Noise Certification Standards: Matternet Model M2 Aircraft
| Published date | 27 August 2021 |
| Citation | 86 FR 48281 |
| Record Number | 2021-17769 |
| Section | Notices |
| Court | Federal Aviation Administration |
Federal Register, Volume 86 Issue 164 (Friday, August 27, 2021)
[Federal Register Volume 86, Number 164 (Friday, August 27, 2021)]
[Notices]
[Pages 48281-48290]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-17769]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
[Docket No.: FAA-2021-0710; Notice No. 21-01]
Noise Certification Standards: Matternet Model M2 Aircraft
AGENCY: Federal Aviation Administration (FAA), Transportation (DOT).
ACTION: Notice of proposed rulemaking (NPRM), rule of particular
applicability.
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SUMMARY: The Federal Aviation Administration (FAA) proposes noise
certification standards that would apply only to the Matternet model M2
quadcopter unmanned aircraft because there are currently no generally
applicable noise certification standards for this aircraft.
DATES: Send comments on or before September 27, 2021.
ADDRESSES: Send comments identified by docket number FAA-2021-0710
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 202-493-2251.
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 www.regulations.gov, as described in the system
of records notice (DOT/ALL-14 FDMS), which can be reviewed at
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 the Docket Operations in Room W12-140
of the West Building Ground Floor at 1200 New Jersey Avenue SE,
Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday,
except Federal holidays.
FOR FURTHER INFORMATION CONTACT: For technical questions concerning
this action, contact Hua (Bill) He, Federal Aviation Administration,
Office of Environment and Energy, 800 Independence Ave. SW, Room 900
West, Washington, DC 20591; telephone (202) 267-3565; email
[email protected].
SUPPLEMENTARY INFORMATION:
I. Authority for This Rulemaking
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 issued under the authority described in subtitle
VII, chapter 447, section 44715. Section 44715(a)(3) states that an
original type certificate for an aircraft may be issued only after the
Administrator of the FAA prescribes noise standards and regulations
under that section that apply to the aircraft. This regulation is
within the scope of that authority.
II. Need for This Rulemaking
Section 44704 of Title 49 of the United States Code requires that
the FAA issue a type certificate to an applicant that presents a
qualified design. Section 44715(a)(3) requires the FAA to prescribe
noise standards for an aircraft before a type certificate may be
issued.
The current noise standards are contained in 14 CFR part 36. Within
part 36, aircraft are distinguished by type, including jet airplanes,
large turboprop airplanes, small airplanes, helicopters, and
tiltrotors. When the FAA began issuing type certificates for unmanned
aircraft (UA) several years ago, it used the noise standards for the
type of manned aircraft that was most like the UA seeking type
certification and that were compatible with the type classification. In
the first two certifications, the FAA applied the small airplane
standards under subpart F and appendix G. The small helicopter
standards of subpart H and appendix J might also be found as applicable
based on the design of an aircraft presented for certification.
The increase of low-altitude UA operations, and the increased
demand for commercial operation using them, has caused the FAA to re-
evaluate whether the requirements for certain categories of aircraft
(e.g., helicopters, tilt-rotors, small propeller-driven fixed wing)
described in part 36 remain appropriate for the noise certification of
particular UA designs like the Matternet M2. The FAA has recently begun
to consider not only the means of propulsion and flight, but the amount
and type of noise generated by UA, which in many cases are small in
size, electrically (battery) powered, and may include distributed
propulsion features or vertical takeoff and landing capabilities. As a
result, it is possible that these aircraft generate less noise than was
contemplated when part 36 was promulgated.
A significant consideration is the expected operating environment
for UA. Manned airplanes and helicopters normally operate from airports
or helipads that include property that serves as a primary buffer from
the general population. The methods of testing and determining proper
noise limits used these proximities to the population as their bases,
with testing done at large airport test locations and at altitudes
representative of takeoff and landing. The UA addressed in this
proposal, however, is an aircraft that is intended to operate in closer
proximity
[[Page 48282]]
to people, such as delivering packages in residential areas. These uses
are expected to have an impact on persons and property from much closer
distances than traditional piloted aircraft.
When tested under the current requirements of part 36 for manned
aircraft, the noise generated by many UA could be lost in the ambient
background noise at the reference altitude of 492 feet required in part
36 appendix J, while the noise in their proposed operating environments
would be more apparent to persons near it.
The use of distributed electric propulsion and a high level of
automated control at each rotor allow UA to operate with a variety of
profiles, unlike those of larger manned aircraft. The complex vortex
field created by the interaction of the rotors, combined with the
airframe, can cause such aircraft to exhibit highly tonal spectral
content and unique noise directivity patterns that are often coupled
with the vehicle flight dynamics and flight profiles. Such noise
characteristics and flight profiles have not been considered previously
under the standards and testing contained in part 36 and its
appendices. These noise characteristics and flight profiles are
examples of the factors that caused the FAA to test these aircraft and
gather consistent data as a means to understand their relevance and
eventual use in informing future standards generally applicable to UA.
Effective generally applicable noise rules require a base of data
gathered from a test environment common for all aircraft, and
certifications of unmanned aircraft such as this one represent the
early stages of such data gathering. At present, the FAA does not have
a sufficient database of information about the noise generated by most
UA models to establish generally applicable noise standards, due to
their novelty and variety. While small UA have operated under part 107
for several years, those aircraft do not have type or airworthiness
certificates, and did not require noise testing; only limited noise
data on those smaller models has been collected, and most of the
collected data was acquired in a manner inconsistent with formal noise
certification test conditions.
As industry seeks both type and airworthiness certification for UA
to allow operation under part 91 or commercial operation under part
135, a commensurate shift in the noise certification paradigm is
occurring as a means to capture new operational concepts that will be
reflected in future regulations. While the FAA will continue to build a
database of noise characteristics as it engages with certification
applicants, such data gathering takes time and requires input about a
number of models and designs before the influences of design on noise
can be fully understood. FAA expects to use data collected through this
proposed rule to inform future particularly and generally applicable
standards.
