[Federal Register Volume 85, Number 71 (Monday, April 13, 2020)]
[Proposed Rules]
[Pages 20431-20447]
[FR Doc No: 2020-07039]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 21 and 36

[Docket No.: FAA-2020-0316; Notice No. 20-06]
RIN 2120-AL29

Noise Certification of Supersonic Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This action proposes to add new supersonic airplanes to the
applicability of noise certification regulations, and proposes landing
and takeoff noise standards for a certain class of new supersonic
airplanes. There is renewed interest in the development of supersonic
aircraft, and the proposed regulations would facilitate the continued
development of airplanes by specifying the noise limits for the
designs, providing the means to certificate the airplanes for subsonic
operation in the United States.

DATES: Send comments on or before July 13, 2020.

ADDRESSES: Send comments identified by docket number FAA-2020-0316
using any of the following methods:
     Federal eRulemaking 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<PHONE_NUMBER>.
    Privacy: In accordance with 5 U.S.C. 553(c), DOT solicits comments
from the public to better inform its rulemaking process. DOT posts
these comments, without edit, including any personal information the
commenter provides, to http://www.regulations.gov, as described in the
system of records notice (DOT/ALL-14 FDMS), which can be reviewed at
http://www.dot.gov/privacy.
    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. If you are submitting confidential business
information as part of a comment, please consult section VI. A. of this
document for the proper submission procedure.

FOR FURTHER INFORMATION CONTACT: For technical questions concerning
this action, contact Sandy R. Liu, Office of Policy, International
Affairs, & Environment, Noise Division (AEE-100), Federal Aviation
Administration, 800 Independence Avenue SW, Washington, DC 20591;
telephone<PHONE_NUMBER>; email<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:

I. Executive Summary

    Current noise certification regulations do not include standards
for supersonic airplanes other than the Concorde. In its 2018
reauthorization,\1\ the FAA was directed to exercise leadership in the
creation of Federal and international policies, regulations, and
standards relating to the certification and the safe and efficient
operation of civil supersonic aircraft. This rulemaking is a step in
that process. The agency is proposing to amend the noise certification
regulations in Title 14, Code of Federal Regulations (14 CFR) parts 21
and 36 to provide for new supersonic airplanes, and to add subsonic
landing and takeoff (LTO) cycle standards for supersonic airplanes that
have a maximum takeoff weight no greater than 150,000 pounds and a
maximum operating cruise speed up to Mach 1.8. This proposal is based
in part on the Supersonic Transport Concept Airplane (STCA) studies
performed by the National Aeronautics and Space Administration (NASA),
information provided to the FAA by U.S. industry, and the continuing
work of the International Civil Aviation Organization (ICAO) Committee
on Aviation Environmental Protection (CAEP). These proposed
certification standards would provide a means to certificate these
airplanes for noise for subsonic operation domestically, but would not
affect the prohibition in 14 CFR 91.817 on the creation of sonic booms
(i.e., supersonic operations over land in the United States would
remain prohibited).
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    \1\ Section 181, Public Law 115-254, FAA Reauthorization Act of
2018 (October 5, 2018).
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    This proposed rule would (1) amend the applicability of part 36 to
include new supersonic airplanes for which type certification is
requested after a final rule takes effect, (2) revise the definition of
supersonic airplane to include newly certificated airplanes but exclude
the Concorde,\2\ (3) provide noise certification reference procedures
to be used for all supersonic airplanes, and (4) establish noise limits
for takeoff and landing that would apply to Supersonic Level 1 (SSL1)
airplanes, as defined in the proposed regulation. The proposed
standards include noise limits that are quieter than the Stage 4 limits
at which most of the current subsonic jet fleet operates, though louder
than the current certification level of Stage 5 for the same aircraft
weights. The proposed standards would allow Variable Noise Reduction
Systems (VNRS) to be used for noise certification testing, and if used
for certification, would require the system to be activated during
normal operations.
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    \2\ The Concorde type certificate remains valid, even though
none are currently operating. The certification regulations in part
36 that apply to the Concorde are limited to the Concorde model and
need to remain in place. The FAA seeks to segregate the Concorde as
a historical matter to prevent any confusion; the certification
regulations proposed here would apply only to new supersonic
airplanes. None of the proposed certification regulations affect the
Concorde operating regulations already in place.
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II. Authority

    The FAA's authority to issue rules on aviation safety is found in
Title 49 of the United States Code. Subtitle I, Section 106 describes
the authority of the FAA Administrator. Subtitle VII, Aviation
Programs, describes in more detail the scope of the agency's authority.
    This rulemaking is promulgated under the authority described in
Subtitle VII, Part A, Subpart III, Section 44715, Controlling aircraft
noise and

sonic boom. Under that section, the FAA is charged with prescribing
regulations to measure and abate aircraft noise. This rulemaking is
also promulgated under the authority of Section 181 of the FAA
Reauthorization Act of 2018, Public Law 115-254, which directs the FAA
Administrator to exercise leadership in the creation of Federal
policies, regulations, and standards related to the certification of
and to the safe and efficient operation of civil supersonic aircraft.
This regulation is within the scope of those authorities because it
provides for the applicability of the regulations to a new class of
supersonic airplanes, and sets the noise limits described in Sec.
44715(a)(3) that are required to be in place before the FAA may issue a
new type certificate.

III. Background

    Current noise certification regulations do not include standards
for supersonic airplanes other than the Concorde. In 1978, the FAA
promulgated its first rule addressing civil supersonic aircraft noise,
establishing takeoff and landing noise standards in 14 CFR part 36
specific to the Concorde airplane.\3\ That rule did ``not establish
certification noise limits for future design [supersonic aircraft]
since the technological feasibility of such standards is at present
unknown.'' \4\ In addition, the FAA established operational noise
limits applicable to civil supersonic airplanes.
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    \3\ Noise and Sonic Boom Requirements, 43 FR 28406 (Jun. 29,
1978).
    \4\ Id.
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    However, the FAA anticipated that there would be future supersonic
aircraft designs that could be economically viable and environmentally
acceptable. In 1978, such an idea was only theoretical, but it was
known that major advancements would need to be made. These advancements
included improvements to noise reduction features, flexible performance
requirements, and environmental acceptability.
    As technology continued to advance, the FAA expressed interest in
amending its regulations to account for the development of supersonic
aircraft other than the Concorde. In 1986, the FAA published an advance
notice of proposed rulemaking (ANPRM) addressing the possibility of
amending parts 36 and 91 to provide for noise type certification and
civil operation of newer supersonic aircraft.\5\ The FAA subsequently
published an NPRM in 1990 that would have required future supersonic
aircraft to meet Stage 3 noise limits, which were then the maximum
noise limits for subsonic airplanes.\6\ In 1994, the FAA withdrew the
NPRM, stating that further research was necessary before developing a
final rule.\7\
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    \5\ 51 FR 39663 (Oct. 30, 1986).
    \6\ Aircraft noise limits have varied over time from Stage 1 in
the 1970s to current Stage 5 certification limits.
    \7\ Withdrawal: 59 FR 39711 (August 4, 1994).
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    In February 2018, the FAA Office of the Chief Counsel published an
interpretation that addressed 14 CFR part 36, and whether it would
apply to an application for type certification of a new supersonic
airplane. The interpretation concluded that part 36 applies only to
subsonic aircraft by its own terms (except for the Concorde, which was
included by name in regulations from the 1970s). The interpretation
also found that if no noise standards for a supersonic aircraft were in
place at the time of an application for type certification, the FAA's
statutory mandate would require the agency to create noise
certification standards applicable to the aircraft before a type
certificate could be issued, even if that set of noise standards only
applied to one aircraft model. The full interpretation is available
online \8\ and a copy has been placed in the docket for this
rulemaking.
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    \8\ The interpretation is titled ``Applicability of part 36 to
new supersonic aircraft.''
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    Currently, FAA regulations prohibit civil aircraft from operating
at speeds exceeding Mach I over land in the United States. (14 CFR
91.817). The FAA does not propose to change that prohibition with this
rule. This proposal is limited to establishing procedures and noise
levels for subsonic operation of supersonic aircraft during landing and
takeoff.
    For a brief history of supersonic airplane operations in the United
States, please consult the background section of the FAA's NPRM titled
Special Flight Authorizations for Supersonic Aircraft, published in the
Federal Register on June 28, 2019, at 84 FR 30961.

A. Statement of the Problem

    Several U.S. manufacturers have begun developing the next
generation of supersonic airplanes. Current regulations do not include
noise standards applicable to new supersonic airplanes, and the FAA's
statutory authority requires that noise regulations be in place before
a new aircraft type certificate may be issued.\9\ Accordingly, the FAA
is proposing to amend its noise certification regulations to apply to
supersonic airplanes, and to adopt noise certification procedures and
noise limits that would apply during the LTO cycle of certain new
supersonic airplanes. Manufacturers have indicated that they expect new
supersonic-capable designs to enter service in the mid- to late-2020s.
The FAA has a statutory duty to both protect the public health and
welfare from aircraft noise and sonic boom,\10\ and when proposing
noise standards, to consider whether the standard is economically
reasonable, technologically practicable, and appropriate for the
aircraft to which the standards apply.\11\ For more than a decade,
aircraft developers have indicated their need for the FAA to establish
reasonable, achievable supersonic LTO cycle noise limits in order to
complete their designs with reasonable certainty that the aircraft will
qualify for type certification in the United States.
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    \9\ 49 U.S.C. 44715(a)(3).
    \10\ 49 U.S.C. 44715(a).
    \11\ 49 U.S.C. 44715(b)(4).
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B. Scope of This Proposal

    All airplanes, including supersonic airplanes, operate at subsonic
speed during the LTO cycle. Under part 36, the amount of noise allowed
to be produced during these phases of flight is determined by aircraft
weight.\12\ This rule proposes LTO cycle noise limits for supersonic
airplanes that have a maximum takeoff weight of 150,000 pounds and a
maximum operating cruise speed of Mach 1.8, defining this class of
airplanes as SSL1. The primary reason for proposing a separate
supersonic category and SSL1 airplane class is to account for the
distinct design of the aircraft (discussed below in paragraph C.) and
the resulting known source noise effects on certain noise measurements.
As industry continues to develop supersonic capable airplane designs
and can provide more data on airplane noise and performance, the FAA
expects to adopt LTO cycle standards for aircraft of greater maximum
takeoff weight and higher operational speeds.
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    \12\ Heavier aircraft require more lift, require more thrust,
create more drag, and have larger aerodynamic surfaces that result
in more noise, relative to smaller aircraft.
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    This proposed rule does not address any noise associated with
normal flight at cruise altitudes or supersonic speeds. The FAA has not
promulgated cruise altitude noise regulations for subsonic airplanes,
and sufficient data are not currently available that would support
rulemaking to develop such standards for supersonic airplanes. Before
any changes to the operating rules could be proposed, more research is
needed on the production of noise at supersonic

cruise speeds and the regulatory approaches that would be appropriate.
Allowing civil airplane operation at speeds in excess of Mach 1 over
land in the U.S. may become possible in the future, but it is not
expected before the development of new technologies reducing the impact
of sonic boom generation or eliminating sonic boom exposure.
Accordingly, nothing about this proposal may be interpreted as
affecting the existing prohibition on exceeding Mach 1 speed (thus
producing a sonic boom) over land in the United States.\13\ The FAA,
NASA, ICAO, and aviation stakeholders worldwide continue to study and
evaluate the methods that would support the next phases of supersonic
development, including the measurement of sonic boom noise and the
effect on people on the ground.
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    \13\ 14 CFR 91.817.
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    As a part of the process to develop this proposed rule, the FAA has
consulted with NASA and other interested parties in the aviation
industry, and has continued its leadership roles at ICAO to assess the
needs of the industry and the public, and the costs and benefits of
introducing these new aircraft.
    When the FAA began to develop this rulemaking in 2018, the agency
asked several entities whether they were developing supersonic airplane
projects and whether they were interested in sharing data regarding the
probable noise characteristics associated with those projects. The FAA
is placing in the docket for this rulemaking the list of questions we
sent interested entities, and a list of those who responded. The FAA
has determined that the information we received in response to our
questions is considered proprietary and subject to the Trade Secrets
Act,\14\ and would be protected from release pursuant to the Freedom of
Information Act (FOIA) under FOIA Exemption 4.\15\ The information we
received was combined with the data from the NASA studies and ongoing
ICAO efforts as part of the overall data set that informed this
proposed rule.
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    \14\ 18 U.S.C. 1905.
    \15\ 5 U.S.C. 552(b)(4).
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C. Establishing Distinct Supersonic Standards

