42796 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Parts 21 and 36

[Docket No. FAA–2000–7587; Notice No. 00–

08]

RIN 2120–AH03

Noise Certification Standards for

Subsonic Jet Airplanes and Subsonic

Transport Category Large Airplanes

AGENCY: Federal Aviation

Administration, DOT.

ACTION: Notice of Proposed Rulemaking

(NPRM).

SUMMARY: The FAA is proposing

changes to the noise certification

standards for subsonic jet airplanes and

subsonic transport category large

airplanes. These proposed changes are

based on the joint effort of the Federal

Aviation Administration (FAA), the

European Joint Aviation Authorities

(JAA), and Aviation Rulemaking

Advisory Committee (ARAC), to

harmonize the U.S. noise certification

regulations and the European Joint

Aviation Requirements (JAR) for

subsonic jet airplanes and subsonic

transport category large airplanes. These

proposed changes would provide nearly

uniform noise certification standards for

airplanes certificated in the United

States and in the JAA countries. The

harmonization of the noise certification

standards would simplify airworthiness

approvals for import and export

purposes.

DATES: Comments must be received on

or before October 10, 2000.

ADDRESSES: Address your comments to

the Docket Management System, U.S.

Department of Transportation, Room

Plaza 401, 400 Seventh Street, SW.,

Washington, DC 20590–0001. You must

identify the docket number FAA–2000–

7587 at the beginning of your

comments, and you should submit two

copies of your comments. If you wish to

receive confirmation that FAA received

your comments, include a selfaddressed, stamped postcard.

You may also submit comments and

you may review public dockets through

the Internet at http://dms.dot.gov. You

may review the public docket

containing comments to these proposed

regulations in person in the Dockets

Office between 9:00 a.m. and 5:00 p.m.,

Monday through Friday, except Federal

holidays. The Dockets Office is on the

plaza level of the NASSIF Building at

the Department of Transportation at the

above address.

FOR FURTHER INFORMATION CONTACT:

James Skalecky, AEE–100, Office of

Environment and Energy (AEE), Federal

Aviation Administration, 800

Independence Avenue, SW.,

Washington, DC 20591; telephone (202)

267–3699; facsimile (202) 267–5594; or

email at james.skalecky@faa.gov.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to

participate in this rulemaking by

submitting written comments, data,

views, or arguments. Comments on the

possible environmental, economic, and

federalism or energy related impact of

the adoption of this proposal are

welcomed.

Comments should carry the regulatory

docket or notice number and should be

submitted in triplicate to the Rules

Docket address specified above. All

comments received and a report

summarizing any substantive public

contact with FAA personnel on this

rulemaking will be filed in the docket.

The docket is available for public

inspection both before and after the

closing date for receiving comments.

Before taking any final action on this

proposal, the Administrator will

consider the comments made on or

before the closing date for comments,

and the proposal may be changed in

light of the comments received.

The FAA will acknowledge receipt of

comments if commenters include a selfaddressed, stamped postcard with the

comments. The postcards should be

marked ‘‘Comments to Docket No. FAA–

2000–7587.’’ When the comments are

received by the FAA, the postcards will

be dated, time stamped, and returned to

the commenters.

Availability of the NPRM

An electronic copy of this document

may be downloaded using a modem and

suitable communications software from

the FAA regulations section of the

FedWorld electronic bulletin board

service (telephone: (703) 321–3339) or

the Government Printing Office (GPO)’s

electronic bulletin board service

(telephone: (202) 512–1661).

Internet users may reach the FAA’s

web page at http://www.faa.gov/avr/

arm/nprm/nprm.htm or the GPO’s web

page at http://www.access.gpo.gov/nara

for access to recently published

rulemaking documents.

Any person may obtain a copy of this

document by submitting 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. Communications must

identify the notice number or docket

number of this NPRM.

Persons interested in being placed on

the mailing list for future rulemaking

documents should request from the

above office a copy of Advisory Circular

No. 11–2A, Notice of Proposed

Rulemaking Distribution System, which

describes the application procedure.

Background

Current Regulations

Under 49 U.S.C. 44715, the

Administrator of the Federal Aviation

Administration is directed to prescribe

‘‘standards to measure aircraft noise and

sonic boom; . . . and regulations to

control and abate aircraft noise and

sonic boom.’’ Part 36 of Title 14 of the

Code of Federal Regulations (part 36)

contains the FAA’s noise standards and

regulations that apply to the issuance of

type certificates for all types of aircraft.

Subparts A, B and C and appendices A,

B and C of part 36 contain the

requirements and standards that apply

to subsonic jet airplanes and subsonic

transport category large airplanes.

Appendices A, B and C of part 36

specify the test conditions, procedures,

and noise levels necessary to

demonstrate compliance.

Government and Industry Cooperation

In June 1990 at a meeting of the Joint

Aviation Authorities (JAA) Council,

which consists of JAA members from

European countries and the FAA, the

FAA Administrator committed the FAA

to support the harmonization of the U.S.

regulations with the Joint Aviation

Regulations (JAR). The Joint Aviation

Regulations are being developed for use

by the European authorities that are

member countries of the JAA.

In January 1991, the FAA established

the Aviation Rulemaking Advisory

Committee to serve as a forum for the

FAA to obtain input from outside the

government on major regulatory issues

facing the agency. The FAA has tasked

ARAC with noise certification issues.

These issues involve the harmonization

of part 36 with JAR 36, the

harmonization of associated guidance

material including equivalent

procedures, and interpretations of the

regulations. On October 17, 1995, the

ARAC established the FAR/JAR

Harmonization Working Group for

Subsonic Transport Category Large

Airplanes and Subsonic Turbojet

Powered Airplanes (60 FR 53824). The

working group task included reviewing

the applicable provisions of subparts A,

B, and C, and appendices A, B, and C

of part 36, and harmonizing them with

the corresponding applicable provisions

Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules 42797

of JAR 36. The working group was asked

to consider the current international

standards and recommended practices,

as issued under International Civil

Aviation Organization (ICAO), Annex

16, Volume 1, and its associated

Technical Manual, as the basis for

development of these harmonization

proposals. A recommendation for

amending part 36 was forwarded to the

ARAC. After due consideration

including a meeting open to the public

on May 18, 2000, this recommendation

agreed to by ARAC was forwarded, in

the form of a draft NPRM, to the FAA

for consideration.

Synopsis of the Proposal

Part 36 contains noise standards for

aircraft type and airworthiness

certification. Subparts A, B, and C, and

the related appendices A, B, and C, of

part 36 prescribe noise levels and test

procedures for subsonic jet airplanes

and subsonic transport category large

airplanes, including rules governing the

issuance of original, amended, or

supplemental type certificates.

This notice of proposed rulemaking

includes changes to part 36 in three

major categories. First, there are

substantive changes to technical

material, such as proposing a revised

method for demonstrating the lateral

noise certification level for propellerdriven large airplanes. These changes

are discussed individually in this

preamble. Second, there are many

proposed changes to regulatory text that

would serve to minimize the language

differences between part 36 and JAR 36,

while having no substantive effect on

the regulatory standards of part 36.

These text changes are not specifically

discussed in this preamble Third, there

are numerous proposed changes to the

section designations of current

Appendices A, B, and C of part 36 that

would more closely align part 36 and

JAR 36 formats. Changes in this category

would have no substantive effect on the

regulatory standards of part 36. The

changes in part 36 appendices

designation are shown in a tabular

format that identifies current part 36

appendices sections and the

corresponding section of the proposed

revision. This redesignation table

appears at the end of the section-bysection discussion.

Section-by-Section Discussion

The following is a section-by-section

discussion of the proposed amendments

that will cover the substantive changes

being proposed for the regulatory

standards of part 36 and its appendices.

Sections that are proposed for

redesignation, but not substantively

changed, will not be discussed, but will

appear only in the redesignation table

that follows the section-by-section

discussion. Throughout the proposed

amendment, the term ‘‘jet’’ has been

used when referring to turbojet and

turbofan engines. This would change

the terminology in current part 36,

which uses the term ‘‘turbojet’’ when

referring to both turbojet and turbofan

engines. This change would result in the

same terminology usage by both part 36

and JAR 36, when referring to turbojet

and turbofan engines.

Section 36.1

The FAA is proposing to remove

§ 36.1(d)(3). This section should have

been removed by Amendment 36–10 (43

FR 28406, June 29, 1978), which

redesignated § 36.1(d)(3) as

§ 36.1(d)(1)(iii).

In § 36.1(f)(1), the terms ‘‘takeoff’’ and

‘‘sideline’’ are proposed to be replaced

with the terms ‘‘flyover’’ and ‘‘lateral’’,

respectively. This change would

harmonize the terminology based on the

international standard.

Section 36.2

Section 36.2, ‘‘Special retroactive

requirements’’ would be removed.

Section 36.2 requires that the noise

certification applicant show compliance

to the part 36 amendment that is in

effect on the date of certification. This

requirement was included in part 36

when the FAA did not have the

authority to prevent the issuance of a

type certificate for an aircraft for which

available and reasonable noise

reduction design practices had not been

incorporated. The FAA subsequently

received this authority under the Noise

Control Act of 1972; the retroactive

requirement contained in § 36.2 is no

longer necessary. This change would

harmonize the applicability designation

of part 36 with that contained in § 1.7

of ICAO annex 16, Chapter 1. In

conjunction with the proposed removal

of the special retroactive requirements

of part 36 § 36.2, this notice proposes

changes to §§ 21.17 and 21.101(a) of part

21 of this chapter to remove references

to part 36 that are contained in these

sections of part 21.

Section 36.6

The FAA proposes to add five

specifications to the incorporated matter

under § 36.6. These specifications are

referred to under proposed section

A36.3, which would update

requirements for measurement and

analysis systems to address the latest

standards and equipment technology.

Updated addresses for the International

Electrotechnical Commission, American

National Standards Institute, and FAA

Regional Headquarters are also included

in proposed § 36.6.

Sections 36.101 and 36.103

Two sections, 36.101, Noise

measurement, and 36.103, Noise

evaluation, would be replaced with a

new § 36.101, Noise measurement and

evaluation. The proposed § 36.101

reflects the proposal to combine the

material contained in current Appendix

A and Appendix B into proposed

Appendix A. This proposed change

would more closely align part 36 and

JAR 36 formats without any substantive

effect. Also for the purpose of aligning

the formats of part 36 and JAR 36, the

FAA proposes to redesignate § 36.201 as

§ 36.103. Current subpart C would be

reserved.

Appendix A—Aircraft Noise

Measurement and Evaluation Under

§ 36.101

The proposed Appendix A to part 36,

Aircraft Noise Measurement and

Evaluation under § 36.101, would

replace current Appendix A, Aircraft

Noise Measurement under § 36.101, and

Appendix B, Aircraft Noise Evaluation

under § 36.103. The harmonization

objective is to develop seamless part 36

and JAR 36 regulations that reflect ICAO

Annex 16 to the extent possible. The

text of JAR 36, Appendix A, is

essentially a copy of Annex 16,

Appendix 2. The proposed Appendix A

to part 36 was developed with the intent

of maintaining a section format

consistent with JAR 36, Appendix A

and ICAO Annex 16, Appendix 2.

Appendix A36.1 Introduction

A new section A36.1.2 would be

added to state that the noise

certification instructions and

procedures given are intended to ensure

uniform results and to permit

comparison between tests of various

types of aircraft conducted in various

geographical locations.

Appendix A36.2 Noise Certification

Test and Measurement Conditions

Proposed section A36.2 would replace

current section A36.1. This proposed

section describes the conditions under

which noise certification testing would

be conducted and the measurement

procedures that would be required.

Under the proposal, current section

A36.5(e)(4), that addresses the use of

equivalent procedures, would be

deleted. The key requirement of the

section, that equivalent procedures must

be FAA-approved, is already addressed

in the regulatory text of § 36.101.

Additional information on the use of

42798 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

equivalent procedures would be

provided in the note contained in

section A36.2.1.1. Therefore, section

A36.5(e)(4) would be deleted since its

content would be addressed in § 36.101.

A note in section A36.2.1.1 would

reference the guidance material on the

use of equivalent procedures contained

in Advisory Circular 36–4C, ‘‘Noise

Standards: Aircraft Type and

Airworthiness Certification’’. Current

AC36–4B, ‘‘Noise Certification

Handbook’’, contains guidance material

on the use of equivalent procedures.

AC36–4B will be revised and

significantly changed in format and

content, and will be designated AC36–

4C, ‘‘Noise Standards: Aircraft Type and

Airworthiness Certification.’’ The FAA

intends to issue the new AC36–4C

concurrently with the final rule that

results from this notice. The AC36–4C is

referred to as ‘‘the current Advisory

Circular for this part’’ throughout the

proposed regulatory text in order to

avoid the need for formal rulemaking

any time the Advisory Circular is

revised. Throughout this preamble,

however, the Advisory Circular is

referred to as Advisory Circular 36–4C.

Most of proposed section A36.2 is

moved from sections A36.1, A36.5 and

A36.9. Under the proposal, the material

in current section A36.1(c)(1) would be

moved to proposed section A36.2.2.2(a)

and revised to remove the word ‘‘rain’’,

since rain is included in the term

‘‘precipitation.’’ The material in section

A36.1(c)(2) would be moved to

proposed section A36.2.2.2(b) and the

minimum test temperature limit

decreased from 36 °F (2.2 °C) to 14 °F

(¥10 °C). The current 36 °F (2.2 °C)

temperature limit is considered

unnecessarily restrictive, given that no

higher levels of atmospheric absorption,

compared with those existing in the

current test window, could be

encountered by lowering the test day

temperature. Under this revised

minimum test temperature limit, testing

would still be required to be conducted

in conformance with the operational

temperature limit for the noise

measuring equipment being used.

Proposed section A36.2.2.2(c), does

not contain the current section

A36.1(c)(3) provision that permits

expanded atmospheric attenuation rates

when the dew point and dry bulb

temperatures used for obtaining relative

humidity are measured with a device

which is accurate to within ±0.5 °C.

This allowance for expanded

atmospheric attenuation rates is already

permitted as an equivalent procedure by

AC36–4B, and will continue to be

permitted as an equivalent procedure in

the revision to AC36–4B (i.e., AC36–

4C). The result would be no change in

the allowance of expanded atmospheric

attenuation rates. This change is

proposed to meet the harmonization

objective to more closely align part 36

and JAR 36 formats.

The requirement to obtain

meteorological measurements within

‘‘25 minutes’’ of each noise test

measurement as required in current

section A36.9(b)(3) would be changed to

‘‘30 minutes’’ in proposed section

A36.2.2.2(g). Thirty minutes is the

established international standard in

ICAO Annex 16. The FAA was unable

to find a technical reason why the

meteorological measurement time was

originally set at 25 minutes. Based on

technical and application

considerations, an increment of 5

minutes does not constitute a

substantive difference. No known

technical criteria exist with which to

assess this minimal time increment.

This change is being proposed to

achieve harmonization by adopting a

single international standard.

Current section A36.9(d)(3) would be

revised and moved to section A36.2.2.3.

This amendment would change the

method used to establish layer depth to

a single international standard. Part 36

does not provide specific criteria for

determining layer depth, except to

require that it be no greater than 100 ft.

The proposed criteria for determining

layer depth is the same as that used to

specify the onset of required layering,

i.e. under weather conditions where the

atmospheric attenuation rate changes by

more than +/¥1.6 dB/1000 ft (+/¥0.5

dB/100m) over the sound propagation

distance. Under this proposal, the

minimum layer depth would be

established as 100 feet (30 meters).

Thus, the layer depth would be 100 feet

(30 meters) in cases where the

atmospheric rate change criteria would

limit the layer depth to less than 100

feet (30 meters).

Section A36.3 Measurement of Aircraft

Noise Received on the Ground

The proposed changes to this section

are intended to update the requirements

for measurement and analysis systems

to address the latest standards and

equipment technology. The changes

were drafted by an international task

group, that has years of knowledge and

experience in the noise certification of

airplanes, and was assembled to update

the ICAO Annex 16 requirements for

measurement and analysis systems. The

proposed changes in section A36.3

incorporates the international task

group’s recommendations, which were

agreed to by Working Group 1 of the

ICAO Committee on Aviation

Environmental Protection (ICAO/CAEP).

Further, the proposed changes are

intended to harmonize with the

international standard, Annex 16. The

primary purpose of this work was to

address considerations related to the use

of digital equipment. Many of these

considerations are addressed in the

International Electro-Technical

Commission (IEC) Standard 61265 and

IEC Standard 61260. Accordingly, much

of the pertinent text from these

standards has been included in the

requirements developed by the

international task group. These IEC

standards also reflect general

improvements to instrumentation

technology that have occurred over the

past decade, although they are not

necessarily related to the advent of

digital technology. In addition to

improvements tied to the IEC standards,

several changes that resulted from the

work of the task group are linked to

general advancements in noise

measurement instrumentation overall.

Proposed section A36.3 includes the

following specific changes to current

section A36.3. Current section A36.3

does not include definitions. Section

A36.3.1, Definitions, would be added to

define the terms used in proposed

section A36.3. Under the proposal,

section A36.3.2, Reference

environmental conditions, would be

added for specifying the performance of

a measurement system.

Section A36.3.3.2 would specify antialias requirements for measurement

systems that include analog to digital

signal conversion.

Proposed section A36.3.4.1 would

add a requirement that windscreen

insertion loss not exceed ±1.5 dB. In

addition, proposed section A36.3.9.10

would specify allowable changes in

windscreen insertion loss.

Proposed sections A36.3.5.3 and

A36.3.5.4 would specify microphone

sensitivity requirements only at the

midband frequencies. This is a

simplification of the current part 36

requirement contained in sections

A36.3(c)(2)(ii) and A36.3(c)(2)(iii).

Sections A36.3.5.3 and A36.3.5.4 would

also specify more stringent tolerances

on microphone sensitivity. Typical

microphones that are currently used in

part 36 noise certification testing

comply with this more stringent

microphone sensitivity requirement.

Proposed section A36.3.6.3 would

add a tolerance for frequency response

of the measurement system.

For analog tape, proposed section

A36.3.6.4 would add a ±0.5 dB tolerance

for amplitude fluctuations of a recorded

1 kHz signal.

Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules 42799

Proposed section A36.3.6.5 would

add a tolerance for amplitude linearity,

at several specific frequencies, for the

measurement system (exclusive of the

microphone.)

Proposed section A36.3.6.6 would

require that the electronic signal level

corresponding to the calibration sound

pressure level be from 5 dB to 30 dB less

than the upper boundary of the

measurement system level range. A

similar requirement in current part 36,

section A36.(c)(3)(i), is 10 dB.

Proposed section A36.3.6.8 would

add a requirement for an overload

indicator in the recording and

reproducing system.

Proposed section A36.3.6.9 would

allow for measurement system

attenuators to operate in known

intervals of decibel steps, rather than in

equal interval steps, as in current part

36 section A36.3(b)(6).

Proposed section A36.3.7.2(e) would

add a requirement that the analyzer

operate in real time from 50 Hz through

at least 12 kHz.

Proposed section A36.3.7.3 would

specify IEC 61260 class 2 electrical

performance requirements as the

minimum standard for analyzers. This

change updates the specifications for

analyzers used in conjunction with part

36 noise certification. Proposed section

A36.3.7.3 would also require that filter

bandwidth adjustments be determined

in accordance with IEC 61260. The IEC

method requires that the adjustment be

based on more frequencies than are

required under current part 36.

Proposed section A36.3.7.4 would

contain a correction to the slow timeweighting characteristics in current

section A36.3(d)(5)(ii) and (iii). Section

A36.3.7.6 would specify that the instant

in time at which a slow time weighted

sound pressure level is characterized

should be 0.75 seconds earlier than the

actual readout time. The current

requirement specifies that the instant in

time at which a readout is characterized

must be the midpoint of the averaging

period.

Proposed section A36.3.7.5 would

specify a continuous exponential

averaging process equation through

which simulated slow weighted sound

pressure levels can be obtained. Section

A36.3.7.5 would also specify an

equation that results in an

approximation of continuous

exponential averaging.

Section A36.3.7.7 would require that

the analyzer resolution must be 0.1 dB

or finer. The current requirement, in

section A36.3(d)(7) specifies that the

amplitude resolution of the analyzer

must be at least ±0.25 dB.

Proposed section A36.3.9.1 would

require that calibration adjustments be

applied to the measured sound levels

determined from the output of the

analyzer; the current rule permits these

calibrations to be applied within the

analyzer. This change is necessary to

enable the FAA to determine whether

these calibration adjustments have been

applied correctly.

Proposed section A36.3.9.3 would

allow the free-field corrections based on

grazing incidence to be applied when

the sound incidence angle is within ±30

degrees of grazing incidence.

Proposed section A36.3.9.4 would

require that at least 30 seconds of pink

noise be recorded for analog tape

recorders; the current section

A36.3(e)(4)(ii) requirement is for at least

15 seconds of pink noise. This change

would result in a more accurate pink

noise correction and would harmonize

with the international standard.

Proposed section A36.3.9.6 would

require that attenuator accuracy be

within 0.1 dB. Section A36.3(b)(6)

currently requires that attenuator

accuracy be within 0.2 dB. The

proposed rule would require that

calibration be checked within six

months of each test series. The current

rule does not specify a time period

within which calibration must be

checked.

Proposed sections A36.3.9.5 and

A36.3.9.7 would change calibration

requirements for the pink noise

generator and sound calibrator to allow

calibration to occur within six months

preceding or succeeding the test instead

of requiring it to be within the

preceding six months as required by

current section A36.3(e)(7).

Proposed section A36.3.9.7 would

add a new calibration requirement that

limits the change in output of the sound

calibrator to not more than 0.2 dB, as

compared to the previous calibration.

Proposed section A36.3.9.8 would

allow for the use of sound calibrators

other than pistonphones, as specified by

current section A36.3(e)(4). Section

A36.3.8.1 would specify the class 1L

requirements of IEC 60942, entitled

‘‘Electroacoustics—Sound calibrators’’,

as the minimum standard for the sound

calibrator.

Proposed section A36.3.9.9 would

add a requirement for the recording

medium (e.g., tape reel) to carry at least

a 10-second sound pressure level

calibration at its beginning and end.

This proposed change would more

precisely define the current section

A36.3(e)(4) sound pressure level

calibration requirement.

Section A36.4 Calculations of Effective

Perceived Noise Level From Measured

Data

To further harmonize the formats of

part 36 and JAR 36, Table B–1,

‘‘Perceived Noisiness (NOYs) as a

Function of Sound Pressure Level’’,

referenced in current section B36.13(a)

would be moved to AC36–4C. The noy

values contained in Table B–1 can be

calculated from the equations contained

in proposed section A36.4.7.3.

A minor technical change is proposed

for the Perceived Noise Level (PNL)

equation in proposed section

A36.4.2.1(c) (current section B36.3(c)).

The more exact term 10/log 2 is

replacing the rounded-off term (33.22).

The difference between PNL values that

are determined using the current and

proposed equations is not expected to

be significant.

To harmonize the formats of part 36

and JAR 36, Figure B1, ‘‘Perceived noise

level as a function of noys’’, would be

moved from current section B36.3(c) to

AC36–4C. The perceived noise level

values contained in Figure B1 can be

calculated from the equations contained

in proposed section A36.4.2.1(c).

Proposed section A36.4.5.2 would

change the value of ‘‘d’’ from 1.0

seconds to 0.5 seconds to reflect current

standard practice. Parallel changes are

proposed for section A36.4.5.4 and

section A36.6. This change is a text

update to reflect the current practice of

using 0.5 second data samples, and

would have no substantive effect.

