[Federal Register Volume 65, Number 194 (Thursday, October 5, 2000)]
[Proposed Rules]
[Pages 59634-59647]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-24634]



[[Page 59633]]

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Part V





Department of Transportation





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Federal Aviation Administration



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14 CFR Part 36



Noise Certification Regulations for Helicopters; Proposed Rule

Federal Register / Vol. 65, No. 194 / Thursday, October 5, 2000 / 
Proposed Rules

[[Page 59634]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 36

[Docket No. FAA-2000-7958; Notice 
No. 00-11]
RIN 2120-AH10


Noise Certification Regulations for Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of Proposed Rulemaking (NPRM).

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SUMMARY: The Federal Aviation Administration (FAA) is proposing changes 
to the noise certification regulations for helicopters. These proposed 
changes are based on a joint effort by the 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 helicopters. These 
proposed changes would provide nearly uniform noise certification 
standards for helicopters certificated in the United States, the JAA 
countries, and other countries that have adopted as their national 
regulation either the United States regulations, the JAA regulations, 
or the International Civil Aviation Organization (ICAO) standards. The 
harmonization of the noise certification standards would simplify 
airworthiness approvals for import and export purposes.

DATES: Comments must be received on or before January 4, 2001.

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-
2000-7958 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 self-addressed, stamped postcard.
    You may also submit comments through the Internet to http://dms.dot.gov. You may review the public docket containing comments to 
these proposed regulations in person in the Dockets Office between 9 
a.m. and 5 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. Also, you may review 
public dockets on the Internet at http://dms.dot.gov.

FOR FURTHER INFORMATION CONTACT: Sandy Liu, AEE-100, Office of 
Environment and Energy (AEE), Federal Aviation Administration, 800 
Independence Avenue, SW., Washington, DC 20591; telephone (202) 493-
4864; facsimile (202) 267-5594; or email at <a href="/cdn-cgi/l/email-protection#a7d4c6c9c3de89cbced2e7c1c6c689c0c8d1"><span class="__cf_email__" data-cfemail="dba8bab5bfa2f5b7b2ae9bbdbabaf5bcb4ad">[email protected]</span></a>.

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, federalism, or energy-related impact 
of the adoption of this proposal are welcomed. Comments concerning the 
proposed implementation and effective date of the rule are also 
specifically requested.
    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 self-addressed, stamped postcard with the comments. The postcards 
should be marked ``Comments to Docket No. FAA-2000-7958.'' When the 
comments are received by the FAA, the postcards will be dated, time 
stamped, and returned to the commenters.

Availability of Rulemaking Documents

    You can get an electronic copy using the Internet by taking the 
following steps:
    (1) Go to the search function of the Department of Transportation's 
electronic Docket Management System (DMS) web page (http://dms.dot.gov/search).
    (2) On the search page type in the last four digits of the Docket 
number shown at the beginning of this notice. Click on ``search.''
    (3) On the next page, which contains the Docket summary information 
for the Docket you selected, click on the document number of the item 
you wish to view.
    You can also get an electronic copy using the Internet through 
FAA's web page at http://www.faa.gov/avr/arm/nprm/nprm.htm or the 
Federal Register's web page at http://www.access.gpo.gov/su_docs/aces/aces140.html.
    You can also get a copy 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. Make 
sure to identify the docket number, notice number, or amendment number 
of this rulemaking.

Background

Statement of the Problem

    Various governmental bodies have developed noise certification 
regulations to control noise emissions from helicopters. The 
International Civil Aviation Organization (ICAO) issues on-going 
prototypical sets of aircraft noise standards which member States, 
including the United States, are encouraged to adopt into their 
respective national regulations. Many ICAO member States have adopted 
the ICAO standards verbatim. The United States has adopted into 14 CFR 
part 36 noise certification regulations that, although similar to the 
ICAO standard, differ substantively with the ICAO version. A third 
body, the Joint Aviation Authorities (JAA), is developing its own 
version of the ICAO standards with JAA member States in Europe. Thus, 
from a practical standpoint, three sets of helicopter noise 
certification requirements exist, each controlled by an independent 
political entity.
    Helicopter manufacturers must demonstrate compliance with at least 
one, and often all three, of the sets of noise certification 
regulations when a helicopter is exported beyond its country of 
manufacture and certification. It has become apparent to the 
manufacturers that the differences among the three versions of the 
helicopter noise standards are an undesirable burden. The manufacturers 
have requested that the regulating agencies harmonize the three sets of 
regulations in order to minimize the costs for demonstrating 
compliance.
    These same aviation certification authorities, United States, JAA 
and ICAO, have previously recognized the value of harmonizing civil 
aircraft certification and operating regulations. The Administrator of 
the FAA supports harmonization and has committed the FAA to support the 
harmonization of the FAA regulations with those of the JAA and ICAO.