    The FAA is proposing noise certification levels specific to
supersonic aircraft, as well as certain changes to existing reference
procedures for measuring aircraft noise during certification. These
proposed noise levels are different than the current Stage 5 noise
levels for subsonic aircraft. This difference reflects the need to take
into account the unique technological and design requirements for
supersonic aircraft to maintain long-distance supersonic flight. As
will be discussed below, the FAA has found that the technological
differences between subsonic and supersonic airplanes require that a
separate set of noise certification levels be established for
supersonics since noise is an intrinsic function of these differences.
This rule proposes standards for the use of airplane-specific noise
abatement technical equipment and procedures (such as VNRS) that are
central to establishing LTO cycle noise levels at certification. The
traditional regulatory framework and the use of the well-understood,
efficient subsonic airplane testing requirements are maintained in this
proposed rule, including the existing means of acoustical measurements,
data evaluation, reference (test) procedures, reference (atmospheric)
conditions, and adjustment analyses for noise certification. The FAA
expects that these proposed regulations would result in noise tests of
new supersonic airplanes being conducted in much the same manner and
under the same conditions as current subsonic airplanes.
    In order to achieve and maintain supersonic flight over long
distances, different technologies need to be incorporated. They are
most evident in the design and performance of (1) the fuselage and wing
shape, and (2) the engine design. Each of those design characteristics
has effects on airplane noise during subsonic operation. The FAA
collected and reviewed data from U.S. manufacturers regarding their
conceptual designs for new supersonic aircraft in an effort to identify
appropriate subsonic LTO cycle noise limits for these airplanes. These
data were also used to support the FAA's efforts to protect the public
from noise and to propose standards that are reasonable. The noise
limits proposed in this rule take into account the technological
advancements that have been made since the Concorde was first flown
commercially in the 1970s. The FAA anticipates that new supersonic
airplane designs will produce LTO cycle noise similar to the fleet of
subsonic airplanes currently in operation.
1. Wing and Fuselage Design
    The recognizable design of the Concorde, with its long, narrow
fuselage and swept-back wings, is not simply about aesthetics. All
aircraft experience drag, the resistance to moving air that requires
power to overcome, similar to putting one's hand out the window of a
moving car. When traveling at supersonic speeds, the amount of drag
increases significantly due to wave drag attributed to shock wave
formation when operating at speeds faster than Mach 1 (the speed of
sound). As a consequence of the large increase in drag at supersonic
speed, supersonic aircraft must have a relatively small cross-section
to minimize the drag effect on the airframe. In practice, supersonic
aircraft designs tend to look more like a dart with a smaller diameter
fuselage than a traditional tube and wing shaped subsonic aircraft.
    Supersonic speeds also require a different wing design than the
typical subsonic airplane. Wave drag, which also burdens subsonic
airplanes, is a more significant contributor to total drag on
supersonic designs because of shock waves that form at speeds greater
than Mach 1. In order to minimize wave drag, the wings of a supersonic
airplane are thinner (in cross-sectional thickness) and have a shorter
swept wingspan (delta shaped) than a subsonic airplane. This wing
design helps minimize wave drag at supersonic speeds; however, it does
not generate lift as well as subsonic airplane wings at lower speeds.
This difference is important when the airplane is taking off and
landing. This difference in wing design requires supersonic airplanes
to operate at higher speeds during takeoff and landing as compared to
subsonic aircraft, requiring more thrust than subsonic airplanes to
generate enough aerodynamic lift to take off and land safely. More
thrust and speed at takeoff and landing results in more noise compared
to a subsonic airplane of a similar weight.
2. Engine Design
    To take off and land safely, jet engines for supersonic aircraft
require relatively greater thrust than subsonic aircraft of a similar
weight, as well as a lower engine bypass ratio to reach and maintain
supersonic speeds in excess of Mach 1. In addition, as discussed above,
the aircraft and wing design are optimized to reduce drag, and the
aircraft require increased thrust during takeoff and landing. An
engine's bypass ratio is a measurement of the relationship between the
diameter of the engine opening and the amount of air that flows through
the fan of the engine and bypasses the core, compared to the amount of
air that flows through the core. Over time, the bypass ratios for
subsonic aircraft have greatly increased as a result of technology and
materials improvements that also led to significant fuel efficiency
improvements and noise reductions. There is limited

opportunity to incorporate increased bypass ratios on engines that
power supersonic aircraft. To reduce the increased drag already noted,
the diameter of the engine inlet must be relatively small and well-
integrated into the airframe/wing design, making the high bypass ratios
(and pod-on-wing design) of engines on modern subsonic aircraft not
technologically feasible. As a result, new supersonic aircraft will
need to utilize integrated lower bypass ratio engines, which are
relatively louder than high bypass ratio engines.
3. A New Noise Category
    As part of its statutory duty to adopt standards that are
economically reasonable, technologically practicable, and appropriate
for a particular aircraft,\16\ the FAA first took into account the
physical and technological differences between subsonic and supersonic
airplanes described above. The FAA studied NASA's modeling efforts for
modern supersonic design technologies, as well as data that
manufacturers developing supersonic products provided to the FAA.\17\
Based on the available information, the FAA concluded that, to comply
with Congress's statutory direction to enable a new generation of
supersonic airplanes, the FAA needed to create a new category for
purposes of noise certification.
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    \16\ 49 U.S.C. 44715(b)(4).
    \17\ Manufacturers submitted confidential or proprietary data.
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    The new category would account for the unique technology and design
characteristics of supersonic airplanes. These unique characteristics
fundamentally affect the way the noise is generated and measured, which
makes comparison to subsonic airplanes neither appropriate nor helpful.
In addition, the data available to the FAA indicate that a modern
supersonic airplane would have little in common with the noise of the
Concorde, and can be expected to incorporate developing technologies
that would lessen the effect on the public of its expected landing and
takeoff noise impacts.
    Based on the data available, the FAA proposes a new noise category
for matters of supersonic noise certification in Part 36, and defines a
first class of supersonic airplanes (defined by weight and maximum
speed) that is expected to encompass most of the projects currently
under design.\18\
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    \18\ If the FAA receives an application for an airplane that
falls outside this class, both the agency and the airplane developer
could use the first class (SSL 1) as a starting point for
establishing an individual certification basis. Establishing this
first class will inform the industry as to the agency's direction
and serve as a foundation for future specific standards once the
distinguishing characteristics of the next class (whatever they may
be) emerge and can be taken into account.
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    The FAA proposes the first class, Supersonic Level 1 (SSL1), for
airplanes capable of supersonic flight that have a maximum takeoff
weight of 150,000 pounds and a maximum operating cruise speed of Mach
1.8. The FAA chose this class definition because the agency anticipates
that most of the designs currently under development will fit within
these parameters. Because this regulatory structure is tailored to
supersonic designs and technology currently under development, it will
foster innovation in this new emerging class of airplanes. In addition,
it will serve as a launching point for adopting appropriate standards
for future classes that could encompass for example, heavier maximum
takeoff weights and faster operating cruise speeds. The FAA does not
intend for today's proposal to be a one-size fits all approach to
emerging supersonic technology. To the contrary, today's proposal seeks
to provide the regulatory certainty necessary to enable the generation
currently under development. Current research suggests that supersonic
airplanes with speeds above Mach 1.8 would have different design
characteristics. These characteristics would affect aircraft noise and
are expected to require different noise standards and different noise
measurements.
4. Reference Procedure Changes
    The FAA's approach to reference procedures in this proposed rule is
based in its long-established paradigm of noise certification that is
broadly applicable. The proposed new supersonic category and proposed
SSL 1 class reflect the FAA's need to accommodate the unique
characteristics of supersonic airplanes. Consistent with the FAA's
long-standing approach to noise certification, the FAA would evaluate
supersonic airplanes under this proposed rule using a standard weight-
to-noise correlation, with the separate noise limits (the curve) needed
to properly account for the inherent design differences and allow
comparison of like products.
    In gathering noise data, an airplane is flown using Part 36 takeoff
and approach reference procedures, which represent specific, repeatable
conditions that ensure accurate noise measurement. This NPRM proposes
using the same measurement locations contained in the existing part 36.
However, to account for all of the differences between supersonic and
subsonic airplanes described in this section, different reference
procedures are proposed for takeoff speed and thrust.
    New supersonic designs are also expected to incorporate advanced
technologies that control the engines and aerodynamic control surfaces
automatically to reduce noise at takeoff and landing to the greatest
extent possible, while still allowing the airplane to operate safely.
The higher thrust needed for takeoff and the lower engine bypass ratio
for supersonic airplanes both contribute to higher lateral noise
levels. This proposed rule would allow for the use of Variable Noise
Reduction Systems (VNRS), as part of the takeoff reference procedure.
Inclusion of VNRS in the proposed standards is designed to allow
maximum flexibility for manufacturers to present VNRS design options to
the FAA that are appropriate for their airplanes. The FAA seeks to
allow the maximum latitude for these designs while they are still in
their infancy. The FAA seeks comment on whether there are other
performance-based standards that could be included that would allow
even greater design flexibilities.

D. International Standard Setting Activity

    The development of international supersonic noise standards for
modern aircraft began in the early 2000s and continues today in ICAO.
Since 1983, the ICAO CAEP has developed environmental standards and
policies for international aviation. The United States is an active
member of the CAEP. Work conducted by the CAEP Noise Technical Working
Group was considered in many of the aspects of this proposed rule. The
FAA continues to work with ICAO to develop an international civil
supersonic LTO cycle noise standard that will allow supersonic
airplanes to be certificated and accepted worldwide. This first
proposal of supersonic noise certification regulations represents an
exercise of the FAA's statutory direction to enable the safe commercial
deployment of civil supersonic aircraft technology and the safe and
efficient operation of civil supersonic aircraft. The United States
understands the need for globally harmonized supersonic LTO cycle noise
standards. The FAA is undertaking this rulemaking to respond to the
demand from U.S. manufacturers to provide regulatory certainty while it
continues to work with the international community to move forward with
the international standard setting process for supersonic LTO cycle
noise.