To harmonize the formats of part 36

and JAR 36, the material in section

B36.5(m) addressing methods for

removing the effects of tones resulting

from ground plane reflections would be

moved to AC36–4C.

The FAA is proposing the deletion of

current section B36.9(e), which specifies

the duration time interval when the

value of PNLT(k) at the 10 dB-down

points is 90 PNdB or less. This

provision was eliminated for

applications made after September 17,

1971 by Amendment 36–5 (41 FR

35053, August 19, 1976). The text

permitting the use of this provision has

erroneously remained in part 36.

In addition, current section B36.9(f)

would also be deleted. The text

contained in current section B36.9(f)

was added to part 36 in Amendment

36–5 to distinguish between the

procedure for determining duration for

applications made before and after

September 17, 1971. This distinction is

no longer necessary if current section

B36.9(e) is deleted as proposed.

Section A36.5 Data Reporting.

Proposed section A36.5.2 would require

42800 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

that the data specified under section

A36.5.2 be reported to the FAA in the

applicant’s noise certification

compliance report. While current part

36 does not specifically identify a

requirement for the applicant to submit

a noise certification compliance report,

these reports represent the standard

practice that is used by applicants for

submitting this information to the FAA.

Proposed section A36.5.2.5 would also

identify the specific airplane

configuration items and engine

operating parameters that must be

reported. Each of these configuration

items and parameters can affect the

airplane noise signature. The reporting

requirement for these items and

parameters already exist under current

section A36.5 which specifies that the

aircraft configuration and engine

performance parameters relative to

noise generation be reported. Further,

these configuration items and

parameters are also included in the

international standard. Their addition to

part 36 would promote harmonization.

Proposed section A36.5.2.5(c) would

require that the test airplane’s center of

gravity be reported to the FAA. Airplane

center of gravity is an example of an

identifying characteristic of the airplane

test configuration and an item that

could influence measured noise levels.

Proposed section A36.5.2.5(d) would

require that airbrake and propeller pitch

angle also be reported. Proposed

sections A36.5.2.5(e), (f), and (j) would,

respectively, require reporting of

whether the auxiliary power unit (APU)

is operating, the status of pneumatic

engine bleeds and engine power takeoffs, and non-standard airplane test

configurations.

Proposed section A36.5.2.5(h)(2)

would require reporting of engine

performance parameters specifically

related to propeller-driven large

airplanes.

Current section A36.5(d)(3) does not

permit an effective perceived noise level

(EPNL) to be computed or reported from

data that more than four one-third

octave bands in any spectrum within

the 10 dB-down points have been

excluded from the EPNL computation.

This section would be removed since

correction (adjustment) methods for

removing the effects of ambient noise

from airplane noise data must be used

in lieu of excluding one-third octave

bands. Proposed section A36.3.9.12

specifies the ambient noise level

limitations that would require

corrections (adjustments) to be made,

and also references AC36–4C, which

contains an acceptable procedure for

removing the affects of ambient noise.

Section A36.6 Nomenclature: Symbols

and Units

Under the proposal, current section

A36.7, Symbols and units, would be

replaced by revised section A36.6,

Nomenclature: Symbols and units. The

proposed section would incorporate

Annex 16 symbols and units, while

retaining the English units. This change

is proposed to more closely align part 36

with JAR 36. No substantive technical

changes to the regulatory standards of

part 36 are anticipated to result from

incorporation of the Annex 16 symbols

and units.

Section A36.7 Sound Attenuation in

Air

Currently, atmospheric attenuation

rates of sound with distance must be

determined in accordance with Society

of Automotive Engineers, Inc. (SAE),

Aerospace Recommended Practice

(ARP) 866A, (SAE ARP 866A) as

specified in current section A36.9(c).

Under the proposal, section A36.7.2

would contain the actual formulation

(equations) from SAE ARP 866A. These

equations are provided in both the

International System of Units and the

English System of Units. Whereas

equations are continuous and provide

consistent values, tables and graphs can

provide minor differences. This

proposed change would further

harmonize part 36 and JAR 36 and is not

expected to result in any substantive

difference in attenuation rates.

Section A36.9 Adjustment of Airplane

Flight Test Results

The current distinction between

allowable/required positive and

negative correction procedures

contained in current sections

A36.11(a)(1) and (2) are not included in

proposed section A36.9.1. The

distinction is no longer relevant, given

the evolution of data correction

procedures since part 36 was originally

promulgated in 1969 and the need for

noise certification levels to reflect

airplane noise characteristics as

accurately as possible. Prior to any noise

certification compliance test, a noise

certification applicant is required to

identify and gain FAA approval of any

planned or anticipated data correction

that is not a mandatory correction

procedure under part 36.

Under the proposal, current section

A36.1(b)(3), which requires that the

corrections prescribed in current section

A36.5(d) be made when the height of

the ground at a noise measuring station

differs from that of the nearest point on

the runway by more than 20 feet, would

be deleted because it is obsolete. A 20-

foot height allowance/tolerance could

change the final EPNL value by several

tenths of a dB under some

circumstances. Under current practices,

corrections (adjustments) are made over

the sound propagation path from the

microphone to airplane height as part of

normal data corrections (adjustments).

These corrections (adjustments) are

specified in current section A36.11 and

proposed section A36.9.

Proposed section A36.9.1.1(d) would

require that the effect that airspeed has

on source noise be considered with

regard to the difference between test day

airplane speed and the airplane

reference flight profile speed. Thus, the

proposed section would specify that,

‘‘in addition to the effect on duration,

the effects of airspeed on component

noise sources must be accounted for as

follows: For conventional airplane

configurations, when differences

between test and reference airspeeds

exceed 15 knots (28 km/h) true airspeed,

test data and/or analysis approved by

the FAA must be used to quantify the

effects of the airspeed adjustment on

resulting certification noise levels.’’

The symbols and figures used to

describe the takeoff and approach

profiles in current sections A36.11(b)

and (c), would be replaced by the JAR

36 symbols and figures that have been

incorporated into proposed section

A36.9.2. There would be no substantive

changes to the takeoff and approach

profile technical requirements as a

result of these changes.

Proposed section A36.9.3.2.1 provides

equations that would enable data

adjustments to be made using either the

English System of Units or International

System of Units.

The material in current section

B36.11(c) would be moved to section

A36.9.3.2.2 and revised to provide that

the adjustment for multiple peak values

of tone-corrected perceived noise level

(PNLT) is based upon the difference in

corrected PNLT values, rather than

upon EPNL as in the current part 36.

This change would more clearly define

the intent of the multiple peak

correction.

Under proposed section A36.9.3.3.2, a

correction term to account for the

difference between test and reference

airplane airspeeds would be added to

the duration correction (∆2) contained

in current section A36.11(e). The speed

correction term would be defined as 10

log (V/Vr), where V is the airplane test

speed and Vr is the airplane reference

speed. This proposed change specifies

the speed correction that is a

requirement of current section

A36.11(f)(1).

Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules 42801

Appendix B—Noise Levels for Transport

Category and Jet Airplanes Under

§ 36.103

Proposed appendix B would include

the material from current appendix C.

The objective is to harmonize proposed

appendix B, and JAR 36, Section 1,

Subpart B. The proposed appendix B is

essentially the same as JAR 36, section

1, subpart B.

Section B36.3 Reference Noise

Measurement Points.

Under the proposal, the material in

current section C36.3 would be moved

to section B36.3 and revised as follows.

The term ‘‘takeoff’’ in current section

C36.3(a) would be replaced with the

term ‘‘flyover’’ in proposed section

B36.3(b).) The term ‘‘sideline’’ in

current section C36.3(c) would be

replaced with ‘‘lateral’’ in proposed

section B36.3(a). These terminology

changes would harmonize the part 36

terminology with that used in JAR 36

and Annex 16.

Proposed section B36.3(a)(2) includes

a simplified test procedure that may be

used in determining the sideline

(lateral) noise level for propeller-driven

large airplanes in demonstrating the

sideline (lateral) noise certification

level. This procedure is also contained

in JAR 36 and ICAO Annex 16. For

propeller-driven airplanes, it can be

difficult to establish the maximum

lateral noise level specified under

current section C36.3C, because this

noise level may occur at a very low

height. There is usually a significant

difference in noise levels between the

port and starboard sides of a propellerdriven large airplane. By measuring fullpower noise at a predetermined point

(650meters) below the takeoff flight

path, many of the difficulties which

arise because of the directional nature of

the noise from propeller-driven

airplanes when measured at the

conventional lateral site will be

eliminated. Ground effects that distort

measurements will also be reduced.

Under the current requirement, it is

difficult to judge the airplane altitude at

which the peak noise level occurs, and

in the past this has required applicants

to conduct as many as 30 flight tests to

satisfy certification authorities, an

expensive process. Moreover, the

current method for testing propellerdriven airplanes has generally resulted

in low confidence in accuracy and

repeatability of measurements. The

simplified test procedure is proposed to

be available as an alternative to the

current section C36.3(c) method for tests

conducted before March 20, 2002, after

which it would become the sole method

for demonstrating sideline (lateral) noise

level compliance.

Current section C36.3(b) would be

moved to section B36.3(c) and text

would be added to define the approach

measurement point relative to the

runway threshold. This change would

more clearly describe the geometric

relationship between the test airplane

and the ground, and would further

harmonize part 36 and JAR 36.

Section B36.4 Test Noise Measurement

Points

As proposed, most of the

requirements of current section

A36.1(b)(7) would be moved to

proposed section B36.4(b). Current

section A36.1(b)(7), allows (when

approved) for the sideline (lateral) noise

certification level demonstration for jet

airplanes to be based on the assumption

that the peak sideline (lateral ) noise

level occurs at an airplane altitude of

1,000 feet (1,440 feet for Stage 1 or Stage

2 four-engine airplanes). Under the

proposed rulemaking, this procedure

would be moved to the guidance

material in AC 36–4C as an equivalent

procedure for demonstrating the

sideline (lateral) noise certification

level. This change would further

harmonize part 36 and JAR 36 and

would have no substantive effect.

Proposed section B36.4(b) would

require that, in demonstrating the

sideline (lateral) noise certification level

for propeller-driven airplanes, noise

measurements be made at symmetrically

located noise measurements points on

either side of the runway for each and

every noise measurement point along

the main sideline (lateral) noise

measurement line. This change is

proposed because of the asymmetric

nature of propeller noise. Because of the

possibility of lateral noise asymmetry,

part 36 has required simultaneous

measurements at one test measurement

point opposite the main lateral

measurement line. In the case of

propeller-driven airplanes, whose noise

field is known to be asymmetrical,

having only one measuring point

opposite the main lateral measurement

line is not adequate to define the peak

lateral noise on the other side of the

runway from the main lateral line. This

change would further harmonize part 36

and JAR 36.

Section B36.5 Maximum Noise Levels

The material in current section C36.5

would be moved to proposed section

B36.5 and revised to include minor

format and language changes to

harmonize with JAR 36. Amendment

36–15 (53 FR 16360, May 6, 1988)

removed section C36.5(c); the reference

to section C36.5(c) in current section

C36.5(a) should have been removed

under that amendment but it was not.

The reference to section C36.5(c) is not

included in this proposal.

In order to further harmonize part 36

and JAR 36, the term ‘‘sideline’’ has

been changed to ‘‘lateral’’ in each place

that it appears throughout section B36.5.

This is a change in terminology that

does not affect the noise measurement/

analysis procedures or noise limits.

Similarly, the term ‘‘takeoff’’ has been

changed to ‘‘flyover.’’ No change in test

procedures should be inferred from this

change.

Section B36.6 Trade-Offs

The material in current section

C36.5(b) would be moved to proposed

section B36.6 and the reference to

section 36.7(d)(3)(i)(B), in current

section C36.5(b), would be changed to

section 36.7(d)(1)(ii). This section

reference should have been changed by

Amendment 36–15 (53 FR 16360, May

6, 1988). This error is corrected by this

proposed revision.

Section B36.7 Noise Certification

Reference Procedures

The material addressing takeoff and

approach reference and test limitations

in current sections C36.7 and C36.9

would be moved to section B36.7,

addressing takeoff and approach

reference procedures, and section B36.8,

addressing takeoff and approach test

procedures. This material would also be

revised as discussed in the following

paragraphs.

Proposed section B36.7(b)(1) requires

the use of ‘‘average engine’’ performance

in defining the takeoff thrust for the

reference takeoff procedures. This

revision of current section C36.7(b)(2)

would further harmonize the takeoff

reference procedure, and would serve to

eliminate confusion in compliance with

the requirement. This change would

also further standardize part 36 and JAR

36 regulations.

Proposed section B36.7(b)(1) would

also specify ‘‘Takeoff thrust/power’’ as

the maximum available for normal

operations as scheduled in the

performance section of the airplane

flight manual for the reference

atmospheric conditions given in

proposed section B36.7(a)(5).

Currently section C36.7(b)(2) specifies

different minimum cutback altitudes for

jet powered and non-jet powered

airplanes. Proposed section

B36.7((b)(1)(ii) would contain the same

minimum cutback altitude for all

airplanes, the same altitude specified in

current section C36.7(b)(2) for jet

airplanes. Since the selection of the

42802 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

minimum cutback altitude is

determined by the minimum safe

altitude for cutback initiation, there is

no reason to distinguish between

propeller-driven and jet airplanes. It is

the FAA’s understanding that this

change would not have a substantive

effect in practice, since cutback

initiation heights greater than 1,500 feet

are generally chosen for propellerdriven airplanes. Thus, the cutback

initiation heights generally chosen are

greater than both the current and

proposed part 36 minimum cutback

height requirements.

Under the proposal, the requirements

of section A36.1(b)(2) is moved to

section B36.7(b)(3) and revised to

require that, for tests conducted after

March 19, 2002, the lateral (sideline)

noise level be demonstrated using full

takeoff power throughout the takeoff

flight path. Before that date, the lateral

noise level may be demonstrated using

the current section A36.1(b)(2)

procedure, under which both the takeoff

(flyover) and sideline (lateral) noise

certification levels are determined using

a single reference flight path that may

include a thrust cutback. This change is

proposed to reflect the intent of the

international standard that the lateral

measurement be based on the full-power

condition. Since the revised lateral

procedure might result in increased

stringency, the use of this procedure

would be optional for tests conducted

before March 20, 2002. This change

would mainly effect three and four

engine airplanes.

The takeoff reference speed

requirement specified in current section

C36.7(e)(2) would be revised to be

consistent with the takeoff reference

speed contained in JAR 36 and Annex

16. The all-engine operating climb

speed range (V2+10 to V2+20 kts)

specified in proposed section

B36.7(b)(4) represents the typical range

of takeoff initial climb speeds seen in

normal operation for most airplanes. For

some airplanes, this proposed change to

part 36 could result in an increase of up

to 10 knots in the noise certification

reference takeoff speed relative to the

current part 36 reference takeoff speed

requirements. For the affected airplanes,

the increased takeoff speed could result

in some noise level reduction at the

sideline (lateral) noise measurement

point with a resulting increase in noise

level at the takeoff (flyover) noise

measurement point. The FAA has found

the change in takeoff reference speed to

be acceptable because of this tradeoff of

sideline (lateral) and takeoff (flyover)

noise levels, although it might not be a

one-to-one tradeoff.

Proposed section B36.7(b)(5) adds the

meaning of configuration. This is not a

change in requirement. Proposed

section B36.7(b)(5) is intended to clarify

the meaning and includes specific

configuration elements, based on

certification experience, that can have

an effect on noise source.

Proposed section B36.7(b)(7) defines

‘‘average engine’’ as the average of all

the certification compliant engines used

during the airplane flight tests up to and

during certification when operating

within the limitations and according to

the procedures given in the Flight

Manual.

Under the proposal, current section

C36.9(e)(1), reference approach speed,

would be revised to incorporate the use

of 1-g stall-based approach speeds by

basing the approach noise certification

reference speed on the reference landing

speed (VREF) that is used for the

airworthiness certification. This

proposal was included in Notice 95–17,

published on January 18, 1996 (61 FR

1260), in which the FAA proposed to

redefine the reference stall speeds for

transport category airplanes as the 1-g

stall speed instead of the minimum

speed obtained in the stalling maneuver.

Under Notice 95–17, a definition of

VREF would be included in 14 CFR part

1. Notice 95–17 has not been issued as

a final rule. If a final rule based on

Notice 95–17 is not issued before this

notice becomes a final rule; the

definition of VREF (i.e., the speed of the

airplanes, in a specified landing

configuration, at the point where it

descends through the landing screen

height in the determination of the

landing distance for manual landings)

would be added to part 36. The

proposed change to section C36.9(e)(1)

would also be consistent with an

anticipated change to ICAO/Annex 16

that is expected to be recommended by

Working Group 1 of the ICAO

Committee on Aviation Environmental

Protection (CAEP) in conjunction with

the current CAEP work program cycle.

Under this proposed change, existing

section C36.9(e)(1) would be

redesignated as section B36.7(c)(2).

Current section C36.9(d) requires that

all engines must operate at

approximately the same power or thrust

for approach tests conducted to

demonstrate compliance with part 36.

Under the proposal, this specific

requirement would be removed, and

instead, proposed section A36.9.3.4

would require that source noise

adjustments be applied to account for

any difference, between test and

reference conditions, in engine

parameters that affect engine noise (e.g.,

corrected low pressure rotor speed).

This proposed change would meet the

intent of the current part 36 requirement

and would also further harmonize with

JAR 36.

Section B36.8—Test Procedures

The current section A36.1(d)(5) and

A36.1(d)(7), limitations on the

difference between the test weight and

the maximum takeoff/approach weight

for which noise certification is

requested, would be replaced by the

limitation in proposed section B36.8(d).

The current section A36.1(d)(5) and

A36.1(d)(7) limitations help insure the

integrity of the final certification results

by indirectly limiting the magnitude of

the EPNL adjustments that may be

applied to the test data in normalizing

to the noise certification reference

conditions. Proposed section B36.8(d)

would directly limit the magnitude of

the correction by specifying a limitation

on the EPNL adjustment that can be

made when correcting between test

weight and maximum certification

weight.

Under the proposal, current section

A36.5(d)(5) would be revised and

moved to section B36.8(f). The amounts

of adjustment permitted when

equivalent test procedures are different

from the reference procedures remain

unchanged, except that the amended

requirements do not specify that

tradeoffs are permitted when comparing

adjusted levels against the appendix C

noise levels, for the purpose of

determining adjustment limits. Several

interpretations of the current section

A36.5(d)(5) requirement are possible as

to whether the proposal represents a

more stringent or less stringent

adjustment limitation as compared with

the current limitation. The FAA believes

that the proposed change to remove the

tradeoff provision from the current

limitation and base the proposed

limitation solely on the difference

between the adjusted noise levels and

the maximum noise levels in proposed

B36.5 meets the intent of the adjustment

limitation, as stated above, and clarifies

ambiguity in its interpretation. The

proposed change would also result in

harmonization of the adjustment

limitation with that in JAR 36 and ICAO

Annex 16.

Proposed section B36.8(g) would

revise the test speed tolerance specified

in current sections C36.7(e)(1) and

C36.9(e)(3). Current section C36.7(e)(1)

specifies that takeoff tests must be

conducted at the test day speeds ±3

knots. Current section C36.9(e)(3)

specifies that a tolerance of ±3 knots

may be used throughout the approach

noise testing. Proposed section B36.8(g)

would specify that during takeoff,

Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules 42803

lateral, and approach tests, the airplane

variation in instantaneous indicated

airspeed must be maintained within +/

¥3% of the average airspeed between

the 10dB-down points. Under the

proposal, the instantaneous indicated

airspeed is determined by the pilot’s

airspeed indicator. However, if the

instantaneous indicated airspeed

exceeds +/¥3 kt (+/¥5.5 km/h) of the

average airspeed over the 10dB-down

points, and is determined by the FAA

representative on the flight deck to be

due to atmospheric turbulence, then the

flight so affected must be rejected for

noise certification purposes.

Appendix G Noise Requirements for

Propeller-Driven Small Airplanes and

Commuter Category Airplanes Under

Subpart F

Current Section G36.105(f)

The proposal would change the

designation of the reference to current

part 36 section A36.3(e) to A36.3.8 and

A36.3.9 to maintain the correct crossreference.

Appendix H Noise Requirements for

Helicopters Under Subpart H

Current Section H36.111(c)(3)

The proposal would change the

designation of the reference to current

part 36 section A36.3(f)(3) to A36.3.9.11

to maintain the correct cross-reference.

Current section H36.201

The proposal would change the

designation of the reference to current

part 36 section B36.5(a) to A36.4.3.1(a)

to maintain the correct cross-reference.