Matternet applied for type certification of its aircraft on May 18,
2018. The aircraft is a quadcopter design UA with a maximum takeoff
weight of 29 pounds including a 4-pound payload, and a proposed
operating altitude of 400 feet or lower. Since the FAA has found that
the current noise certification standards cannot be effectively applied
to the Matternet Model M2 UA, in order to fulfill the statutory
requirement under section 44715(a)(3), the FAA is proposing a set of
noise certification standards described in this Rule of Particular
Applicability that would apply only to the Matternet model M2.
Without this proposed rule, Matternet would be unable to
certificate its aircraft until such time as the FAA was able to
establish a rule of general applicability for UA noise certification.
The benefits of this proposal include establishing a noise
certification basis for Matternet to seek type certification, the
fulfillment of the FAA's obligation to provide noise standards under 49
U.S.C. 44715, and the collection of additional data that will be used
to inform the development of a larger UA noise database from which
future standards of general applicability may be developed.
III. Discussion of the Proposal
This proposed rule presents only the noise certification basis for
one new model of UA seeking type certification, the Matternet M2.
Nothing in this proposed rule is intended to affect the airworthiness
certification of this aircraft model or any operational approvals.\1\
Those findings are made separately by the FAA in accordance with the
applicable aircraft certification and operating rules.
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\1\ In addition, this rule neither assesses the environmental
impacts of any eventual operation of the subject aircraft, nor
constitutes any environmental review that may be required by the FAA
before granting operational approval. Any such environmental review
would be completed in advance of granting operational approval(s).
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When an applicant presents an aircraft (of any type) for
certification, the FAA must determine which among its many regulations
apply to the aircraft presented. This is true for airworthiness
standards and noise standards. This is an iterative process, during
which the FAA determines the standards and processes that apply, taking
into account any new or novel features of the aircraft. The FAA works
closely with the applicant to ensure that the applicant understands
what standards apply, and what must be demonstrated during
certification.
As previously discussed, in the case of the Matternet model M2 UA,
the FAA reviewed part 36, including its appendices, and determined that
while the subject aircraft has some characteristics that are similar to
a small helicopter that would be noise certificated under appendix J,
the differences require noise certification test criteria and standards
tailored to the size and features of the UA. The FAA then worked with
Matternet to understand the novel features and expected operating
environment of the aircraft so that the FAA could determine the
appropriate modifications and additions to the limits and procedures to
develop a complete noise certification basis that would effectively
profile the aircraft. The results of the agency's assessments are
presented in this proposed rule. The proposed rule text is annotated at
the beginning of each paragraph to indicate similar requirements in
appendix J for those unfamiliar with noise certification requirements.
The requirements presented in this proposal stand alone for
certification of the M2 aircraft.
In addition to the data gathered for noise certification of the
model M2, the applicant has agreed to conduct another test and give the
resulting data to the FAA to inform the larger database of noise
experience with UA. Data from the supplemental test are not part of the
type or airworthiness certification basis of the aircraft and will not
be evaluated against any noise limits or regulatory criteria for noise
certification purposes.
The supplemental test is designed to gather further information on
an aircraft that is capable of hovering. The FAA developed the
supplemental testing procedure with a consideration toward minimal test
efforts; for example, no new or extra equipment is required.
Additionally, rather than placing microphones at different spatial
locations, the microphone is placed at height 4 feet above the ground
in accordance with paragraph (22) of this proposed rule and remains in
place.
Differences From Generally Applicable Noise Regulations
As stated above, the FAA began its determination of the noise
certification basis for the Matternet M2 aircraft using the outline of
standards and procedures for small helicopters. To compensate for
[[Page 48283]]
the novel aircraft design features, including the size, propulsion
system, and proposed flight operations, the FAA proposes the following
new standards for inclusion in the M2 noise certification basis:
1. The reference altitude for the level flyover test is 250 feet
(rather than 492 feet in appendix J), item 6 in the proposed standard.
This lower reference altitude addresses the nominal altitude for this
UA, and was determined to be representative of the lowest cruise
altitude for this UA based on operational data provided by the
applicant. A major consideration in choosing reference altitude was the
ability to collect sufficient noise signals that exceeded the
background (ambient) noise at a typical test site (maintaining an
acceptable signal-to-noise ratio). As tests are conducted, an applicant
may be directed by the FAA to fly the aircraft at an altitude lower
than the reference height to achieve a signal-to-noise ratio that meets
the certification test requirements. If that occurs, the noise data
collected at the actual test altitude would be mathematically adjusted
to the reference altitude after the testing is complete. All such
adjustments would be included in the test report.
2. The reference airspeeds for flyover testing are: (a) Maximum
flight speed at empty weight; and (b) highest cruise speed at maximum
takeoff weight, (rather than a single reference speed as is used for
small helicopters), paragraph (6)(c) in the proposed rule. Although
both speed and aircraft weight contribute to noise generation, the FAA
does not have sufficient data regarding these two factors to know which
dominates in UA designs such as the Matternet model M2. The proposed
rule requires the aircraft to be tested at two sets of reference
conditions to address the potential noise conditions over a range of
operations determined to be representative of the aircraft operation.
3. The sound exposure level limit is 78 dB at the prescribed new
reference level flyover altitude of 250 feet. Two considerations
resulted in this new limit. The first consideration accounts for the
lower reference altitude, which, without a consideration for weight,
would increase the noise to 85.7 dB, or 3.7 dB higher than 82 dB in
appendix J for a small helicopter weighting less than 3,215 lbs. and
flying at reference altitude of 492 ft. The second consideration is for
aircraft weight. The curve that flattens out at 82 dB in appendix J
applies to small manned helicopters weighing between 0 and 3,125 lbs.;
this curve was simplified to include the possibility of manned
ultralight helicopters of unknown weight. In evaluating the Matternet
M2 noise, the noise curve section reduced at a constant, resulting in
the limit proposed here, which is 7.7 dB lower. The two adjustments
together yields the new noise limit of 78 dB (78 = 82 + 3.7-7.7).