[[Page 59635]]

Current United States Helicopter Noise Certification 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 (14 CFR) contains the FAA's noise standards and 
regulations that apply to the issuance of type certificates, changes in 
type design, and airworthiness certificates for specified classes and 
categories of aircraft. Subpart H and appendices H and J of part 36 
contain the requirements and standards that apply to helicopters. 
Appendices H and J of part 36 specify the test conditions, procedures, 
and noise levels required to demonstrate compliance with certification 
requirements for helicopters. The original helicopter noise 
certification standards and regulations, including appendix H, were 
issued on February 5, 1988 (53 FR 3534). On September 16, 1992 (57 FR 
42846), the FAA published an alternative noise certification procedure, 
appendix J, for helicopters that do not exceed 6,000 pounds maximum 
takeoff weight.

ICAO Helicopter Noise Certification Standards

    The International Civil Aviation Organization (ICAO) has also 
adopted a set of Standards and Recommended Practices for aircraft noise 
certification. These ICAO standards are similar to the United States 
regulations. The ICAO Annex 16 standards, which have no legal standing 
of their own, are intended to be prototypical regulations upon which 
the Contracting States to ICAO may base their own national regulations. 
For helicopters, Chapter 8 of Annex 16 is the approximate equivalent of 
part 36, appendix H; Chapter 11 of Annex 16 is the approximate ICAO 
equivalent to part 36, appendix J. The ICAO standards are issued as 
International Standards and Recommended Practices, Environmental 
Protection, Annex 16 to the Convention on International Civil Aviation, 
Volume 1, Aircraft Noise.

Joint Aviation Authorities Helicopter Noise Certification Standards

    The civil aviation authorities of certain European countries have 
agreed to common comprehensive and detailed airworthiness and operating 
requirements; these are known as the Joint Aviation Requirements 
(JARs). The JARs are intended to minimize type certification 
differences on multi-national European ventures and to facilitate the 
export and import of aviation products between European nations. 
Aviation authorities of participating countries recognize the JARs as 
an acceptable basis for showing compliance with their national aviation 
codes. The JAA added aircraft noise certification (JAR 36), including 
the helicopter requirements of Subsection D to the JARs effective May 
23, 1997. The JAA's JAR 36 study group is tasked with the technical 
responsibilities for overseeing the noise certification standards. 
Another group, Abatement of Nuisances Caused by Air Transport (ANCAT), 
created under the auspices of the European Civil Aviation Conference 
(ECAC), oversees the policy interests for the JAA. The ANCAT previously 
decided that the JAR aircraft noise certification standards does mirror 
the standards adopted by ICAO.

Aviation Rulemaking Advisory Committee (ARAC)

    In January 1991, the FAA established the Aviation Rulemaking 
Advisory Committee (ARAC) to serve as a forum for the FAA to obtain 
input from outside the government on major regulatory issues. The FAA 
has tasked ARAC with several 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 May 3, 1994, the ARAC 
established the FAR/JAR Harmonization Working Group for Helicopters (59 
FR 22883). The Helicopter Harmonization Working Group (HHWG) is 
comprised of helicopter noise certification experts, and is responsible 
for addressing tasks assigned by ARAC. The United States and European 
interests are represented in the HHWG, which includes representatives 
of the helicopter manufacturers and aviation authority representatives 
from the FAA and the JAA/ANCAT. The HHWG is co-chaired by industry 
representatives from the United States and Europe, and meetings are 
held alternately in the United States and Europe.
    The HHWG reviewed the helicopter noise certification provisions of 
14 CFR part 36, subparts A and H, and appendices H and J, and the 
corresponding applicable provisions of JAR 36 and ICAO Annex 16. 
Differences between the regulations were identified and discussed. The 
goal of the HHWG is to harmonize the regulations by modifying or 
deleting conflicting requirements. The HHWG is not authorized to make 
recommendations for the creation of new requirements or the removal of 
existing requirements that are common among the different sets of 
regulations. Methods for resolving the differences were agreed to and 
forwarded to each regulatory body for approval. A recommendation for 
amending part 36 was forwarded to the ARAC. After due consideration 
including a meeting open to the public on August 23, 2000, ARAC agreed 
to this recommendation and forwarded, in the form of a draft NPRM, to 
the FAA for consideration.
    The overall structure for harmonizing the Federal Aviation 
Regulations and the Joint Aviation Regulations is described in the JAA/
FAA Harmonization Work Program.
    Under the Harmonization Work Program, the FAA and JAA agreed to 
form a Harmonization Working Group to harmonize the aircraft noise 
certification requirements of 14 CFR part 36 and JAR 36. The Working 
Group serves under the auspices of both ARAC and the JAA's JAR 36 Study 
Group. The JAA has adopted the ICAO noise certification standards; any 
recommended changes to the JARs resulting from a harmonization process, 
must first be acted on and approved by ICAO before they are considered 
by the JAA.