Redesignation Table for Proposed

Appendices A and B

CROSS REFERENCE TABLE

Old Section New Section

A36.1 ...................................... A36.1, A36.2

A36.1(a) ................................. A36.1.1, A36.2.1.1

A36.1(b) ................................. A36.2.2

A36.1(b)(1) ............................. A36.2.3.2, B36.3

A36.1(b)(2) ............................. B36.7(b)(1)(iii)

A36.1(b)(3) ............................. Deleted

A36.1(b)(4) ............................. A36.2.2.1

A36.1(b)(5) ............................. A36.2.2.4

A36.1(b)(6) ............................. A36.2.2.1

A36.1(b)(7) ............................. A36.9.3.5, A36.9.3.5.1,

B36.4(b)

A36.1(c) ................................. A36.2.2.2

A36.1(c)(1) ............................. A36.2.2.2(a)

A36.1(c)(2) ............................. A36.2.2.2(b)

A36.1(c)(3) ............................. A36.2.2.2(c)

AC36–4C

A36.1(c)(4) ............................. A36.2.2.2(e)

A36.1(c)(5) ............................. A36.2.2.2(f)

A36.1(d)(1) ............................. B36.8(b), B36.2

A36.1(d)(2) ............................. A36.2.3.1

A36.1(d)(3) ............................. A36.2.3.2, A36.2.3.3

A36.1(d)(4) ............................. B36.7(b), B36.8

A36.1(d)(5) ............................. B36.8(d)

A36.1(d)(6) ............................. B36.7(c), B36.8(e)

A36.1(d)(7) ............................. B36.8(d)

A36.1(d)(8) ............................. A36.2.3.3

A36.3 ...................................... A36.3

A36.3(a) ................................. A36.3.3

A36.3(b) ................................. A36.3.3.1

A36.3(c)(2)(i-iv), A36.3(f)(1) ... A36.3.5

CROSS REFERENCE TABLE—Continued

Old Section New Section

A36.3(c)(2)(v) ......................... A36.3.4

A36.3(c)(3) ............................. A36.3.6

A36.3(d) ................................. A36.3.7

A36.3(e)(1–6), A36.3(f)(2) ..... A36.3.9

A36.3(f)(2–4) .......................... A36.3.9.11

A36.3(e)(7) ............................. A36.3.8

A36.5(a) ................................. A36.5.1.1, A36.5.1.2,

A36.5.1.3

A36.5(b)(1) ............................. A36.5.2.1

A36.5(b)(2) ............................. A36.5.2.2

A36.5(b)(3) ............................. A36.5.2.3

A36.5(b)(4) ............................. A36.5.2.4

A36.5(b)(5)(i-vi) ...................... A36.5.2.5

A36.5(b)(vii) ........................... A36.5.2.5(i)

A36.5(b)(6) ............................. A36.2.3.2, A36.2.3.3

A36.5.2.5(i)

A36.5(c) ................................. A36.5.3

A36.5(c)(1) ............................. B36.7(a)(5)

A36.5(c)(2) ............................. B36.3(c),

B36.7(b)(1)(vi),

B36.7(c)(1)(i),

B36.7(c)(1)(iv)

A36.5(d)(1) ............................. A36.5.3.1, A36.9, B36.8(c)

A36.5(d)(2) ............................. A36.9.1

A36.5(d)(2)(i)-(iv) ................... B36.8(d)

A36.5(d)(3) ............................. A36.3.9.12

A36.5(d)(4) ............................. A36.3.9.12

A36.5(d)(5) ............................. B36.8(f)

A36.5(e)(1) ............................. A36.5.4.1

A36.5(e)(2) ............................. A36.5.4.2

A36.5(e)(3) ............................. A36.5.4.3

A36.5(e)(4) ............................. Deleted

A36.7 ...................................... A36.6, A36.9.5, A36.9.6

A36.9(a) ................................. A36.9.1.1

A36.9(b)(1) ............................. A36.2.2.4

A36.9(b)(2) ............................. A36.2.2.2(b)

A36.9(b)(3) ............................. A36.2.2.2(g)

A36.9(c) ................................. A36.7

A36.9(d)(1) ............................. A36.9.1, A36.9.1.1

A36.9(d)(2) ............................. A36.2.2.2(d)

A36.9(d)(3) ............................. A36.2.2.3

A36.11(a) ............................... A36.9.1

A36.11(a)(1) ........................... Deleted

A36.11(a)(2) ........................... Deleted

A36.11(a)(3)(i) ........................ A36.9.1, B36.7

A36.11(a)(3)(ii) ....................... A36.9.1.1

A36.11(a)(3)(iii) ...................... A36.9.1.1

A36.11(a)(3)(iv) ...................... A36.9.1.1, A36.9.3.4

A36.11(a)(3)(v) ....................... A36.9.1

A36.11(b)(1)(i-ii) ..................... A36.9.2.1(c)

A36.11(b)(2) ........................... A36.9.3.1, A36.9.4.1

A36.11(b)(3) ........................... A36.9.3.2(a)

A36.11(c) ............................... A36.9.2.2

A36.11(c)(1) ........................... A36.9.3.2(a-c)

A36.11(c)(2) ........................... A36.9.3.2(a)

A36.11(d)(1–3) ....................... A36.9.3,

A36.9.3.1,

A36.9.3.2.1,

A36.9.3.2.1.1,

A36.9.3.2.1.2

A36.11(e)(1–2) ....................... A36.9.3.3.1,

A36.9.3.3.2

A36.11(f) ................................ B36.4(a), AC36–4C

A36.11(f)(1) ............................ A36.9.1.2

A36.11(f)(2) ............................ A36.9.1.2

A36.11(f)(2)(i-ii) ...................... A36.9.4

B36.1 ...................................... A36.1, A36.1.1,

A36.4.1.3

B36.1(a) ................................. B36.4.1.3(a)

B36.1(b) ................................. A36.4.1.3(b)

B36.1(c) ................................. A36.4.1.3(c)

B36.1(d) ................................. A36.4.1.3(d)

B36.1(e) ................................. A36.4.1.3(e)

B36.3 ...................................... A36.4.2.1

B36.3(a) ................................. A36.4.2.1, Step 1

B36.3(b) ................................. A36.4.2.1, Step 2

B36.3(c) ................................. A36.4.2.1, Step 3,

AC 36–4B

B36.5 ...................................... A36.4.3.1

B36.5(a) ................................. A36.4.3.1, Step 1

B36.5(b) ................................. A36.4.3.1, Step 2

B36.5(c) ................................. A36.4.3.1, Step 3

B36.5(d) ................................. A36.4.3.1, Step 4

B36.5(e) ................................. A36.4.3.1, Step 5

B36.5(f) .................................. A36.4.3.1, Step 6

B36.5(g) ................................. A36.4.3.1, Step 7

B36.5(h) ................................. A36.4.3.1, Step 8

B36.5(i) .................................. A36.4.3.1, Step 9

B36.5(j) .................................. A36.4.3.1, Step 10

B36.5(k) ................................. A36.4.3.1, Step 10

B36.5(l) .................................. A36.4.3.1, Step 10

B36.5(m) ................................ A36.4.3.1, Step 10

Note, AC36–4C

B36.5(n) ................................. A36.4.4.2

CROSS REFERENCE TABLE—Continued

Old Section New Section

B36.7 ...................................... A36.4.4

B36.7(a) ................................. A36.4.4.1,

A36.4.4.1 Note 1

B36.7(b) ................................. A36.4.4.1-Note 2

B36.9 ...................................... A36.4.5.1

B36.9(a) ................................. A36.4.5.2

B36.9(b) ................................. A36.4.5.3

B36.9(c) ................................. A36.4.5.4

B36.9(d) ................................. A36.4.5.5

B36.9(e) ................................. Deleted

B36.9(f) .................................. Deleted

B36.11(a) ............................... A36.4.6.1

B36.11(b) ............................... Deleted

B36.11(c) ............................... A36.9.3.2.2

B36.13(a) ............................... A36.4.7.1, Table A1 moved

to AC 36–4C

B36.13(a)(1),(2),(3) ................ A36.4.7.2(a-c)

B36.13(b) ............................... A36.4.7.3

B36.13(c) ............................... A36.4.7.4

C36.1 ..................................... B36.1

C36.3(a) ................................. B36.3(b)

C36.3(b) ................................. B36.3(c)

C36.3(c) ................................. B36.3(a)

C36.5(a) ................................. B36.5

C36.5(a)(1) ............................. B36.5(a)

C36.5(a)(2) ............................. B36.5(b)

C36.5(a)(2)(i) ......................... B36.5(b)(1)

C36.5(a)(2)(ii) ......................... B36.5(b)(2)

C36.5(a)(3) ............................. B36.5(c)

C36.5(a)(3)(i)(A) ..................... B36.5(c)(1)(i)

C36.5(a)(3)(i)(B) ..................... B36.5(c)(1)(ii)

C36.5(a)(3)(i)(C) .................... B36.5(c)(1)(iii)

C36.5(a)(3)(ii) ......................... B36.5(c)(2)

C36.5(a)(3)(iii) ........................ B36.5(c)(3)

C36.5(b)(1) ............................. B36.6

C36.5(b)(2) ............................. B36.6

C36.5(b)(3) ............................. B36.6

C36.7(a) ................................. B36.7(a)(3)

C36.7(b) ................................. B36.7(b)(1)(i)

C36.7(b)(1) ............................. B36.7(b)(1)(i)

C36.7(b)(1)(i) ......................... B36.7(b)(1)(i)

C36.7(b)(1)(ii) ......................... B36.7(b)(1)(i)

C36.7(b)(2)(i) ......................... B36.7(b)(1)(i)

C36.7(b)(2)(ii) ......................... B36.7(b)(1)(i)

C36.7(b)(2)(iii) ........................ B36.7(b)(1)(i)

C36.7(b)(2)(iv) ........................ B36.7(b)(1)(i)

C36.7(c) ................................. B36.7(b)(1)(ii)

C36.7(d) ................................. B36.7(b)(1)(v)

C36.7(e)(1) ............................. B36.7(b)(1)(iv)

C36.7(e)(1) Next to last sentence.B36.8(g)

C36.7(e)(2) ............................. B36.7(b)(1)(iv)

C36.7(e)(3) ............................. B36.7(a)(5), A36.9.1

C36.9(a) ................................. B36.7(a)(3), B36.7(c)(1)

C36.9(b) ................................. B36.7(c)(1)(iii) &

B36.7(c)(1)(v)

C36.9(c) ................................. B36.7(c)(1)(i),

B36.7(c)(iii)

C36.9(d) ................................. Deleted

C36.9(e)(1) ............................. B36.7(c)(1)(ii)

C36.9(e)(2) ............................. B36.7(c)(1)(ii)

C36.9(e)(3) ............................. B36.8(g)

CROSS REFERENCE TABLE

New Section Old Section

A36.1 ...................................... A36.1, B36.1

A36.1.1 ................................... A36.1(a), B36.1

A36.1.2 ................................... New section

A36.1.3 ................................... New section

A36.2 ...................................... A36.1

A36.2.1 ................................... A36.1(a)

A36.2.1.1 ................................ A36.1(a)

A36.2.2 ................................... A36.1(b)

A36.2.2.1 ................................ A36.1(b)(4), A36.1(b)(6)

A36.2.2.2 ................................ A36.1(c)

A36.2.2.2(a) ........................... A36.1(c)(1)

A36.2.2.2(b) ........................... A36.1(c)(2), A36.9(b)(2)

B36.2.2.2(c) ........................... A36.1(c)(3)

B36.2.2.2(d) ........................... A36.9(d)(2)

A36.2.2.2(e) ........................... A36.1(c)(4)

A36.2.2.2(f) ............................ A36.1(c)(5)

A36.2.2.2(g) ........................... A36.9(b)(3)

A36.2.2.3 ................................ A36.9(d)(3)

A36.2.2.4 ................................ A36.1(b)(5), A36.9(b)(1)

A36.2.3 ................................... A36.1(d)

A36.2.3.1 ................................ A36.1(d)(2)

A36.2.3.2 ................................ A36.1(b)(1),

A36.1(d)(3),

A36.5(b)(6)

A36.2.3.3 ................................ A36.1(d)(8), A36.5(b)(6)

A36.3 ...................................... A36.3

42804 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

CROSS REFERENCE TABLE—Continued

New Section Old Section

A36.3.1 ................................... New

A36.3.2 ................................... New

A36.3.3 ................................... A36.3(a)

A36.3.3.1 ................................ A36.3(b)

A36.3.3.2 ................................ New

A36.3.4 ................................... A36.3(c)(2)(v)

A36.3.5 ................................... A36.3(c)(2)(i-iv),

A36.3(f)(1)

A36.3.6 ................................... A36.3(c)(3)

A36.3.7 ................................... A36.3(d)

A36.3.8 ................................... A36.3(e)(7)

A36.3.9 ................................... A36.3(e)(1–6),

A36.3(f)(2)

A36.3.9.11 .............................. A36.3(f)(2–4)

A36.3.9.12 .............................. A36.5(d)(3–4)

A36.4 ...................................... B36.1

A36.4.1 ................................... B36.1

A36.4.1.1 ................................ B36.1

A36.4.1.2 ................................ B36.1

A36.4.1.3 ................................ B36.1

A36.4.2 ................................... B36.3

A36.4.2.1 ................................ B36.3; AC 36–4C

A36.4.3 ................................... B36.5

A36.4.3.1 ................................ B36.5(a-m)

A36.4.3.2 ................................ B36.5(n)

A36.4.4 ................................... B36.7

A36.4.4.1 ................................ B36.7(a) & (b)

A36.4.4.2 ................................ B36.5(n)

A36.4.5 ................................... B36.9

A36.4.5.1 ................................ B36.9

A36.4.5.2 ................................ B36.9(a)

A36.4.5.3 ................................ B36.9(b)

A36.4.5.4 ................................ B36.9(c)

A36.4.5.5 ................................ B36.9(d)

A36.4.6 ................................... B36.11

A36.4.6.1 ................................ B36.11(a)

A36.4.7 ................................... B36.13

A36.4.7.1 ................................ B36.13(a)

A36.4.7.2 ................................ B36.13(a)(1–3)

A36.4.7.3 ................................ B36.13(b)

A36.4.7.4 ................................ B36.13(c)

A36.5 ...................................... A36.5

A36.5.1 ................................... A36.5(a)

A36.5.1.1 ................................ A36.5(a)

A36.5.1.2 ................................ A36.5(a)

A36.5.1.3 ................................ A36.5(a)

A36.5.2 ................................... A36.5(b)

A36.5.2.1 ................................ A36.5(b)(1)

A36.5.2.2 ................................ A36.5(b)(2)

A36.5.2.3 ................................ A36.5(b)(3)

A36.5.2.4 ................................ A36.5(b)(4)

A36.5.2.5 ................................ A36.5(b)(5)

A36.5.3 ................................... A36.5(c)

A36.5.3.1 ................................ A36.5(d)(1)

A36.5.4 ................................... A36.5(e)

A36.5.4.1 ................................ A36.5(e)(1)

A36.5.4.2 ................................ A36.5(e)(2)

A36.5.4.3 ................................ A36.5(e)(3)

A36.6 ...................................... A36.7

A36.7.1–A36.7.3 .................... A36.9(c)

A36.8 ...................................... New section—Reserved

A36.9 ...................................... A36.5(d)(1), A36.11

A36.9.1 ................................... A36.5(d)(2),

A36.9(d)(1),

A36.11(a),

A36.11(a)(3)(i) & (v)

A36.9.1.1 ................................ A36.9(a), A36.9(d)(1),

A36.11(a)(3)(ii-iii),

A36.11(a)(3)(iv)

A36.9.1.2 ................................ A36.11(f)(1–2)

A36.9.2 ................................... A36.11(b)&(c)

A36.9.2.1 ................................ A36.11(b)(1)(i-ii)

A36.9.2.2 ................................ A36.11(c)

A36.9.3 ................................... A36.11

A36.9.3.1 ................................ A36.11(a), A36.11(f)(1)

A36.9.3.2(a) ........................... A36.11(b)(3), A36.11(c)(2)

A36.9.3.2(b) ........................... New section

A36.9.3.2.1 ............................. A36.9(d)(1–3)

A36.9.3.2.1.1 .......................... A36.11(d)(1)(ii)

A36.9.3.2.1.2 .......................... A36.11(d)(1)(ii)

A36.9.3.2.2 ............................. B36.11(c)

A36.9.3.3 ................................ A36.11(e)

A36.9.3.3.1 ............................. A36.11(e)(1)(2)

A36.9.3.3.2 ............................. A36.11(e)

A36.9.3.4 ................................ A36.11(a)(3)(iv)

A36.9.3.4.1 ............................. A36.11(a)(3)(iv)

A36.9.3.4.2 ............................. A36.11(a)(3)(iv)

A36.9.3.5 ................................ A36.1(b)(7)

A36.9.3.5.1 ............................. A36.1(b)(7)

A36.9.4 ................................... A36.11(f)(2)(i-ii)

A36.9.4.1 ................................ A36.11(b)(2),

A36.11(f)(2)(i-ii)

A36.9.4.2 ................................ A36.11(f)(2)(i-ii)

A36.9.4.2.2 ............................. A36.11(f)(2)(i-ii)

CROSS REFERENCE TABLE—Continued

New Section Old Section

A36.9.4.2.3 ............................. A36.11(f)(2)(i-ii)

A36.9.4.3 ................................ A36.11(f)(2)(i-ii)

A36.9.4.4 ................................ A36.11(f)(2)(i-ii)

A36.9.4.4.1 ............................. A36.11(f)(2)(i-ii)

A36.9.5 ................................... A36.7

A36.9.6 ................................... A36.7

B36.1 ...................................... C36.1

B36.2 ...................................... A36.1(d)(1)

B36.3(a) ................................. C36.3(c)

B36.3(b) ................................. C36.3(a)

B36.3(c) ................................. A36.5(c)(2), C36.3(b)

B36.4(a) ................................. A36.11(f)

B36.4(b) ................................. A36.1(b)(7)

B36.5 ...................................... C36.5(a)

B36.5(a) ................................. C36.5(a)(1)

B36.5(b) ................................. C36.5(a)(2)

B36.5(b)(1) ............................. C36.5(a)(2)(i)

B36.5(b)(2) ............................. C36.5(a)(2)(ii)

B36.5(c) ................................. C36.5(a)(3)

B36.5(c)(1)(i) .......................... C36.5(a)(3)(i)(A)

B36.5(c)(1)(ii) ......................... C36.5(a)(3)(i)(B)

B36.5(c)(1)(iii) ........................ C36.5(a)(3)(i)(C)

B36.5(c)(2) ............................. C36.5(a)(3)(ii)

B36.5(c)(3) ............................. C36.5(a)(3)(iii)

B36.6 ...................................... C36.5(b)(1)-(3)

B36.7(a)(1)

B36.7(a)(2) ............................. A36.11(a)(3)(i)

B36.7(a)(3) ............................. C36.7(a), C36.9(a)

B36.7(a)(4) ............................. New section—Reserved

B36.7(a)(5) ............................. A36.5(c)(1), C36.7(e)(3)

B36.7(b)(1) ............................. C36.7(b), C36.7(b)(2)

B36.7(b)(2) ............................. C36.7(c)

B36.7(b)(3) ............................. A36.1(b)(2)

B36.7(b)(4) ............................. C36.7(e)(1–2)

B36.7(b)(5) ............................. C36.7(d)

B36.7(b)(6) ............................. A36.5(c)(2)

B36.7(b)(7) ............................. New section

B36.7(c) ................................. C36.9

B36.7(c) ................................. C36.9(a)

B36.7(c)(1) ............................. A36.5(c)(2), C36.9(c)

B36.7(c)(2) ............................. C36.9(e)(1), C36.9(e)(2)

B36.7(c)(3) ............................. C36.9(b-c)

B36.7(c)(4) ............................. A36.5(c)(2)

B36.7(c)(5) ............................. C36.9(b)

B36.8(a) ................................. New section

B36.8(b) ................................. A36.1(d)(1)

B36.8(c) ................................. A36.5(d), A36.11(a)

B36.8(d) ................................. A36.1(d)(5–7)

B36.8(e) ................................. A36.1(d)(6)

B36.8(f) .................................. A36.5(d)(5)

B36.8(g) ................................. C36.7(e)(1), C36.9(e)(3)

Paperwork Reduction Act

In this NPRM, Noise Certification

Standards for Subsonic Jet Airplanes

and Subsonic Transport Category Large

Airplanes, Part 36, proposed §§ A36.5.2

and A36.5.2.5 contain information

collection requirements. As required by

the Paperwork Reduction Act of 1995

(44 U.S.C. 3507(d)), the FAA has

submitted a copy of these proposed

sections to the Office of Management

and Budget (OMB) for its review.

The information to be collected is

needed for the applicant’s noise

compliance report that is required by

the Aircraft Noise Abatement Act of

1968. This statute authorized FAA to

prescribe standards for the measurement

of aircraft noise and to prescribe

regulations providing for the control

and abatement of aircraft noise. The

noise compliance report information is

part of the aircraft certification test. The

collected information is incorporated

into the noise compliance report that is

provided to and approved by the FAA.

The annual burden for § A36.5.2 is

estimated to range from $80 × 80 hours

at $6,400 per noise certification project

to $100 × 160 hours at $16,000 per noise

certification project. The annual burden

for § A36.5.2.5 is estimated to range

from $500 (5 hours × $100 per hour) to

$2,000 (25 hours × $80 per hour) per

certification. If proprietary information

is submitted, it will be protected in

accordance with appropriate laws.

The agency is soliciting comments to

(1) evaluate whether the proposed

collection of information is necessary;

(2) evaluate the accuracy of the agency’s

estimate of the burden; (3) enhance the

quality, utility, and clarity of the

information to be collected; and (4)

minimize the burden of the collection of

information on those who are to

respond, including through the use of

appropriate automated, electronic,

mechanical, or other technological

collection techniques or other forms of

information technology (for example,

permitting electronic submission of

responses).

Individuals and organizations may

submit comments on the information

collection requirement by September 11,

2000 and should direct them to the

address listed in the ADDRESSES section

of this document.

According to the regulations

implementing the Paperwork Reduction

Act of 1995, (5 CFR 1320.8(b)(2)(vi)), an

agency may not conduct or sponsor, and

a person is not required to respond to,

a collection of information unless it

displays a currently valid Office of

Management and Budget (OMB) control

number. The public will be notified of

the OMB control number when it is

assigned.

Compatibility With ICAO Standards

In keeping with the U.S. obligations

under the Convention on International

Civil Aviation, it is FAA policy to

comply with International Civil

Aviation Organization (ICAO) Standards

and Recommended Practices to the

maximum extent practicable. The FAA

has reviewed the corresponding ICAO

Standards and Recommended Practices

and has identified the following

differences with these proposed

regulations. If this proposal is adopted,

the FAA intends to file these differences

with ICAO.

Wind Speed. Section A36.2.2.2(e) of

the proposal requires that tests be

carried out under atmospheric

conditions where the average wind

velocity 10 meters above ground does

not exceed 12 knots and the crosswind

velocity for the airplane does not exceed

7 knots. Section A36.2.2.2(e) of the

proposal also specifies that maximum

wind velocity 10 meters above ground is

not to exceed 15 knots and the

crosswind velocity is not to exceed 10

Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules 42805

knots during the 10 dB down time

interval. Section 2.2.2(e) of ICAO Annex

16, Appendix 2 contains a similar

average wind speed limitation, but

specifies a maximum windspeed

limitation only in cases where an

anemometer with a built-in detector

time constant of less than 30 seconds is

used. The FAA does not agree to adopt

this Annex 16 provision because it

could result in tests being conducted in

windspeed conditions that exceed those

currently permitted under part 36; the

effect of these higher wind conditions

might have on the resulting noise levels

could not be determined based on the

information that was available to the

harmonization working group.

Adjustments to PNL and PNLT. In

adjusting measured sound pressure

level data to reference conditions,

section 9.3.2.1 of Annex 16 Appendix 2

requires that when a sound pressure

level value is equal to zero (for example,

as a result of applying a background

noise correction) the adjusted sound

pressure level must be kept equal to

zero in the adjustment process. The

FAA did not agree to adopt this

provision. The FAA’s view is that the

sound pressure level values should be

carried through the adjustment process

regardless of whether they are greater

than zero, equal to zero, or less than

zero. It is entirely possible for a negative

or zero sound pressure level value that

results from the background noise

correction process to become positive

when adjustments are applied to

account for the difference between the

test and reference airplane heights

above the noise measurement point.

Design characteristics that require

different reference procedures. Section

3.6.1.4 of ICAO Annex 16, Appendix 2

permits the certificating authority to

approve reference procedures that

depart from those contained in section

3.6.2 and 3.6.3 of Annex 16 Appendix

2 when design characteristics of an

airplane would prevent flight from

being conducted in accordance with the

3.6.2 and 3.6.3 reference procedures.

FAA did not agree to adopt this

provision since it views the need to

depart from the specified reference

procedures due to airplane design

characteristics as an indication that part

36 may not be appropriate for a given

airplane. In this case, under U.S.

procedures, the exemption or

rulemaking processes, which include a

public comment period would be

followed to develop an appropriate

noise certification basis.

Noise Certificates. Section 1.2 of

ICAO Annex 16, Chapter 1 specifies that

the documents attesting noise

certification may take the form of a

separate Noise Certificate or a suitable

statement contained in another

document approved by the State of

Registry and required by that State to be

carried in the aircraft. However, under

49 U.S.C. 44702, the FAA is not

authorized to issue Noise Certificates.

Section 36.1581 of part 36 requires that

the certificated noise levels be included

in the Airplane Flight Manual.

However, the FAA does not require the

Airplane Flight Manual to be carried in

the airplane. An operations manual that

does not contain certificated noise

levels is carried in some airplanes. The

FAA is aware of a number of cases in

which airplane operators had difficulty

in substantiating airplane noise

compliance status to the satisfaction of

airport authorities. The FAA invites

comments on the extent of any problems

encountered due to the absence of noise

compliance substantiation when the

Airplane Flight Manual is not on board

the airplane.

Economic Evaluation

Proposed changes to Federal

regulations undergo several economic

analyses. First, Executive Order 12866

directs that each Federal agency propose

or adopt a regulation only upon a

determination that the benefits of the

intended regulation justify its costs.