This proposed rule also contains updated terminology, equipment
references, recording standards, and relevant best practices that have
become standard in the industry since appendix J was first adopted in
1992 and are used in current noise certification. As an example, the
FAA included more detailed requirements for the area immediately
surrounding a test microphone regarding the condition of the ground
surface, which is expected to be more sensitive to smaller aircraft
with a single microphone arrangement. Such additions were sourced from
FAA guidance materials and agency orders.
This proposed rule also includes the requirement to create and get
approval for a test plan, which is used during certification testing
but may be unfamiliar to newer certification applicants. An applicant
seeking noise type certification must prepare a test plan when testing
is required to demonstrate compliance to the regulations. The applicant
should submit the test plan early enough to allow the FAA time to
review and approve the test plan before the planned start of testing. A
test plan typically contains descriptions of the aircraft, equipment,
calibration procedures, and test procedures.
The FAA seeks specific input from interested persons concerning the
considerations the agency used to select the proposed reference test
height of 250 feet AGL for flyover noise testing of UAS, as discussed
here. Commenters are encouraged to submit any data that supports the
use of different considerations that would be appropriate for aircraft
of this type.
IV. Regulatory Notices and Analyses
A. Executive Order 12866, Regulatory Planning and Review
This proposed rule of particular applicability is not subject to
review under Executive Order 12866, Regulatory Planning and Review, as
that Executive Order applies only to rules of general applicability.
B. Regulatory Flexibility Act
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 proposed 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 proposed rule is not expected
to have a significant economic impact on a substantial number of small
entities, section 605(b) of the RFA provides that the head of the
agency may so certify, and a regulatory flexibility analysis is not
required.
This proposed rule only impacts Matternet, which is considered a
small business based on the U.S. Small Business Administration (SBA)
size standards. The SBA lists small business size standards based on
the North American Industry Classification System (NAICS). NAICS code
336411 is titled ``Miscellaneous Aircraft Manufacturing,'' and includes
the manufacture of unmanned and robotic aircraft. The SBA defines
industries within this code to be small if they employ 1,500 employees
or less.
The FAA expects this proposed rule of particular applicability
would have small costs for Matternet to conduct tests and gather data.
These would be one-time test costs representing a very small cost
relative to the overall costs of seeking of type certification. This
proposed rule would benefit Matternet by enabling a noise certification
basis for it to complete the type certification it seeks. The FAA
expects this proposed rule would not have a significant economic impact
on Matternet.
If an agency determines that a rulemaking will not result in a
significant economic impact on a substantial number of small entities,
the head of the agency may so certify under section 605(b) of the RFA.
Therefore, based on the foregoing discussion, as provided in section
605(b), the head of the FAA certifies that this rulemaking will not
result in a significant economic impact on a substantial number of
small entities. The FAA requests comments on this certification.
[[Page 48284]]
C. International Trade Impact
The Trade Agreements Act of 1979 (Pub. L. 96-39), as amended by the
Uruguay Round Agreements Act (Pub. L. 103-465), 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 these Acts, 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
determined this proposed rule would not present any obstacle to foreign
commerce of the United States. In addition, this proposed rule is not
contrary to international standards since no international standards
for UA noise certification exist.
D. Unfunded Mandates Reform Act
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 million in lieu of $100
million. This proposed 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. The FAA has determined that
this proposed rule does not impose any new requirement for information
collection covered by the Act.
F. International Compatibility
The FAA remains actively involved in the International Civil
Aviation Organization's (ICAO) Committee on Aviation Environmental
Protection (CAEP) and CAEP's Working Group 1 that addresses aircraft
noise. Working Group 1 began activities to address noise from UA in
2013. There are at present no noise or other environmental standards
for UA that have been adopted into ICAO Annex 16. The FAA has
determined that there are no ICAO Standards and Recommended Practices
that correspond to these proposed regulations so as to require
conformance.
While the FAA has begun type and noise certification of UA, the
European Union Aviation Safety Agency (EASA) has focused on operational
regulations. In March 2020, EASA published its Easy Access Rules for
Unmanned Aircraft (Regulation 2019/947 and delegated regulation 2019/
945), which contain the applicable rules and procedures for the
operation of unmanned aircraft in the EU. While the regulations contain
some requirements for noise measurement depending on the operating
environment of the UA, they are limited to operations in the EU and are
not a certification standard as is proposed here.
G. Environmental Analysis
FAA Order 1050.1F identifies FAA actions that are categorically
excluded from preparation of an environmental assessment or
environmental impact statement under the National Environmental Policy
Act in the absence of extraordinary circumstances. The FAA has
determined this rulemaking action qualifies for the categorical
exclusion identified in paragraph 5-6.6 (d) (Categorical Exclusions for
Regulatory Actions) since it is a rulemaking action that proposes a
certification test standard, and would not presume the acceptability of
operation of any particular aircraft in any location. No extraordinary
circumstances are involved.
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. 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 (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.
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 FAA will consider comments filed
after the comment period has closed if it is possible to do so without
incurring expense or delay. 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.'' The 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 Hua (Bill) He, Federal Aviation Administration, Office of
Environment and Energy, 800 Independence Ave. SW, Room 900
[[Page 48285]]
West, Washington, DC 20591; telephone (202) 267-3565; email
[email protected]. Any commentary that the FAA receives which 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--
1. Searching the Federal eRulemaking Portal (www.regulations.gov);
2. Visiting the FAA's Regulations and Policies web page at
www.faa.gov/regulations_policies or
3. Accessing the Government Printing Office's web page at
www.GovInfo.gov.