Synopsis of the Proposal

    Part 36 of the Federal Aviation Regulations (14 CFR) contains noise 
standards for aircraft type and airworthiness certification. Subpart H 
of part 36 and its related appendices H, and J prescribe noise levels 
and test procedures used for certification of civil helicopters in the 
normal, transport, restricted, or primary category, including rules 
governing the issuance of original, amended, or supplemental type 
certificates for helicopters for which application is made on or after 
March 6, 1986.
    The FAA is proposing to amend some of the technical specifications 
included in appendices H and J, and proposes a new definition under 
Sec. 36.1. No changes to the applicability of part 36 are proposed. The 
proposed changes would not substantively alter the prescribed noise 
limits nor change the relative stringency of the regulations, i.e., the 
relationship between the noise level limits and the measured noise 
level of a given helicopter. These proposed changes may be categorized 
as (a) replacing an existing specification with a similar ICAO 
specification; (b) adding an existing ICAO specification to part 36 
where a corresponding part 36 specification does not presently exist; 
or (c) removing an existing part 36

[[Page 59636]]

specification where there is no corresponding ICAO specification.
    The FAA has examined the helicopter noise certification process and 
analyzed how the proposed changes would have affected previous 
helicopter noise certification projects. The cumulative effect of the 
proposed changes on a single certification would not typically exceed 
<plus-minus> 0.1 decibels and would not be expected to exceed 
<plus-minus> 0.3 decibels under a worst-case combination of conditions. 
The FAA has determined that the proposed changes would not 
substantively alter the noise certification levels or the finding of 
compliance of helicopters currently certificated under either appendix 
H or appendix J. Accordingly, the FAA has determined that these 
proposed changes are consistent with the statutory criteria for 
amending aircraft noise abatement regulations.

Section-by-Section Discussion

    The following is a section-by-section discussion of the proposed 
amendment.

Section 36.1  Applicability and Definitions.

    The FAA is proposing the addition of a new definition to 
Sec. 36.1(h)(5) for ``maximum normal operating RPM.'' This would be 
defined as ``the highest rotor speed for each reference procedure 
corresponding to the airworthiness limit imposed by the manufacturer 
and approved by the FAA.'' This term would cover instances where a 
tolerance on the highest rotor speed is specified and where the rotor 
speed is automatically linked with flight condition or can be changed 
by pilot action. As shown to apply to reference section H36.107(b)(5) 
and J36.105(c)(2).

Section 36.11  Acoustical Change: Helicopters.

    The proposed change would increase the maximum takeoff weight limit 
for appendix J applicability from 6,000 pounds to 7,000 pounds. The 
proposed change reflects a new requirement in the 14 CFR part 27 
airworthiness standards for normal category rotorcraft. The part 27 
revision, adopted in Amendment 27-37 and effective on October 18, 1999, 
increases the passenger seat limitation to nine, update of safety 
standards and consequential weight growth.

Subpart H--Helicopters

    The proposed change to Subpart H regarding compliance with appendix 
J, is being made to conform to the weight change described above in the 
discussion of Sec. 36.11. The same reasons for adoption apply to this 
change.

Subpart O--Operating Limitations and Information

    Subpart O of part 36 specifies requirements for documentation of 
noise levels in an airplane flight manual or rotorcraft flight manual. 
The FAA is proposing to add the word ``Documentation'' as the first 
word of the subpart title to more specifically identify the subject 
matter of subpart O.
    Proposed section 36.1581(a)(2) would be amended by changing the 
reference from appendix F to appendix G. The noise certification 
requirement for propeller-driven small airplanes were moved to appendix 
G in Amendment 36-16 (53 FR 47394, November 22, 1988), and this 
reference was overlooked.
    A new proposed section 36.1581(a)(3) would be added to require that 
helicopter noise levels be included in the rotorcraft flight manual. 
This change specifies the noise certification documentation 
requirements; these would be similar to requirements for other types of 
aircraft. This would provide uniform noise level documentation 
requirements for each aircraft category and would standardize 
documentation procedures. This amendment is intended to improve 
certification tracking and documentation referencing.

