or recharging system must be 
designed to--
    (1) Prevent improper refilling or recharging; and
    (2) [Reserved]
    (3) Prevent the occurrence of hazard to the aircraft or to persons 
during refilling or recharging.

Sec.  23.2435 Powerplant Induction and Exhaust Systems

    (a) through (b) [Applicable to JAS4-1]

JS4.2440 Powerplant Fire Protection

    There must be means to isolate and mitigate hazards to the aircraft 
in the event of a powerplant-system fire or overheat in operation.

Subpart F--Equipment

Sec. 23.2500 Airplane Level Systems Requirements

    (a) through (b) [Applicable to JAS4-1]

Sec. 23.2505 Function and Installation

    [Applicable to JAS4-1]

Sec. 23.2510 Equipment, Systems, and Installations

    (a) through (c) [Applicable to JAS4-1]

JS4.2515 Electrical- and Electronic-System Lightning Protection

    (a) Each electrical or electronic system that performs a function, 
the failure of which would prevent the continued safe flight and 
landing of the aircraft, must be designed and installed such that--

[[Page 67407]]

    (1) The function at the aircraft level is not adversely affected 
during and after the time the aircraft is exposed to lightning; and
    (2) The system recovers normal operation of that function in a 
timely manner after the aircraft is exposed to lightning unless the 
system's recovery conflicts with other operational or functional 
requirements of the system.
    (b) For an aircraft approved for operation under instrument flight 
rules (IFR), each electrical and electronic system that performs a 
function, the failure of which would significantly reduce the 
capability of the aircraft or the ability of the flightcrew to respond 
to an adverse operating condition, must be designed and installed such 
that the system recovers normal operation of that function in a timely 
manner after the aircraft is exposed to lightning.

Sec. 23.2520 High-Intensity Radiated Fields (HIRF) Protection

    (a) through (b) [Applicable to JAS4-1]

Sec. 23.2525 System Power Generation, Storage, and Distribution

    (a) through (c) [Applicable to JAS4-1]

Sec. 23.2530 External and Cockpit Lighting

    (a) through (e) [Applicable to JAS4-1]

Sec. 23.2535 Safety Equipment

    [Applicable to JAS4-1]

JS4.2540 Flight in Icing Conditions

    An applicant who requests certification for flight in icing 
conditions must show the following in the icing conditions for which 
certification is requested:
    (a) The ice protection system provides for safe operation; and
    (b) The aircraft design must provide protection from slowing to 
less than the minimum safe speed when the autopilot is operating.

Sec. 23.2545 Pressurized Systems Elements

    [Applicable to JAS4-1]

Sec. 23.2550 Equipment Containing High-Energy Rotors

    [Applicable to JAS4-1]

Subpart G--Flightcrew Interface and Other Information

JS4.2600 Flightcrew Interface

    (a) The pilot compartment, its equipment, and its arrangement to 
include pilot view, must allow each pilot to perform their duties for 
all sources of lift and phases of flight and perform any maneuvers 
within the operating envelope of the aircraft, without excessive 
concentration, skill, alertness, or fatigue.
    (b) The applicant must install flight, navigation, surveillance, 
and powerplant controls and displays, as needed, so qualified 
flightcrew can monitor and perform defined tasks associated with the 
intended functions of systems and equipment, without excessive 
concentration, skill, alertness, or fatigue. The system and equipment 
design must minimize flightcrew errors, which could result in 
additional hazards.

Sec. 23.2605 Installation and Operation

    (a) through (c) [Applicable to JAS4-1]

Sec. 23.2610 Instrument Markings, Control Markings, and Placards

    (a) through (c) [Applicable to JAS4-1]

JS4.2615 Flight, Navigation, and Powerplant Instruments

    (a) Installed systems must provide the flightcrew member who sets 
or monitors parameters for the flight, navigation, and powerplant, the 
information necessary to do so during each source of lift and phase of 
flight. This information must--
    (1) Be presented in a manner that the crewmember can monitor the 
parameter and determine trends, as needed, to operate the aircraft; and
    (2) Include limitations, unless the limitations cannot be exceeded 
in all intended operations.
    (b) Indication systems that integrate the display of flight or 
powerplant parameters to operate the aircraft, or are required by the 
operating rules of title 14, chapter I, must--
    (1) Not inhibit the primary display of flight or powerplant 
parameters needed by any flightcrew member in any normal mode of 
operation; and
    (2) In combination with other systems, be designed and installed so 
information essential for continued safe flight and landing will be 
available to the flightcrew in a timely manner after any single failure 
or probable combination of failures.

JS4.2620 Aircraft Flight Manual

    The applicant must provide an Aircraft Flight Manual that must be 
delivered with each aircraft.
    (a) The Aircraft Flight Manual must contain the following 
information--
    (1) Aircraft operating limitations;
    (2) Aircraft operating procedures;
    (3) Performance information;
    (4) Loading information; and
    (5) Other information that is necessary for safe operation because 
of design, operating, or handling characteristics.
    (b) The portions of the Aircraft Flight Manual containing the 
information specified in paragraphs (a)(1) through (a)(4) of this 
section must be approved by the FAA in a manner specified by the 
Administrator.