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 (202) 267-9680.
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 in item
(1) above.
The Proposed Noise Certification Basis
In consideration of the foregoing, and under the authority of Title
49 of the United States Code, section 44715(a), the Federal Aviation
Administration proposes that the following standards and procedures
apply as the noise certification basis of the Matternet M2 model
aircraft.
All statutory references in this Rule of Particular Applicability
(rule) refer to Title 49 of the United States Code. All regulatory
references refer to Title 14 of the Code of Federal Regulations, part
21 or part 36 and its appendices, unless otherwise cited.
Noise Certification Requirements for the Matternet M2 Model
Aircraft:
(1) General: The requirements and limitations of 14 CFR 36.3 and
36.6 apply to the Matternet M2 model aircraft, except as described
herein.
(a) Limitations (Reference Sec. 36.5, as modified): Pursuant to 49
U.S.C. 44715(b)(4), the noise level in this Rule of Particular
Applicability (rule) has been determined to be as low as is
economically reasonable, technologically practicable, and appropriate
for this aircraft. No determination is made that these noise levels are
or should be acceptable or unacceptable for operation at, into, or out
of, any airport, landing or launch pad, community, or any other
environment that may be impacted or is sensitive to noise.
(b) Acoustical Change (Reference Sec. 36.9 as modified): If, after
type certification using the requirements stated herein, the aircraft
incorporates a change in type design, the changed design is subject to
an acoustical change analysis and approval in accordance with Sec.
21.93(b). After such change in design, the aircraft may not
subsequently exceed the noise limits specified in this rule.
(2) Noise Measurement (Reference Sec. 36.801, as modified): The
noise generated by the aircraft must be measured at the noise measuring
point and under the test conditions prescribed in paragraphs (7)
through (23) of this rule, or using an equivalent procedure approved by
the FAA before testing. Any procedure not approved by the FAA before a
test is performed is subject to disapproval and may require the
aircraft to be retested using an approved procedure.
(3) Noise Evaluation (Reference Sec. 36.803, as modified): The
noise measurement data required by paragraph (2) of this rule must be
obtained using the test procedures in paragraphs (7) through (23) of
this rule, and:
(a) Corrected to the reference conditions contained in paragraphs
(5) and (6) of this rule; and
(b) Evaluated using the procedures in paragraphs (24) through (26)
of this rule, or using an FAA-approved equivalent procedure. Any
procedure not approved by the FAA before a test is performed is subject
to disapproval and may require the aircraft to be retested using an
approved procedure.
(4) Noise Limits (Reference Sec. 36.805, as modified): Compliance
with the noise limits prescribed in paragraphs (28) and (29) of this
rule must be shown for this aircraft for which application for issuance
of a type certificate in the special class is made under part 21.
(5) Reference Conditions--General (Reference part 36 appendix J,
section J36.1, as modified): Paragraphs (6) through (29) of this rule
prescribe the noise certification requirements for this aircraft
including:
(a) The conditions under which each noise certification test must
be conducted and the measurement procedure that must be used to measure
the aircraft noise during the test;
(b) The procedures that must be used to correct the measured data
to the reference conditions, and to calculate the noise evaluation
quantity designated as the A-weighted Sound Exposure Level (SEL,
denoted by symbol LAE); and
(c) The noise limit with which compliance must be shown.
(6) Reference Conditions--Test (Reference part 36 appendix J,
section J36.3, as modified):
(a) Meteorological Conditions--The following are the noise
certification reference atmospheric conditions that are assumed to
exist from the surface to the aircraft altitude:
i. Sea level pressure of 2,116 pounds per square foot (76
centimeters of mercury);
ii. Ambient temperature of 77 degrees Fahrenheit (25 degrees
Celsius);
iii. Relative humidity of 70 percent; and
iv. Zero wind.
(b) Reference test site. The reference test site is flat and
without line-of-sight obstructions, including any area across the
flight path that is long enough to encompass the 10 dB down points of
the A-weighted time history.
(c) Level flyover reference profile. For UA, the reference flyover
profile is a level flight, 250 feet (76.2 meters) above ground level as
measured at the noise measuring station. The reference flyover profile
has a linear flight track and passes directly over the noise monitoring
station. The applicable reference airspeed is stabilized and maintained
throughout the measured portion of the flyover. Rotor speed is normal
operating RPM throughout the 10 dB-down time interval. For UA,
applicable reference airspeeds are:
i. Vmax ~ 0.9VNE, where VNE is the
never-exceed airspeed (at empty weight).
ii. Vcruise ~VH, where VH is the
maximum performance airspeed (at maximum certificated takeoff weight
(MTOW)),
(d) Two series of flyover tests are required. Each series must be
flown at the weight and applicable reference speed conditions as
follows:
i. MTOW (inclusive of payload) and Vcruise; and
ii. Empty weight (no payload) and Vmax.
(7) Noise Measurement Procedures--General (Reference part 36,
appendix J, section J36.101(a) as modified): Paragraphs (8) through
(10) of this rule prescribe the conditions under which the aircraft
noise certification tests must be conducted, and the measurement
procedures that must be used to measure the aircraft noise during each
test.
(8) Test site requirements (Reference: Part 36, appendix J, section
J36.101(b), as modified):
(a) The noise measuring station must be surrounded by terrain
having no
[[Page 48286]]
excessive sound absorption characteristics, such as might be caused by
thick, matted, or tall grass, shrubs, wooded areas, or loose soil.
Grass is acceptable if mowed to 3 inches or less in a 25 foot radius
around any sound measuring stations.
(b) During the period when the flyover noise measurement is within
10 dB of the maximum A-weighted sound level, no obstruction that
significantly influences the sound field from the aircraft may exist
within a conical space above the noise measuring position (the point on
the ground vertically below the microphone). The cone is defined by an
axis normal to the ground and by half-angle 80 degrees from this axis.