Section H36.3  Reference Test Conditions

    Proposed section H36.3(a)(1) would add sea level pressure in metric 
units in addition to English units already specified. This would 
prevent possible variations in measured data that could result from 
differing conversion factors by applicants using metric units.
    Proposed section H36.3(c)(2) would remove a redundant designation 
regarding FAA approval. No substantive change in the approval process 
is intended.
    Proposed section H36.3(d) would delete the reference to rotor speed 
because it is an unnecessary parameter in describing a flight profile. 
This reference was included in error.
    Proposed section H36.3(d) would add two new criteria for reference 
airspeeds: 0.9V<INF>NE</INF> and 0.45V<INF>NE</INF>+65 knots. 
Currently, the reference airspeeds specified are limited to either 
0.9V<INF>H</INF> or 0.45V<INF>H</INF>+65 knots, whichever is less.

[Note: V<INF>NE</INF> is the never-exceed airspeed, an airworthiness 
limitation, imposed by the manufacturer and approved by the FAA.] 
The advent of more powerful engines and improved gearboxes have 
resulted in helicopters that can have a V<INF>H</INF> airspeed in 
excess of the power-on V<INF>NE</INF> airspeed. Therefore, new noise 
certification airspeed criteria are necessary to be consistent with 
technological advances and still accommodate the airworthiness 
limitations imposed for safety. These two new reference airspeed 
criteria would serve to satisfy these advances.

    Section H36.3(d) would be amended as follows:
    1. Specifically, change the symbol ``D'' to be replaced by ``Dr'' 
and the symbol ``J'' to be replaced by ``Jr''.
    1. Deleting the reference to rotor speed; it is unnecessary for 
definition of flight profile.
    2. Adding the word ``reference'' prior to the words ``airspeed'' 
and ``rotor speed'' to indicate that the specifications are for 
reference flight conditions.
    Proposed section H36.3(f)(1)(i) would be amended by changing the 
approach profile reference from ``EK'' to ``ErKr'', and changing the 
angle measure ``6 deg. <plus-minus> 0.5  deg.'' to ``6 deg.,'' 
respectively. For a reference situation, no such tolerances are 
necessary.
    Proposed section H36.3(f)(1)(ii) would add test approach angle 
tolerance limits between 5.5 deg. and 6.5 deg. that were removed from 
section H36.3(f)(1)(i). This is the appropriate paragraph for these 
tolerances.

Section H36.5  Symbols and Units

    Proposed section H36.5 would remove the symbols S, S<INF>r</INF>, 
T, and T<INF>r</INF> and their descriptions in the Flight Profile 
Identification-Positions table and remove the symbols AS<INF>r</INF>, 
AT, and AT<INF>r</INF> and their meanings in the Flight Profile 
Distances table. The typographical errors; Alr and Anr would be 
corrected to AL<INF>r</INF> and AN<INF>r</INF>. In addition, the three 
new symbols and their descriptions would be added to the Flight Profile 
Identification-Positions table of this section as follows:

F<INF>r</INF>--Position on reference takeoff path directly above 
noise measuring Station A.
G<INF>r</INF>--Position on reference flyover path directly above 
noise measuring Station A.
H<INF>r</INF>--Position on reference approach path directly above 
noise measuring Station A.

    These changes and corrections will make these tables consistent 
with amended Figures H1 and H3 (reference section H36.205 for proposed 
changes.

Section H36.101  Noise Certification Test and Measurement Conditions

    Proposed section H36.101(b)(6)(iii) would remove the paragraph for 
additional flight test data to determine the variation of EPNL with 
weight for the takeoff condition. In takeoff, noise generation is a 
function of torque (power) to the rotor systems, not weight, making the 
current requirement unnecessary.
    Proposed section H36.101(b)(8)(ii) would require approach tests to 
be

