Federal Register / Vol. 86, No. 164 / Friday, August 27, 2021 / Notices 48281 

• Contact information, including the 

full legal name of the organization 

making the comment, whether the 

commenter is a third party (e.g., law 

firm, trade association, or customs 

broker) submitting on behalf of an 

organization or industry, and the name 

of the third party organization, if 

applicable. 

• The annex (annexes A, B, C, or D) 

of the December 29 notice (85 FR 85831) 

with the exclusion you are commenting 

on, the specific exclusion (number for 

the exclusion on which you are 

commenting as provided in the annex of 

the December 29 notice). 

• Whether you support or oppose 

extending the exclusion beyond 

September 30, 2021. 

• Rationale for supporting or 

opposing an extension. 

Commenters also may provide any 

other information or data that they 

consider relevant. 

D. Submission Instructions 

To be assured of consideration, you 

must submit your comment when the 

public docket on the portal is open— 

from August 27, 2021, to September 27, 

2021. Parties seeking to comment on 

two or more exclusions must submit a 

separate comment for each exclusion. 

By submitting a comment, the 

commenter certifies that the information 

provided is complete and correct to the 

best of their knowledge. 

Greta M. Peisch, 

General Counsel, Office of the United States 

Trade Representative. 

[FR Doc. 2021–18521 Filed 8–26–21; 8:45 am] 

BILLING CODE 3290–F1–P 

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. 

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 hua.he@faa.gov. 

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 


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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). 

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. 

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 


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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-forprofit 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. 


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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 


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West, Washington, DC 20591; telephone 

(202) 267–3565; email hua.he@faa.gov. 

Any commentary that the FAA receives 

which is not specifically designated as 

CBI will be placed in the public docket 

for this rulemaking. 

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 § 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 

§ 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 § 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 

§ 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 

§ 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 § 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 


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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 halfangle 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 


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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. 

(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: 

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: 


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11:1 

0 

#3 

4' microphone 

• l 

ol 

! 

! 

I 

Sketch of supplemental hover test conditions. D = 20 feet. 

2 

L = 10 log 2. rtz (P A(t)) dt (dB) AE 10 To h1 Po 
48288 Federal Register / Vol. 86, No. 164 / Friday, August 27, 2021 / Notices 

Where LA(t) is the time varying Aweighted 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 FAAapproved 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 Aweighted sound exposure level (LAE) 

integration process includes, at 


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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: 

>delta< J1 = 12.5 log10(HT/250) (dB) 

Where >delta<J1 is the quantity in 

decibels that must be algebraically 

added to the measured LAE 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: 

>delta< J3 = 10 log10(VRA/VR) (dB); 

Where >delta<J3 is the quantity in 

decibels that must be algebraically 

added to the measured LAE 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 


lotter on DSK11XQN23PROD with NOTICES1
48290 Federal Register / Vol. 86, No. 164 / Friday, August 27, 2021 / Notices 

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 §§ 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 

DEPARTMENT OF TRANSPORTATION 

Federal Highway Administration 

Notice of Final Federal Agency Action 

on a Proposed Highway Project in 

Wisconsin 

AGENCY: Federal Highway 

Administration (FHWA), Department of 

Transportation (DOT). 

ACTION: Notice of limitation on claims 

for judicial review of actions. 

SUMMARY: The FHWA is issuing this 

notice to announce actions taken that 

are final Federal agency actions. The 

final agency actions relate to a proposed 

highway project, along United States 

Highway (US) 51 in Dane County, 

Wisconsin between Interstate 39/90 east 

of the city of Stoughton and US 12/18 

in the city of Madison. Those actions 

grant approvals for the project. 

DATES: By this notice, the FHWA is 

advising the public of final agency 

actions subject to 23 U.S.C. 139(l)(1). A 

claim seeking judicial review of the 

Federal agency actions on the highway 

project will be barred unless the claim 

is filed on or before January 24, 2022. 

If the Federal law that authorizes 

judicial review of a claim provides a 

time period of less than 150 days for 

filing such a claim, then that shorter 

time period still applies. 

FOR FURTHER INFORMATION CONTACT: For 

FHWA, Bethaney Bacher-Gresock, 

Environmental Program and Project 

Specialist, FHWA Wisconsin Division 

Office, City Center West, 525 Junction 

Road, Suite 8000, Madison, WI 53717; 

email bethaney.bacher-gresock@dot.gov; 

telephone: (608) 662–2119. For 

Wisconsin Department of 

Transportation (WisDOT), Jeff Berens, 

WisDOT Project Manager, WisDOT SWRegion, Madison Office, 2101 Wright 

Street, Madison WI, 53704; email 

jeff.berens@dot.wi.gov; telephone: (608) 

245–2656. 

SUPPLEMENTARY INFORMATION: The 

FHWA, in cooperation with the 

WisDOT, proposes roadway 

improvements to US 51 on existing 

alignment in Dane County, Wisconsin 

between Interstate 39/90, east of the city 

of Stoughton, and US 12/18 in Madison. 

The proposed improvement would 

include: 

1. Reconstruction of 2-lane US 51 east 

of Stoughton. 

2. Reconstruction of US 51 through 

Stoughton. 

3. Urban 4-lane reconstruction and 

capacity expansion along the west side 

of Stoughton. 

4. Reconstruction of rural 2-lane US 

51 (Stoughton to McFarland) with 

intersection improvements. 

5. Urban 4-lane reconstruction in 

McFarland. 

6. Pavement replacement between 

Larson Beach Road and Terminal Drive/ 

Voges Road in McFarland. 

The actions by the Federal agencies, 

and the laws under which such actions 

were taken, are described in the 

Environmental Assessment (EA)/ 

Finding of No Significant Impact 

(FONSI) for the project, approved on 

August 17, 2021 and in other documents 

in the FHWA project records. The EA, 

FONSI and other project records are 

available by contacting WisDOT or 

FHWA at the addresses provided in the 

‘‘For Further Information Contact’’ 

section of this notice. The EA/FONSI 

may be viewed and downloaded from 

the project website at https:// 


lotter on DSK11XQN23PROD with NOTICES1