(9) Weather restrictions (Reference: Part 36, appendix J, section
J36.101(c) as modified): Each test must be conducted under the
following atmospheric conditions:
(a) No rain or other precipitation.
(b) Ambient air temperature between 36 degrees and 95 degrees
Fahrenheit (2 degrees and 35 degrees Celsius), inclusively, and
relative humidity between 20 percent and 95 percent inclusively, except
that testing may not take place where combinations of temperature and
relative humidity result in a rate of atmospheric attenuation greater
than 10 dB per 100 meters (30.5 dB per 1,000 feet) in the one-third
octave band centered at 8 kiloHertz.
(c) Wind velocity that does not exceed 10 knots (19 km/h) and a
crosswind component that does not exceed 5 knots (9 km/h). The wind
must be determined using a continuous averaging process of no greater
than 30 seconds.
(d) Measurements of ambient temperature, relative humidity, wind
speed, and wind direction must be made between 4 feet (1.2 meters) and
33 feet (10 meters) above the ground. Unless otherwise approved by the
FAA, ambient temperature and relative humidity must be measured at the
same height above the ground.
(e) No anomalous wind conditions (including turbulence) or other
anomalous meteorological conditions that could significantly affect the
noise level of the aircraft when the noise is recorded at the noise
measuring station.
(f) If the measurement site is within 6,560 feet (2,000 meters) of
a fixed meteorological station (such as those found at airports or
other facilities), the weather measurements reported at that station
may be used for temperature, relative humidity and wind velocity, when
approved by the FAA before the test is conducted. The use of
measurements reported at a fixed meteorological station, if not
approved by the FAA before a test is performed, may cause the test to
be disapproved and require that the aircraft be retested.
(10) Aircraft test procedures (Reference part 36, appendix J,
section J36.101(d), as modified):
(a) The aircraft test procedures and noise measurements must be
conducted and processed in a manner that yields the noise evaluation
measure designated LAE, as defined in paragraph (17) of this
rule.
(b) The aircraft height relative to the noise measurement point
sufficient to make corrections required in paragraph (26) of this rule
must be determined by an FAA-approved method that is independent of
normal flight instrumentation, such as a Differential Global
Positioning System (DGPS), or photographic scaling techniques. The
aircraft position in three dimensions relative to the microphone must
be monitored and recorded at all times during the test and data
collection, with correlation via time synchronization to the acoustic
noise data collection. The accuracy of the aircraft location system,
and all sources of inaccuracy, along with possible error introduction
when correlating to measured and recorded noise (inaccuracies of timing
devices and methods), must be determined and reported. A description of
the aircraft location system and its accuracy must be included as part
of the noise test plan required by paragraph (31) of this rule, and
approved by the FAA before use.
(c) If an applicant demonstrates that the design characteristics of
the aircraft would prevent flight from being conducted in accordance
with the reference test conditions prescribed in paragraph (6) of this
rule, then the applicant may request a variance in reference test
conditions to be used. Any variance from standard reference test
conditions is limited to that required for the subject aircraft design
characteristics that make compliance with the reference test conditions
impossible.
(11) Flyover Test Conditions (Reference part 36, appendix J,
section J36.105(a), as modified): Paragraphs (12) through (15) of this
rule prescribe the flight test conditions and allowable random
deviations for flyover noise tests conducted to demonstrate compliance
with this rule.
(12) Level flight height and lateral path tolerances (Reference
part 36, appendix J, section J36.105(b), as modified): A test series
must consist of at least six flights. The number of level flights made
with a headwind component must be equal to the number of level flights
made with a tailwind component over the noise measurement station:
(a) In level flight and in cruise configuration;
(b) At the test height above the ground level over the noise
measuring station as defined in paragraph (6) of this rule. For the
selected height, the vertical tolerance of this height should be 10% value; and
(c) Within 10 degrees from the zenith.
(13) Airspeed and Controls (Reference part 36, appendix J, section
J36.105(c), as modified): Each flyover noise test flight must be
conducted:
(a) At the reference airspeed specified in paragraph (6)(c) of this
rule; and
(b) With the flight controls stabilized during the period when the
measured aircraft noise level is within 10 dB of the maximum A-weighted
sound level (LAmax).
(14) Aircraft weight (Reference part 36, appendix J, section
J36.105(d), as modified): For the weight at which noise certification
is requested, the aircraft test weight for each flyover test series
must be specified for:
(a) MTOW (inclusive of payload); and
(b) Empty weight (no payload).
(15) Flyover height adjustment (Reference part 36, appendix J,
section J36.105(e), as modified): If ambient noise at the measurement
station, measured in accordance with paragraphs (17) through (21) of
this rule, is found to be within 15 A-weighted decibels (dB(A)) of the
A-weighted aircraft noise level (LAmax), measured at the
same location, the applicant may request the FAA approve an alternate
flyover height. If an alternate flyover height is approved, the results
must be adjusted to the reference flyover height specified in paragraph
(6)(c) of this rule using an FAA-approved method.
(16) Supplemental hover test conditions--This is a supplemental
test to collect data for assessment of community noise impacts, and to
inform later general noise and test standards for UA. This supplemental
test does not require compliance with a noise limit and does not affect
the noise certification findings for the subject aircraft.
The aircraft is required to hover at different spatial locations
relative to the microphone in accordance with subparagraphs (a) through
(f) of this paragraph.
(a) The aircraft must be at MTOW, inclusive of maximum payload
weight of cargo.
(b) To ensure that the widest dimensional profile of the noise
source is captured in the recordings, for each aircraft attitude
heading (0, 90, 180 and
[[Page 48287]]
270 degrees) relative to the microphone position for hover conditions
described in paragraphs (16)(c) and (d) of this rule, stabilize the
aircraft in hover and record the sound in accordance with paragraph
(16)(f) of this rule.