E. Analysis of Proposed Rule Text

    The following section contains a discussion of select portions of
rule text. It does not repeat the rule text, but is designed to be read
as a companion to the proposed rule language presented at the end of
this document.
    Part 21, Sec.  21.93 Classification of changes in type design. The
FAA is proposing to add supersonic airplanes to the list of aircraft in
Sec.  21.93(b). That section provides that any voluntary change in the
aircraft's type design that may increase noise levels (defined as an
``acoustical change'') must meet the applicable requirements in part 36
for design changes. Supersonic airplanes would be subject to acoustical
change requirements equivalent to other aircraft types. None of the
exceptions set forth in paragraphs (b)(2), (3), and (4) for subsonic
jet airplanes, certain propeller-driven commuter or small airplanes,
and helicopters, respectively, are appropriate for new supersonic
airplanes. As discussed in subsequent sections, this proposed rule
seeks to distinguish new supersonic airplanes from the Concorde model.
As a result, this rule proposes to add the Concorde to Sec.  21.93 to
preserve its place in the regulations.
    Part 36, Sec.  36.1 Applicability and definitions. The FAA is
proposing to add supersonic airplanes, as defined in this NPRM, to the
applicability of part 36. As discussed earlier in this preamble, the
current applicability of part 36 is limited by its terms to subsonic
aircraft. Expanding the applicability is necessary to include the noise
limits for supersonic airplanes that the FAA is proposing in new
subpart E and new appendix C to part 36.
    Throughout part 36, this proposed rule would add the term
``subsonic'' before ``jet airplane'' when needed to distinguish between
the part 36 requirements that are not applicable to both subsonic and
supersonic jet airplanes.
    The FAA is proposing to amend the title of subpart B by inserting
the word ``Subsonic'' before the word ``Jet'' to indicate that the
regulations in that subpart do not apply to supersonic airplanes.
    The FAA is proposing to revise the definition of supersonic
airplane in Sec.  36.1 and move it from paragraph (f) to new paragraph
(j). The move will allow the definitions related to new supersonic
airplanes to be grouped in one paragraph of Sec.  36.1. The revised
definition would exclude the Concorde from the definition of supersonic
airplane. The part 36 regulations that apply to the Concorde are
specific to the Concorde and the FAA seeks to segregate them as a
historical matter to prevent any confusion as to which standards apply
to the Concorde as opposed to those for new supersonic airplanes being
proposed here.
    The FAA is proposing a definition of SSL1 airplane that refers to
proposed Appendix C, which would apply to supersonic airplanes with a
maximum certificated takeoff weight of 150,000 pounds and a maximum
operating speed of Mach 1.8 or less. This definition would include most
of the proposed supersonic airplane design concepts that U.S.
manufacturers have described to the FAA. The FAA anticipates that when
data is available to establish LTO cycle noise standards for other
weight and speed supersonic airplanes, other similar classes of
airplane and noise level would be added to Sec.  36.1(j) with separate
definitions.
    The FAA is proposing a definition of LTO cycle to specify that the
proposed supersonic noise standards are associated with the departure
and arrival of supersonic airplanes at subsonic speeds at airports. The
LTO cycle noise levels consist of the flyover, lateral, and approach
noise levels as specified in proposed Appendix C to part 36. The
definition is necessary to distinguish that the noise limits proposed
in Appendix C are not applicable to noise created during flight at
supersonic speeds.
    The FAA is proposing a definition of VNRS and of Programmed Lapse
Rate (PLR) to describe the function of various configuration controls
that are intended to limit noise during the LTO cycle. Since these are
new aircraft systems, the FAA specifically requests comment on the
scope of these definitions and any suggested additions or changes that
might be common to all developers of such systems.
    Part 36, Subpart D. The FAA is proposing to change the title only
of Subpart D to indicate that the regulations presented in that subpart
apply only to Concorde airplanes, removing the term supersonic from the
subpart title. Although no Concorde airplanes are currently
operational, the regulations on the Concorde would not be removed
because the aircraft type certificate remains valid. Regulations that
apply to new supersonic airplanes would be placed in a new Subpart E.
    Part 36, Subpart E. The FAA is proposing to add Subpart E to
establish the noise measurement and evaluation requirements applicable
to new supersonic airplanes. This new subpart would retain the familiar
structure of other subparts in part 36, but apply only to new
supersonic airplanes in accordance with the definition proposed in this
rule. As discussed elsewhere in this rulemaking, the applicability of
the regulations proposed for new subpart E is limited to SSL1
airplanes.
    As a corollary to other aircraft types to which part 36 is
applicable, the FAA is proposing a new Sec.  36.15 to add acoustical
change requirements for supersonic airplanes. This is the companion
regulation to the proposed change made in Sec.  21.93 that adds
supersonic airplanes to the applicability of that section. As with
other types of aircraft, a certificated supersonic airplane, after a
change in the type design, would still be required to meet at least the
noise level that was applicable to the design prior to the change.
    Section 36.1581, Manuals, markings, and placards. Several changes
to this section are being proposed to address noise level information
for new supersonic airplanes that must be made part of the Aircraft
Flight Manual (AFM). Proposed paragraph (a)(4) establishes the general
AFM requirements involving noise certification for supersonic
airplanes.
    Paragraph (h) would restrict the maximum weight of the airplane to
be the weight at which an LTO cycle noise level that complies with part
36 was established.
    The proposed rule would also establish operating limitations in
Sec.  36.1581(i) for supersonic airplanes. If applicable, the
limitations must be included in the AFM. The FAA seeks comment
specifically on Sec. Sec.  36.1581(i)(2) and (3). Proposed paragraph
(i)(2) would require an operating limitation if a VNRS is used to show
compliance with the proposed noise limits. The limitation would require
the flight crew to verify that the VNRS is functioning properly before
each takeoff. This verification of functionality prior to each takeoff
is necessary because a malfunctioning or inoperable VNRS would present
an immediate noise issue and indicate that the aircraft is not in
compliance with part 36 as certificated.
    While a VNRS is not required, if a manufacturer chooses to
incorporate a VNRS, the FAA proposes a requirement to verify that the
VNRS is functioning properly. This requirement is a performance based
standard: The FAA does not propose to prescribe the method or
technology that a flight crew would use to conduct that verification.
To the contrary, how a flight crew is able to verify that any VNRS
system is functioning properly is dependent on its design. One way, but
not the only way, to verify might be to require it to be part

of a flight crew checklist. Another way could include equipment or
technology that would verify functionality prior to takeoff. The FAA
intentionally declines to specify design standards to allow
manufacturers flexibility and to allow for innovation.
    The FAA requests comment on whether developers have an equivalent
means for flight crews to ensure the functionality of any certificated
VNRS.
    The other proposed operating limitation on which the FAA seeks
specific comment is in Sec.  36.1581(i)(3) regarding airplanes that
incorporate PLR to limit thrust to a programmed level and decrease
noise. To exceed PLR thrust after takeoff, the applicant must have
demonstrated during testing that ending the programmed thrust does not
produce a noise impact on the ground that exceeds the levels measured
at the certification measurement points. Until the point at which no
effect from increased thrust is determined, the PLR would need to
remain in active operation. This point is not specified in these
regulations because it is expected to be unique to each airplane
design. The point determined for an individual PLR system would become
an operating limitation for that airplane.
    The intent of the proposed limitation is to account for any noise
issues that are unique to the design of a particular supersonic
airplane model that may be caused by an increase in thrust when PLR use
is completed.
    Appendix A to part 36, Aircraft Noise Measurement and Evaluation:
Appendix A would be revised to make its procedures applicable to
supersonic airplanes. Current Appendix A applies to transport category
airplanes, subsonic jet airplanes, and the Concorde. Except as
described below, the FAA proposes to require new supersonic airplanes
to use the same noise measurement and evaluation conditions and
procedures as these other aircraft. Based on the information provided
by developers, new supersonic airplanes are expected to be sufficiently
similar in design to other jet-powered fixed-wing aircraft such that
the requirements in Appendix A remain appropriate for noise
certification testing. The FAA seeks comment on whether any of the
provisions in Appendix A would not be appropriate for new supersonic
airplanes, including what alternative procedures would be appropriate.
    One proposed change to Appendix A for supersonic airplanes
addresses VNRS reference procedures. When a VNRS (included in new
Appendix C) is used to demonstrate compliance with part 36, Sec.
A<IP_ADDRESS> would require use of the integrated method of adjustment
described in existing Sec.  A36.9.4. Rarely are certification flight
test conditions ever identical to the reference atmospheric conditions
prescribed. Appendix A requires that appropriate adjustments be made to
the measured noise data using either a simplified or an integrated
method of adjustment, as described in Sec.  A36.9. These methods adjust
the noise results to account for differences in both the airplane to
microphone distance, and the variations in atmospheric conditions
between the actual test day and the prescribed reference day. Under
current regulations that apply to all aircraft, if the simplified
method results in either adjustments that exceed specified decibel
levels or a final effective perceived noise evaluation metric level
(EPNL) that falls within one decibel of the applicable noise limit, the
integrated method of adjustment must instead be used to ensure
accuracy. The simplified method adjusts noise only once, at the maximum
peak, while the integrated method adjusts at each half-second of the
entire noise segment of flight. The integrated method computes EPNL
directly by recalculating, under reference conditions, the data points
of the tone-corrected perceived noise level time history that
corresponds to measured points obtained during testing. The FAA has
found that the integrated method of adjustment accounts for the dynamic
aspects of VNRS procedures more accurately than the simplified method
of adjustment. For that reason, the FAA proposes that the integrated
method always be used for supersonics that use VNRS. The simplified
method is unable to provide sufficient data processing fidelity of the
measured noise signal that is the expected result of VNRS influence in
flight.
    Appendix C to part 36, ``Noise Levels for Supersonic Airplanes.''
This is a new appendix applicable to supersonic airplanes as defined in
this proposed rule. The proposed appendix corresponds to existing
Appendix B, which prescribes procedures for determining noise levels
for transport category large airplanes, subsonic jet airplanes, and the
Concorde. The FAA is proposing to incorporate into the new Appendix C
many of the same technical requirements currently in Appendix B for
subsonic airplanes, including the EPNL and the reference noise
measurement points (lateral, flyover, and approach) because both the
metric and reference measurement locations are appropriate in the
demonstration of noise certification compliance. Except as noted
before, new supersonic airplane designs are anticipated to be similar
in their takeoff and landing characteristics as airplanes subject to
Appendix B. The FAA seeks comment on whether any of the provisions from
Appendix B that are being proposed for inclusion in new Appendix C are
inappropriate for new supersonic airplanes, including what alternatives
would be appropriate. The primary differences between the appendix
requirements are as follows:
    Proposed Sec.  C36.5 sets the LTO cycle noise limits for SSL1
airplanes. As noted previously in this preamble, the proposed limits
are based primarily on NASA's Supersonic Transport Concept Airplanes
(STCA) studies. The models and methodologies used in the STCA studies
for estimating noise certification levels were developed by NASA using
the most advanced physics-based scientific and engineering methods, and
were supplemented with 2- and 3-engine supersonic design concepts and
data from industry developers.
    In seeking to design a supersonic transport based on ``near-term
technologies,'' the models produced by NASA researchers generally
assumed design elements the researchers perceived as being economically
viable and technologically practicable. For example, the notional
engines equipped on each modeled aircraft is based on an ``off-the-
shelf'' subsonic turbofan. However, there are also a number of design
and performance elements assumed into the notional aircrafts that were
specifically or secondarily incorporated because of their noise-
abatement benefits. The research did not discuss the impacts to noise
if these technologies were not included, nor did researchers discuss
the cost impacts to design or operation if any of these processes or
technologies were excluded.
    Relatedly, NASA researchers also explored alternative engine
designs that included noise abatement mechanisms not ultimately
included in their main noise impact projections. For example, NASA ran
one alternative projection for an engine with a higher bypass ratio and
second alternative projection for incorporating nozzle chevrons as a
noise reduction technology to the original, lower bypass ratio engine.
In both cases, NASA found the alternative technologies reduced the
effective perceived noise level but came with a reduction in the flight
range of the aircraft.
    Therefore, while the noise data sets generated by the NASA research
indicates a range of potential noise outputs by these modeled aircraft,
these noise assumptions are already