[[Page 59637]]

conducted between 90 percent and 105 percent of the rotorcraft's 
maximum certification weight. This change is needed to make this 
section consistent with section H36.101(b)(6)(ii), and simplifies the 
rules for the three conditions. (See Secs. H36.101(b)(6)(ii) for 
takeoff and flyover).
    Proposed section H36.101(b)(8)(iii) removes the paragraph for 
additional flight test data that is used to determine the variation of 
EPNL with weight for the approach condition. In approach, noise 
generation is predominantly a function of complex aeroacoustic sources 
associated with main rotor blade vortex interaction, not weight, making 
the current requirement unnecessary. This would further harmonize 
measurement procedures and streamline certification testing.
    Proposed section H36.101(b)(6) requires at least one flight at, or 
above, the noise certification weight for each of the three flight 
procedures. The proposal also removes the requirement for correction of 
off-reference weight for the takeoff and approach procedures. This 
paragraph is also being removed from section H36.205.
    Proposed section H36.101(c)(2) would change the minimum test 
temperature from 36 deg.F (2.2 deg.C) to 14 deg.F (-10 deg.C). The 
current 36 deg.F (2.2 deg.C) temperature limit is unnecessarily 
restrictive, given that no higher levels of atmospheric absorption 
could be encountered by lowering the test day temperature. Although 
there is a revised minimum test air temperature limit, the limit for 
the noise measuring equipment is unchanged.
    Proposed section 36.101(c)(2) would also specify that the 
temperature test window be based on the 10-meter temperature values and 
that the 10-meter temperature and relative humidity values be used to 
adjust the sound propagation path for propagation path absorption. 
Noise certification data collected to date has demonstrated that EPNL 
values corrected using atmospheric data measured at 10 meters are 
acoustically identical to those corrected using averaged temperature 
and relative humidity data. The proposed changes would replace 
historically unreliable temperature data collection.
    Proposed section H36.101(c)(3) would specify allowing the use of 
only the relative humidity and ambient temperature values of the 10-
meter measurement station for allowable sound attenuation in the one-
third octave band centered at 8 kHz and no longer require the use of 
aircraft relative humidity and ambient temperature measurements. This 
change is supported by years of noise certification data demonstrating 
that atmospheric measurements at 10-meters satisfies both the sound 
attenuation and relative humidity range requirements. Helicopter noise 
certification test experience has shown that relative humidity 
measurements at the helicopter position is difficult and subject to 
error given the available instrumentation and procedures. Analysis has 
indicated minimal differences between humidity measured at the 
helicopter position and the 10-meter measurement position. Corrections 
have been no greater than 0.1 dB except under extreme conditions that 
otherwise would be considered an anomalous meteorological condition.
    Proposed section H36.101(c)(5) would specify that tests not be 
conducted under anomalous wind or anomalous meteorological conditions. 
If these conditions exist at test sites in a desert environment, 
temperature and relative humidity must be established using FAA-
approved procedures.
    Proposed section H36.101(d) would specify that the helicopter 
height and lateral position is determined relative to the reference 
flight track, not the centerline or runway. The differential global 
positioning system is acceptable as an independent method of 
determining the position of the helicopter.

Section H36.103  Takeoff Test Conditions

    Proposed section H36.103(b)(1) would specify that the takeoff 
procedure airspeed be established prior to entering the 10dB-down time 
interval of the climbout as opposed to the current requirement that the 
takeoff procedure airspeed must be established during the horizontal 
portion of the takeoff test procedure. This change more clearly 
specifies that the portion of the takeoff at which the required 
airspeed must be maintained; this procedure allows the pilot to 
establish and stabilize required power settings at the time the climb 
is started. This proposal would simplify the pilot workload by 
requiring one less parameter (power) that must be stabilized at the 
time the climb is stated. This method is only satisfactory if the 
initial 10 dB-down time interval occurs during the climb portion of the 
profile.
    Proposed section H36.103(b)(3) would more clearly define gearbox 
torque limit. It also adds the alternate of maximum take-off power. The 
lower of the two is used for specifying required takeoff condition. 
This change more closely aligns part 36 with JAR 36 without any 
substantive change. This section will no longer contain paragraphs (i) 
and (ii); the material is included in the text of (b)(3) as described.
    Proposed section H36.103(b)(4)would clarify that portion of the 
takeoff at which the required best rate of climb airspeed, or the 
lowest airworthiness approved takeoff speed must be maintained. This 
section will no longer contain paragraphs (i) and (ii); the material is 
included in the text of (b)(3) as described. This change more closely 
aligns part 36 with JAR 36 without any substantive change.
    Proposed section H36.103(b)(5) would define the highest rotor speed 
used in takeoff. It also states that the rotor's average rpm, rather 
than instantaneous rpm is required to be within <plus-minus>1.0 percent 
during the 10 dB-down time interval.
    Proposed section H36.103(b)(6) would add a new alternate allowable 
altitude criteria of a wider zenith tolerance in meters for low 
altitudes near the start point. The criteria retains the current 
permitted zenith tolerance defined in degrees throughout the 10 dB-down 
time interval. This change more closely aligns part 36 with JAR 36 
without any substantive change.
    Proposed section H36.103 (b)(7) would add a new paragraph that 
requires that a constant takeoff configuration be maintained, and that 
the landing gear may be retracted when establishing the best rate-of-
climb and corresponding speed as required by the U.S. airworthiness 
standards.