Subpart H--Electric Engine Requirements

Sec. 33.5 Instruction Manual for Installing and Operating the Engine

    (a) through (c) [Applicable to JAS4-1]

Sec. 33.7 Engine Ratings and Operating Limitations

    (a) [Applicable to JAS4-1]
    (b) through (d) [Not applicable to JAS4-1]

JS4.2702 Engine Ratings and Operating Limits

    Ratings and operating limits must be established and included in 
the type certificate data sheet based on:
    (a) Shaft power, torque, rotational speed, and temperature for:
    (1) Rated takeoff power;
    (2) Rated maximum continuous power; and
    (3) Rated maximum temporary power and associated time limit.
    (b) Duty Cycle and the rating at that duty cycle. The duty cycle 
must be declared in the type certificate data sheet.
    (c) Cooling fluid grade or specification.
    (d) Power-supply requirements.
    (e) Any other ratings or limitations that are necessary for the 
safe operation of the engine.

Sec. 33.8 Selection of Engine Power and Thrust Ratings

    (a) through (b) [Applicable to JAS4-1]

Sec. 33.15 Materials

    (a) through (b) [Applicable to JAS4-1]

Sec. 33.17 Fire Protection

    (a) through (g) [Applicable to JAS4-1]

JS4.2704 Fire Protection

    High-voltage electrical wiring interconnect systems must be 
protected against arc faults. Non-protected electrical wiring 
interconnects must be analyzed to show that arc faults do not cause a 
hazardous engine effect.

JS4.2705 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 ICA.

Sec. 33.21 Engine Cooling

    [Applicable to JAS4-1]

[[Page 67408]]

JS4.2706 Engine Cooling

    If cooling is required to satisfy the safety analysis as described 
in JS4.2717, the cooling-system monitoring features and usage must be 
documented in the engine installation manual.

Sec. 33.23 Mounting Attachment and Structure

    (a) through (b) [Applicable to JAS4-1]

Sec. 33.25 Accessory Attachments

    [Applicable to JAS4-1]

JS4.2709 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 
JS4.2717(d)(2). Compliance with this paragraph must be shown by test, 
validated analysis, or a combination of both. Applicable assumed rotor 
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 test, 
validated analysis, or a combination thereof.
    (c) The engine must not exceed the rotor-speed operational 
limitations that could affect rotor structural integrity.

Sec. 33.28 Engine Control Systems

    (b)(1)(i), (b)(1)(iii), and (b)(1)(iv) [Applicable to JAS4-1]
    (a), (b)(1)(ii), (b)(2) through (m) [Not applicable to JAS4-1]

JS4.2710 Engine Control Systems

    (a) Applicability.
    These requirements apply to any system or device that is part of 
the engine type design 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 its 
operating limits, including in failure conditions where the fault or 
failure results in a change from one control mode to another, from one 
channel to another, or from the primary system to the back-up system, 
if applicable.
    (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 test, 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 demonstration, validated analysis, or a combination thereof 
must be demonstrated by the system and component tests in JS4.2727.
    (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 aircraft 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 results in hazardous engine 
effects; and
    (4) Not have any likely failures or malfunctions that lead to local 
events in the intended aircraft application.
    (g) System-safety assessment.
    The applicant must perform a system-safety assessment. This 
assessment must identify faults or failures that affect normal 
operation, together with the predicted frequency of occurrence of these 
faults or failures. The intended aircraft application must be taken 
into account to assure the assessment of the engine control system 
safety is valid.
    (h) Protection systems.
    The engine control devices and systems' design and function, 
together with engine instruments, operating instructions, and 
maintenance instructions, must ensure that engine operating limits 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 
JS4.2717(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.
    (1) 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 
JS4.2717(d)(2), the unacceptable transmission of erroneous data, or 
continued engine operation in the absence of the control function. The 
engine control system must be capable of resuming normal operation when 
aircraft-supplied power returns to within the declared limits.
    (2) The applicant must identify and declare, in the engine 
installation manual, the characteristics of any electrical power 
supplied from the aircraft to the engine control system for starting 
and operating the engine, including transient and steady-state voltage 
limits, or electrical power supplied from the engine to the aircraft 
via energy regeneration, and any other characteristics necessary for 
safe operation of the engine.

Sec. 33.29 Instrument Connection

    (a), (e), and (g) [Applicable to JAS4-1]
    (b) through (d) and (h) [Not applicable to the JAS4-1]

JS4.2711 Instrument Connection

    (a) In addition, as part of the system-safety assessment of 
JS4.2710(g) and JS4.2733(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.
    (b) The applicant must provide instrumentation enabling the 
flightcrew to monitor the functioning of the engine cooling system 
unless evidence shows that:
    (1) Other existing instrumentation provides adequate warning of 
failure or impending failure;
    (2) Failure of the cooling system would not lead to hazardous 
engine effects before detection; or
    (3) The probability of failure of the cooling system is extremely 
remote.

JS4.2712 Stress Analysis

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

[[Page 67409]]

JS4.2713 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 a