(c) Hover condition #1 (sound elevation angle at zero degrees): The
aircraft maintains a hover condition at a lateral distance of 20 feet
to the microphone and at 4 feet AGL (rotors in the same plane as the
microphone). Test when the conditions are optimal for minimal influence
of wind on the noise recording.
(d) Hover condition #2 (sound elevation angle at 45 degrees): The
aircraft maintains a hover condition at a lateral distance of 20 feet
to the microphone position and at 20 feet AGL. Test when the conditions
are optimal for minimal influence of wind on the noise recording.
(e) Hover condition #3 (overhead, or sound elevation angle at 90
degrees): The aircraft maintains a hover condition at 20 feet AGL and
hold centered within a one foot radial over the microphone location.
(f) For the noise measurements at each hover condition, record the
value of the equivalent sound level (Leq) and SPL in \1/3\ octave bands
for a minimum of 30 seconds for each of the test conditions (paragraphs
16(c) through (e) of this rule).
(g) The tolerance of the hover height or lateral distance is within
1 ft., and the tolerance of the headings is within 5 degrees.
[GRAPHIC] [TIFF OMITTED] TN27AU21.007
(17) Measurement of aircraft noise received on the ground--General
(Reference: Part 36, appendix J, section J36.109(a), as modified):
Aircraft noise measurements made for the purpose of noise certification
in accordance with the requirements of this regulation must be obtained
using:
(a) The noise evaluation metric prescribed in paragraph (18) of
this rule;
(b) Acoustic equipment that meets the specifications prescribed in
paragraphs (19) and (20) of this rule; and
(c) The calibration and measurement procedures prescribed in
paragraphs (21) and (22) of this rule.
(18) Measurement of aircraft noise received on the ground--Noise
unit definition (Reference part 36, appendix J, section J36.109(b), as
modified):
(a) The sound exposure level, as expressed in LAE, is
defined as the level, in decibels, of the time integral of squared `A'-
weighted sound pressure (PA) over a given time period or
event, with reference to the square of the standard reference sound
pressure (P0) of 20 micropascals and a reference duration of
one second.
(b) The sound exposure level in units of decibels (dB) is defined
by the expression:
[GRAPHIC] [TIFF OMITTED] TN27AU21.008
Where T0 is the reference integration time of one second
and (t2-t1) is the integration time interval.
(c) The integral equation of paragraph (18)(b) can also be
expressed as:
[[Page 48288]]
[GRAPHIC] [TIFF OMITTED] TN27AU21.009
Where LA(t) is the time varying A-weighted sound level.
(d) The integration time (t2-t1) in practice
must not be less than the time interval during which LA(t)
first rises to within 10 dB(A) of its maximum value (LAmax)
and last falls below 10 dB(A) of its maximum value.
(19) Measurement of Aircraft Noise Received on the Ground--
Measurement System (Reference part 36, appendix J, section J36.109(c),
as modified):
(a) Acoustical measurement system instrumentation must be
equivalent to the following and approved by the FAA:
i. A microphone system with frequency response that is compatible
with the measurement and analysis system accuracy prescribed in
paragraph (20) of this rule;
ii. Tripods or similar microphone mountings that minimize
interference with the sound energy being measured; and
iii. Recording and reproducing equipment with characteristics,
frequency response, and dynamic range that are compatible with the
response and accuracy requirements of paragraph (20) of this rule.
(b) The calibration and checking of measurement systems must be
accomplished in accordance with the procedures described in part 36,
appendix A, section A36.3.9.
(20) Measurement of Aircraft Noise Received on the Ground--Sensing,
recording, and reproducing equipment (Reference part 36, appendix J,
section J36.109(d), as modified):
(a) The sound pressure time-history (audio) signals obtained from
aircraft flyovers under this paragraph must be recorded digitally at a
minimum sample rate of 44 kilohertz (kHz) for a minimum bandwidth of 20
hertz (Hz) to 20 kHz, and encoded using a minimum of 16 bit linear PCM
(or equivalent) during analog to digital conversion. Digital audio
recording must also meet the additional requirements specified in part
36, appendix A, section A36.3.6 ``Recording and Reproducing Systems.''
(b) The LAE value from each flyover and A-weighed Leq
(LAeq) values from each hover test flight condition may be
determined directly from an integrating sound level meter that meets
the specifications of International Electrotechnical Commission (IEC)
Standard 61672-1 (2013) for a Class 1 instrument set at ``slow''
response.
(c) The acoustic signal from the aircraft, along with the
calibration signals specified in paragraph (21) and the background
noise signal required by paragraph (22) of this rule, must be recorded
in a digital audio format as specified in paragraph (20)(a) of this
rule for subsequent analysis for an integrating sound level meter
identified in paragraph (20)(b) of this rule. The record/playback
system must conform to the requirements prescribed in part 36, appendix
A, section A36.3.6 ``Recording and Reproducing Systems''. The recorder
must comply with the specifications of IEC standard 61265 2nd edition
(2018).
(d) The characteristics of the complete system must meet the
specifications of IEC standard 61672-1 for the microphone, amplifier,
and indicating instrument characteristics.
(e) The response of the complete system to a plane, progressive
wave of constant amplitude must lie within the tolerance limits
specified for Class 1 instruments in IEC standard 61672-1 for weighting
curve ``A'' over the frequency range of 45 Hz to 20 kHz.
(f) A windscreen must be used with the microphone during each
measurement of the aircraft flyover noise. Correction for any insertion
loss produced by the windscreen, as a function of the frequency of the
acoustic calibration required by paragraph (21) of this rule, must be
applied to the measured data, and each correction applied must be
included in the test report.