constrained by optional design elements the researchers did or did not
choose to model as inputs for their final noise projections.
    Additional data provided to the FAA by U.S. industry and the
ongoing work by the ICAO CAEP were also used to inform the agency's
decision on noise limits. All of this technical information served as
the basis for noise limits proposed in Sec.  C36.5. That section
contains the noise limits for 2- or 3-engine supersonic airplanes with
a maximum certificated takeoff weights of 150,000 pounds and a maximum
operating speed of Mach 1.8 or less.
    The FAA proposes SSL1 noise limits and an applicability range using
its established noise standard-setting process. The FAA based its
proposal on the noise data sets from the NASA STCA program for that
agency's 100,000 and 120,000 pound (45- and 55-metric ton) airplanes
with two or three engines installed, as well as additional proprietary
information from manufacturers developing supersonic airplanes. The FAA
plotted these data sets, including associated design and modeling
uncertainties, on a coordinate graph based on weight (in pounds) and
noise (in EPNdB) for each airplane.
    Using this information plotted on the graph, the FAA developed a
series of potential limit lines for airplanes of different weights and
numbers of engines. The FAA evaluated these potential limit lines
taking into account the FAA's statutory considerations of technological
feasibility, economic reasonableness, and appropriateness for the
aircraft type. This evaluation process relied on the FAA's expertise in
noise evaluation of supersonic technologies and their qualitative
assessment of the economic and social costs that weigh on the process
to determine the intersection of elements that would result in a
proposed noise limit line that addressed both industry design needs and
agency statutory obligations. The novelty of the technology and the
limited data sets result in an inherent uncertainty regarding whether
these proposed noise standards fully optimize available noise reduction
while considering what is economically reasonable and technologically
practicable for modern supersonic aircraft. The FAA's intent in its
approach is to set a standard that could require adoption of most or
all known noise-abatement technologies to meet the noise limits,
including ones that may cause marginal reductions in aircraft
performance (e.g. reduce flight range), or marginal increases in the
cost of manufacturing.
    This process resulted in the noise limits proposed in Sec.  C36.5.
The proposed noise limits represent a range of applicability that takes
into account the spectrum of information provided, while also
addressing the FAA's statutory responsibilities regarding noise
regulation.
    As the industry develops and more information becomes available,
the FAA will consider whether to broaden the applicability of this
proposed rule or establish a separate class for larger or faster
supersonic airplanes.\19\ The proposed noise limits are consistent with
the agency's statutory duty to control and abate aircraft noise while
``consider[ing] whether the standard or regulation is economically
reasonable, technologically practicable, and appropriate for the
applicable aircraft, aircraft engine, appliance, or certificate.'' \20\
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    \19\ As noted previously, the FAA anticipates that the
parameters for SSL1 noise standards will serve as the foundation for
future generations of supersonic airplanes that may exceed the
weight and speed limits set in this rule. That said, If the FAA
receives an application for an airplane that exceeds the weight or
speed limits for SSL1, both the agency and the airplane developer
could use the SSL 1 standards as a starting point for establishing
an individual certification basis.
    \20\ 49 U.S.C. 44715(b)(4).
---------------------------------------------------------------------------

    As discussed above, the FAA does not propose to change the
fundamental approach to setting noise levels in its existing paradigm.
Accordingly, in proposing the SSL1 noise limits, FAA relies on its
existing approach, which uses weight as a correlating factor for noise
levels. This means that noise limits are applied on a curve taking into
account the fact that heavier aircraft will be louder, as weight is a
fundamental component of aircraft noise generation. Consistent with the
FAA's existing paradigm, the allowance for weight is not unlimited; the
noise limits set for various aircraft categories take into account the
entire range of aircraft in each category. The FAA does not propose to
deviate from this paradigm for supersonic aircraft. Weight remains the
correlating factor, without reference to the shape or thrust or other
capacity of an individual model. The noise limits proposed in this
rulemaking may be summarized as follows:
    A three-engine SSL1 airplane that has a maximum takeoff weight of
150,000 pounds may not exceed 94.0 effective perceived noise decibel
(EPNdB) at the flyover measurement point, 96.5 EPNdB at the lateral
measurement point, and 100.2 EPNdB at the approach measurement point.
    A two-engine SSL1 airplane that has a maximum takeoff weight of
150,000 pounds may not exceed 91.0 EPNdB at flyover, 96.5 EPNdB at the
lateral measurement point, and 100.2 EPNdB at the approach measurement
point.
    For SSL1 airplanes that seek certification at a lower maximum
takeoff weight, the noise limit would decrease linearly with the
logarithm of the airplane weight, at the rates set forth in proposed
Sec. Sec.  C36.5(a), (b), and (c), and remain constant for airplanes at
or below certain specified weights. This logarithmic decrease mirrors
the current requirements applied to subsonic airplanes under Appendix
B.
    As described above, the FAA does not propose to alter its
fundamental paradigm for noise certification as a part of this rule.
Accordingly, the FAA sets a proposed cumulative noise limit. The
proposed cumulative noise limit is presented in Sec.  C36.5(e), which
provides that the sum of the differences (i.e., the difference between
the limits and maximum levels) at all three measurements points (i.e.,
flyover, lateral, and approach) may not be less than 13.5 EPNdB.
    Proposed Sec.  C36.6 specifies the requirements when a VNRS is
included in an applicant's design and is used to show compliance with
the LTO cycle requirements of part 36. The inclusion of VNRS is
intended to enable the incorporation of advanced concepts and systems
technologies that reduce noise using fully automated changeable
properties or features. The two best known of the VNRS concepts are
automated configuration changes, and Programmed Lapse Rate (PLR), as
defined in proposed in Sec.  36.1. The FAA does not intend to limit the
development of automated noise reduction systems, and under this
regulatory provision will consider any design features presented at
certification that seek to lessen the LTO cycle noise impacts of
supersonic airplanes. When a VNRS is presented as part of an airplane
design at certification, it must be accounted for in any reference
procedures requested by the applicant, demonstrated, and approved by
the FAA before the certification tests are conducted.
    Section C36.7 specifies the noise certification reference
procedures and conditions that apply to supersonic airplanes, and
includes alternative provisions when a VNRS is used. Reference
procedures are required conditions and procedures for the measurement
of noise at the three reference measurement points (lateral, flyover,
and approach). For example, proposed Sec.  C36.7(b) specifies takeoff
reference procedures that include the minimum height that an airplane
must achieve and the engine thrust level that

must be used for the noise data to qualify for certification. Use of a
VNRS allows the applicant to develop individual reference takeoff and
approach procedures that must be approved by the FAA before noise
certification testing if the VNRS is used to show compliance with part
36. Each VNRS will likely be different, and the FAA does not yet know
how these systems will be implemented in individual supersonic type
designs. This proposed rule provides flexibility for the applicant to
request alternative takeoff and approach procedures to accommodate
varying VNRS designs. Applicants using VNRS must still comply with
proposed Sec. Sec.  C36.7(d) VNRS Takeoff reference procedure and (e)
VNRS Approach Reference Procedure when developing any alternative
takeoff and approach procedures. Takeoff and approach reference
profiles must be defined by applicants in accordance with these
requirements so that the measured test data can be properly adjusted
for deviations relative to the reference profile and recomputed for
reference meteorological conditions. These requirements are intended to
ensure that the procedures establish a common reference noise
certification basis of standard adjustments and specified reference
conditions that each applicant follows when using a VNRS. Such level-
setting procedures maintain fairness for all noise certification
applicants in demonstrating compliance. As noted previously, use of
VNRS to demonstrate compliance with part 36 will require its use during
normal operations in accordance with Sec.  36.1581(i).
    Section C36.7(b) proposes the minimum cutback height and thrust
requirements that are required for subsonic jet airplanes as a standard
takeoff reference procedure. When VNRS (including PLR) is used, the
takeoff reference procedure to be used prior to reaching minimum
cutback height is presented in Sec.  C36.7(d).
    Section C36.7(c)(5) addresses the weight and configuration of the
airplane during standard approach reference procedures. Weight and
configuration for approach reference procedures using VNRS are
addressed in Sec.  C36.7(e)(5). The FAA seeks specific comments
regarding any additional considerations that would be appropriate for
VNRS approach reference procedures, such as when and how VNRS is
triggered on approach, and what indication will be used to show that it
is functional and active on approach if used for noise certification.
All suggested changes should be supported by additional data as
appropriate.
    Section C36.8 addresses noise certification test procedures. Noise
adjustments for speed and thrust from test to reference conditions
follow the same methods of Appendix A, unless VNRS procedures and data
adjustments are approved by the FAA.
    Interested persons are encouraged to review all of the proposed
rule text in detail and submit comments regarding the organization and
substance of the requirements for the LTO cycle noise certification of
SSL1 airplanes.

IV. Regulatory Notices and Analyses

    Changes to Federal regulations must undergo several economic
analyses. First, Executive Orders 12866 and 13563 direct that each
Federal agency shall propose or adopt a regulation only upon a reasoned
determination that the benefits of the intended regulation justify its
costs. Second, the Regulatory Flexibility Act of 1980 (Pub. L. 96-354),
as codified in 5 U.S.C. 603 et seq., requires agencies to analyze the
economic impact of regulatory changes on small entities. Third, the
Trade Agreements Act of 1979 (Pub. L. 96-39), 19 U.S.C. Chapter 13,
prohibits agencies from setting standards that create unnecessary
obstacles to the foreign commerce of the United States. In developing
U.S. standards, the Trade Agreements Act requires agencies to consider
international standards and, where appropriate, that they be the basis
of U.S. standards. Fourth, the Unfunded Mandates Reform Act of 1995
(Pub. L. 104-4), as codified in 2 U.S.C. Chapter 25, requires agencies
to prepare a written assessment of the costs, benefits, and other
effects of proposed or final rules that include a Federal mandate
likely to result in the expenditure by State, local, or tribal
governments, in the aggregate, or by the private sector, of $100
million or more annually (adjusted for inflation with base year of
1995). The FAA has provided a more detailed Preliminary Regulatory
Impact Analysis of this proposed rule in the docket of this rulemaking.
This portion of the preamble summarizes this analysis.
    In conducting its analyses, FAA has determined that this proposed
rule has benefits that justify its costs. This proposed rule is a
significant regulatory action, as defined in section 3(f) of Executive
Order 12866, as it raises novel policy issues contemplated under that
Executive Order. This proposed rule is also significant under DOT's
Regulatory Policies and Procedures for the same reason. The proposed
rule would not have a significant economic impact on a substantial
number of small entities, would not create unnecessary obstacles to the
foreign commerce of the United States, and would not impose an unfunded
mandate on State, local, or tribal governments, or on the private
sector by exceeding the threshold.

A. Regulatory Evaluation

i. Baseline Problem and Statement of Need
    Without this proposal, aircraft developers would not be certain
that their aircraft could qualify for type certification in the United
States. As previously discussed, some U.S. manufacturers have begun
developing the next generation of supersonic airplanes. Current
regulations do not include noise standards applicable to supersonic
airplanes, and the FAA's statutory authority requires that noise
regulations be in place before a new aircraft type certificate may be
issued. The FAA is proposing to amend its noise certification
regulations to apply to new supersonic airplanes, and to adopt noise
certification procedures and noise limits that would apply during the
takeoff and landing (LTO) cycle of certain new supersonic airplanes.
Aircraft developers have indicated their need for the FAA to establish
noise limits in order to complete their designs with reasonable
certainty that the aircraft will qualify for type certification in the
United States.
ii. Enabled Supersonic Aircraft Potentially Qualifying for Type
Certification
    As previously discussed, aircraft developers provided FAA with
information and indicated that new supersonic-capable designs could
enter service in the mid- to late-2020s. Based on this data and the
proposed range of applicability, the FAA estimates two supersonic
airplanes, one 2-engine and one 3-engine, with maximum certificated
takeoff weight of 150,000 pounds and a maximum operating speed of Mach
1.8, would qualify for type certification as a result of this proposal
and potentially begin production by 2025.
    Based on data provided by aircraft developers and supersonic
airplane studies, the FAA estimates a production of 25 airplanes per
certificate for 50 total airplanes per year, a production period of ten
years, and airplane life of 20 years. Aircraft developers indicate that
50 percent or more of production would be sold to foreign operators.
Therefore, the potential life cycle of the first U.S. civil supersonic
fleet results in deliveries to U.S. operators of 25 airplanes per year
(same to foreign operators) until the U.S. operating fleet reaches a
potential peak of 250 airplanes

in 2034.\21\ We use these estimates to frame our analysis of future
impacts. The FAA seeks comment on its estimate of the expected timing
for development of supersonic aircraft and on its estimate of
production volumes.
---------------------------------------------------------------------------

    \21\ By 2034, U.S. aircraft developers could potentially produce
500 supersonic airplanes operating domestically and abroad.
---------------------------------------------------------------------------