Second, the Regulatory Flexibility Act

of 1980 requires agencies to analyze the

economic impact of regulatory changes

on small entities. Third, the Trade

Agreements Act (19 U.S.C. section

2531–2533) prohibits agencies from

setting standards that create

unnecessary obstacles to the foreign

commerce of the United States. In

developing U.S. standards, this Trade

Act also requires agencies to consider

international standards and, where

appropriate, use them as the basis of

U.S. standards. And fourth, the

Unfunded Mandates Reform Act of 1995

requires agencies to prepare a written

assessment of the costs, benefits and

other effects of proposed or final rules

that include a Federal mandate likely to

result in the expenditure by State, local

or tribal governments, in the aggregate,

or by the private sector, of $100 million

or more annually (adjusted for

inflation.)

In conducting these analyses, the FAA

has determined that this rule (1) has

benefits which do justify its cost, is not

a ‘‘significant regulatory action’’ as

defined in the Executive Order and the

Department of Transportation’s (DOT)

Regulatory Policies and Procedures; (2)

will not have a significant impact on a

substantial number of small entities; (3)

reduces barriers to international trade;

and (4) does not impose an unfunded

mandate on state, local, or tribal

governments, or the private sector.

These analyses, available in the docket,

are summarized below.

Costs

Many of the changes in the proposed

rule are either editorial or procedural in

nature. These types of proposed

revisions would not add any new

requirements or impose costs. However,

38 sections of the proposed changes to

part 36 entail changes, which warranted

further evaluation to determine whether

they involve changes in criteria or could

impose additional costs. The key factor

in evaluating the proposed changes in

criteria was assessing whether an

applicant could pass the noise

certification test under the proposed

change but fail the test under the

current rule or vice versa, indicating a

change in the stringency of the existing

standard.

Eight sections that would be removed

by the proposed rule warranted further

evaluation. These include sections that

had previously been eliminated by an

earlier amendment but the text had

erroneously remained in part 36, as well

as sections that are no longer relevant

given improvements in test equipment

and the enhancement of data correction

procedures since the time part 36 was

originally promulgated. The deletion of

these sections has no cost impact.

The FAA evaluated the remaining

items to determine whether costs would

be incurred and examined the

magnitude of the cost. The sections of

the proposed rule with potential cost

fall into four categories: (1) Software

costs, (2) additional testing procedures,

(3) additional or new measuring

provisions, and (4) additional reporting

requirements.

Software Costs—Five proposed

provisions address the maintenance of

the computer programs used to correct

as-measured noise certification data to

14 CFR part 36 reference conditions.

Such maintenance often times involves

administrative cost. However, based on

discussions with staff at the Volpe

National Transportation Center, which

work under contract to the FAA and

evaluate certification software, the FAA

has determined that four of these

proposed changes would have no cost

impact. The fifth, Section A36.3.7.6,

would deal with technical differences in

the ‘‘readout’’ time of the time-weighted

measurement of the sound pressure

level between the test data and the

reference data. Implementation of this

change would require modifying the

computer software used by the

applicants. The estimated times

required for each applicant to

42806 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

implement the software change and for

the FAA to verify correct

implementation the change are 40 and

20 hours, respectively at hourly wage

rates of $85 and $75, respectively. The

FAA estimates that 39 applicants would

incur this one-time cost, and that these

software costs would be incurred in the

first 3 years after the proposed rule’s

implementation. The total cost to

industry and the FAA are $132,600 and

$58,500 ($116,000 and $51,200

discounted), respectively.

Testing Costs—Three proposed

changes relate to the operating

specifications of test aircraft, but none

have any cost impacts.

Measurement Costs—The FAA has

determined that of the ten proposed

changes that could affect the allowable

test conditions and correction of test

results to reference conditions, only one

would have a cost impact. Under the

proposed changes to Appendix B36.4(b),

a special requirement would be added

for propeller-driven airplanes that

would require the placement of

symmetrical positioned microphones at

each and every test measurement point.

However, most applicants already take

advantage of FAA-approved equivalent

test procedures that require only one set

of symmetrical microphones for sideline

noise measurements. Changing part 36

would not result in increased costs for

most applicants. However, an applicant

choosing to use multiple pairs of

microphones could incur additional

costs ranging up to an estimated $28,000

per test. These costs would involve an

increase in the number of microphone

systems, including cable, calibration,

site surveys, and data recording,

analysis and reporting. The FAA has

calculated costs assuming that two

domestic large-propeller applicants

would conduct 4 tests meeting this

requirement over the next 10 years. The

total cost would be $112,000, or

$79,200, discounted.

Reporting Costs—Section A36.5.2

would require applicants to include test

results in their noise certification

compliance report. While part 36

currently does not specifically require

applicants to submit a compliance

report it is a standard practice for

applicants to do so, since applicants

already address these data elements

under JAR 36 or ICAO Annex 16. The

addition of this provision would codify

industry practice. Since the information

is already provided, the FAA does not

believe there will be additional costs to

comply with this requirement. The FAA

requests comments on this assumption

and requests that all comments be

accompanied by clear documentation

supporting any proposed changes.

The FAA has determined that one

proposed change, to section A36.5.2.3,

would add new data elements to the

required test report. There would be five

new elements. All of these are test

airplane operating configuration items

that could effect the airplanes noise

signature and are already a part of the

international standard. Additional labor

costs for documenting data not

previously reported are estimated to

range from $500 (5 hours × $100 per

hour) to $2,000 (25 hours × $80 per

hour) per test. These estimates are based

on the number of additional items to be

reported and on the assumption of a

lower and upper range of required labor

hour increases of 5 to 8 hours and 20 to

25 hours, respectively, at hourly labor

rates that range from $80 to $100 per

hour.

Based on FAA estimates, 14 noise

certification projects involving flight

tests are undertaken each year. Four of

these projects are conducted among the

15 foreign firms which already comply

with these proposed reporting

requirements under JAR 36 or ICAO

Annex 16 and thus would not incur

additional reporting costs. Ten projects

are conducted from among 24 domestic

firms engaged in flight-testing and the

FAA estimates that these firms would

conduct 100 tests over the next 10 years.

The FAA further estimates that some

domestic firms will incur additional

reporting costs of $1,250 per test based

on the midpoint of the estimated

additional labor costs. Domestic firms

with a large international presence are

estimated to conduct 40 of the 100 tests

to be conducted over the next 10 years,

based on the composition of the

industry. Since these larger firms

already frequently comply with the

existing international reporting

standard, the FAA estimates that only

10 of the 40 tests to be conducted by

these firms would incur the additional

reporting costs of $1,250 each, or a total

of $12,500. The FAA estimates that of

the 60 tests to be conducted by smaller

domestic firms 24 tests would incur the

additional reporting costs of $1,250 per

test or a total of $30,000 over the next

10 years. Thus, the additional labor

costs for reporting the additional

information would total $42,500

($30,000 plus $12,500) for these affected

firms.

However, it is possible that some

applicants might accrue additional

costs. If an applicant was required to

invest in new instrumentation or data

recording equipment to comply with

these requirements, the estimated total

reporting costs could increase to

between $5,000 and $10,000 per test.

This is based on a range of estimates

and scenarios involving purchasing and

installing additional instrumentation,

and labor for adding recording

capability, data analysis, etc. For

example, one possible scenario would

entail the purchase and installation of

instrumentation hardware at $4,200

($2,500 for hardware and $1,700 for

labor [20 hours × $85 per hour]), plus

the labor cost for adding recording

capability and data recording/analysis at

$3,400 (40 hours × $85 per hour) for a

total of $7,600 of additional cost. The

FAA estimates that only three firms

would incur this additional cost of

$7,600 per test and that these firms

would conduct a total of 12 tests over

the next 10 years at a total cost of

$91,200. Thus, the total additional

reporting costs to the industry would be

$133,700, or $93,900 discounted, based

on the minimal additional reporting

costs of $42,500 incurred by some firms

and $91,200 incurred by the three firms

requiring additional instrumentation/

data recording.

Summary of Costs

The total costs for this proposed rule

are $436,800, or $340,300 discounted.

Of this total, industry costs are

$378,300, or $289,100 discounted, and

FAA costs are $58,500, or $51,200

discounted. Comments are invited on

these additional cost elements; the FAA

requests that all comments be

accompanied by clear economic

documentation.

Cost Savings

Several of the proposed changes could

result in cost savings to applicants,

depending upon the current inventory

of the applicant’s test equipment and

the particular weather circumstances of

the flight test. However, given the

uncertainty in the annual number and

duration of flight tests, it is difficult to

accurately quantify these savings. For

example, Section A36.2.2.2(b) would

lower the minimum test temperature

from 36 degrees Fahrenheit to 14

degrees Fahrenheit. This proposed

change is based on technical data from

extensive noise testing experience and

is within the operational temperature

limit of the noise measuring equipment.

One of the largest cost elements of the

test certification process is the cost

associated with airplane down time; by

extending the temperature range, down

time could be minimized. Down time

occurs when the test aircraft, crew,

equipment and technicians are ready to

commence testing but testing is delayed

or postponed because the weather

conditions specified in Section A36.2

are not met. While airplane noise testing

is not normally planned for cold

Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules 42807

weather, circumstances may dictate that

the test be conducted under conditions

which could take advantage of this new

lower temperature. Under this

circumstance, assuming various

scenarios of daily temperature warming

patterns that could result in reduced

hours of airplane down time, an

applicant might reduce total on-site test

time of a typical certification flight test

conducted under these conditions by 10

to 15 percent.

As an example of the impact of

permitting testing to be conducted at a

lower temperature, assuming an on-site

test time of 5 to 7 days to complete a

typical certification flight test under

these conditions, the applicant might

reduce the total test time between half

a day to one full day by testing during

a time period when the lower

temperature condition prevailed.

Assuming a cost factor of $150,000 to

$200,000 per day for larger planes and

$70,000 to $140,000 per day for smaller

airplanes, cost reductions per test made

possible by this change in minimum test

temperatures could range between

approximately $75,000 and $200,000 for

larger airplanes and manufacturers and

between $35,000 and $140,000 for

smaller airplanes and manufacturers.

The number of such tests conducted

under cold weather conditions might be,

at most, one per applicant over a 10 year

period. Some applicants might not

encounter this situation during a 10 year

period.

The FAA estimates that 24 larger

applicants would each derive cost

savings of $137,500 per test and 13

smaller firms would save $87,500 each

per test. The estimated industry cost

savings over ten years totals $4.44

million, or $3.12 million discounted.

Comments on these estimates are

invited; the FAA requests that all

comments be accompanied by clear

documentation supporting any

proposed changes.

Proposed section B36.3(a) includes a

simplified test procedure that may be

used in determining the sideline

(lateral) noise level for propeller-driven

large airplanes. This test procedure

would allow the full power noise

measurement to be obtained at a point

(650m) below the takeoff flight path and

thus eliminate the problems associated

with obtaining this measurement from

the conventional sideline site.

According to industry sources, 40 to 45

fly-bys per test could be eliminated and

between 2 and 8 microphone systems

could be eliminated depending on the

size of the array used by the applicant.

(Many applicants currently use a 2-

microphone sideline array.) In addition

to the significant savings resulting from

the reduction in the number of fly-bys

and the number of microphone systems,

further cost savings could result from a

reduction in site surveying and field setup expenses in addition to the analysis

and reporting savings that result from

fewer fly-bys. The total cost savings of

these changes are estimated at $200,000

to $350,000 per test for manufacturers of

propeller-driven large planes. These

estimates are based on a range of

potential scenarios involving

combinations of the above elements (the

number of fly-bys and the number of

microphones used, flight test costs, etc.).

As an example, based on a reduction of

42 fly-bys, the midpoint of the estimated

range, and an example cost factor of

$6,000 per fly-by, cost savings of

$252,000 would be realized. In addition,

assuming a reduction of 4 microphone

systems, including surveying, setup,

recording analysis and reporting at an

assumed cost factor of $7,000 per

system, another $28,000 (4 systems ×

$7,000 per system) in savings would be

realized, for a total example savings of

$280,000 per test under this example.

Given the increasing demand for

regional jets, and the financial status of

large propeller-driven manufacturers,

the FAA estimates that no more than 10

tests would be conducted over the next

10 years and that the derived cost

savings would total $2.80 million or

$1.97 million discounted.

Industry sources estimate that cost

savings on the order of $37,500 per year

for those applicants with considerable

certification activity would be realized

by the harmonization of testing, data

measurement and analysis, reporting

and documentation. Industry sources

also claim that these cost savings would

be achieved by a reduction in the

confusion and the multiple

interpretations that lead to delays,

duplicate effort and costly negotiation

caused by the existing dual certification

standards. The FAA estimates that 10

firms engaged in noise certification

activities would achieve cost savings of

$375,000 annually for the industry. The

estimated industry cost savings over ten

years totals $3.75 million, or $2.63

million discounted.

Total quantifiable cost savings over

ten years would be $10.99 million, or

$7.72 million discounted. The FAA has

not been able to quantify other potential

savings made possible by the greater

efficiencies and flexibility resulting

from the uniformity that the proposed

rule would provide. Comments are

invited; the FAA requests that all

comments be accompanied by clear

documentation. The FAA would

particularly appreciate specific cost

savings data.

Benefits

Currently, airplane manufacturers

must satisfy both the FAA and the

European noise certification standards

in order to market their aircraft in both

the United States and Europe. Meeting

two sets of noise certification

requirements raises the cost of

developing a new transport category

airplane, often with no increase in

safety or environmental benefit.

Adoption of these proposed changes to

the noise certification standards of part

36 will foster international trade, lower

the cost of aircraft development, and

make the certification process more

efficient.

Cost-Benefit Analysis

If the proposed rule becomes

effective, U.S. noise certification

procedures would be nearly uniform

with the JAA procedures. This

harmonization between the test

conditions, procedures, and noise levels

necessary to demonstrate compliance

with certification requirements for

subsonic jet airplanes and subsonic

transport category large airplanes would

result in significant cost savings without

compromising the environmental

benefits of the noise certification

standards.

The proposed rule’s cost savings, over

ten years (attributable to specific

proposed changes to part 36 and

achieving near uniformity of the

standards), would be $7.24 million,

$5.08 million discounted. In addition,

$3.75 million, $2.63 million discounted,

would be derived from overall

efficiencies attributable to the

harmonization effort in achieving near

uniformity of the FAA and JAA

standards for a total savings of $10.99

million, $7.72 million, discounted

which exceeds the proposed rule’s cost

of $436,800 ($340,300, discounted).

Since the potential cost savings exceed

the additional costs, the proposed rule

would be cost beneficial.

Initial Regulatory Flexibility Act

The Regulatory Flexibility Act of 1980

(Act) establishes ‘‘as a principle of

regulatory issuance that agencies shall

endeavor, consistent with the objective

of the rule and applicable statues, to fit

regulatory and informational

requirements to the scale of the

business, organizations, and

governmental jurisdictions subject to

regulation.’’ To achieve that principle,

the Act requires agencies to solicit and

consider flexible regulatory proposals

and to explain the rational for their

actions. Agencies must perform a review

to determine whether a proposed or

42808 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

final rule will have a significant

economic impact on a substantial

number of small entities. If the

determination is that it will, the agency

must prepare a regulatory flexibility

analysis (RFA) as described in the Act.

However, if an agency determines that

a proposed or final rule is not expected

to have a significant economic impact

on a substantial number of small

entities, section 605(b) of the 1980 act

provides that the head of the agency

may so certify and an RFA is not

required. The certification must include

a statement providing the factual basis

for this determination, and the

reasoning should be clear.

Enactment of this proposal would

impose costs of $436,800 on the FAA

and noise certification applicants over

the ten year period of which $250,400

would be incurred by smaller

applicants. The FAA has assumed that

two smaller applicants which is not a

substantial number of applicants would

each incur measurement costs of

$56,000, or a total of $112,000.

Additional reporting costs requiring

additional instrumentation/data

recording totaling $60,800 over the ten

year period would be incurred by 2

other smaller applicants or $30,400

each. Additional labor costs for new

reporting requirements totaling $30,000

over the 10 year period would be

incurred by 6 smaller applicants at a

cost to each of these smaller applicants

over the 10 year period of $5,000.

All the small (14) applicants at a cost

of $3,400 each or a total of $47,600

would incur one time software costs and

for four of these firms this would be the

only cost they incur. The first-year cost

to each of the six small applicants

incurring both software and additional

labor reporting costs would be $4,650.

In this case, the FAA has determined

this would not be a significant cost to

a substantial number of small noise

certification applicants. Therefore, the

FAA had determined that this proposed

rule would not have a significant

economic impact on a substantial

number of small entities.

International Trade Impact Assessment

The Trade Agreement Act of 1979

prohibits Federal agencies from

engaging in any standards or related

activity that create unnecessary

obstacles to the foreign commerce of the

United States. Legitimate domestic

objectives, such as safety, are not

considered unnecessary obstacles. The

statute also requires consideration of

international standards and where

appropriate, that they be the basis for

U.S. standards. In addition, consistent

with the Administration’s belief in the

general superiority and desirability of

free trade, it is the policy of the

Administration to remove or diminish,

to the extent feasible, barriers to

international trade, including both

barriers affecting the export of American

goods and services to foreign countries

and barriers affecting the import of

foreign goods and services into the U.S.

In accordance with the above statute

and policy, the FAA has assessed the

potential effect of this proposed rule

and has determined that it will impose

the same costs on domestic and

international entities and thus has a

neutral trade impact.

Executive Order 13132, Federalism

The FAA has analyzed this proposed

rule under the principles and criteria of

Executive Order 13132, Federalism. The

FAA has determined that this action

would not have substantial direct effects

on the States, on the relationship

between the national Government and

the States, or on the distribution of

power and responsibilities among the

various levels of government. Therefore,

the FAA has determined that this notice

of proposed rulemaking would not have

federalism implications.

Unfunded Mandates

The Unfunded Mandates reform Act

of 1995 (2 U.S.C. 1532–1538) requires

the FAA to assess the effects of Federal

Regulatory actions on state, local, and

tribal governments, and on the private

sector of proposed rules that contain a

Federal intergovernmental or private

sector mandate that exceeds $100

million in any one year. This action

does not contain such a mandate.

Environmental Assessment

FAA Order 1050.1D defines FAA

actions that may be categorically

excluded from preparation of a National

Environmental Policy Act (NEPA)

environmental assessment (EA) or

environmental impact statement (EIS).

In accordance with FAA Order 1050.1D,

appendix 4, paragraph 4(j), regulations,

standards, and exemptions (excluding

those, which if implemented may cause

a significant impact on the human

environment) qualify for a categorical

exclusion. The FAA proposes that this

rule qualifies for a categorical exclusion

because no significant impacts to the

environment are expected to result from

its finalization or implementation.

Energy Impact

The energy impact of the notice has

been assessed in accordance with the

Energy Policy and Conservation Act

(EPCA) Pub. L. 94–163, as amended (42

U.S.C. 6362) and FAA Order 1053.1. It

has been determined that the notice is

not a major regulatory action under the

provisions of the EPCA.

List of Subjects in 14 CFR Part 21 and

36

Aircraft, Noise control.

The Proposed Amendment

In consideration of the foregoing the

Federal Aviation Administration

proposes to amend 14 CFR parts 21 and

36, as follows:

PART 21—CERTIFICATION

PROCEDURES FOR PRODUCTS AND

PARTS

1. The authority citation for part 21

continues to read as follows:

Authority: 42 U.S.C. 7572; 49 U.S.C.

106(g), 40105, 40113, 44701–44702, 44707,

44709, 44711, 44713, 44715, 45303.

§ 21.17 [Amended]

2. Amend paragraph (a) of § 21.17 by

removing the word ‘‘parts’’ and adding

the word ‘‘part’’ and removing the

words ‘‘and 36’’.

§ 21.101 [Amended]

3. Amend paragraph (a) of § 21.101 by

removing the word ‘‘parts’’ and adding

the word ‘‘part’’ and removing the

words ‘‘and 36’’.

PART 36—NOISE STANDARDS:

AIRCRAFT TYPE AND

AIRWORTHINESS CERTIFICATION

1. The authority citation for part 36

continues to read as follows:

Authority: 42 U.S.C. 4321 et seq.; 49 U.S.C.

106(g), 40113, 44701–44702, 44704, 44715;

sec. 305, Pub. L. 96–193, 94 Stat. 50, 57; E.O.

11514, 35 FR 4247, 3 CFR, 1966–1970 Comp.,

p. 902.

§ 36.1 [Amended]

2. Amend § 36.1 as follows:

a. In paragraph (a)(1) remove the

words ‘‘turbojet powered’’ and add the

word ‘‘jet’’ in its place.

b. In paragraph (d), introductory text,

remove the words ‘‘turbojet powered’’

and add the word ‘‘jet’’ in its place.

c. Remove paragraph (d)(3).

d. In paragraph (f) remove the words

‘‘turbojet powered’’ and insert the word

‘‘jet’’ in its place.

e. In paragraph (f)(1) remove the

reference to ‘‘C36.5(a)(2)’’ and add

‘‘B36.5(b)’’ in its place; remove the word

‘‘takeoff’’ and add the word ‘‘flyover’’ in

its place; and remove the word

‘‘sideline’’ and add the word ‘‘lateral’’ in

its place;

f. In paragraph (f)(3) remove the

reference to ‘‘C36.5(a)(2)’’ and add

‘‘B36.5(b)’’ in its place and remove the

Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules 42809

reference to ‘‘C36.5(a)(3)’’ and insert

‘‘B36.5(c)’’ in its place;

g. In paragraph (f)(4) remove the

reference to ‘‘C36.5’’ and add ‘‘B36.5(b)’’

in its place;

h. In paragraph (f)(5) remove the

reference to ‘‘C36.5(a)(3)’’ and add

‘‘B36.5(c)’’ in its place;

i. In paragraph (f)(6) remove the

reference to ‘‘C36.5’’ and add ‘‘B36.5(c)’’

in its place; and.

j. In paragraph (g) remove the word

‘‘turbojet’’ and add the word ‘‘jet’’ in its

place.

§ 36.2 [Removed and reserved]

3. Remove and reserve § 36.2.

§ 36.6 [Amended]

* * * * *

4. Amend § 36.6 as follows:

a. Add paragraphs (c)(1)(vi) through

(x);

b. Revise paragraphs (d)(1)(i) and (ii),

(e)(3)(ii), (e)(3)(vii), and (e)(3)(ix).

The additions and revisions read as

follows:

(c) * * *

(1) * * *

(vi) IEC Publication 61094–3, entitled

‘‘Measurement Microphones—Part 3:

Primary Method for Free-Field

Calibration of Laboratory Standard

Microphones by the Reciprocity

Technique’’, edition 1.0, dated 1995.

(vii) IEC Publication 61094–4, entitled

‘‘Measurement Microphones—Part 4:

Specifications for Working Standard

Microphones’’, edition 1.0, dated 1995.

(viii) IEC Publication 61260, entitled

‘‘Electroacoustics-Octave-Band and

Fractional-Octave-Band filters’’, edition

1.0, dated 1995.

(ix) IEC Publication 61265, entitled

‘‘Instruments for Measurement of

Aircraft Noise-Performance

Requirements for Systems to Measure

One-Third-Octave-Band Sound pressure

Levels in Noise Certification of

Transport-Category Aeroplanes’’,

edition 1.0, dated 1995.

(x) IEC Publication 60942, entitled

‘‘Electroacoustics-Sound Calibrators’’,

edition 2.0, dated 1997.