(21) Measurement of Aircraft Noise Received on the Ground--
Calibrations (Reference part 36, appendix J, section J36.109(e), as
modified):
(a) For the aircraft acoustic signal recorded for subsequent
analysis, the measuring system and components of the recording system
must be calibrated as prescribed in Title 14 CFR, part 36, appendix A.
(b) If the aircraft acoustic signal is measured directly using an
integrating sound level meter:
i. The overall sensitivity of the measuring system must be checked
before and after the series of flyover tests and at intervals (not
exceeding a two-hour duration) during the flyover tests using an
acoustic calibrator generating a sinusoidal signal at a known sound
pressure level and at a known frequency.
ii. The performance of equipment in the system is considered
satisfactory if, during each day's testing, the variation in the
measured value for the acoustic calibrator does not exceed 0.5 dB. The
LAE data collected during the flyover tests must be adjusted
to account for any variation in the calibration value.
iii. A performance calibration analysis of each piece of
calibration equipment, including acoustic calibrators, reference
microphones, and voltage insertion devices, must have been made during
the six calendar months preceding the beginning of the aircraft flyover
series. Each calibration must be traceable to the National Institute of
Standards and Technology.
(22) Measurement of Aircraft Noise Received on the Ground--Noise
measurement procedures (Reference part 36, appendix J, section
J36.109(f), as modified):
(a) The microphone must be of a pressure-sensitive capacitive type
designed for nearly uniform grazing incidence response. The microphone
must be mounted with the center of the sensing element 4 feet (1.2
meters) above the local ground surface and must be oriented for grazing
incidence such that the sensing element (diaphragm) is substantially in
the plane defined by the nominal flight path of the aircraft and the
noise measurement station. A microphone that satisfies the requirements
of this paragraph must be used when determining compliance with the
noise limit prescribed in paragraph (29) of this rule.
(b) For each aircraft acoustic signal recorded for subsequent
analysis, the frequency response of the electrical system must be
determined at a level within 10 dB of the full-scale reading used
during the test.
(c) The background noise, including both ambient acoustical sound
present at the microphone site and electrical noise of the measurement
systems, must be determined in the test area and the system gain set at
levels which will be used for aircraft noise measurements. If aircraft
sound levels do not exceed the background sound levels by at least 15
dB(A), flyovers at an FAA-approved lower height may be used; the
results must be adjusted to the reference measurement point by an FAA-
approved method.
(d) When an integrating sound level meter is used to measure the
aircraft noise, the instrument operator must monitor the continuous A-
weighted (slow response) noise levels throughout each flyover to ensure
that the A-weighted sound exposure level (LAE) integration
process includes, at
[[Page 48289]]
minimum, all of the noise signal between the LAmax and the
10 dB down points in the flyover time history. The instrument operator
must note the actual dB(A) levels at the start and stop of the
LAE integration interval and document these levels along
with the value of LAmax and the integration interval (in
seconds) for inclusion in the noise data submitted as part of the
reporting requirements in paragraph (23) of this regulation.
(23) Data Reporting--General (Reference part 36, appendix J,
section J36.111(a), as modified): Data representing physical
measurements, and corrections to that measured data, including
corrections to measurements for equipment response deviations, must be
recorded in permanent form and appended to the test reports required by
this rule. Each correction is subject to FAA approval.
(24) Data Submission (Reference part 36, appendix J, section
J36.111(b), as modified): After the completion of all certification
tests required by this rule, the following must be submitted to the
FAA:
(a) A test report containing the following:
(i) Measured and corrected sound levels obtained with equipment
conforming to the standards prescribed in paragraphs (17) through (22)
of this rule;
(ii) A description of the equipment and systems used for
measurement and analysis of all acoustic, aircraft performance and
flight path, and meteorological data;
(iii) The atmospheric environmental data required to demonstrate
compliance with this rule, as measured throughout the test period;
(iv) Conditions of local topography, nearby ground cover (if any),
or events that may have interfered with a sound recording;
(v) The following aircraft information:
(A) Type, model, and serial numbers, if any, of aircraft, engine(s)
and rotor(s) and/or propellers tested;
(B) Gross dimensions of aircraft, location of engines or motors,
rotors or propellers, number of blades for each rotor or propeller, and
the range of rotational speeds of the rotors;
(C) MTOW at which certification under this rule is requested;
(D) Aircraft configuration, including landing gear positions;
(E) Aircraft Airspeeds: VNE and Vmax for both
empty weight and maximum payload configuration, or for maximum range,
whichever is greatest, and applicable as reference and operational
airspeeds;
(F) Aircraft gross weight for each test run;
(G) Indicated and true airspeed for each test run; if indicated and
true airspeed for each run are not available, then ground speed as
measured from a DGPS, or from an alternate method, may be approved by
the FAA;
(H) Ground speed, if measured, for each run;
(I) Aircraft engine performance as determined from aircraft
instruments and manufacturer's data; and
(J) Aircraft flight path above ground level, referenced to the
microphone position of the noise measurement station, in feet,
determined using an FAA-approved method that is independent of normal
flight instrumentation, such as DGPS or photo scaling techniques at the
microphone location;
(vi) Aircraft position and performance data necessary to make the
adjustments prescribed in paragraph (27) of this rule and to
demonstrate compliance with the performance and position restrictions
prescribed in paragraphs (11) through (16) of this rule; and
(vii) The aircraft position in three dimensions and orientation
(for hover) relative to the microphone must be monitored and recorded
at all times during the test and data collection, with correlation via
time synchronization to the acoustic noise data collection.
(b) All of the recorded audio data from all phases of all flight
tests used to demonstrate compliance with this rule.
(c) All recordings and data collected during the measurement
activity required by paragraph (16) of this rule. These data will not
affect the outcome of this certification findings intended to
demonstrate compliance with this rule and may be submitted separately
from data that affects certification.