    There is uncertainty with estimating a future U.S. civil supersonic
fleet. The FAA acknowledges that data from current and future research
and development of supersonic aircraft along with additional regulatory
changes may expand the size of the future U.S. civil supersonic fleet.
In addition, this proposal only provides a standard for potentially
qualifying for type certification--it does not guarantee certification
and does not fully enable or guarantee future production or domestic
operation. The effect of current U.S. regulations may limit future
operations. The existing prohibition on exceeding Mach 1 over land in
the United States would limit any supersonic airplane to subsonic
speeds while operated in the United States; the proposed regulations
would cover only subsonic operation during departure and arrival at
airports.
iii. Incremental Change of Proposed LTO Cycle Noise Limits
    The impact of the incremental change in the certificated noise
level resulting from the proposed LTO cycle noise limits is low. The
FAA looked at the average cumulative noise level of airplanes in the
2034 subsonic fleet and the cumulative noise levels of the 2- and 3-
engine supersonic airplanes that would be covered under this proposed
rule.
    The 2034 subsonic fleet has a median certificated noise level,
expressed in EPNdB level, of 267.1 and a mean certificated noise level
of almost the same at 267.0 with a standard deviation of 11.3.\22\ The
anticipated certification noise levels of the 2-engine supersonic
airplane is 269.3, a noise level at the 57th percentile of the subsonic
fleet, meaning that 57 percent of the airplanes in the subsonic fleet
in 2034 would have overall lower certification noise levels and 43
percent have overall higher certification noise levels than the 2-
engine supersonic airplane. The anticipated certification noise level
of the 3-engine supersonic airplane is 274.5, a noise level at the 74th
percentile of the subsonic fleet. The noise level of the 2-engine
supersonic is just one-fifth of a standard deviation above the mean of
the airplanes in the subsonic fleet and the 3-engine supersonic
airplane is just two-thirds of a standard deviation above the mean of
the airplanes in the subsonic fleet. In addition, the number of
supersonic airplanes potentially enabled by the proposal (i.e., those
supersonic airplane models expected to be certificated as SSL1) is
small and would represent less than three percent of the combined
subsonic and supersonic U.S. fleet in 2034. Therefore, while the
anticipated certification noise levels of the supersonic airplanes are
higher than the average certificated level of airplanes in the subsonic
fleet, the difference is moderate.
---------------------------------------------------------------------------

    \22\ When the mean and median are the same, it may imply a
standard normal distribution and symmetry of the database
distribution without significant outliers.
---------------------------------------------------------------------------

iv. Benefits and Costs
    For more than a decade, airplane producers interested in developing
the next generation of supersonic airplanes have sought standards in
the form of regulatory noise limits. Without such limits, potential
producers are reluctant to expend millions of dollars on airplane
designs that might ultimately fail to meet a future noise standard. The
FAA has been unable to set such standards without knowing what is
possible by way of noise mitigation for new designs.
    This proposed rule is the first step in bridging that gap. Aircraft
developers have shared data on their designs and a range of expected
noise levels. In turn, the FAA has used that information along with the
work conducted by NASA to propose these LTO cycle noise limits for a
certain size supersonic-capable airplane. Accordingly, the primary
benefit of this proposed certification rule is that it reduces a
current barrier to the development of the next generation of supersonic
aircraft. This is accomplished through the establishment of a design
and noise standard for developers and producers, providing them some
reasonable certainty that their investments will result in airplanes
that meet noise regulations that have been adopted by the FAA.
    The proposed rule supports future innovation in new supersonic
designs that incorporate advanced technologies, such as VNRS, that
reduce the noise at takeoff and landing to the greatest extent possible
while allowing the airplane to operate safely. The proposed standards
are designed to allow maximum flexibility for the manufacturers to
enhance designs using advances in technology. The FAA seeks to allow
the maximum latitude for these designs while they are still in their
infancy.
    The FAA seeks comment on the following issues related to the
impacts of the proposal:
     The potential noise effects of the proposed standard and
how these might be analyzed;
     The expected time savings or other benefits to the
travelling public from the ability to travel via supersonic airplane
instead of subsonic airplane;
     The manufacturing costs of possible technologies that
manufacturers are likely to use to meet the standard and their effects
on performance, weight and safety; and
     The costs and benefits of alternative noise limits or
reference procedures and their impacts on costs and benefits to
manufacturers, airlines and the public, including the likely choice of
alternative compliance technologies.
    The proposed rule has a positive effect on the development of U.S.
standards and industry for both domestic and international markets. The
proposal provides an initial benchmark for the international
development of standards for supersonic LTO cycle noise that would have
a positive effect on the innovation and expansion of the U.S.
supersonic airplane and transport industry. As previously discussed,
aircraft developers indicate that 50 percent or more of production
would be delivered to foreign operators.
    The establishment of certification LTO cycle noise standards for
subsonic operations of supersonic-capable airplanes allows industry and
FAA to look at the impact of subsonic operations on noise with more
certainty. When these aircraft are designed, certificated, and placed
in service, knowledge of these noise limits will make it easier to
determine the subsonic impacts at individual airports, which is
necessary for approval of operations specifications within the United
States.
    This proposal does not result in additional required regulatory
costs. Issuance of a type certificate requires compliance with the
applicable noise requirements of part 36. Full noise certification
testing is required for each new aircraft type and for certain
voluntary changes to type design that are classified as an acoustical
change under Sec.  21.93(b). The noise certification costs occur for
new type certification, or when a change to a type design results from
an acoustical change. Because the requirements for noise certification
already exist, any associated costs are not incremental costs of this
proposal.\23\
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    \23\ In the Paperwork Reduction Act section of this proposal,
the FAA provides estimates of changes to the paperwork related
burden and the cost to comply with the existing information
collection as required by the Paperwork Reduction Act and related
Office of Management and Budget (OMB) guidance. These costs are not
a result of a new collection requirement.

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

    As previously discussed, this proposal would allow the use of VNRS
during noise certification testing and during normal operation of
certificated airplanes. Based on industry information, these systems
are being developed without this rulemaking as part of the designs
themselves to reduce the noise produced by these supersonic airplanes.
Because no VNRS are currently certificated on airplanes, this proposal
adds VNRS to part 36 as an option for producers to use in their
designs. Because VNRS is not a requirement, it is not an additional
cost of the proposal. Rather, the addition of VNRS incorporates current
industry innovation, and the failure to allow this technology would
result in costs to industry.
v. Alternatives Considered
    No Action. The alternative of ``no action'' would entail the
foregone opportunity to develop civil supersonic airplanes with a
subsonic LTO cycle noise certification that reduces noise at takeoff
and landing to the greatest extent possible while allowing the airplane
to operate safely. In addition, Congress directed the FAA to exercise
leadership in the creation of policies, regulations, and standards
relating to the certification and safe and efficient operation of civil
supersonic aircraft.\24\ The FAA was directed to take action to advance
the deployment of supersonic aircraft, both domestically and
internationally, through the development of proposed noise
certification standards to address the constraints of noise and enable
supersonic flight. This proposed rule responds to this Congressional
direction.
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    \24\ Section 181 of the Federal Aviation Administration
Reauthorization Act of 2018 (https://www.congress.gov/115/bills/hr302/BILLS-115hr302enr.pdf).
---------------------------------------------------------------------------

    No constraint on maximum certificated take-off weight and speed.
The proposed rule applies only to supersonic airplanes with maximum
certificated take-off weight of 150,000 pounds and maximum operating
cruise speed of Mach 1.8. The FAA considered, but rejected, a proposed
rule with no limit on maximum certificated take-off weight or Mach
speed. Neither the NASA STCA analyses nor the aircraft data provided by
industry were sufficient to provide a technically feasible basis to
allow a reasonable estimate of certification noise limits for an open-
ended set of aircraft weights and Mach speeds; the goal remains a set
of certification standards that would reduce noise to the greatest
extent possible while allowing the airplane to operate safely.

B. Regulatory Flexibility Determination

    The Regulatory Flexibility Act of 1980 (Pub. L. 96-354) (RFA)
establishes ``as a principle of regulatory issuance that agencies shall
endeavor, consistent with the objectives of the rule and of applicable
statutes, to fit regulatory and informational requirements to the scale
of the businesses, organizations, and governmental jurisdictions
subject to regulation. To achieve this principle, agencies are required
to solicit and consider flexible regulatory proposals and to explain
the rationale for their actions to assure that such proposals are given
serious consideration.'' The RFA covers a wide range of small entities,
including small businesses, not-for-profit organizations, and small
governmental jurisdictions.
    Agencies must perform a review to determine whether a rule will
have a significant economic impact on a substantial number of small
entities. If the agency determines that it will, the agency must
prepare a regulatory flexibility analysis as described in the RFA.
However, if an agency determines that a rule is not expected to have a
significant economic impact on a substantial number of small entities,
Sec.  605(b) of the RFA provides that the head of the agency may so
certify and a regulatory flexibility analysis is not required. The
certification must include a statement providing the factual basis for
this determination, and the reasoning should be clear.
    Based on industry information, the FAA estimates two U.S. aircraft
developers to apply for part 36 LTO cycle noise certification under
this proposed rule. These developers are large entities that have a
variety of private and public partnerships and high levels of
investment capable of designing and producing the next generation of
technically advanced and high value supersonic aircraft.
    As discussed in the Regulatory Evaluation section, the FAA expects
this proposed rule would have small certification costs on affected
entities developing supersonic airplanes. In addition, this proposed
rule would result in positive business impacts since it would establish
a design and noise standard for entities developing and producing
supersonic airplanes, providing them some reasonable certainty that
their investments will result in airplanes that meet noise regulations.
    Therefore, as provided in Sec.  605(b), the head of the FAA
certifies that this rulemaking will not have a significant economic
impact on a substantial number of small entities.

C. International Trade Impact Assessment

    The Trade Agreements Act of 1979 (Pub. L. 96-39) prohibits Federal
agencies from establishing standards or engaging in related activities
that create unnecessary obstacles to the foreign commerce of the United
States. Pursuant to this Act, the establishment of standards is not
considered an unnecessary obstacle to the foreign commerce of the
United States, so long as the standard has a legitimate domestic
objective, such as the protection of safety, and does not operate in a
manner that excludes imports that meet this objective. The statute also
requires consideration of international standards and, where
appropriate, that they be the basis for U.S. standards.
    The FAA has assessed the effect of this proposed rule and
determined that its purpose would be to allow supersonic-capable
aircraft to be noise certificated in the United States, which will
permit domestic subsonic LTO cycle operations and supersonic operations
outside U.S. airspace and would not pose an unnecessary obstacle to the
foreign commerce of the United States. Therefore, the rule would comply
with the Trade Agreements Act.

D. Unfunded Mandate Assessment

    Title II of the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-
4) requires each Federal agency to prepare a written statement
assessing the effects of any Federal mandate in a proposed or final
agency rule that may result in an expenditure of $100 million or more
(in 1995 dollars) in any one year by State, local, and tribal
governments, in the aggregate, or by the private sector; such a mandate
is deemed to be a ``significant regulatory action.'' The FAA currently
uses an inflation-adjusted value of $155.0 million in lieu of $100
million.
    This final rule does not contain such a mandate. Therefore, the
requirements of Title II of the Act do not apply.