* * * * *

(d) * * *

(1) * * *

(i) International Electrotechnical

Commission, 3, rue de Varembe, Case

postale 131, 1211 Geneva 20,

Switzerland

(ii) American National Standard

Institute, 11 West 42nd Street, New

York City, New York 10036

(e) * * *

(3) * * *

(iii) Southern Region Headquarters,

1701 Columbia Avenue, College Park,

Georgia, 30337.

* * * * *

(vi) Southwest Region Headquarters,

2601 Meacham Boulevard, Fort Worth,

Texas, 76137–4298.

(vii) Northwest Mountain Region

Headquarters, 1601 Lind Avenue,

Southwest, Renton, Washington 98055.

* * * * *

(ix) Alaskan Region Headquarters, 222

West 7th Avenue, 14, Anchorage,

Alaska, 99513.

* * * * *

§ 36.7 [Amended]

5. Amend § 36.7 to read as follows:

a. In paragraph (a) remove the words

‘‘turbojet powered’’ and add the word

‘‘jet’’ in its place.

b. In paragraph (b)(1) remove the

reference to ‘‘Appendices A and B’’ and

add ‘‘Appendix B’’ in its place.

c. In paragraph (b)(2) remove the

reference to ‘‘C36.9’’ and add ‘‘B36.8’’ in

its place.

d. In paragraph (c)(1) remove the

reference to ‘‘C36.5(b)’’ and add ‘‘B36.6’’

in its place.

e. In paragraph (d)(1) remove the

word ‘‘turbojet’’ and add the word ‘‘jet’’

in its place.

f. In paragraph (d)(1)(ii) remove the

reference to ‘‘C36.5(b)’’ and add ‘‘B36.6’’

in its place.

g. In paragraph (d)(2) remove the

word ‘‘turbojet’’ and add the word ‘‘jet’’

in its place.

Subpart B—Transport Category Large

Airplanes and Jet Airplanes

6. Revise the heading of Subpart B to

read as set forth above.

7. Revise § 36.101 to read as follows:

§ 36.101 Noise measurement and

evaluation.

For transport category large airplanes

and jet airplanes, the noise generated by

the airplane must be measured and

evaluated under appendix A of this part

or under an approved equivalent

procedure.

8. Revise § 36.103 to read as follows:

§ 36.103 Noise Limits.

(a) For subsonic transport category

large airplanes and subsonic jet

airplanes compliance with this section

must be shown with noise levels

measured and evaluated as prescribed

in Appendix A of this part, and

demonstrated at the measuring points,

and in accordance with the flight test

conditions under section C36.8 (or an

approved equivalent procedure), stated

under appendix C of this part.

(b) Type certification applications for

subsonic transport category large

airplanes and all subsonic jet airplanes

must show that the noise levels of the

airplane are no greater than the Stage 3

noise limits stated in section B36.5(c) of

appendix B of this part.

§ 36.201 (Subpart C) [Removed]

9. Remove and reserve subpart C,

consisting of § 36.201.

§ 36.1581 [Amended]

10. Amend § 36.1581(a)(1) and (d) by

removing the words ‘‘turbojet powered’’

and adding the word ‘‘jet’’ in its place.

11. Revise appendix A of part 36 to

read as follows:

Appendix A to Part 36—Aircraft Noise

Measurement and Evaluation Under § 36.101

Sec.

A36.1 Introduction.

A36.2 Noise certification test and

measurement conditions.

A36.3 Measurement of aircraft noise

received on the ground.

A36.4 Calculations of effective perceived

noise level from measured data.

A36.5 Reporting of data to the FAA.

A36.6 Nomenclature: Symbols and units.

A36.7 Sound attenuation in air.

A36.8 [Reserved]

A36.9 Adjustment of airplane flight test

results.

Section A36.1 Introduction.

A36.1.1 This appendix prescribes the

conditions under which airplane noise

certification tests must be conducted and

states the measurement procedures that must

be used to measure airplane noise during

each test conducted on or after [insert

effective date of final rule]. The procedures

that must be used to determine the noise

evaluation quantity designated as effective

perceived noise level, EPNL, under §§ 36.101

and 36.803 are also stated.

A36.1.2 The instructions and procedures

given are intended to ensure uniformity

during compliance tests and to permit

comparison between tests of various types of

airplane conducted in various geographical

locations.

A36.1.3 A complete list of symbols and

units, the mathematical formulation of

perceived noisiness, a procedure for

determining atmospheric attenuation of

sound, and detailed procedures for correcting

noise levels from non-reference to reference

conditions are included in sections A36.6 to

A36.9 of this appendix.

Section A36.2 Noise certification test and

measurement conditions.

A36.2.1 General.

A36.2.1.1 This section prescribes the

conditions under which noise certification

must be conducted and the measurement

procedures that must be used.

Note: Many noise certifications involve

only minor changes to the airplane type

design. The resultant changes in noise can

often be established reliably without the

necessity of resorting to a complete test as

outlined in this appendix. For this reason the

FAA permits the use of appropriate

‘‘equivalent procedures’’. There are also

equivalent procedures that may be used in

full certification tests, in the interest of

42810 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

reducing costs and providing reliable results.

Guidance material on the use of equivalent

procedures in the noise certification of

subsonic jet and propeller-driven large

airplanes is provided in the current Advisory

Circular for this part.

A36.2.2 Test environment.

A36.2.2.1 Locations for measuring noise

from an airplane in flight must be

surrounded by relatively flat terrain having

no excessive sound absorption characteristics

such as might be caused by thick, matted, or

tall grass, shrubs, or wooded areas. No

obstructions that significantly influence the

sound field from the airplane must exist

within a conical space above the point on the

ground vertically below the microphone, the

cone being defined by an axis normal to the

ground and by a half-angle 80° from this axis.

Note: Those people carrying out the

measurements could themselves constitute

such obstruction.

A36.2.2.2 The tests must be carried out

under the following atmospheric conditions.

(a) No precipitation;

(b) Ambient air temperature not above 95°F

(35°C) and not below 14°F (-10°C), and

relative humidity not above 95% and not

below 20% over the whole noise path

between a point 33 ft (10 m) above the

ground and the airplane.

Note: Care should be taken to ensure that

the noise measuring, airplane flight path

tracking and meteorological instrumentation

are operated within their environmental

limitations.

(c) Relative humidity and ambient

temperature over the whole noise path

between a point 33 ft (10 m) above the

ground and the airplane such that the sound

attenuation in the one-third octave band

centered on 8 kHz will not be more than 12

dB/100 m;

(d) If the atmospheric absorption

coefficients vary over the PNLTM sound

propagation path by more than ±1.6dB/1000ft

(±0.5dB/100m) in the 3150Hz one-third

octave band from the value of the absorption

coefficient derived from the meteorological

measurement obtained at 33 ft (10 m) above

the surface, ‘‘layered’’ sections of the

atmosphere must be used as described in

section A36.2.2.3 to compute equivalent

weighted sound attenuations in each onethird octave band; the FAA will determine

whether a sufficient number of layered

sections have been used. For each

measurement, where multiple layering is not

required, equivalent sound attenuations in

each one-third octave band must be

determined by averaging the atmospheric

absorption coefficients for each such band at

33 ft (10 m) above ground level, and at the

flight level of the airplane at the time of

PNLTM, for each measurement;

(e) Average wind velocity 10 meters above

ground is not to exceed 12 knots and the

crosswind velocity for the airplane is not to

exceed 7 knots. The average wind velocity

must be determined using a thirty-second

averaging period spanning the 10 dB down

time interval. Maximum wind velocity 10

meters above ground is not to exceed 15

knots and the crosswind velocity is not to

exceed 10 knots during the 10 dB down time

interval.

(f) No anomalous meteorological or wind

conditions that would significantly affect the

measured noise levels when the noise is

recorded at the measuring points specified by

the FAA; and

(g) Meteorological measurements must be

obtained within 30 minutes of each noise test

measurement; meteorological data must be

interpolated to actual times of each noise

measurement.

A36.2.2.3 When a multiple layering

calculation is required by section

A36.2.2.2(d) the atmosphere between the

airplane and 33 ft (10 m) above the ground

must be divided into layers of equal depth.

The depth of the layers must be set to not

more than the depth of the narrowest layer

across which the variation in the atmospheric

absorption coefficient of the 3150 Hz onethird octave band is not greater than +/-1.6

dB/1000 ft (+/-0.5 dB/100m), with a

minimum layer depth of 100 ft (30 m). This

requirement must be met for the propagation

path at PNLTM. The mean of the values of

the atmospheric absorption coefficients at the

top and bottom of each layer may be used to

characterize the absorption properties of each

layer.

A36.2.2.4 The airport control tower or

another facility must be approved by the

FAA for use as the central location at which

measurements of atmospheric parameters are

representative of those conditions existing

over the geographical area in which noise

measurements are made.

A36.2.3 Flight path measurement.

A36.2.3.1 The airplane height and lateral

position relative to the flight track must be

determined by a method independent of

normal flight instrumentation such as radar

tracking, theodolite triangulation, or

photographic scaling techniques, to be

approved by the FAA.

A36.2.3.2 The airplane position along the

flight path must be related to the noise

recorded at the noise measurement locations

by means of synchronizing signals over a

distance sufficient to assure adequate data

during the period that the noise is within 10

dB of the maximum value of PNLT.

A36.2.3.3 Position and performance data

required to make the adjustments referred to

in section A36.9 of this appendix must be

automatically recorded at an approved

sampling rate. Measuring equipment must be

approved by the FAA.

Section A36.3 Measurement of Airplane

Noise Received on the Ground.

A36.3.1 Definitions

For the purposes of this section the

following definitions apply:

A36.3.1.1 Measurement system means the

combination of instruments used for the

measurement of sound pressure levels,

including a sound calibrator, windscreen,

microphone system, signal recording and

conditioning devices, and one-third octave

band analysis system.

Note: Practical installations may include a

number of microphone systems, the outputs

from which are recorded simultaneously by

a multi-channel recording/analysis device via

signal conditioners, as appropriate. For the

purpose of this section, each complete

measurement channel is considered to be a

measurement system to which the

requirements apply accordingly.

A36.3.1.2 Microphone system means the

components of the measurement system

which produce an electrical output signal in

response to a sound pressure input signal,

and which generally include a microphone,

a preamplifier, extension cables, and other

devices as necessary.

A36.3.1.3 Sound incidence angle means

in degrees, an angle between the principal

axis of the microphone, as defined in IEC

61094–3 and IEC 61094–4, as amended and

a line from the sound source to the center of

the diaphragm of the microphone.

Note: When the sound incidence angle is

0°, the sound is said to be received at the

microphone at ‘‘normal (perpendicular)

incidence’’; when the sound incidence angle

is 90°, the sound is said to be received at

‘‘grazing incidence’’.

A36.3.1.4 Reference direction means, in

degrees, the direction of sound incidence

specified by the manufacturer of the

microphone, relative to a sound incidence

angle of 0°, for which the free-field

sensitivity level of the microphone system is

within specified tolerance limits.

A36.3.1.5 Free-field sensitivity of a

microphone system means, in volts per

Pascal, for a sinusoidal plane progressive

sound wave of specified frequency, at a

specified sound incidence angle, the quotient

of the root mean square voltage at the output

of a microphone system and the root mean

square sound pressure that would exist at the

position of the microphone in its absence.

A36.3.1.6 Free-field sensitivity level of a

microphone system means, in decibels,

twenty times the logarithm to the base ten of

the ratio of the free-field sensitivity of a

microphone system and the reference

sensitivity of one volt per Pascal.

Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules 42811

Note: The free-field sensitivity level of a

microphone system may be determined by

subtracting the sound pressure level (in

decibels re 20 μPa) of the sound incident on

the microphone from the voltage level (in

decibels re 1 V) at the output of the

microphone system, and adding 93.98 dB to

the result.

A36.3.1.7 Time-average band sound

pressure level means in decibels, ten times

the logarithm to the base ten, of the ratio of

the time mean square of the instantaneous

sound pressure during a stated time interval

and in a specified one-third octave band, to

the square of the reference sound pressure of

20 μPa.

A36.3.1.8 Level range means, in decibels,

an operating range determined by the setting

of the controls that are provided in a

measurement system for the recording and

one-third octave band analysis of a sound

pressure signal. The upper boundary

associated with any particular level range

must be rounded to the nearest decibel.

A36.3.1.9 Calibration sound pressure

level means, in decibels, the sound pressure

level produced, under reference

environmental conditions, in the cavity of

the coupler of the sound calibrator that is

used to determine the overall acoustical

sensitivity of a measurement system.

A36.3.1.10 Reference level range means,

in decibels, the level range for determining

the acoustical sensitivity of the measurement

system and containing the calibration sound

pressure level.

A36.3.1.11 Calibration check frequency

means, in hertz, the nominal frequency of the

sinusoidal sound pressure signal produced

by the sound calibrator.

A36.3.1.12 Level difference means, in

decibels, for any nominal one-third octave

midband frequency, the output signal level

measured on any level range minus the level

of the corresponding electrical input signal.

A36.3.1.13 Reference level difference

means, in decibels, for a stated frequency, the

level difference measured on a level range for

an electrical input signal corresponding to

the calibration sound pressure level, adjusted

as appropriate, for the level range.

A36.3.1.14 Level non-linearity means, in

decibels, the level difference measured on

any level range, at a stated one-third octave

nominal midband frequency, minus the

corresponding reference level difference, all

input and output signals being relative to the

same reference quantity.

A36.3.1.15 Linear operating range means,

in decibels, for a stated level range and

frequency, the range of levels of steady

sinusoidal electrical signals applied to the

input of the entire measurement system,

exclusive of the microphone but including

the microphone preamplifier and any other

signal-conditioning elements that are

considered to be part of the microphone

system, extending from a lower to an upper

boundary, over which the level non-linearity

is within specified tolerance limits.

Note. Microphone extension cables as

configured in the field need not be included

for the linear operating range determination.

A36.3.1.16 Windscreen insertion loss

means, in decibels, at a stated nominal onethird octave midband frequency, and for a

stated sound incidence angle on the inserted

microphone, the indicated sound pressure

level without the windscreen installed

around the microphone minus the sound

pressure level with the windscreen installed.

A36.3.2 Reference environmental

conditions.

A36.3.2.1 The reference environmental

conditions for specifying the performance of

a measurement system are:

(a) air temperature—73.4°F (23°C);

(b) static air pressure—101.325 kPa; and

(c) relative humidity—50 %.

A36.3.3 General.

Note. Measurements of aircraft noise that

use instruments that conform to the

specifications of this section yield one-third

octave band sound pressure levels as a

function of time. These one-third octave band

levels are to be used for the calculation of

effective perceived noise level as described

in section A36.4.

A36.3.3.1 The measurement system must

consist of equipment approved by the FAA

and equivalent to the following:

(a) A windscreen (see A36.3.4);

(b) A microphone system (see A36.3.5);

(c) A recording and reproducing system to

store the measured aircraft noise signals for

subsequent analysis (see A36.3.6 );

(d) A one-third octave band analysis

system (see A36.3.7); and

(e) Calibration systems to maintain the

acoustical sensitivity of the above systems

within specified tolerance limits (see

A36.3.8).

A36.3.3.2 For any component of the

measurement system that converts an analog

signal to digital form, such conversion must

be performed so that the levels of any

possible aliases or artifacts of the digitization

process will be less than the upper boundary

of the linear operating range by at least 50 dB

at any frequency less than 12.5 kHz. The

sampling rate must be at least 28 kHz. An

anti-aliasing filter must be included before

the digitization process.

A36.3.4 Windscreen.

A36.3.4.1 In the absence of wind and for

sinusoidal sounds at grazing incidence, the

insertion loss caused by the windscreen of a

stated type installed around the microphone

must not exceed ±1.5 dB at nominal onethird octave midband frequencies from 50 Hz

to 10 kHz inclusive.

A36.3.5 Microphone system.

A36.3.5.1 The microphone system must

conform to the specifications in sections

A36.3.5.2 to A36.3.5.4. Various microphone

systems may be approved by the FAA on the

basis of demonstrated equivalent overall

electroacoustical performance. Where two or

more microphone systems of the same type

are used, demonstration that at least one

system conforms to the specifications in full

is sufficient to demonstrate conformance.

Note. This demonstration of equivalent

performance does not eliminate the need to

calibrate and check each system as defined

in section A36.3.9.

A36.3.5.2 The microphone must be

mounted with the sensing element 4 ft (1.2

m) above the local ground surface and must

be oriented for grazing incidence, i.e., with

the sensing element substantially in the

plane defined by the predicted reference

flight path of the aircraft and the measuring

station. The microphone mounting

arrangement must minimize the interference

of the supports with the sound to be

measured. Figure A36–1 illustrates sound

incidence angles on a microphone.

A36.3.5.3 The free-field sensitivity level

of the microphone and preamplifier in the

reference direction, at frequencies over at

least the range of one-third-octave nominal

midband frequencies from 50 Hz to 5 kHz

inclusive, must be within ±1.0 dB of that at

the calibration check frequency, and within

±2.0 dB for nominal midband frequencies of

6.3 kHz, 8 kHz and 10 kHz.

A36.3.5.4 For sinusoidal sound waves at

each one-third octave nominal midband

frequency over the range from 50 Hz to 10

kHz inclusive, the free-field sensitivity levels

of the microphone system at sound incidence

angles of 30°, 60°, 90°, 120° and 150°, must

not differ from the free-field sensitivity level

at a sound incidence angle of 0° (‘‘normal

incidence’’) by more than the values shown

in Table A36–1. The free-field sensitivity

level differences at sound incidence angles

between any two adjacent sound incidence

angles in

42812 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

Table A36–1 must not exceed the tolerance

limit for the greater angle.

MAXIMUM DIFFERENCE BETWEEN THE FREE-FIELD SENSITIVITY LEVEL OF A MICROPHONE SYSTEM AT NORMAL INCIDENCE

AND THE FREE-FIELD SENSITIVITY LEVEL AT SPECIFIED SOUND INCIDENCE ANGLES

Nominal midband frequency kHz

dB Sound incidence angle degrees

30 60 90 120 150

0.05 to 1.6 ............................................................................ 0.5 0.5 1.0 1.0 1.0

2.0 ........................................................................................ 0.5 0.5 1.0 1.0 1.0

2.5 ........................................................................................ 0.5 0.5 1.0 1.5 1.5

3.15 ...................................................................................... 0.5 1.0 1.5 2.0 2.0

4.0 ........................................................................................ 0.5 1.0 2.0 2.5 2.5

5.0 ........................................................................................ 0.5 1.5 2.5 3.0 3.0

6.3 ........................................................................................ 1.0 2.0 3.0 4.0 4.0

8.0 ........................................................................................ 1.5 2.5 4.0 5.5 5.5

10.0 ...................................................................................... 2.0 3.5 5.5 6.5 7.5

Table A36–1 Microphone Directional

Response Requirements

A36.3.6 Recording and reproducing

systems.

A36.3.6.1 A recording and reproducing

system, such as a digital or analog magnetic

tape recorder, a computer-based system or

other permanent data storage device, must be

used to store sound pressure signals for

subsequent analysis. The sound produced by

the aircraft must be recorded in such a way

that a record of the complete acoustical

signal is retained. The recording and

reproducing systems must conform to the

specifications in sections A36.3.6.2 to

A36.3.6.9 at the recording speeds and/or data

sampling rates used for the noise certification

tests. Conformance must be demonstrated for

the frequency bandwidths and recording

channels selected for the tests.

A36.3.6.2 The recording and reproducing

systems must be calibrated as described in

section A36.3.9.

(a) For aircraft noise signals for which the

high frequency spectral levels decrease

rapidly with increasing frequency,

appropriate pre-emphasis and

complementary de-emphasis networks may

be included in the measurement system. If

pre-emphasis is included, over the range of

nominal one-third octave midband

frequencies from 800 Hz to 10 kHz inclusive,

the electrical gain provided by the preemphasis network must not exceed 20 dB

relative to the gain at 800 Hz.

A36.3.6.3 For steady sinusoidal electrical

signals applied to the input of the entire

measurement system including all parts of

the microphone system except the

microphone at a selected signal level within

5 dB of that corresponding to the calibration

sound pressure level on the reference level

range, the time-average signal level indicated

by the readout device at any one-third octave

nominal midband frequency from 50 Hz to 10

kHz inclusive must be within ±1.5 dB of that

at the calibration check frequency. The

frequency response of a measurement system,

which includes components that convert

analog signals to digital form, must be within

±0.3 dB of the response at 10 kHz over the

frequency range from 10 kHz to 11.2 kHz.

Note: Microphone extension cables as

configured in the field need not be included

for the frequency response determination.

This allowance does not eliminate the

requirement of including microphone

extension cables when performing the pink

noise recording in section A36.3.9.5.

A36.3.6.4 For analog tape recordings, the

amplitude fluctuations of a 1 kHz sinusoidal

signal recorded within 5 dB of the level

corresponding to the calibration sound

pressure level must not vary by more than

±0.5 dB throughout any reel of the type of

magnetic tape used. Conformance to this

requirement must be demonstrated using a

device that has time-averaging properties

equivalent to those of the spectrum analyzer.

A36.3.6.5 For all appropriate level ranges

and for steady sinusoidal electrical signals

applied to the input of the measurement

system, including all parts of the microphone

system except the microphone, at one-thirdoctave nominal midband frequencies of 50

Hz, 1 kHz and 10 kHz, and the calibration

check frequency, if it is not one of these

frequencies, the level non-linearity must not

exceed ±0.5 dB for a linear operating range

of at least 50 dB below the upper boundary

of the level range.

Note 1: Level linearity of measurement

system components may be tested according

Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules 42813

to the methods described in IEC 61265 as

amended.

Note 2: Microphone extension cables

configured in the field need not be included

for the level linearity determination.

A36.3.6.6 On the reference level range,

the level corresponding to the calibration

sound pressure level must be at least 5 dB,

but no more than 30 dB less than the upper

boundary of the level range.

A36.3.6.7 The linear operating ranges on

adjacent level ranges must overlap by at least

50 dB minus the change in attenuation

introduced by a change in the level range

controls.

Note: It is possible for a measurement

system to have level range controls that

permit attenuation changes of either 10 dB or

1 dB, for example. With 10 dB steps, the

minimum overlap required would be 40 dB,

and with 1 dB steps the minimum overlap

would be 49 dB.

A36.3.6.8 An overload indicator must be

included in the recording and reproducing

systems so that an overload indication will

occur during an overload condition on any

relevant level range.

A36.3.6.9 Attenuators included in the

measurement system to permit range changes

must operate in known intervals of decibel

steps.

A36.3.7 Analysis systems.

A36.3.7.1 The analysis system must

conform to the specifications in sections

A36.3.7.2 to A36.3.7.7 for the frequency

bandwidths, channel configurations and gain

settings used for analysis.

A36.3.7.2 The output of the analysis

system must consist of one-third octave band

sound pressure levels as a function of time,

obtained by processing the noise signals

(preferably recorded) through an analysis

system with the following characteristics:

(a) A set of 24 one-third octave band filters,

or their equivalent, having nominal midband

frequencies from 50 Hz to 10 kHz inclusive;

(b) Response and averaging properties in

which, in principle, the output from any onethird octave filter band is squared, averaged

and displayed or stored as time-averaged

sound pressure levels;

(c) The interval between successive sound

pressure level samples must be 500 ms ±5

milliseconds (ms) for spectral analysis with

or without slow time weighting, as defined

in section A36.3.7.4;

(d) For those analysis systems that do not

process the sound pressure signals during the

period of time required for readout and/or

resetting of the analyzer, the loss of data must

not exceed a duration of 5 ms; and

(e) The analysis system must operate in

real time from 50 Hz through at least 12 kHz

inclusive. This requirement applies to all

operating channels of a multi-channel

spectral analysis system.