(25) Noise Evaluation and Calculations--Noise Evaluation Expressed
in LAE (Reference: Part 36, appendix J, section J36.201, as
modified): The noise evaluation measure must be expressed as the
LAE in units of dB(A) as prescribed in paragraph (18) of
this rule. The LAE value for each flyover may be determined
directly using an integrating sound level meter. Specifications for the
integrating sound level meter and requirements governing the use of
such instrumentation are prescribed in paragraphs (17) through (22) of
this rule.
(26) Noise Evaluation and Calculations--Calculation of Noise Levels
(Reference part 36, appendix J, section J36.203, as modified):
(a) To demonstrate compliance with the noise level limits specified
in paragraph (29) of this rule, the LAE noise levels from
each valid flyover, corrected as necessary to reference conditions in
accordance with paragraph (27) of this rule, must be arithmetically
averaged to obtain a single LAE dB(A) mean value for each
flyover series. No individual flyover run may be omitted from the
averaging process, unless approved by the FAA.
(b) The minimum sample size acceptable for the aircraft flyover
certification measurements is six. The number of samples must be
sufficient to establish statistically a 90 percent confidence limit
that does not exceed 1.5 dB(A).
(c) All data used and calculations performed under this paragraph,
including the calculated 90 percent confidence limits, must be
documented and provided in accordance with the data reporting and
submission requirements of paragraphs (23) and (24) of this rule.
(27) Data Correction Procedures (Reference part 36, appendix J,
section J36.205, as modified):
(a) When certification test conditions measured in accordance with
paragraphs (7) through (23) of this rule differ from the reference test
conditions prescribed in paragraph (6) of this rule, appropriate
adjustments must be made to the measured noise data in accordance with
the methods set out in paragraphs (27)(b) and (c) of this rule. At
minimum, appropriate adjustments in accordance with paragraph (27)(b)
of this rule must be made for off-reference altitude and for any
difference between reference airspeed and adjusted reference airspeed
in accordance with paragraph (27)(c) of this rule.
(b) The adjustment for off-reference altitude may be approximated
from:
>deltadeltaAE noise level to correct for an off-
reference flight path, HT is the height, in feet, of the
test aircraft when directly over the noise measurement point, and the
constant (12.5) accounts for the effects on spherical spreading and
duration from the off-reference altitude.
(c) The adjustment for the difference between reference airspeed
and adjusted reference airspeed is calculated from:
>deltadeltaAE noise level to correct for the
influence of airspeed on the integration duration of the measured
flyover event as received at the noise measurement station;
VR is the reference airspeed as prescribed in
[[Page 48290]]
paragraph (6)(c) of this rule, and VRA is a speed adjustment
applied to the reference airspeed to allow flying at an airspeed that
provides the reference tip Mach speed. The reference airspeed must be
adjusted for the atmospheric conditions on site.
(d) All data used and calculations performed under this paragraph
must be documented and submitted in accordance with paragraphs (22) and
(23).
(28) Noise Limit Compliance--Noise Measurement, Evaluation, and
Calculation (Reference part 36, appendix J, section J36.301, as
modified): In demonstrating compliance with this rule, the aircraft
noise levels must be measured, evaluated, and calculated in accordance
with paragraphs (7) through (26) of this rule.
(29) Noise Limit (Reference part 36, appendix J, section J36.305,
as modified): The calculated noise levels of the aircraft, at the
measuring point described in paragraphs (7) through (10) of this rule,
must be shown to not exceed 78.0 decibels LAE at the
reference altitude of 250 feet.
(30) Manuals, Markings, and Placards (Reference part 36 Sec. Sec.
36.1501 and 36.1581, as modified):
(a) All procedures, weights, configurations, and information or
data used to obtain the certified noise levels required to demonstrate
compliance with this rule, including equivalent procedures used for
flight, testing, and analysis, must be approved by the FAA.
(b) Noise levels achieved during type certification must be
included in the approved portion of each Unmanned Aircraft Flight
Manual for the subject aircraft. If an Unmanned Aircraft Flight Manual
is not approved, the procedures and information must be furnished in a
combination of manual material, markings, and placards approved by the
FAA. The noise level information that must be included is as follows:
i. The noise level information must be one value for flyover as
defined and required by these specifications; the value is determined
at the maximum reference speed, weight and configuration in accordance
with paragraph (6)(c) of this rule. The noise level value must also
indicate the series from which it was determined.
ii. If supplemental operational noise level information is included
in the approved portion of the Unmanned Aircraft Flight Manual, it must
be segregated, identified as information that is provided in addition
to the certificated noise levels, and clearly distinguished from the
information required by paragraph (30)(b)(i) of this rule.
iii. The following statement must be included in each approved
manual near the listed noise level:
No determination has been made by the Federal Aviation
Administration that the noise levels of this aircraft are or should be
acceptable or unacceptable for operation at, into, or out of any
location or environment that may be affected by operational noise.
(31) Test Plan Preparation and Approval: Prior to conducting any
testing and data collection required by this rule, the applicant must
prepare a test plan and obtain approval of it from the FAA's Aircraft
Certification Service, Policy & Innovation Division (P&I) (or another
FAA employee designated by the P&I Division).
(32) Test Witnessing: The FAA P&I (or another FAA employee
designated by the P&I Division) must witness the test and data
collection required by this rule for the results to be valid for
certification. Other acoustic focals from FAA's Aircraft Certification
Office and Acoustic Engineer(s) from the Office of Environment and
Energy or Volpe National Transportation Systems Center may also be
present to observe the tests.
(33) Test Report Preparation and Approval: The applicant must
prepare a report that includes all of the findings and data required
under this rule. The report must be approved by the FAA P&I Division
(or another FAA employee designated by the P&I Division) as a part of
the aircraft certification record.
Issued in Washington, DC.
Kevin Welsh,
Executive Director, Office of Environment and Energy.
[FR Doc. 2021-17769 Filed 8-26-21; 8:45 am]
BILLING CODE 4910-13-P