E. Paperwork Reduction Act

    The Paperwork Reduction Act of 1995 (44 U.S.C. 3507(d)) requires
that the FAA consider the impact of paperwork and other information
collection burdens imposed on the public. According to the 1995
amendments to the Paperwork Reduction Act (5 CFR

1320.8(b)(2)(vi)), an agency may not collect or sponsor the collection
of information, nor may it impose an information collection requirement
unless it displays a currently valid OMB control number.
    This action contains the following proposed amendments to the
existing information collection requirements previously approved under
OMB Control Number 2120-0659. As required by the Paperwork Reduction
Act of 1995 (44 U.S.C. 3507(d)), the FAA has submitted these proposed
information collection amendments to OMB for its review.
    In accordance with the Paperwork Reduction Act of 1995, FAA invites
public comments about our intent to request OMB approval to revise an
existing information collection. The information is collected when an
applicant seeking noise certification of aircraft demonstrates noise
compliance in accordance with 14 CFR part 36. The demonstration of
compliance by submitting noise test data was originally implemented
under the Aircraft Noise Abatement Act of 1968, and is now part of the
overall codification of aircraft noise authority in 49 U.S.C. 44715.
    You are asked to comment on any aspect of this information
collection, including (a) whether the proposed collection of
information is necessary for FAA's performance; (b) the accuracy of the
estimated burden; (c) ways for FAA to enhance the quality, utility, and
clarity of the information collection; and (d) ways that the burden
could be minimized without reducing the quality of the collected
information. The FAA will summarize and/or include your comments in the
request for OMB's clearance of this information collection.
    Background: The aircraft noise certification regulations of 14 CFR
part 36 currently include information collection requirements for the
certification of subsonic airplanes (jet airplanes and subsonic
transport category large airplanes). The information collected are the
results of noise certification tests that demonstrate compliance with
14 CFR part 36. The original information collection was implemented to
show compliance in accordance with the Aircraft Noise Abatement Act of
1968; that statute is now part of the overall codification of the FAA's
regulatory authority over aircraft noise in 49 U.S.C. 44715.
    Appendix A to part 36, Sec.  A36.5.2, requires applicants to
include test results in their noise certification compliance report.
Aircraft certification applicants typically certificate an airplane
model once. The current information collection estimate includes 14
noise certification projects involving flight tests undertaken each
year. For this NPRM, the FAA proposes to revise this PRA collection to
include noise tests on supersonic aircraft, for an increased estimate
of 16 total noise certification projects per year. The FAA estimates
that there are two entities that would submit applications for
certification of supersonic airplanes under this proposal. Each
applicant's collected information is incorporated into a noise
compliance report that is provided to and approved by the FAA. The
noise compliance report is used by the FAA in making a finding that the
airplane is in compliance with the regulations. These compliance
reports are required only once when an applicant wants to certificate
an aircraft type. Without this data collection, the FAA would be unable
to make the required noise certification compliance finding. The
proposed PRA data collection revisions are as follows:
    Respondents: Aircraft manufacturer/applicant seeking type
certification;
    Frequency: Estimated 16 total applicants per year, which includes a
proposed increase of 2 new supersonic airplane applications;
    Estimated Average Burden per Response: Estimated 200 hours per
applicant for the compliance report; and
    Estimated Total Annual Burden: $25,000 per applicant or cumulative
total $400,000 per year for 16 applicants.

F. International Compatibility

    In keeping with U.S. obligations under the Convention on
International Civil Aviation, it is FAA policy to conform to
International Civil Aviation Organization Standards and Recommended
Practices to the maximum extent practicable. The FAA has reviewed the
corresponding ICAO Standards and Recommended Practices and has
identified no differences with these regulations; ICAO does not
currently have standards for subsonic LTO cycle of supersonic capable
airplanes.

G. Environmental Analysis

    In accordance with the provisions of regulations issued by the
Council on Environmental Quality (40 CFR parts 1500-1508), FAA Order
1050.1F identifies certain FAA actions that may be categorically
excluded from the preparation of an Environmental Assessment or an
Environmental Impact Statement. The FAA has determined that this NPRM
is covered by the CATEX described in paragraph 5-6.6(d) of FAA Order
1050.1F. Pursuant to FAA Order 1050.1F, paragraph 5-5.6(d), this
rulemaking action qualifies for a categorical exclusion because no
significant impacts to the environment are expected from publication of
this NPRM. This CATEX finding applies only to this proposed rule. The
FAA will initiate a separate review of any final rule, including the
adoption of any supersonic airplane noise certification standards that
would permit the subsonic operation of such airplanes in the United
States.

V. Executive Order Determinations

A. Executive Order 13132, Federalism

    The FAA has analyzed this proposed rule under the principles and
criteria of Executive Order 13132, Federalism (64 FR 43255, August 10,
1999). The agency has determined that this action would not have a
substantial direct effect on the States, or the relationship between
the Federal Government and the States, or on the distribution of power
and responsibilities among the various levels of Government, and,
therefore, would not have federalism implications.

B. Executive Order 13211, Regulations That Significantly Affect Energy
Supply, Distribution, or Use

    The FAA analyzed this proposed rule under Executive Order 13211,
Actions Concerning Regulations that Significantly Affect Energy Supply,
Distribution, or Use (66 FR 28355, May 18, 2001). The agency has
determined that it would not be a ``significant energy action'' under
the executive order and would not be likely to have a significant
adverse effect on the supply, distribution, or use of energy.

C. Executive Order 13609, Promoting International Regulatory
Cooperation

    Executive Order 13609, Promoting International Regulatory
Cooperation (77 FR 26413, May 4, 2012) promotes international
regulatory cooperation to meet shared challenges involving health,
safety, labor, security, environmental, and other issues and to reduce,
eliminate, or prevent unnecessary differences in regulatory
requirements. The FAA has analyzed this action under the policies and
agency responsibilities of Executive Order 13609, and has determined
that this action would have no effect on international regulatory
cooperation.

D. Executive Order 13771, Reducing Regulation and Controlling
Regulatory Costs

    This proposed rule is a deregulatory action under Executive Order
13771, Reducing Regulation and Controlling Regulatory Costs (82 FR
9339, February 3, 2017). Details on the enabling aspects

of this proposed rule that expand production and consumption options
can be found in the Regulatory Evaluation.

VI. Additional Information

A. Comments Invited

    The FAA invites interested persons to participate in this
rulemaking by submitting written comments, data, or views. The agency
also invites comments relating to the economic, environmental, energy,
or federalism impacts that might result from adopting the proposals in
this document. The most helpful comments reference a specific portion
of the proposal, explain the reason for any recommended change, and
include supporting data. To ensure the docket does not contain
duplicate comments, commenters should send only one copy of written
comments, or if comments are filed electronically, commenters should
submit only one time.
    The FAA will file in the docket all comments it receives, as well
as a report summarizing each substantive public contact with FAA
personnel concerning this proposed rulemaking. Before acting on this
proposal, the FAA will consider all comments it receives on or before
the closing date for comments. The agency may change this proposal in
light of the comments it receives.
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 NPRM 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 NPRM, it is important that you
clearly designate the submitted comments as CBI. Please mark each page
of your submission containing CBI as ``PROPIN.'' FAA will treat such
marked submissions as confidential under the FOIA, and they will not be
placed in the public docket of this NPRM. Submissions containing CBI
should be sent to the person identified in the FOR FURTHER INFORMATION
CONTACT section of this document. Any information the FAA receives that
is not specifically designated as CBI will be placed in the public
docket for this rulemaking.

B. Availability of Rulemaking Documents

    An electronic copy of rulemaking documents may be obtained from the
internet by--
     Searching the Federal eRulemaking Portal (http://www.regulations.gov);
     Visiting the FAA's Regulations and Policies web page at
http://www.faa.gov/regulations_policies; or
     Accessing the Government Publishing Office's web page at
http://www.gpo.gov/fdsys/.
    Copies may also be obtained by sending a request to the Federal
Aviation Administration, Office of Rulemaking, ARM-1, 800 Independence
Avenue SW, Washington, DC 20591, or by calling<PHONE_NUMBER>.
Commenters must identify the docket or notice number of this
rulemaking.
    All documents the FAA considered in developing this proposed rule,
including economic analyses and technical reports, may be accessed from
the internet through the Federal eRulemaking Portal referenced above.

C. Small Business Regulatory Enforcement Fairness Act

    The Small Business Regulatory Enforcement Fairness Act of 1996
(SBREFA) requires FAA to comply with small entity requests for
information or advice about compliance with statutes and regulations
within its jurisdiction. A small entity with questions regarding this
document may contact its local FAA official, or the person identified
in the FOR FURTHER INFORMATION CONTACT heading at the beginning of the
preamble. To find out more about SBREFA on the internet, visit http://www.faa.gov/regulations_policies/rulemaking/sbre_act/.

List of Subjects

14 CFR Part 21

    Aircraft, Aviation safety, Exports, Imports, Reporting and
recordkeeping requirements.

14 CFR Part 36

    Aircraft, Noise control.

The Proposed Amendment

    In consideration of the foregoing, the Federal Aviation
Administration proposes to amend chapter I of Title 14, Code of Federal
Regulations as follows:

PART 21--CERTIFICATION PROCEDURES FOR PRODUCTS AND ARTICLES

0
1. The authority citation for part 21 is revised to read as follows:

    Authority:  42 U.S.C. 7572; 49 U.S.C. 106(f), 106(g), 40105,
40113, 44701-44702, 44704, 44707, 44709, 44711, 44713, 44715, 45303;
Pub. L. 115-254.

0
2. Amend Sec.  21.93 by revising paragraph (b)(2) and adding paragraph
(b)(6) to read as follows:

Sec.  21.93  Classification of changes in type design.

* * * * *
    (b) * * *
    (2) Subsonic jet (Turbojet powered) airplanes (regardless of
category) and Concorde airplanes. For airplanes to which this paragraph
applies, ``acoustical changes'' do not include changes in type design
that are limited to one of the following--
    * * *
    (6) Supersonic airplanes.
* * * * *

PART 36--NOISE STANDARDS: AIRCRAFT TYPE AND AIRWORTHINESS
CERTIFICATION

0
3. The authority citation for part 36 is revised to read as follows:

    Authority:  42 U.S.C. 4321 et seq.; 49 U.S.C. 106(g), 40113,
44701-44702, 44704, 44715; sec. 305, Pub. L. 96-193, 94 Stat. 50,
57; E.O. 11514, 35 FR 4247, 3 CFR, 1966-1970 Comp., p. 902; Pub. L.
115-254.

0
4. Amend Sec.  36.1 by
0
a. Adding paragraph (a)(6);
    b. Revising paragraph (c);
0
c. Revising the introductory text of paragraph (d);
0
d. Revising the introductory text of paragraph (f);
0
e. Revising paragraph (g);
0
f. Removing and reserving paragraph (f)(8); and
0
e. Adding paragraph (j).
    The additions and revisions read as follows:

Sec.  36.1  Applicability and definitions.

    (a) * * *
    (6) Type certificates, changes to those certificates, and standard
airworthiness certificates, for supersonic airplanes.
* * * * *
    (c) Each person who applies under part 21 of this chapter for
approval of an acoustical change described in Sec.  21.93(b) of this
chapter must show that the aircraft complies with the applicable
provisions of Sec. Sec.  36.7, 36.9, 36.11, 36.13, or 36.15 of this
part in addition to the applicable airworthiness requirements of this
chapter.
    (d) Each person who applies for the original issue of a standard
airworthiness certificate for a transport category large airplane or
for a subsonic jet airplane under Sec.  21.183 must, regardless of date
of application, show compliance with the following

provisions of this part (including appendix B):
* * * * *
    (f) For the purpose of showing compliance with this part for
transport category large airplanes and subsonic jet airplanes
regardless of category, the following terms have the following
meanings:
* * * * *
    (g) For the purpose of showing compliance with this part for
transport category large airplanes and subsonic jet airplanes
regardless of category, each airplane may not be identified as
complying with more than one stage or configuration simultaneously.
* * * * *
    (j) For the purpose of showing compliance with this part, for
supersonic airplanes regardless of category, the following terms have
the meanings specified:
    Landing and Takeoff (LTO) cycle, as used in reference to a
supersonic airplane, means the segments of subsonic flight that include
flyover, lateral and approach noise levels prescribed in appendix C of
this part.
    Programmed Lapse Rate (PLR) is a fully automated feature
incorporated into the engine controls as part of the engine thrust
rating structure as a means of reducing noise.
    Supersonic airplane means--
    (i) An airplane:
    (A) For which the maximum operating limit speed, Mmo,
exceeds a Mach number of 1; and
    (B) That receives an original type certificate after [EFFECTIVE
DATE OF FINAL RULE].
    (ii) Does not include any Concorde model airplane. No regulation in
this part that references the Concorde applies to any non-Concorde
supersonic airplane.
    Supersonic Level 1 (SSL1) noise level means a noise level at or
below the noise limit prescribed in Sec.  C36.5 of appendix C to this
part.
    Variable Noise Reduction System (VNRS) is a dynamic system
integrated into the design of an aircraft that functions automatically
to produce a change in the configuration of the aircraft to reduce
noise. Such systems may include:
    (i) Hardware or software components that control engine parameters
or airframe configuration; or
    (ii) Controls initiated through a flight management system as a
means of noise reduction during normal operation.
0
5. Amend Sec.  36.7 by revising the section heading and paragraph (a)
to read as follows:

Sec.  36.7  Acoustical change: Transport category large airplanes and
subsonic jet airplanes.