A36.3.7.3 The minimum standard for the

one-third octave band analysis system is the

class 2 electrical performance requirements

of IEC 61260 as amended, over the range of

one-third octave nominal midband

frequencies from 50 Hz through 10 kHz

inclusive.

Note: Tests of the one-third octave band

analysis system may be made according to

the methods described in IEC 61260 for

relative attenuation, anti-aliasing filters, real

time operation, level linearity, and filter

integrated response (effective bandwidth).

A36.3.7.4 When slow time averaging is

performed in the analyzer, the response of

the one-third octave band analysis system to

a sudden onset or interruption of a constant

sinusoidal signal at the respective one-third

octave nominal midband frequency, must be

measured at sampling instants 0.5, 1, 1.5 and

2 seconds(s) after the onset and 0.5 and 1 s

after interruption. The rising response must

be -4 ± 1 dB at 0.5 s, -1.75 ± 0.75 dB at 1

s, -1 ± 0.5 dB at 1.5 s and -0.5 ± 0.5 dB at

2 s relative to the steady-state level. The

falling response must be such that the sum

of the output signal levels, relative to the

initial steady-state level, and the

corresponding rising response reading is -6.5

± 1 dB, at both 0.5 and 1 s. At subsequent

times the sum of the rising and falling

responses must be -7.5 dB or less. This

equates to an exponential averaging process

(slow weighting) with a nominal 1 s time

constant (i.e., 2 s averaging time).

A36.3.7.5 When the one-third octave band

sound pressure levels are determined from

the output of the analyzer without slow time

weighting, slow time weighting must be

simulated in the subsequent processing.

Simulated slow weighted sound pressure

levels can be obtained using a continuous

exponential averaging process by the

following equation:

Ls(i,k) = 10 log [(0.60653)10

0.1Ls[i,(k ndash;1)] + (0.39347) 10

0.1 L(i,k)]

Where Ls(i,k) is the simulated slow weighted

sound pressure level and L(i,k) is the asmeasured 0.5 s time average sound

pressure level determined from the

output of the analyzer for the k-th instant

of time and the i-th one-third octave

band. For k =1, the slow weighted sound

pressure Ls[i,(k-1=0)] on the right hand

side should be set to 0 dB. An

approximation of the continuous

exponential averaging is represented by

the following equation for a four sample

averaging process for k ≥( 4:

Ls(i,k) = 10 log [(0.13)10 0.1L[i,(k ndash;3)] +

(0.21) 10 0.1L[i,(k ndash;2)] +(0.27) 10

0.1L[i,(k ndash;1)] + (0.39)10 0.1L[i,k]]

Where Ls(i,k) is the simulated slow weighted

sound pressure level and L(i,k) is the as

measured 0.5 s time average sound

pressure level determined from the

output of the analyzer for the k-th instant

of time and the i-th one-third octave

band.

The sum of the weighting factors is 1.0 in

the two equations. Sound pressure levels

calculated by means of either equation are

valid for the sixth and subsequent 0.5 s data

samples, or for times greater than 2.5 s after

initiation of data analysis.

Note: The coefficients in the two equations

were calculated for use in determining

equivalent slow weighted sound pressure

levels from samples of 0.5 s time average

sound pressure levels. The equations should

not be used with data samples where the

averaging time differs from 0.5 s.

A36.3.7.6 The instant in time by which a

slow time weighted sound pressure level is

characterized must be 0.75 s earlier than the

actual readout time.

Note: The definition of this instant in time

is required to correlate the recorded noise

with the aircraft position when the noise was

emitted and takes into account the averaging

period of the slow weighting. For each 0.5

second data record this instant in time may

also be identified as 1.25 seconds after the

start of the associated 2 second averaging

period.

A36.3.7.7 The resolution of the sound

pressure levels, both displayed and stored,

must be 0.1 dB or finer.

A36.3.8 Calibration systems.

A36.3.8.1 The acoustical sensitivity of the

measurement system must be determined

using a sound calibrator generating a known

sound pressure level at a known frequency.

The minimum standard for the sound

calibrator is the class 1L requirements of IEC

60942 as amended.

A36.3.9 Calibration and checking of

system.

A36.3.9.1 Calibration and checking of the

measurement system and its constituent

components must be carried out to the

satisfaction of the FAA by the methods

specified in sections A36.3.9.2 through

A36.3.9.10. The calibration adjustments,

including those for environmental effects on

sound calibrator output level, must be

reported to the FAA and applied to the

measured one-third-octave sound pressure

levels determined from the output of the

analyzer. Data collected during an overload

indication are invalid and may not be used.

If the overload condition occurred during

recording, the

42814 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

associated test data are invalid, whereas if

the overload occurred during analysis, the

analysis must be repeated with reduced

sensitivity to eliminate the overload.

A36.3.9.2 The free-field frequency

response of the microphone system may be

determined by use of an electrostatic actuator

in combination with manufacturer’s data or

by tests in an anechoic free-field facility. The

correction for frequency response must be

determined within 90 days of each test series.

The correction for non-uniform frequency

response of the microphone system must be

reported to the FAA and applied to the

measured one-third octave band sound

pressure levels determined from the output

of the analyzer.

A36.3.9.3 When the angles of incidence of

sound emitted from the aircraft are within

±30° of grazing incidence at the microphone

(see Figure A36–1), a single set of free-field

corrections based on grazing incidence is

considered sufficient for correction of

directional response effects. For other cases,

the angle of incidence for each 0.5 second

sample must be determined and applied for

the correction of incidence effects.

A36.3.9.4 For analog magnetic tape

recorders, each reel of magnetic tape must

carry at least 30 seconds of pink random or

pseudo-random noise at its beginning and

end. Data obtained from analogue taperecorded signals will be accepted as reliable

only if level differences in the 10 kHz onethird-octave-band are not more than 0.75 dB

for the signals recorded at the beginning and

end.

A36.3.9.5 The frequency response of the

entire measurement system while deployed

in the field during the test series, exclusive

of the microphone, must be determined at a

level within 5 dB of the level corresponding

to the calibration sound pressure level on the

level range used during the tests for each

one-third octave nominal midband frequency

from 50 Hz to 10 kHz inclusive, utilizing

pink random or pseudo-random noise. The

output of the noise generator must be

determined by a method traceable to the U.S.

National Institute of Standards and

Technology or an equivalent national

standards laboratory as determined by the

FAA within six months of each test series.

Any changes in the relative output from the

previous calibration at each one-third octave

band may not exceed 0.2 dB. The correction

for frequency response must be reported to

the FAA and applied to the measured onethird octave sound pressure levels

determined from the output of the analyzer.

A36.3.9.6 The performance of switched

attenuators in the equipment used during

noise certification measurements and

calibration must be checked within six

months of each test series to ensure that the

maximum error does not exceed 0.1 dB.

A36.3.9.7 The sound pressure level

produced in the cavity of the coupler of the

sound calibrator must be calculated for the

test environmental conditions using the

manufacturer’s supplied information on the

influence of atmospheric air pressure and

temperature. This sound pressure level is

used to establish the acoustical sensitivity of

the measurement system. Within six months

of each test series the output of the sound

calibrator must be determined by a method

traceable to the U.S. National Institute of

Standards and Technology or an equivalent

national standards laboratory as determined

by the FAA. Changes in output from the

previous calibration must not exceed 0.2 dB.

A36.3.9.8 Sufficient sound pressure level

calibrations must be made during each test

day to ensure that the acoustical sensitivity

of the measurement system is known at the

prevailing environmental conditions

corresponding with each test series. The

difference between the acoustical sensitivity

levels recorded immediately before and

immediately after each test series on each

day may not exceed 0.5 dB. The 0.5 dB limit

applies after any atmospheric pressure

corrections have been determined for the

calibrator output level. The arithmetic mean

of the before and after measurements must be

used to represent the acoustical sensitivity

level of the measurement system for that test

series. The calibration corrections must be

reported to the FAA and applied to the

measured one-third octave band sound

pressure levels determined from the output

of the analyzer.

A36.3.9.9 Each recording medium, such

as a reel, cartridge, cassette, or diskette, must

carry a sound pressure level calibration of at

least 10 seconds duration at its beginning and

end.

A36.3.9.10 The free-field insertion loss of

the windscreen for each one-third octave

nominal midband frequency from 50 Hz to 10

kHz inclusive must be determined with

sinusoidal sound signals at the incidence

angles determined to be applicable for

correction of directional response effects per

section A36.3.9.3. The interval between

angles tested must not exceed 30 degrees. For

a windscreen that is undamaged and

uncontaminated, the insertion loss may be

taken from manufacturer’s data.

Alternatively, within six months of each test

series the insertion loss of the windscreen

may be determined by a method traceable to

the U.S. National Institute of Standards and

Technology or an equivalent national

standards laboratory as determined by the

FAA. Changes in the insertion loss from the

previous calibration at each one-third-octave

frequency band must not exceed 0.4 dB. The

correction for the free-field insertion loss of

the windscreen must be reported to the FAA

and applied to the measured one-third octave

sound pressure levels determined from the

output of the analyzer.

A36.3.9.11 Ambient noise, including both

acoustical background and electrical noise of

the measurement system, must be recorded

for at least 10 seconds at the measurement

points with the system gain set at the levels

used for the aircraft noise measurements.

Ambient noise must be representative of the

acoustical background that exists during the

flyover test run. The recorded aircraft noise

data is acceptable only if the ambient noise

levels, when analyzed in the same way, and

quoted in PNL (see A36.4.1.3 (a)), are at least

20 dB below the maximum PNL of the

aircraft.

A36.3.9.12 Aircraft sound pressure levels

within the 10 dB-down points (see A36.4.5.1)

must exceed the mean ambient noise levels

determined in section A36.3.9.11 by at least

3 dB in each one-third octave band, or must

be adjusted using a method approved by the

FAA; one method is described in the current

Advisory Circular for this part.

Section A36.4 Calculation of Effective

Perceived Noise Level From Measured Data.

A36.4.1 General.

A36.4.1.1 The basic element for noise

certification criteria is the noise evaluation

measure known as effective perceived noise

level, EPNL, in units of EPNdB, which is a

single number evaluator of the subjective

effects of airplane noise on human beings.

Simply stated, EPNL consists of

instantaneous perceived noise level, PNL,

corrected for spectral irregularities, and for

duration. The spectral irregularity correction,

called ‘‘tone correction factor’’, is made at

each time increment for only the maximum

tone.

A36.4.1.2 Three basic physical properties

of sound pressure must be measured: Level,

frequency distribution, and time variation.

To determine EPNL, the instantaneous sound

pressure level in each of the 24 one-third

octave bands

Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules 42815

is required for each 0.5 second increment of

time during the airplane noise measurement.

A36.4.1.3 The calculation procedure that

uses physical measurements of noise to

derive the EPNL evaluation measure of

subjective response consists of the following

five steps:

(a) The 24 one-third octave bands of sound

pressure level are converted to perceived

noisiness (noy) using one of the methods of

sub-section A36.4.2.1(a). The noy values are

combined and then converted to

instantaneous perceived noise levels, PNL(k).

(b) A tone correction factor C(k) is

calculated for each spectrum to account for

the subjective response to the presence of

spectral irregularities.

(c) The tone correction factor is added to

the perceived noise level to obtain tonecorrected perceived noise levels PNLT(k), at

each one-half second increment:

PNLT(k) = PNL(k) + C(k)

The instantaneous values of tone-corrected

perceived noise level are derived and the

maximum value, PNLTM, is determined.

(d) A duration correction factor, D, is

computed by integration under the curve of

tone-corrected perceived noise level versus

time.

(e) Effective perceived noise level, EPNL, is

determined by the algebraic sum of the

maximum tone-corrected perceived noise

level and the duration correction factor:

EPNL = PNLTM + D

A36.4.2 Perceived noise level.

A36.4.2.1 Instantaneous perceived noise

levels, PNL(k), must be calculated from

instantaneous one-third octave band sound

pressure levels, SPL(i,k) as follows:

(a) Step 1: For each one-third octave band

from 50 through 10,000 Hz, convert SPL(i,k)

to perceived noisiness n(i,k), by using the

mathematical formulation of the noy table

given in section A36.4.7, or to the Table of

Perceived Noisiness in the current Advisory

Circular for this part.

(b) Step 2: Combine the perceived

noisiness values, n(i,k), determined in step 1

by using the following formula:

Nk nk nik nk

nk nik

i

i

( ) = ( ) + ( ) 



 



 − ( )





















= ( ) + ( )

=

=

∑

∑

0 15

0 85 0 15

1

24

1

24

. ,

. .,

Where n(k) is the largest of the 24 values of

n(i,k) and N(k) is the total perceived

noisiness.

(c) Step 3: Convert the total perceived

noisiness, N(k), determined in Step 2 into

perceived noise level, PNL(k), using the

following formula:

PNL k N k ( ) = + 40 0 ( ) 10

2 . log log

Note: PNL(k) is plotted in the current

Advisory Circular for this part.

A36.4.3 Correction for spectral

irregularities.

A36.4.3.1 Noise having pronounced

spectral irregularities (for example, the

maximum discrete frequency components or

tones) must be adjusted by the correction

factor C(k) calculated as follows:

(a) Step 1: After applying the corrections

specified under section A36.3.9, start with

the sound pressure level in the 80 Hz onethird octave band (band number 3), calculate

the changes in sound pressure level (or

‘‘slopes’’) in the remainder of the one-third

octave bands as follows:

s(3,k) = no value

s(4,k) = SPL (4,k)¥SPL(3,k)

•

•

s(i,k) = SPL(i,k)¥SPL (i¥1,k)

•

•

s(24,k) = SPL(24,k)¥SPL(23,k)

(b) Step 2: Encircle the value of the slope,

s(i, k), where the absolute value of the change

in slope is greater than five; that is where:

|∆s(i,k)| = |s(i,k)¥s(i¥1,k)|>5

(c) Step 3:

(1) If the encircled value of the slope s(i,k)

is positive and algebraically greater than the

slope s(i¥1,k) encircle SPL(i, k).

(2) If the encircled value of the slope s(i,

k) is zero or negative and the slope s(i¥1,k)

is positive, encircle SPL(i¥1,k).

(3) For all other cases, no sound pressure

level value is to be encircled.

(d) Step 4: Compute new adjusted sound

pressure levels SPL′(i,k) as follows:

(1) For non-encircled sound pressure

levels, set the new sound pressure levels

equal to the original sound pressure levels,

SPL′(i,k) = SPL(i,k).

(2) For encircled sound pressure levels in

bands 1 through 23 inclusive, set the new

sound pressure level equal to the arithmetic

average of the preceding and following sound

pressure levels as shown below:

SPL′(i,k) = 1⁄2[SPL(i¥1,k)+SPL(i+1,k)]

(3) If the sound pressure level in the

highest frequency band (i =24) is encircled,

set the new sound pressure level in that band

equal to:

SPL′(24, k) = SPL(23, k)+s(23,k)

(e) Step 5: Recompute new slope s’(i,k),

including one for an imaginary 25th band, as

follows:

s′(3,k) = s′(4,k)

s′(4,k) = SPL′(4,k) ¥ SPL′(3,k)

•

•

s′(i,k) = SPL′(i,k) ¥ SPL′(i¥1,k)

•

•

s′(24,k) = SPL′(24,k) ¥ SPL′(23,k)

s′(25,k) = s′(24,k)

(f) Step 6: For i, from 3 through 23,

compute the arithmetic average of the three

adjacent slopes as follows:

s

 ̄

(i,k) = 1⁄3[s′(i,k) + s′(i + 1,k) + s′(i + 2,k)]

(g) Step 7: Compute final one-third octaveband sound pressure levels, SPL′′(i,k), by

beginning with band number 3 and

proceeding to band number 24 as follows:

SPL′′(3,k) = SPL(3,k)

SPL′′(4,k) = SPL′′(3,k) + s

 ̄

(3,k)

•

•

SPL′′(i,k) = SPL′′(i–1,k) + s

 ̄

(i–1,k)

•

•

SPL′′(24,k) = SPL′′(23,k) + s

 ̄

(23,k)

(h) Step 8: Calculate the differences, F (i,k),

between the original sound pressure level

and the final background sound pressure

level as follows:

F(i,k) = SPL (i,k) ¥ SPL′′(i,k)

and note only values equal to or greater than

1.5.

(i) Step 9: For each of the relevant onethird octave bands (3 through 24), determine

tone correction factors from the sound

pressure level differences F (i,k) and Table

A36–2.

42816 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

(j) Step 10: Designate the largest of the tone

correction factors, determined in Step 9, as

C(k). (An example of the tone correction

procedure is given in the current Advisory

Circular for this part.) Tone-corrected

perceived noise levels PNLT(k) must be

determined by adding the C(k) values to

corresponding PNL(k) values, that is:

PNLT(k) = PNL(k) + C(k)

For any i-th one-third octave band, at any kth increment of time, for which the tone

correction factor is suspected to result

from something other than (or in

addition to) an actual tone (or any

spectral irregularity other than airplane

noise), an additional analysis may be

made using a filter with a bandwidth

narrower than one-third of an octave. If

the narrow band analysis corroborates

these suspicions, then a revised value for

the background sound pressure level

SPL’’(i,k), may be determined from the

narrow band analysis and used to

compute a revised tone correction factor

for that particular one-third octave band.

Other methods of rejecting spurious tone

corrections may be approved.

A36.4.3.2 The tone correction procedure

will underestimate EPNL if an important tone

is of a frequency such that it is recorded in

two adjacent one-third octave bands. An

applicant must demonstrate that either:

(a) No important tones are recorded in two

adjacent one-third octave bands; or

(b) That if it has occurred that the tone

correction has been adjusted to the value it

would have had if the tone had been

recorded fully in a single one-third octave

band.

A36.4.4 Maximum tone-corrected

perceived noise level.

A36.4.4.1 The maximum tone-corrected

perceived noise level, PNLTM, must be the

maximum calculated value of the tonecorrected perceived noise level PNLT(k). It

must be calculated using the procedure of

section A36.4.3. To obtain a satisfactory

noise time history, measurements must be

made at 0.5 second time intervals.

Note 1: Figure A36–2 is an example of a

flyover noise time history where the

maximum value is clearly indicated.

Note 2: In the absence of a tone correction

factor, PNLTM would equal PNLM.

Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules 42817

A36.4.4.2 After the value of PNLTM is

obtained, the frequency band for the largest

tone correction factor is identified for the two

preceding and two succeeding 500 ms data

samples. This is performed in order to

identify the possibility of tone suppression at

PNLTM by one-third octave band sharing of

that tone. If the value of the tone correction

factor C(k) for PNLTM is less than the

average value of C(k) for the five consecutive

time intervals, the average value of C(k) must

be used to compute a new value for PNLTM.

A36.4.5 Duration correction.

A36.4.5.1 The duration correction factor

D determined by the integration technique is

defined by the expression:

D

T

PNLT dt PNLTM

t

t

= 























−

( )

( )

∫ 10 1

10 1

2

 log antilog

Where T is a normalizing time constant,

PNLTM is the maximum value of PNLT, t(1)

is the first point of time after which PNLT

becomes greater than PNLTM–10, and t(2) is

the point of time after which PNLT remains

constantly less than PNLTM–10.

A36.4.5.2 Since PNLT is calculated from

measured values of sound pressure level

(SPL), there is no obvious equation for PNLT

as a function of time. Consequently, the

equation is to be rewritten with a summation

sign instead of an integral sign as follows:

D

T

t

PNLT k

PNLTM

k

d t

= 







 ( )



 



 −

=

10 ∑1

10 0

 log antilog ∆

∆

.

Where ∆t is the length of the equal

increments of time for which PNLT(k) is

calculated and d is the time interval to the

nearest 0.5s during which PNLT(k) remains

greater or equal to PNLTM–10.

A36.4.5.3 To obtain a satisfactory history

of the perceived noise level use one of the

following:

(a) Half-second time intervals for ∆t; or

(b) A shorter time interval with approved

limits and constants.

A36.4.5.4 The following values for T and

∆t must be used in calculating D in the

equation given in section A36.4.5.2:

T = 10 s, and

∆t = 0.5 s (or the approved sampling time

interval).

Using these values, the equation for D

becomes:

42818 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

D

PNLT k

PNLTM

k

d

=  ( )



 



 − −

=

10 ∑ 1013

0

2

log antilog

Where d is the duration time defined by the

points corresponding to the values PNLTM–

10.

A36.4.5.5–If in using the procedures given

in section A36.4.5.2, the limits of PNLTM–

10 fall between the calculated PNLT(k)

values (the usual case), the PNLT(k) values

defining the limits of the duration interval

must be chosen from the PNLT(k) values

closest to PNLTM–10. For those cases with

more than one peak value of PNLT(k), the

applicable limits must be chosen to yield the

largest possible value for the duration time.

A36.4.6–Effective perceived noise level.

A36.4.6.1–The total subjective effect of an

airplane noise event, designated effective

perceived noise level, EPNL, is equal to the

algebraic sum of the maximum value of the

tone-corrected perceived noise level,

PNLTM, and the duration correction D. That

is:

EPNL = PNLTM + D

Where PNLTM and D are calculated using

the procedures given in sections A36.4.2,

A36.4.3, A36.4.4. and A36.4.5.

A36.4.7–Mathematical formulation of noy

tables.

A36.4.7.1–The relationship between sound

pressure level (SPL) and the logarithm of

perceived noisiness is illustrated in Figure

A36–3 and Table A36–3.

A36.4.7.2–The bases of the mathematical

formulation are:

(a) The slopes (M(b), M(c), M(d) and M(e))

of the straight lines;

(b) The intercepts (SPL(b) and SPL(c)) of

the lines on the SPL axis; and

(c) The coordinates of the discontinuities,

SPL(a) and log n(a); SPL(d) and log n = -1.0;

and SPL(e) and log n = log (0.3).

A36.4.7.3 Calculate noy values using the

following equations:

(a)

SPL ≥ SPL(a)

n = antilog {M(c)[SPL - SPL(c)]}

(b)

SPL(b) ≤ SPL < SPL(a)

n = antilog {M(b)[SPL - SPL(b)]}

(c)

SPL(e)≤SPL <SPL(b)

n = 0.3antilog {M(e)[SPL - SPL(e)]}

(d)

SPL(d)≤SPL <SPL(e)

n = 0.1 antilog {M(d)[SPL - SPL(d)]}

A36.4.7.4 Table A36–3 lists the values of

the constants necessary to calculate

perceived noisiness as a function of sound

pressure level.

Section A36.5 Reporting Of data to the

FAA.

A36.5.1 General.

A36.5.1.1 Data representing physical

measurements and data used to make

corrections to physical measurements must

be recorded in an approved permanent form

and appended to the record.

A36.5.1.2 All corrections must be

reported to and approved by the FAA. In

particular, the corrections to measurements

for equipment response deviations must be

reported.

Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules 42819

A36.5.1.3 Applicants may be required to

submit estimates of the individual errors

inherent in each of the operations employed

in obtaining the final data.

A36.5.2 Data reporting.

The following must be reported to the FAA

in the applicant’s noise certification

compliance report.

A36.5.2.1 The applicant must present

measured and corrected sound pressure

levels in one-third octave band levels that are

obtained with equipment conforming to the

standards described in section A36.3 of this

appendix.

A36.5.2.2 The applicant must report the

make and model of equipment used for

measurement and analysis of all acoustic

performance and meteorological data.