    (a) Applicability. This section applies to all transport category
large airplanes and subsonic jet airplanes for which an acoustical
change approval is applied for under Sec.  21.93(b) of this chapter.
* * * * *
0
6. Add Sec.  36.15 to subpart A to read as follows:

Sec.  36.15  Acoustical change: Supersonic airplanes.

    (a) Applicability. This section applies to all supersonic airplanes
for which an acoustical change approval is applied for under Sec.
21.93(b) of this chapter.
    (b) General requirements. For supersonic airplanes, the acoustical
change approval requirements are as follows:
    (1) In showing compliance, noise levels must be measured and
evaluated in accordance with the applicable procedures and conditions
prescribed in appendix A of this part.
    (2) Compliance with the SSL1 noise limits prescribed in Sec.  C36.5
of appendix C of this part must be shown in accordance with the
applicable provisions of Sec. Sec.  C36.7 and C36.8 of appendix C of
this part.
    (c) If a supersonic airplane is an SSL1 airplane prior to a change
in type design, after a change in type design it must remain an SSL1
airplane as specified in Sec.  C36.5 of appendix C of this part.
0
7. Revise the heading of subpart B to read as follows.

Subpart B--Transport Category Large Airplanes and Subsonic Jet
Airplanes

0
8. Amend Sec.  36.101 to read as follows:
    For subsonic transport category large airplanes and subsonic jet
powered airplanes the noise generated by the airplane must be measured
under appendix A of this part or under an approved equivalent
procedure.
0
9. Revise the heading of subpart D to read as follows.

Subpart D--Noise Limits for Concorde Airplanes

0
10. Add subpart E to read as follows:

Subpart E --Noise Limits for Supersonic Airplanes

Sec.
36.401 Noise measurement and evaluation.
36.403 Noise limits.

Sec.  36.401  Noise measurement and evaluation.

    For supersonic airplanes, the noise generated by the airplane must
be measured and evaluated in accordance with appendix A of this part or
an approved equivalent procedure.

Sec.  36.403  Noise limits.

    For supersonic airplanes, compliance with this section is
determined by:
    (a) Tests conducted in accordance with Sec.  36.401 of this part.
    (b) Demonstration of the noise levels produced using the reference
procedures and conditions in Sec.  C36.7, and the test procedures of
Sec.  C36.8 of appendix C of this part or an approved equivalent
procedure.
    (c) For an airplane for which type certification application is
made after [EFFECTIVE DATE OF FINAL RULE], the noise levels
demonstrated may not exceed the SSL1 noise limits prescribed in Sec.
C36.5(c) of appendix C of this part.
0
11. Amend Sec.  36.1581 by:
0
a. Revising paragraph (a)(1);
0
b. Adding paragraph (a)(4);
0
c. Revising paragraph (d);
0
d. Removing and reserving paragraph (g); and
0
e. Adding paragraph (h) and (i).
    The additions and revisions read as follows:

Sec.  36.1581  Manuals, markings, and placards.

    (a) * * *
    (1) For transport category large airplanes, subsonic jet airplanes,
and the Concorde, the noise level information must be one value for
each flyover, lateral, and approach as defined and required by appendix
B of this part, along with the maximum takeoff weight, maximum landing
weight, and configuration.
* * * * *
    (4) For supersonic airplanes, LTO cycle noise level information
must:
    (i) Be determined in accordance with appendix C of this part;
    (ii) Be one value for each flyover, lateral, and approach condition
as defined; and
    (iii) Correspond to the maximum takeoff weight, the maximum landing
weight, and the configuration for each of these conditions.
* * * * *
    (d) For transport category large airplanes and subsonic jet
airplanes, for which the weight used in meeting the takeoff or landing
noise requirements of this part is less than the maximum weight
established under the applicable airworthiness requirements, those
lesser weights must be furnished, as operating limitations in the
operating limitations section of the Airplane Flight Manual. Further,
the maximum takeoff weight must not exceed the takeoff weight that

is most critical from a takeoff noise standpoint.
* * * * *
    (h) For supersonic airplanes, no maximum landing or takeoff weight
may exceed the weight used to establish an LTO cycle noise level that
shows compliance with this part.
    (i) The following conditions each require an operating limitation
that must be included in the operating limitations section of the
Airplane Flight Manual.
    (1) When any weight used in showing compliance with an LTO cycle
noise requirement of this part is less than the maximum weight
established under the applicable airworthiness requirements, the weight
used to show compliance with a noise requirement of this part becomes
an operating limitation.
    (2) When a VNRS has been used to show compliance with the SSL1
noise limits of Sec.  C36.5 of appendix C of this part, or with the
reference procedures of Sec. Sec.  C36.7(d) and C36.7(e) of appendix C
of this part, the flight crew must ensure that the VNRS is functioning
properly prior to takeoff;
    (3) When PLR has been used to show compliance with the SSL1 noise
limits of Sec.  C36.5 of appendix C of this part, or with the reference
procedures of Sec. Sec.  C36.7(d) and C36.7(e) of appendix C of this
part, the airplane may not be programmed to exceed PLR thrust during
normal operations except at specified thrust levels for which the
airplane has been shown not to cause any significant noise impact on
the ground.
0
12. In appendix A to part 36 revise the heading and Sec.  A.36.1.1 to
read as follows:

Appendix A to Part 36--Aircraft Noise Measurement and Evaluation

* * * * *
    A36.1.1 This appendix prescribes the conditions under which
airplane noise certification tests must be conducted and states the
measurement procedures that must be used to measure airplane noise.
This appendix also describes the procedures that must be used to
determine the noise evaluation quantity designated as effective
perceived noise level, EPNL, as referenced in Sec. Sec.  36.101, 36.401
and 36.803.
* * * * *
0
c. Revise the note to Sec.  A<IP_ADDRESS> to read as follows:
* * * * *

    Note:  Many noise certifications involve only minor changes to
the airplane type design. The resulting changes in noise can often
be established reliably without resorting to a complete test as
outlined in this appendix. For this reason, the FAA permits the use
of approved equivalent procedures. There are also equivalent
procedures that may be used in full certification tests, in the
interest of reducing costs and providing reliable results. Guidance
material on the use of equivalent procedures in the noise
certification of subsonic jet, propeller-driven large airplanes, and
supersonic airplanes is provided in the current advisory circular
for this part.

* * * * *
0
d. Revise paragraph A36.5.2(h)(1) to read as follows:
* * * * *
    A<IP_ADDRESS> * * *
    (h) * * *
    (1) For subsonic jet airplanes and supersonic airplanes: engine
performance in terms of net thrust, engine pressure ratios, jet exhaust
temperatures and fan or compressor shaft rotational speeds as
determined from airplane instruments and manufacturer's data for each
test run;
* * * * *
0
e. Revise paragraph A<IP_ADDRESS> to read as follows:
* * * * *
    A<IP_ADDRESS> For supersonic airplanes, the integrated method of
adjustment, described in Sec.  A36.9.4, must be used when VNRS
reference procedures in C36.7(d) and C36.7(e) are used to demonstrate
compliance with this part.
* * * * *
0
13. Revise the heading of appendix B to part 36, to read as follows.

Appendix B to Part 36--Noise Levels for Transport Category and Subsonic
Jet Airplanes Under Sec.  36.103 and Concorde Airplanes Under Sec.
36.301

0
14. Add appendix C to part 36 to read as follows:

Appendix C to Part 36--Noise Levels for Supersonic Airplanes

Sec.
C36.1 Noise Measurement and Evaluation.
C36.2 Noise Evaluation Metric.
C36.3 Reference Noise Measurement Points.
C36.4 Test Noise Measurement Points.
C36.5 Noise Limits.
C36.6 Use of a Variable Noise Reduction System (VNRS).
C36.7 Noise Certification Reference Procedures and Conditions.
C36.8 Noise Certification Test Procedures.
Section C36.1 Noise Measurement and Evaluation
    The procedures of appendix A of this part, or approved equivalent
procedures, must be used to determine the noise levels of a supersonic
airplane. The noise levels determined using these procedures must be
used to show compliance with the requirements of this appendix.
Section C36.2 Noise Evaluation Metric
    The noise evaluation metric is the effective perceived noise level
expressed in EPNdB, as calculated using the procedures of appendix A of
this part.
Section C36.3 Reference Noise Measurement Points
    When tested using the procedures of this part, an airplane may not
exceed the noise levels specified in Sec.  C36.5 at the following
points on level terrain:
    (a) Lateral full-power reference noise measurement point: The point
on a line parallel to and 1,476 feet (450 meters) from the runway
centerline, or extended centerline, where the noise level after lift-
off is at a maximum during takeoff. When approved by the FAA, the
maximum lateral noise at takeoff thrust may be assumed to occur at the
point (or its approved equivalent) along the extended centerline of the
runway where the airplane reaches 985 feet (300 meters) altitude above
ground level. The altitude of the airplane as it passes the noise
measurement points must be within + 328 to -164 feet (+100 to -50
meters) of the target altitude.
    (b) Flyover reference noise measurement point: The point on the
extended centerline of the runway that is 21,325 feet (6,500 meters)
from the start of the takeoff roll;
    (c) Approach reference noise measurement point: The point on the
extended centerline of the runway that is 6,562 feet (2,000 meters)
from the runway threshold. On level ground, this corresponds to a
position that is 394 feet (120 meters) vertically below the 3-degree
descent path, which originates at a point on the runway 984 feet (300
meters) beyond the threshold.
Section C36.4 Test Noise Measurement Points
    (a) If the test noise measurement points are not located at the
reference noise measurement points, any corrections for the difference
in position are to be made using the same adjustment procedures as for
the differences between test and reference flight paths.
    (b) The applicant must use a sufficient number of lateral test
noise measurement points to demonstrate to the FAA that the maximum
noise level on the appropriate lateral line has been determined. For
supersonic airplanes, simultaneous measurements must be made at one
test noise measurement point at its symmetrical point on the other side
of the runway. The measurement points are considered to be symmetrical
if they are