A36.5.2.3 The applicant must report the

following atmospheric environmental data,

as measured immediately before, after, or

during each test at the observation points

prescribed in section A36.2 of this appendix.

(a) Air temperature and relative humidity;

(b) Maximum, minimum and average wind

velocities; and

(c) Atmospheric pressure.

A36.5.2.4 The applicant must report

conditions of local topography, ground cover,

and events that might interfere with sound

recordings.

A36.5.2.5 The applicant must report the

following:

(a) Type, model and serial numbers (if any)

of airplane, engine(s), or propeller(s) (as

applicable);

(b) Gross dimensions of airplane and

location of engines;

(c) Airplane gross weight for each test run

and center of gravity range for each series of

test runs;

42820 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

(d) Airplane configuration such as flap,

airbrakes and landing gear positions and

propeller pitch angles (if applicable) for each

test run;

(e) Whether auxiliary power units (APU),

when fitted, are operating for each test run;

(f) Status of pneumatic engine bleeds and

engine power take-offs for each test run;

(g) Indicated airspeed in knots or

kilometers per hour for each test run;

(h) Engine performance data:

(1) For jet airplanes: engine performance in

terms of net thrust, engine pressure ratios, jet

exhaust temperatures and fan or compressor

shaft rotational speeds as determined from

airplane instruments and manufacturer’s data

for each test run;

(2) For propeller-driven airplanes: engine

performance in terms of brake horsepower

and residual thrust; or equivalent shaft

horsepower; or engine torque and propeller

rotational speed; as determined from airplane

instruments and manufacturer’s data for each

test run;

(i) Airplane flight path and ground speed

during each test run; and

(j) The applicant must report whether the

airplane has any modifications or nonstandard equipment likely to affect the noise

characteristics of the airplane. Any such

modifications or non-standard equipment

must be approved by the FAA.

A36.5.3 Reporting of noise certification

reference conditions. 

A36.5.3.1 Airplane position and

performance data and the noise

measurements must be corrected to the noise

certification reference conditions specified in

the relevant sections of appendix C of this

part. The applicant must report these

conditions, including reference parameters,

procedures and configurations.

A36.5.4 Validity of results.

A36.5.4.1 Three average reference EPNL

values and their 90 per cent confidence

limits must be produced from the test results

and reported, each such value being the

arithmetical average of the adjusted

acoustical measurements for all valid test

runs at each measurement point (flyover,

lateral, or approach. If more than one

acoustic measurement system is used at any

single measurement location, the resulting

data for each test run must be averaged as a

single measurement. The calculation must be

performed by:

(a) Computing the arithmetic average for

each flight phase using the values from each

microphone point; and

(b) Computing the overall arithmetic

average for each reference condition (flyover,

lateral or approach) using the values in

paragraph (a) of this section and the related

90 per cent confidence limits.

A36.5.4.2 For each of the three

certification measuring points, the minimum

sample size is six. The sample size must be

large enough to establish statistically for each

of the three average noise certification levels

a 90 per cent confidence limit not exceeding

±1.5 EPNdB. No test result may be omitted

from the averaging process unless approved

by the FAA.

Note: Methods available for calculating the

90 per cent confidence interval are shown in

the current Advisory Circular for this part.

A36.5.4.3 The average EPNL figures

obtained by the process described in section

A36.5.4.1 must be those by which the noise

performance of the airplane is assessed

against the noise certification criteria.

Section A36.6 Nomenclature: Symbols and

Units.

Symbol Unit Meaning

antilog ............................ ..................................... Antilogarithm to the base 10.

C(k) ................................ dB ............................... Tone correction factor. The factor to be added to PNL(k) to account for the presence of

spectral irregularities such as tones at the k-th increment of time.

d .................................... s .................................. Duration time. The time interval between the limits of t(1) and t(2) to the nearest 0.5 second.

D .................................... dB ............................... Duration correction. The factor to be added to PNLTM to account for the duration of the

noise.

EPNL ............................. EPNdB ........................ Effective perceived noise level. The value of PNL adjusted for both spectral irregularities

and duration of the noise. (The unit EPNdB is used instead of the unit dB).

f(i) .................................. Hz ............................... Frequency. The geometrical mean frequency for the i-th one-third octave band.

F(i,k) .............................. dB ............................... Delta-dB. The difference between the original sound pressure level and the final background

sound pressure level in the i-th one-third octave band at the k-th interval of time. In this

case, background sound pressure level means the broadband noise level that would be

present in the one-third octave band in the absence of the tone.

h .................................... dB ............................... dB-down. The value to be subtracted from PNLTM that defines the duration of the noise.

H .................................... per cent ....................... Relative humidity. The ambient atmospheric relative humidity.

i ...................................... ..................................... Frequency band index. The numerical indicator that denotes any one of the 24 one-third octave bands with geometrical mean frequencies from 50 to 10,000 Hz.

k ..................................... ..................................... Time increment index. The numerical indicator that denotes the number of equal time increments that have elapsed from a reference zero.

Log ................................ ..................................... Logarithm to the base 10.

log n(a) .......................... ..................................... Noy discontinuity coordinate. The log n value of the intersection point of the straight lines

representing the variation of SPL with log n.

M(b), M(c), etc. .............. ..................................... Noy inverse slope. The reciprocals of the slopes of straight lines representing the variation

of SPL with log n.

n .................................... noy .............................. The perceived noisiness at any instant of time that occurs in a specified frequency range.

n(i,k) .............................. noy .............................. The perceived noisiness at the k-th instant of time that occurs in the i-th one-third octave

band.

n(k) ................................ noy .............................. Maximum perceived noisiness. The maximum value of all of the 24 values of n(i) that occurs

at the k-th instant of time.

N(k) ................................ noy .............................. Total perceived noisiness. The total perceived noisiness at the k-th instant of time calculated

from the 24-instantaneous values of n(i,k).

p(b), p(c), etc. ................ ..................................... Noy slope. The slopes of straight lines representing the variation of SPL with log n.

PNL ............................... PNdB .......................... The perceived noise level at any instant of time. (The unit PNdB is used instead of the unit

dB).

PNL(k) ........................... PNdB .......................... The perceived noise level calculated from the 24 values of SPL (i,k), at the k-th increment of

time. (The unit PNdB is used instead of the unit dB).

PNLM ............................ PNdB .......................... Maximum perceived noise level. The maximum value of PNL(k). (The unit PNdB is used instead of the unit dB).

Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules 42821

Symbol Unit Meaning

PNLT ............................. TPNdB ........................ Tone-corrected perceived noise level. The value of PNL adjusted for the spectral irregularities that occur at any instant of time. (The unit TPNdB is used instead of the unit dB).

PNLT(k) ......................... TPNdB ........................ The tone-corrected perceived noise level that occurs at the k-th increment of time. PNLT(k)

is obtained by adjusting the value of PNL(k) for the spectral irregularities that occur at the

k-th increment of time. (The unit TPNdB is used instead of the unit dB).

PNLTM .......................... TPNdB ........................ Maximum tone-corrected perceived noise level. The maximum value of PNLT(k). (The unit

TPNdB is used instead of the unit dB).

PNLTr ............................ TPNdB ........................ Tone-corrected perceived noise level adjusted for reference conditions.

s(i,k) ............................... dB ............................... Slope of sound pressure level. The change in level between adjacent one-third octave band

sound pressure levels at the i-th band for the k-th instant of time.

δs(i,k) ............................. dB ............................... Change in slope of sound pressure level.

s’(i,k) .............................. dB ............................... Adjusted slope of sound pressure level. The change in level between adjacent adjusted onethird octave band sound pressure levels at the i-th band for the k-th instant of time.

s

 ̄

(i,k) ............................... dB ............................... Average slope of sound pressure level.

SPL ................................ dB re 20 μPa .............. Sound pressure level. The sound pressure level that occurs in a specified frequency range

at any instant of time.

SPL(a) ........................... dB re 20 μPa .............. Noy discontinuity coordinate. The SPL value of the intersection point of the straight lines

representing the variation of SPL with log n.

SPL(b) SPL(c) ............... dB re 20 μPa .............. Noy intercept. The intercepts on the SPL-axis of the straight lines representing the variation

of SPL with log n.

SPL(i,k) .......................... dB re 20μPa ............... The sound pressure level at the k-th instant of time that occurs in the i-th one-third octave

band.

SPL’(i,k) ......................... dB re 20μPa ............... Adjusted sound pressure level. The first approximation to background sound pressure level

in the i-th one-third octave band for the k-th instant of time.

SPL(i) ............................ dB re 20μPa ............... Maximum sound pressure level. The sound pressure level that occurs in the i-th one-third

octave band of the spectrum for PNLTM.

SPL(i)r ........................... dB re 20μPa ............... Corrected maximum sound pressure level. The sound pressure level that occurs in the i-th

one-third octave band of the spectrum for PNLTM corrected for atmospheric sound absorption.

SPL′′(i,k) ........................ dB re 20μPa ............... Final background sound pressure level. The second and final approximation to background

sound pressure level in the i-th one-third octave band for the k-th instant of time.

t ..................................... s .................................. Elapsed time. The length of time measured from a reference zero.

t(1), t(2) ......................... s .................................. Time limit. The beginning and end, respectively, of the noise time history defined by h.

∆t ................................... s .................................. Time increment. The equal increments of time for which PNL(k) and PNLT(k) are calculated.

T .................................... s .................................. Normalizing time constant. The length of time used as a reference in the integration method

for computing duration corrections, where T = 10s.

t(°F)(°C) ......................... °F, °C .......................... Temperature. The ambient air temperature.

α(i) ................................. dB/1000ft dB/100m ..... Test atmospheric absorption. The atmospheric attenuation of sound that occurs in the i-th

one-third octave band at the measured air temperature and relative humidity.

α(i)o ............................... dB/1000ft dB/100m ..... Reference atmospheric absorption. The atmospheric attenuation of sound that occurs in the

i-th one-third octave band at a reference air temperature and relative humidity.

A1 ................................... degrees ....................... First constant climb angle (Gear up, speed of at least V2+10 kt (V2 +19 km/h), takeoff thrust)

A2 ................................... degrees ....................... Second constant climb angle (Gear up, speed of at least V2+10 kt (V2 +19 km/h), after cutback)

δ, ε ................................. degrees ....................... Thrust cutback angles. The angles defining the points on the takeoff flight path at which

thrust reduction is started and ended respectively.

η .................................... degrees ....................... Approach angle.

ηr ................................... degrees ....................... Reference approach angle.

θ .................................... degrees ....................... Noise angle (relative to flight path). The angle between the flight path and noise path. It is

identical for both measured and corrected flight paths.

φ .................................... degrees ....................... Noise angle (relative to ground). The angle between the noise paths and the grounds. It is

identical for both measured and corrected flight paths.

μ .................................... ..................................... Engine noise emission parameter.

μr ................................... ..................................... Reference engine noise emission parameter.

∆1 ................................... EPNdB ........................ PNLT correction. The correction to be added to the EPNL calculated from measured data to

account for noise level changes due to differences in atmospheric absorption and noise

path length between reference and test conditions.

∆2 ................................... EPNdB ........................ Adjustment to duration correction. The adjustment to be made to the EPNL calculated from

measured data to account for noise level changes due to the noise duration between reference and test conditions.

∆3 ................................... EPNdB ........................ Source noise adjustment. The adjustment to be made to the EPNL calculated from measured data to account for noise level changes due to differences between reference and

test engine operating conditions.

Section A36.7 Sound Attenuation in Air.

A36.7.1 The atmospheric attenuation of

sound must be determined in accordance

with the procedure presented in section

A36.7.2.

A36.7.2 The relationship between sound

attenuation, frequency, temperature, and

humidity is expressed by the following

equations.

A36.7.2(a) For calculations using the

English System of Units:

a i

n

f

f

( ) =

+ ( ) ×

( )+× − [ ]

( ) = ×− [ ]

−

−

10

10

2 05 1000 6 10 1 45325

4 6833 10 2 4215

0 4

0 3

. .33 .

log . .

 log θ

θ

δ

and

42822 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

δ θ

θ θ

= ( )

×

( ) − +×

( ) − × +×

−

− −

1010

0

10

10

1 97274664 2 288074

9 589 10 3 0 10

2

52 73

f

log . .

. .

 H 10

Where

η(δ) is listed in Table A36–4 and f0 in Table

A36–5;

α(i) is the attenuation coefficient in dB/1000

ft;

θ is the temperature in °F; and

H is the relative humidity, expressed as a

percentage.

A36.7.2(b) For calculations using the

International System of Units (SI):

a i

n

f

f

( ) =

+ ( ) ×

( ) +×− [ ]

( ) + ×− [ ]

−

−

10

10

2 05 1000 11394 1 916984

8 42994 10 2 755624

0 3

0 3

. ..

log . .

 log 10

 

θ

θ

δ

and

δ θ

θ θ

=

×

( ) =+ ×

( ) − × +×

−

− −

1010 10

10

0

1 3 179768 10

2 173716 10 1 7496 10

2

42 63

f

log .328924 .

. .

 H

Where

η(δ) is listed in Table A36–4 and f0 in Table

A36–5;

α(i) is the attenuation coefficient in dB/100

m;

θ is the temperature in °C; and

H is the relative humidity, expressed as a

percentage.

A36.7.3 The values listed in table A36–4

are to be used when calculating the equations

listed in section A36.7.2. A term of quadratic

interpolation is to be used where necessary.

Section A36.8 [Reserved]

TABLE A36–4.—VALUES OF η(δ)

δ η(δ) δ η(δ)

0.00 0.000 2.50 0.450

0.25 0.315 2.80 0.400

0.50 0.700 3.00 0.370

0.60 0.840 3.30 0.330

0.70 0.930 3.60 0.300

0.80 0.975 4.15 0.260

0.90 0.996 4.45 0.245

1.00 1.000 4.80 0.230

1.10 0.970 5.25 0.220

1.20 0.900 5.70 0.210

1.30 0.840 6.05 0.205

1.50 0.750 6.50 0.200

1.70 0.670 7.00 0.200

2.00 0.570 10.00 0.200

2.30 0.495 ................ ................

TABLE A36–5.—VALUES OF F0

One-third

octave

center

frequency

f0 (Hz)

One-third

octave

center

frequency

f0 (Hz)

50 50 800 800

63 63 1000 1000

80 80 1250 1250

100 100 1600 1600

125 125 2000 2000

160 160 2500 2500

200 200 3150 3150

250 250 4000 4000

315 315 5000 4500

400 400 6300 5600

500 500 8000 7100

630 630 10000 9000

Section A36.9 Adjustment of Airplane

Flight Test Results.

A36.9.1 When certification test

conditions are not identical to reference

conditions, appropriate adjustments must be

made to the measured noise data using the

methods described in this section.

A36.9.1.1 Adjustments to the measured

noise values must be made using one of the

methods described in sections A36.9.3 and

A36.9.4 for differences in the following:

(a) Attenuation of the noise along its path

as affected by ‘‘inverse square’’ and

atmospheric attenuation.

(b) Duration of the noise as affected by the

distance and the speed of the airplane

relative to the measuring point.

(c) Source noise emitted by the engine as

affected by the differences between test and

reference engine operating conditions.

(d) Airplane/engine source noise as

affected by differences between test and

reference airspeeds. In addition to the effect

on duration, the effects of airspeed on

component noise sources must be accounted

for as follows: For conventional airplane

configurations, when differences between

test and reference airspeeds exceed 15 knots

(28 km/h) true airspeed, test data and/or

analysis approved by the FAA must be used

to quantify the effects of the airspeed

adjustment on resulting certification noise

levels.

A36.9.1.2 The ‘‘integrated’’ method of

adjustment, described in section A36.9.4,

must be used on takeoff or approach under

the following conditions:

(a) When the amount of the adjustment

(using the ‘‘simplified’’ method) is greater

than 8 dB on flyover, or 4 dB on approach;

or

(b) When the resulting final EPNL value on

flyover or approach (using the simplified

method) is within 1 dB of the limiting noise

levels as prescribed in Section B36.5 of this

part.

A36.9.2 Flight profiles.

As described below, flight profiles for both

test and reference conditions are defined by

their geometry relative to the ground,

together with the associated airplane speed

relative to the ground, and the associated

engine control parameter(s) used for

determining the noise emission of the

airplane.

A36.9.2.1 Takeoff Profile.

Note: Figure A36–4 illustrates a typical

takeoff profile.

(a) The airplane begins the takeoff roll at

point A, lifts off at point B and begins its first

climb at a constant angle at point C. Where

thrust or power (as appropriate) cut-back is

used, it is started at point D and completed

at point E. From here, the airplane begins a

second climb at a constant angle up to point

F, the end of the noise certification takeoff

flight path.

(b) Position K1 is the takeoff noise

measuring station and AK1 is the distance

from start of roll to the flyover measuring

point. Position K2 is the lateral noise

measuring station, which is located on a line

parallel to, and the

Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules 42823

specified distance from, the runway center

line where the noise level during takeoff is

greatest.

(c) The distance AF is the distance over

which the airplane position is measured and

synchronized with the noise measurements,

as required by section A36.2.3.2 of this part.

A36.9.2.2 Approach Profile.

Note.: Figure A36–5 illustrates a typical

approach profile.

(a) The airplane begins its noise

certification approach flight path at point G

and touches down on the runway at point J,

at a distance OJ from the runway threshold.

(b) Position K3 is the approach noise

measuring station and K3O is the distance

from the approach noise measurement point

to the runway threshold.

(c) The distance GI is the distance over

which the airplane position is measured and

synchronized with the noise measurements,

as required by section A36.2.3.2 of this part.

The airplane reference point for approach

measurements is the instrument landing

system (ILS) antenna.

BILLING CODE 4910–13–P

42824 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

A36.9.3 Simplified method of

adjustment.

A36.9.3.1 General. As described below,

the simplified adjustment method consists of

applying adjustments (to the EPNL, which is

Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules 42825

calculated from the measured data) for the

differences between measured and reference

conditions at the moment of PNLTM.

A36.9.3.2 Adjustments to PNL and PNLT.

(a) The portions of the test flight path and

the reference flight path described below,

and illustrated in Figure A36–6, include the

noise time history that is relevant to the

calculation of flyover and approach EPNL. In

figure A36–6:

(1) XY represents the portion of the

measured flight path that includes the noise

time history relevant to the calculation of

flyover and approach EPNL; XrYr represents

the corresponding portion of the reference

flight path.

(2) Q represents the airplane’s position on

the measured flight path at which the noise

was emitted and observed as PNLTM at the

noise measuring station K. Qr is the

corresponding position on the reference

flight path, and Kr the reference measuring

station. QK and Qrkr are, respectively, the

measured and reference noise propagation

paths, Qr being determined from the

assumption that QK and QrKr form the same

angle θ with their respective flight paths.

(b) The portions of the test flight path and

the reference flight path described in

paragraphs (b)(1) and (2) of this section

below, and illustrated in Figure A36–7(a) and

(b), include the noise time history that is

relevant to the calculation of Lateral EPNL.

(1) In figure A36–7(a), XY represents the

portion of the measured flight path that

includes the noise time history that is

relevant to the calculation of Lateral EPNL;

in figure A36–7(b), XrYr represents the

corresponding portion of the reference flight

path. For the Lateral noise measurement,

sound propagation is affected not only by

inverse square and atmospheric attenuation,

but also by ground absorption and reflection

effects which depend mainly on the angle ψ.

(2) Q represents the airplane position on

the measured flight path at which the noise

was emitted and observed as PNLTM at the

noise measuring station K. Qr is the

corresponding position on the reference

flight path, and Kr the reference measuring

station. QK and QrKr are, respectively, the

measured and reference noise propagation

paths. In this case Kr is only specified as

being on a particular Lateral line; Kr and Qr

are therefore determined from the

assumptions that QK and QrKr:

(i) Form the same angle θ with their

respective flight paths; and

(ii) Form the same angle ψ with the ground.

42826 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

A36.9.3.2.1 The one-third octave band

levels SPL(i) comprising PNL (the PNL at the

moment of PNLTM observed at K) must be

adjusted to reference levels SPL(i)r as

follows:

A36.9.3.2.1(a) For calculations using the

English System of Units:

SPL(i)r = SPL(i) + 0.001[α(i)–α(i)o]QK

+ 0.001α(i)o (QK – QrKr

+ 20log(QK/QrKr)

In this expression,

(1) The term 0.001[α(i)–α(i)o]QK is the

adjustment for the effect of the change in

sound attenuation coefficient, and α(i) and

α(i)o are the coefficients for the test and

reference atmospheric conditions

respectively, determined under section A36.7

of this appendix;

(2) The term 0.001α(i)o(QK–QrKr) is the

adjustment for the effect of the change in the

noise path length on the sound attenuation;

(3) The term 20log(QK/QrKr) is the

adjustment for the effect of the change in the

noise path length due to the ‘‘inverse square’’

law;

(4) QK and QrKr are measured in feet and

α(i) and α(i)o are expressed in dB/1000 ft.

A36.9.3.2.1(b) For calculations using the

International System of Units:

SPL(i)r = SPL(i) + 0.01[α(i)–α(i)o]QK

+ 0.01α(i)o (QK – QrKr

+ 20log(QK/QrKr)

In this expression,

(1) The term 0.01[α(i)–α(i)o]QK is the

adjustment for the effect of the change in

sound attenuation coefficient, and α(i) and

α(i)o are the coefficients for the test and

reference atmospheric conditions

respectively, determined under section A36.7

of this appendix;

(2) The term 0.01α(i)o (QK–QrKr is the

adjustment for the effect of the change in the

noise path length on the sound attenuation;

(3) The term 20log(QK/QrKr) is the

adjustment for the effect of the change in the

noise path length due to the inverse square

law;

(4) QK and QrKr are measured in meters

and α(i) and α(i)o are expressed in dB/100 m.

A36.9.3.2.1.1 PNLT Correction.

(a) Convert the corrected values, SPL(i)r, to

PNLTr;

(b) Calculate the correction term using the

following equation:

∆1 = PNLTr – PNLTM

A36.9.3.2.1.2 Add ∆1 arithmetically to the

EPNL calculated from the measured data.

A36.9.3.2.2 If, during a test flight, several

peak values of PNLT that are within 2 dB of

PNLTM are observed, the procedure defined

in section A36.9.3.2.1 must be applied at

each peak, and the adjustment term,

calculated according to section A36.9.3.2.1,

must be added to each peak to give

corresponding adjusted peak values of PNLT.

If these peak values exceed the value at the

moment of PNLTM, the maximum value of

such exceedance must be added as a further

Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules 42827

adjustment to the EPNL calculated from the

measured data.

A36.9.3.3 Adjustments to duration

correction.

A36.9.3.3.1 Whenever the measured

flight paths and/or the ground velocities of

the test conditions differ from the reference

flight paths and/or the ground velocities of

the reference conditions, duration

adjustments must be applied to the EPNL

values calculated from the measured data.

The adjustments must be calculated as

described below.

A36.9.3.3.2 For the flight path shown in

Figure A36–6, the adjustment term is

calculated as follows:

∆2 = ¥7.5log(QK/QrKr) + 10log(V/Vr)

(a) Add ∆2 arithmetically to the EPNL

calculated from the measured data.

A36.9.3.4 Source noise adjustments.

A36.9.3.4.1 To account for differences

between the parameters affecting engine

noise as measured in the certification flight

tests, and those calculated or specified in the

reference conditions, the source noise

adjustment must be calculated and applied.

The adjustment is determined from the

manufacturer’s data approved by the FAA.

Typical data used for this adjustment are

illustrated in Figure A36–8 that shows a

curve of EPNL versus the engine control

parameter μ, with the EPNL data being

corrected to all the other relevant reference

conditions (airplane mass, speed and

altitude, air temperature) and for the

difference in noise between the test engine

and the average engine (as defined in section

B36.7(b)(7)). A sufficient number of data

points over a range of values of μr are

required to calculate the source noise

adjustments for lateral, flyover and approach

noise measurements.

A36.9.3.4.2 Calculate adjustment term ∆3

by subtracting the EPNL value corresponding

to the parameter μ from the EPNL value

corresponding to the parameter μr. Add ∆3

arithmetically to the EPNL value calculated

from the measured data.

A36.9.3.5 Symmetry adjustments.

A36.9.3.5.1 A symmetry adjustment to

each lateral noise value (determined at the

section B36.4(b) measurement points), is to

be made as follows:

(a) If the symmetrical measurement point

is opposite the point where the highest noise

level is obtained on the main lateral

measurement line, the certification noise

level is the arithmetic mean of the noise

levels measured at these two points (see

Figure A36–9(a));

(b) If the condition described in paragraph

(a) of this section is not met, then it is

assumed that the variation of noise with the

altitude of the airplane is the same on both

sides; there is a constant difference between

the lines of noise versus altitude on both

sides (see Figure A36–9(b)). The certification

noise level is the maximum value of the

mean between these lines.

42828 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

A36.9.4 Integrated method of adjustment

A36.9.4.1 General. As described in this

section, the integrated adjustment method

consists of recomputing under reference

conditions points on the PNLT time history

corresponding to measured points obtained

during the tests, and computing EPNL

directly for the new time history obtained in

this way. The main principles are described

in sections A36.9.4.2 through A36.9.4.4.1.

A36.9.4.2 PNLT computations.

(a) The portions of the test flight path and

the reference flight path described in

paragraph (a)(1) and (2) of this section, and

illustrated in Figure A36–10, include the

noise time history that is relevant to the

calculation of flyover and approach EPNL. In

figure A36–10:

(1) XY represents the portion of the

measured flight path that includes the noise

time history relevant to the calculation of

flyover and approach EPNL; XrYr represents

the corresponding reference flight path.

(2) The points Q0, Q1, Qn represent airplane

positions on the measured flight path at time

t0, t1 and tn respectively. Point Q1 is the point

at which the noise was emitted and observed

as one-third octave values SPL(i)1 at the noise

measuring station K at time t1. Point Qr1

represents the corresponding position on the

reference flight path for noise observed as

SPL(i)r1 at the reference measuring station Kr

at time tr1. Q1K and Qr1Kr are respectively the

measured and reference noise propagation

paths, which in each case form the angle (01

with their respective flight paths. Qrθ and Qrn

are similarly the points on the reference

flight path corresponding to Q0 and Qn on the

measured flight path. Q0 and Qn are chosen

so that between Qr0 and Qrn all values of

PNLTr (computed as described in paragraphs

A36.9.4.2.2 and A36.9.4.2.3) within 10 dB of

the peak value are included.

(b) The portions of the test flight path and

the reference flight path described in

paragraphs (b)(1) and (2) of this section, and

illustrated in Figure A36–11(a) and (b),

include the noise time history that is relevant

to the calculation of lateral EPNL.

(1) In figure A36–11(a) XY represents the

portion of the measured flight path that

includes the noise time history that is

relevant to the calculation of Lateral EPNL;

in figure A36–11(b), XrYr represents the

corresponding portion of the reference flight

path. For the Lateral noise measurement,

sound propagation is affected not only by

‘‘inverse square’’ and atmospheric

attenuation, but also by ground absorption

and reflection effects which depend mainly

on the angle ψ.

(2) The points Q0, Q1 and Qn represent

airplane positions on the measured flight

path at time t0, t1 and tn respectively. Point

Q1 is the point at which the noise was

emitted and observed as one-third octave

values SPL(i)1 at the noise measuring station

K at time t1. The point Qr1 represents the

corresponding position on the reference

flight path for noise observed as SPL(i)r1 at

the measuring station Kr at time tr1. Q1K and

Qr1Kr are respectively the measured and

reference noise propagation paths. Qr0 and

Qrn are similarly the points on the reference

flight path corresponding to Q0 and Qn on the

measured flight path. Q0 and Qn are chosen

so that between Qro and Qrn all values of

PNLTr (computed as described in paragraphs

A36.9.4.2.2 and A36.9.4.2.3) within 10 dB of

the peak value are included. In this case Kr

is only specified as being on a particular

lateral line. The position of Kr and Qr1 are

determined from the following requirements:

(A) Q1K and Qr1Kr form the same angle θ1

with their respective flight paths; and

(B) The differences between the angles ψ1

and ψr1 must be minimized using a method,

approved by the FAA. The differences

between the angles are minimized since, for

geometrical reasons, it is generally not

possible to choose Kr so that the condition

described in paragraph A36.9.4.2(b)(2)(A) is

met while at the same time keeping ψ1 and

ψr1 equal.

A36.9.4.2.1 In paragraphs A36.9.4.2(a)(2)

and (b)(2) the time tr1 is

Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules 42829

later (for Qr1Kr > Q1K) than t1 by two separate

amounts:

(1) The time taken for the airplane to travel

the distance Qr1Qr0 at a speed Vr less the time

taken for it to travel Q1Q0 at V;

(2) The time taken for sound to travel the

distance Qr1Kr–Q1K.

Note 1: For the flight paths described in

paragraphs A36.9.4.2(a) and (b), if thrust or

power cut-back is used there will be test and

reference flight paths at full thrust or power

and at cut-back thrust or power. Where the

transient region between these affects the

final result an interpolation must be made

between them by an approved method such

as that given in the current Advisory Circular

for this part.

A36.9.4.2.2 The measured values of

SPL(i)1 must be adjusted to the reference

values SPL(i)r1 to account for the differences

between measured and reference noise path

lengths and between measured and reference

atmospheric conditions, using the methods of

section A36.9.3.2.1 of this appendix. A

corresponding value of PNLr1 must be

computed according to the method in section

A36.4.2. Values of PNLr must be computed

for times t0 through tn.

A36.9.4.2.3 For each value of PNLr1, a

tone correction factor C1 must be determined

by analyzing the reference values SPL(i)r

using the methods of section A36.4.3 of this

appendix, and added to PNLr1 to yield

PNLTr1. Using the process described in this

paragraph, values of PNLTr must be

computed for times t0 through tn.

A36.9.4.3 Duration correction.

A36.9.4.3.1 The values of PNLTr

corresponding to those of PNLT at each onehalf second interval must be plotted against

time (PNLTr1 at time tr1). The duration

correction must then be determined using the

method of section A36.4.5.1 of this appendix,

to yield EPNLr.

A36.9.4.4 Source Noise Adjustment.

A36.9.4.4.1 A source noise adjustment,

∆3, must be determined using the methods of

section A36.9.3.4 of this appendix.

A36.9.5 Flight path identification

positions.

Position Description

A ...................................................... Start of Takeoff roll.

B ...................................................... Lift-off.

C ...................................................... Start of first constant climb.

D ...................................................... Start of thrust reduction.

E ...................................................... Start of second constant climb.

F ...................................................... End of noise certification Takeoff flight path.

G ..................................................... Start of noise certification Approach flight path.

H ...................................................... Position on Approach path directly above noise measuring station.

I ....................................................... Start of level-off.

J ...................................................... Touchdown.

K ...................................................... Noise measurement point.

Kr ..................................................... Reference measurement point.

K1 .................................................... Flyover noise measurement point.

K2 .................................................... Lateral noise measurement point.

K3 .................................................... Approach noise measurement point.

M ..................................................... End of noise certification Takeoff flight track.

O ..................................................... Threshold of Approach end of runway.

P ...................................................... Start of noise certification Approach flight track.

Q ..................................................... Position on measured Takeoff flight path corresponding to apparent PNLTM at station K See section

B36.9.3.2.

Qr ..................................................... Position on corrected Takeoff flight path corresponding to PNLTM at station K. See section A36.9.3.2.

V ...................................................... Airplane test speed.

Vr ..................................................... Airplane reference speed.

A36.9.6 Flight path distances.

Distance Unit Meaning

AB .................................. Feet (meters) .............. Length of takeoff roll. The distance along the runway between the start of takeoff roll and lift

off.

AK .................................. Feet (meters) .............. Takeoff measurement distance. The distance from the start of roll to the takeoff noise measurement station along the extended center line of the runway.

AM ................................. Feet (meters) .............. Takeoff flight track distance. The distance from the start of roll to the takeoff flight track position along the extended center line of the runway after which the position of the airplane

need no longer be recorded.

QK ................................. Feet (meters) .............. Measured noise path. The distance from the measured airplane position Q to station K.

QrKr ............................... Feet (meters) .............. Reference noise path. The distance from the reference airplane position Qr to station Kr.

K3H ................................ Feet (meters) .............. Airplane approach height. The height of the airplane above the approach measuring station.

OK3 ................................ Feet (meters) .............. Approach measurement distance. The distance from the runway threshold to the approach

measurement station along the extended center line of the runway.

OP ................................. Feet (meters) .............. Approach flight track distance. The distance from the runway threshold to the approach flight

track position along the extended center line of the runway after which the position of the

airplane need no longer be recorded.

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42830 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules 42831

12. Appendix B of part 36 is revised

to read as follows:

Appendix B to Part 36—Noise Levels for

Transport Category and Jet Airplanes Under

§ 36.103

Sec.

B36.1 Noise measurement and evaluation.

B36.2 Noise evaluation metric.

B36.3 Reference noise measurement points.

B36.4 Test noise measurement.

B36.5 Maximum noise levels.

B36.6 Trade-offs.

B36.7 Noise certification reference

procedures.

B36.8 Test procedures.

Section B36.1 Noise Measurement and

Evaluation

Compliance with this appendix must be

shown with noise levels measured and

evaluated using the procedures of appendix

A of this part, or under approved equivalent

procedures.

Section B36.2 Noise Evaluation Metric

The noise evaluation metric is the effective

perceived noise level expressed in EPNdB, as

calculated using the procedures of appendix

A of this part.

Section B36.3 Reference Noise

Measurement Points

When tested using the procedures of this

part, except as provided in section B36.6, an

airplane may not exceed the noise levels

specified in section B36.5 at the following

points on level terrain:

(a) Lateral full-power reference noise

measurement point:

(1) For jet airplanes: The point on a line

parallel to and 1,476 feet (450 m) from the

runway centerline, or extended centerline,

where the noise level after lift-off is at a

maximum during takeoff. For the purpose of

showing compliance with Stage 1 or Stage 2

noise limits for an airplane powered by more

than three jet engines, the distance from the

runway centerline must be 0.35 nautical

miles (648 m).

(2) For propeller-driven airplanes: the

point on the extended centerline of the

runway above which the airplane, at full

takeoff power, reaches a height of 2,133 feet

(650 meters). For tests conducted before

March 20, 2002, an applicant may use the

measurement point specified in section

B36.3(a)(1) as an alternative.

(b) Flyover reference noise measurement

point: The point on the extended centerline

of the runway that is 21,325 feet (6,500m)

from the start of the takeoff roll;

(c) Approach reference noise measurement

point: The point on the extended centerline

of the runway that is 6,562 feet (2,000 m)

from the runway threshold. On level ground,

this corresponds to a position that is 394 feet

(120 m) vertically below the 3° descent path,

which originates at a point on the runway

984 feet (300 m) beyond the threshold.

Section B36.4 Test Noise Measurement

Points

(a) If the test noise measurement points are

not located at the reference noise

measurement points, any corrections for the

difference in position are to be made using

the same adjustment procedures as for the

differences between test and reference flight

paths.

(b) The applicant must obtain a sufficient

number of lateral test noise measurement

points to demonstrate to the FAA that the

maximum noise level on the appropriate

lateral line has been determined. For jet

airplanes, simultaneous measurements must

be made at one test noise measurement point

at its symmetrical point on the other side of

the runway. Propeller-driven airplanes have

an inherent asymmetry in lateral noise.

Therefore, simultaneous measurements must

be made at each and every test noise

measurement point at its symmetrical

position on the opposite side of the runway.

The measurement points are considered to be

symmetrical if they are longitudinally within

33 feet ((±10 meters) of each other.

Section B36.5 Maximum Noise Levels

Except as provided in section B36.6 of this

appendix, maximum noise levels, when

determined in accordance with the noise

evaluation methods of appendix A of this

part, may not exceed the following:

(a) For acoustical changes to Stage 1

airplanes, regardless of the number of

engines, the noise levels prescribed under

§ 36.7(c) of this part.

(b) For any Stage 2 airplane regardless of

the number of engines:

(1) Flyover: 108 EPNdB for maximum

weight of 600,000 pounds or more; for each

halving of maximum weight (from 600,000

pounds), reduce the limit by 5 EPNdB; the

limit is 93 EPNdB for a maximum weight of

75,000 pounds or less.

(2) Lateral and approach: 108 EPNdB for

maximum weight of 600,000 pounds or more;

for each halving of maximum weight (from

600,000 pounds), reduce the limit by 2

EPNdB; the limit is 102 EPNdB for a

maximum weight of 75,000 pounds or less.

(c) For any Stage 3 airplane:

(1) Flyover.

(i) For airplanes with more than 3 engines:

106 EPNdB for maximum weight of 850,000

pounds or more; for each halving of

maximum weight (from 850,000 pounds),

reduce the limit by 4 EPNdB; the limit is 89

EPNdB for a maximum weight of 44,673

pounds or less;

(ii) For airplanes with 3 engines: 104

EPNdB for maximum weight of 850,000

pounds or more; for each halving of

maximum weight (from 850,000 pounds),

reduce the limit by 4 EPNdB; the limit is 89

EPNdB for a maximum weight of 63,177

pounds or less; and

(iii) For airplanes with fewer than 3

engines: 101 EPNdB for maximum weight of

850,000 pounds or more; for each halving of

maximum weight (from 850,000 pounds),

reduce the limit by 4 EPNdB; the limit is 89

EPNdB for a maximum weight of 106,250

pounds or less.

(2) Lateral, regardless of the number of

engines: 103 EPNdB for maximum weight of

882,000 pounds or more; for each halving of

maximum weight (from 882,000 pounds),

reduce the limit by 2.56 EPNdB; the limit is

94 EPNdB for a maximum weight of 77,200

pounds or less.

(3) Approach, regardless of the number of

engines: 105 EPNdB for maximum weight of

617,300 pounds or more; for each halving of

maximum weight (from 617,300 pounds),

reduce the limit by 2.33 EPNdB; the limit is

98 EPNdB for a maximum weight of 77,200

pounds or less.

Section B36.6 Trade-Offs

Except when prohibited by sections

36.7(c)(1) and 36.7(d)(1)(ii), if the maximum

noise levels are exceeded at any one or two

measurement points, the following

conditions must be met:

(a) The sum of the exceedance(s) may not

be greater than 3 EPNdB;

(b) Any exceedance at any single point may

not be greater than 2 EPNdB, and

(c) Any exceedance(s) must be offset by a

corresponding amount at another point or

points.

Section B36.7 Noise Certification Reference

Procedures

(a) General conditions:

(1) All reference procedures must meet the

requirements of section 36.3 of this part.

(2) Calculations of airplane performance

and flight path must be made using the

reference procedures and must be approved

by the FAA.

(3) Applicants must use the takeoff and

approach reference procedures prescribed in

paragraphs (b) and (c) of this section.

(4) [Reserved]

(5) The reference procedures must be

determined for the following reference

conditions. The reference atmosphere is

homogeneous in terms of temperature and

relative humidity when used for the

calculation of atmospheric absorption

coefficients.

(i) Sea level atmospheric pressure of 2116

pounds per square foot (psf) (1013.25 hPa);

(ii) Ambient sea-level air temperature of

77°F (25°C, i.e. ISA+10°C);

(iii) Relative humidity of 70 per cent; and

(iv) Zero wind.

(v) In defining the reference takeoff flight

path(s) for the takeoff and lateral noise

measurements, the runway gradient is zero.

(b) Takeoff reference procedure:

The takeoff reference flight path is to be

calculated using the following:

(1) Average engine takeoff thrust or power

must be used from the start of takeoff to the

point where at least the following height

above runway level is reached. The takeoff

thrust/power used must be the maximum

available for normal operations given in the

performance section of the airplane flight

manual under the reference atmospheric

conditions given in section B36.7(a)(5).

(i) For Stage 1 airplanes and for Stage 2

airplanes that do not have jet engines with

a bypass ratio of 2 or more, the following

apply:

(A): For airplanes with more than three jet

engines—700 feet (214 meters).

(B): For all other airplanes—1,000 feet (305

meters).

(ii) For Stage 2 airplanes that have jet

engines with a bypass ratio of 2 or more and

for Stage 3 airplanes, the following apply:

(A): For airplanes with more than three

engines—689 feet (210 meters).

42832 Federal Register / Vol. 65, No. 133 / Tuesday, July 11, 2000 / Proposed Rules

(B): For airplanes with three engines—853

feet (260 meters).

(C) For airplanes with fewer than three

engines—984 feet (300 meters).

(2) Upon reaching the height specified in

paragraph (b)(1) of this section, airplane

thrust or power must not be reduced below

that required to maintain either of the

following, whichever is greater:

(i) A climb gradient of 4 per cent; or

(ii) In the case of multi-engine airplanes,

level flight with one engine inoperative.

(3) For the purpose of determining the

lateral noise level, the reference flight path

must be calculated using full takeoff power

throughout the test run without a reduction

in thrust or power. For tests conducted before

March 20, 2002, a single reference flight path

that includes thrust cutback in accordance

with paragraph (b)(1) of this section, is an

acceptable alternative in determining the

lateral noise level.

(4) The takeoff reference speed is the allengine operating takeoff climb speed selected

by the applicant for use in normal operation;

this speed must be at least V2+10kt

(V2+19km/h) but may not be greater than

V2+20kt (V2+37km/h). This speed must be

attained as soon as practicable after lift-off

and be maintained throughout the takeoff

noise certification test. For Concorde

airplanes, the test day speeds and the

acoustic day reference speed are the

minimum approved value of V2 +35 knots,

or the all-engines-operating speed at 35 feet,

whichever speed is greater as determined

under the regulations constituting the type

certification basis of the airplane; this

reference speed may not exceed 250 knots.

For all airplanes, noise values measured at

the test day speeds must be corrected to the

acoustic day reference speed.

(5) The takeoff configuration selected by

the applicant must be maintained constantly

throughout the takeoff reference procedure,

except that the landing gear may be retracted.

Configuration means the center of gravity

position, and the status of the airplane

systems that can affect airplane performance

or noise. Examples include, the position of

lift augmentation devices, whether the APU

is operating, and whether air bleeds and

engine power take-offs are operating;

(6) The weight of the airplane at the brake

release must be the maximum takeoff weight

at which the noise certification is requested,

which may result in an operating limitation

as specified in § 36.1581(d); and

(7) The average engine is defined as the

average of all the certification compliant

engines used during the airplane flight tests,

up to and during certification, when

operating within the limitations and

according to the procedures given in the

Flight Manual. This will determine the

relationship of thrust/power to control

parameters (e.g., N1 or EPR). Noise

measurements made during certification tests

must be corrected using this relationship.

(c) Approach reference procedure:

The approach reference flight path must be

calculated using the following:

(1) The airplane is stabilized and following

a 3° glide path;

(2) For subsonic airplanes, a steady

approach speed of VREF + 10 kts (VREF + 19

km/h) with thrust and power stabilized must

be established and maintained over the

approach measuring point. For Concorde

airplanes, a steady approach speed that is

either the landing reference speed + 10 knots

or the speed used in establishing the

approved landing distance under the

airworthiness regulations constituting the

type certification basis of the airplane,

whichever speed is greater. This speed must

be established and maintained over the

approach measuring point.

(3) The constant approach configuration

used in the airworthiness certification tests,

but with the landing gear down, must be

maintained throughout the approach

reference procedure;

(4) The weight of the airplane at

touchdown must be the maximum landing

weight permitted in the approach

configuration defined in paragraph (c)(3) of

this section at which noise certification is

requested, except as provided in § 36.1581(d)

of this part; and

(5) The most critical configuration must be

used; this configuration is defined as that

which produces the highest noise level with

normal deployment of aerodynamic control

surfaces including lift and drag producing

devices, at the weight at which certification

is requested. This configuration includes all

those items listed in section A36.5.2.5 of

appendix A of this part that contribute to the

noisiest continuous state at the maximum

landing weight in normal operation.

Section B36.8 Noise Certification Test

Procedures

(a) All test procedures must be approved

by the FAA.

(b) The test procedures and noise

measurements must be conducted and

processed in an approved manner to yield

the noise evaluation metric EPNL, in units of

EPNdB, as described in appendix A of this

part.

(c) Acoustic data must be adjusted to the

reference conditions specified in this

appendix using the methods described in

appendix A of this part. Adjustments for

speed and thrust must be made as described

in section A36.9 of this part.

(d) If the airplane’s weight during the test

is different from the weight at which noise

certification is requested, the required EPNL

adjustment may not exceed 2 EPNdB for each

takeoff and 1 EPNdB for each approach. Data

approved by the FAA must be used to

determine the variation of EPNL with weight

for both takeoff and approach test conditions.

The necessary EPNL adjustment for

variations in approach flight path from the

reference flight path must not exceed 2

EPNdB.

(e) For approach, a steady glide path angle

of 3° ± 0.5° is acceptable.

(f) If equivalent test procedures different

from the reference procedures are used, the

test procedures and all methods for adjusting

the results to the reference procedures must

be approved by the FAA. The adjustments

may not exceed 16 EPNdB on takeoff and 8

EPNdB on approach. If the adjustment is

more than 8 EPNdB on takeoff, or more than

4 EPNdB on approach, the resulting numbers

must be more than 2 EPNdB below the limit

noise levels specified in section B36.5.

(g) During takeoff, lateral, and approach

tests, the airplane variation in instantaneous

indicated airspeed must be maintained

within +/¥3% of the average airspeed

between the 10dB-down points. This

airspeed is determined by the pilot’s airspeed

indicator. However, if the instantaneous

indicated airspeed exceeds +/¥3 kt (+/¥5.5

km/h) of the average airspeed over the 10dBdown points, and is determined by the FAA

representative on the flight deck to be due to

atmospheric turbulence, then the flight so

affected must be rejected for noise

certification purposes.

Note: Guidance material on the use of

equivalent procedures is provided in the

current Advisory Circular for this part.

13. Remove and reserve appendix C of part

36.

Section G36.105 [Amended]

14. Amend paragraph (f) of section G36.105

of appendix G by removing the reference

‘‘paragraph A36.3(e) of Appendix A’’ and

adding ‘‘paragraphs A36.3.8 and A36.3.9 of

Appendix A’’ in its place.

Section H36.111 [Amended]

15. Amend paragraph (c)(3) of section

H36.111 of appendix H by removing the

reference ‘‘A36.3(f)(3)’’ and adding

‘‘A36.3.9.11’’ in its place.

Section H36.201 [Amended]

16. Amended paragraph (b) of section

H36.201 of appendix H by removing the

reference ‘‘B36.5(a)’’ and adding

‘‘A36.4.3.1—Step 1’’ in its place.

Issued in Washington, DC, on June 29,

2000.

Paul R. Dykeman,

Acting Director of Environment and Energy.

[FR Doc. 00–16913 Filed 7–10–00; 8:45 am]

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