longitudinally within 33 feet (10 meters) of each other.
Section C36.5 Noise Limits
    When determined in accordance with the noise evaluation methods of
appendix A of this part, the noise levels of a Supersonic Level 1
airplane may not exceed the following:
    (a) Flyover.
    (1) For an airplane with three engines:
    (i) For which noise certification is requested at a maximum
certificated takeoff weight (mass) of 150,000 pounds (68,039 kilograms
(kg)), the noise limit is 94.0 EPNdB.
    (ii) For which noise certification is requested at a maximum
certificated takeoff weight of less than 150,000 pounds (68,039 kg),
the noise limit begins at 94.0 EPNdB and decreases linearly with the
logarithm of the airplane weight (mass) at the rate of 4 EPNdB per
halving of weight (mass) down to 89 EPNdB at 63,052 pounds (28,600 kg)
after which the limit is constant.
    (2) For an airplane with two engines or fewer:
    (i) For which noise certification is requested at a maximum
certificated takeoff weight (mass) of 150,000 pounds (68,039 kg), the
noise limit is 91.0 EPNdB.
    (ii) For which noise certification is requested at a maximum
certificated takeoff weight (mass) of less than 150,000 pounds (68,039
kg), the noise limit begins at 91.0 EPNdB and decreases linearly with
the logarithm of the airplane weight (mass) at the rate of 4 EPNdB per
halving of weight (mass) down to 89 EPNdB at 106,042 pounds (48,100
kg), after which the limit is constant.
    (b) Lateral. Regardless of the number of engines, for an airplane
at the reference noise measurement point:
    (1) For which noise certification is requested at a maximum
certificated takeoff weight (mass) of 150,000 pounds (68,039 kg) the
noise limit is 96.5 EPNdB.
    (2) For which noise certification is requested at a maximum
certificated take-off weight (mass) of less than 150,000 pounds (68,039
kg), the noise limit begins at 96.5 EPNdB and decreases linearly with
the logarithm of the weight (mass) down to 94 EPNdB at 77,162 pounds
(35,000 kg), after which the limit remains constant.
    (c) Approach. Regardless of the number of engines, for an airplane:
    (1) For which noise certification is requested at a maximum
certificated takeoff weight (mass) of 150,000 pounds (68,039 kg) the
noise limit is 100.2 EPNdB.
    (2) For which noise certification is requested at a maximum
certificated takeoff weight (mass) of less than 150,000 pounds (68,039
kg), the noise limit begins at 100.2 EPNdB and decreases linearly with
the logarithm of the mass down to 98 EPNdB at 77,162 pounds (35.0k kg),
after which the limit remains constant.
    (d) No airplane may exceed the noise limits described in this
section at any measurement point.
    (e) The sum of the differences at all three measurement points
between the maximum noise levels and the noise limits specified in
Sec. Sec.  C36.5(a), C36.5(b) and C36.5(c) may not be less than 13.5
EPNdB.
Section C36.6 Use of a Variable Noise Reduction System (VNRS)
    For any airplane that includes a VNRS as part of an airplane design
for noise certification, the applicant must--
    (a) Submit reference procedures to be approved by the FAA as part
of its noise certification test plan.
    (b) Demonstrate the approved VNRS reference procedures for takeoff
as defined in Sec.  C36.7(d), or for approach as defined in C36.7(e),
when conducting certification tests.
Section C36.7 Noise Certification Reference Procedures and Conditions
    (a) General conditions:
    (1) All reference procedures must meet the requirements of Sec.
36.3 of this part.
    (2) Calculations of airplane performance and flight path must be
made using the reference procedures and must be approved by the FAA.
    (3) Standard reference procedures--When using standard reference
procedures, the following apply--
    (i) For takeoff, Sec.  C36.7(b);
    (ii) For lateral, Sec.  C 36.7(b)(3); and
    (iii) For approach, Sec.  C36.7(c).
    (4) VNRS reference procedures--For airplanes that use a VNRS, the
following reference procedures apply--
    (i) For takeoff and lateral, Sec.  C36.7(d); and
    (ii) For approach, Sec.  C36.7(e).
    (5) The following reference conditions must be specified in the
reference procedures. When used for the calculation of atmospheric
absorption coefficients, the reference atmosphere is homogeneous in
terms of temperature and relative humidity.
    (i) Sea level atmospheric pressure of 2,116 pounds per square foot
(psf) (1013.25 hPa);
    (ii) Ambient sea-level air temperature of 77 [deg]F (25 [deg]C,
i.e., ISA + 10 [deg]C);
    (iii) Relative humidity of 70 percent;
    (iv) Zero wind.
    (v) In defining the reference takeoff flight path(s) for the
takeoff and lateral noise measurements, the runway gradient is zero.
    (b) Standard takeoff reference procedure:
    The takeoff reference flight path must be calculated using the
following:
    (1) The takeoff thrust/power used must be the maximum specified by
the applicant for normal takeoff operations (and is presumed to be less
than maximum thrust/power for supersonic cruise speed) as listed in the
performance section of the airplane flight manual under the reference
atmospheric conditions given in Sec.  C36.7(a)(5). Average engine
takeoff thrust or power must be used from brake release to the point
where the minimum height above runway level is reached, as follows--
    The minimum height to be used--
    (i) For airplanes with three engines: 853 feet (260 meters).
    (ii) For airplanes with two engines or fewer: 984 feet (300
meters).
    (2) Upon reaching the height specified in paragraph (b)(1) of this
section, airplane thrust or power must not be reduced below that
required to maintain the greater of--
    (i) A climb gradient of 4 percent; or
    (ii) For multi-engine airplanes, level flight with one engine
inoperative.
    (3) To determine the lateral noise level, the reference flight path
must be calculated using full takeoff power throughout the test run
without a reduction in thrust or power.
    (4) The takeoff reference true airspeed is the all-engine operating
takeoff climb speed using the procedures approved by the FAA--
    (i) For the shortest runway on which the airplane is approved to
operate;
    (ii) When the aircraft reaches the measurement location distance
from brake release.
    (iii) That is determined by the applicant when calculating the
reference profile using the reference conditions stated in Sec.
C36.7(5).
    (iv) The reference speed may not exceed 250 knots.
    (5) The takeoff configuration selected by the applicant and
approved by the FAA must be maintained constantly throughout the
takeoff reference procedure, except that the landing gear may be
retracted.
    (6) The weight of the airplane at the brake release must be the
maximum takeoff weight at which the noise certification is requested.
This weight may be required as an operating limitation in accordance
with Sec.  36.1581(i) of this part; and
    (7) The average engine is defined as the average of all the
certification

compliant engines used during the airplane flight tests, up to and
during certification, when operating within the limitations, and
according to the procedures given in the Flight Manual. This will
determine the relationship of thrust/power to control parameters (e.g.,
N1 or EPR). Noise measurements made during certification tests must be
corrected using this relationship.
    (c) Standard approach reference procedure:
    The approach reference flight path must be calculated using the
following:
    (1) The airplane is stabilized and following a 3-degree glide path;
    (2) A steady approach speed of Vref + 10 kts (Vref + 19 km/h) with
thrust and power stabilized must be established and maintained over the
approach measuring point.
    (3) The constant approach configuration used in the airworthiness
certification tests, but with the landing gear down, must be maintained
throughout the approach reference procedure;
    (4) The weight of the airplane at touchdown must be the maximum
landing weight permitted in the approach configuration defined in
paragraph (c)(3) of this section at which noise certification is
requested. This weight may be required as an operating limitation in
accordance with Sec.  36.1581(i) of this part; and
    (5) The weight at which certification is requested, with the
airplane in the most critical configuration, defined as--
    (i) That which produces the highest noise level with normal
deployment of aerodynamic control surfaces including lift and drag
producing devices, and
    (ii) All equipment listed in Sec.  A<IP_ADDRESS> of appendix A of this
part that can be operated during normal flight.
    (d) VNRS Takeoff reference procedure:
    (1) The VNRS takeoff reference flight path is to be specified by
the applicant using the following--
    (i) Maximum engine takeoff thrust or power (of an average engine)
used to determine takeoff true airspeed from brake release to the
activation of VNRS using the reference atmospheric conditions of Sec.
C36.7(a)(5).
    (ii) The segment of the flight path from the activation of VNRS to
the point at which VNRS is no longer active;
    (iii) The applicant must maintain climb power throughout the
remaining segment of the reference flight path;
    (iv) The following minimum heights must be reached before engine
cutback is initiated:
    (A) For airplanes with three engines: 853 feet (260 meters);
    (B) For airplanes with two engines or fewer: 984 feet (300 meters);
and
    (v) Upon reaching the height specified in paragraph (d)(4) of this
section, airplane thrust or power must not be reduced below that
required to maintain either of the following, whichever is greater:
    (A) A climb gradient of 4 percent; or
    (B) In the case of multi-engine airplanes, level flight with one
engine inoperative.
    (2) The VNRS reference flight path determined under paragraph
(d)(1) of this section must be used when demonstrating and measuring
the lateral noise level to show compliance with Sec.  C36.5 of this
appendix.
    (3) The takeoff reference true airspeed to be used is calculated
using the all engine operating takeoff climb speed, as determined
using--
    (i) The shortest approved runway length;
    (ii) Maximum certificated takeoff weight at which the noise
certification is requested, which may result in an operating limitation
as specified in Sec.  36.1581(d);
    (iii) The reference conditions stated in Sec.  C36.7(5);
    (iv) The calculated true airspeed at the overhead measurement
point, defined in Sec.  C36.3(b);
    (v) The takeoff reference true airspeed must be attained as soon as
practicable after lift-off; and
    (vi) The takeoff reference true airspeed may not exceed 250 knots;
    (4) For all airplanes, noise values measured during testing must be
corrected to the reference acoustic day takeoff speed.
    (5) The takeoff configuration selected by the applicant and
approved by the FAA must be maintained throughout the takeoff reference
procedure, except that the landing gear may be retracted; and
    (6) The weight of the airplane at brake release must be the maximum
takeoff weight at which noise certification is requested. This weight
may be required as an operating limitation in accordance with Sec.
36.1581(i) of this part; and
    (7) As used in paragraph (d)(1)(i) of this section, average engine
means the average of all the certification compliant engines used
during the airplane flight tests, up to and during certification, when
operating within the limitations and according to the procedures given
in the Flight Manual. The average engine must be used to determine the
relationship of thrust/power to control parameters (e.g., N1 or EPR).
    (e) VNRS Approach reference procedure:
    The VNRS approach reference flight path must be calculated using
the following:
    (1) The airplane is stabilized and following a 3-degree glide path;
    (2) The approach reference speed is Vref + 10 kts (Vref + 19 km/h);
    (3) The applicant must use the approach configuration (landing gear
down) established for normal operations as part of the airworthiness
certification.
    (4) The weight of the airplane at touchdown, at which noise
certification is requested, must be the maximum landing weight
permitted in the approach configuration defined in paragraph (e)(3) of
this section, in accordance with Sec.  36.1581(h) of this part; an
    (5) The weight at which certification is requested, with the
airplane in the most critical configuration, defined as--
    (i) The configuration that produces the highest noise level with
normal deployment of aerodynamic control surfaces including lift and
drag producing devices; and
    (ii) All equipment listed in Sec.  A<IP_ADDRESS> of appendix A of this
part that can be operated during normal flight.
Section C36.8 Noise Certification Test Procedures
    (a) All test procedures must be approved by the FAA before
certification tests are conducted.
    (b) The test procedures and noise measurements must be conducted
and processed in an approved manner to yield the noise evaluation
metric EPNL, in units of EPNdB, as described in appendix A of this
part.
    (c) Acoustic data must be adjusted to the reference conditions
specified in this appendix using the methods described in appendix A of
this part. Adjustments for speed and thrust must be made as described
in Sec.  A36.9 of this part, unless separate VNRS procedures and the
data adjustments are approved.
    (d) If the airplane's weight during the test is different from the
weight at which noise certification is requested, the required EPNL
adjustment may not exceed 2 EPNdB for each takeoff and 1 EPNdB for each
approach. Data approved by the FAA must be used to determine the
variation of EPNL with weight for both takeoff and approach test
conditions. The necessary EPNL adjustment for variations in approach
flight path from the reference flight path must not exceed 2 EPNdB.
    (e) For approach, a steady glide path angle of 3 degrees 0.5 degree is acceptable.
    (f) If equivalent test procedures different from the reference
procedures are used, the test procedures and all methods for adjusting
the results to the reference procedures must be approved

by the FAA. The adjustments may not exceed 16 EPNdB on takeoff and 8
EPNdB on approach. If the adjustment is more than 8 EPNdB on takeoff,
or more than 4 EPNdB on approach, the resulting numbers must be more
than 2 EPNdB below the noise limit specified in Sec.  C36.5.
    (g) During takeoff, lateral, and approach tests, the airplane
variation in instantaneous indicated airspeed must be maintained within
3% of the average airspeed between the 10 dB-down points.
This airspeed is determined by the pilot's airspeed indicator. However,
if the instantaneous indicated airspeed exceeds 3 kt
(5.5 km/h) of the average airspeed over the 10 dB-down
points, and is determined by the FAA representative on the flight deck
to be due to atmospheric turbulence, then the flight so affected may
not be used for noise certification purposes.

    Issued in Washington, DC, under the authority of 49 U.S.C.
106(f), 44701(a)(5), 44715, and Sec.  181 of the FAA Reauthorization
Act of 2018, on March 30, 2020.
Kevin W. Welsh,
Executive Director, Office of Environment & Energy.
[FR Doc. 2020-07039 Filed 4-10-20; 8:45 am]
 BILLING CODE 4910-13-P