Section H36.105  Flyover Test Conditions

    Proposed section H36.105(b) would specify in detail that an even 
number of flights (6 or more) is required to assure balanced 
measurement of any directional effects that may be related to flight 
path orientation.
    Proposed section H36.105(b)(1) would add the term ``cruise 
configuration'' in requiring that a constant cruise configuration be 
maintained. This change adopts a commonly understood term and will 
minimize misinterpretation of allowance for unsteady, variable speed 
operations during flyover test conditions.
    Proposed section H36.105(c)(1) would add two alternative flyover 
airspeed criteria to the current requirement of continuous power 
(V<INF>H</INF>). The proposed additional level flyover reference 
airspeeds are 90 percent of the never-exceed airspeed, V<INF>NE</INF>, 
and 45 percent of the never-exceed airspeed plus 65 knots; the least of 
the three is the required airspeed. As explained above in section 
H36.3(d), the advent of more powerful engines and improved gearboxes 
have resulted in helicopters that can have a

[[Page 59638]]

V<INF>H</INF> airspeed in excess of the power-on V<INF>NE</INF> 
airspeed. Therefore, new noise certification airspeed criteria are 
necessary to be consistent with technological advances but still 
accommodate the airworthiness limitations imposed for safety. These two 
new reference airspeed criteria would serve to satisfy these advances. 
This change more closely aligns part 36 with JAR 36 without any 
substantive change.
    Proposed section H36.105(c)(2) would define the highest rotor speed 
used in flyover. It also states that the rotor's average rpm, rather 
than instantaneous rpm, is required to be within <plus-minus> 1.0 
percent during the 10 dB-down time interval.

Section H36.107  Approach Test Conditions

    Proposed section H36.107(b)(3) would add a new alternate allowable 
altitude criteria of a wider zenith tolerance in meters for low 
altitudes near the end point of the approach. The criteria retains the 
current permitted zenith tolerance defined in degrees throughout the 10 
dB-down time interval. This change more closely aligns part 36 with JAR 
36 without any substantive change.
    Proposed section H36.107(b)(5) defines the highest rotor speed to 
be used in approach. It also states that the rotor's average rpm, 
rather than instantaneous rpm, is required to be within <plus-minus>1.0 
percent during the 10 dB-down time interval. Thus, each noise 
certification condition will be tested at the highest operating rotor 
RPM as specified in the Flight Manual. These amendments are intended to 
more closely replicate actual operating rotor speed when conducting 
noise certification tests.
    Proposed section H36.107(b)(6) would add a new paragraph that 
requires that a constant takeoff configuration be maintained, and that 
the landing gear may be retracted when establishing the best rate-of-
climb and corresponding speed as required by the airworthiness 
standards.

Section H36.109  Measurement of Helicopter Noise Received on the Ground

    Under this proposal, section H36.109  would be revised to reference 
section B36.3.

    Note: The jet noise harmonization proposed rule (65 FR 42796, 
July 11, 2000) includes a proposal for amending the values in 
section B36.3. The proposed change would also apply to helicopter 
noise and tests.

Section H36.111  Reporting and Correcting Measured Data

    Proposed section H36.111(c)(2) would add a permissible EPNL 
correction for takeoff flight condition only. The amount of this 
allowable correction is limited. Corrections for duration are described 
in sections H36.205(f)(1) and H36.205(g)(1)(i). This change will reduce 
the number of takeoff flights during testing.
    Paragraphs (c)(2)(i) through (iv) are being re-designated. 
Paragraph (c)(2)(i) contains a minor editorial correction. Paragraph 
(c)(2)(ii) is revised to include only the difference between actual and 
reference flight paths. This change eliminates specific application 
that have become obsolete by recent technology. The text of current 
paragraph (c)(2)(iii) is deleted; it is no longer needed if the 
previous changes are made. The text of current paragraph (c)(2)(iv) is 
re-designated (c)(2)(iii) and is revised by retaining only the 
reference to H36.205.
    Proposed section H36.111(c)(3) changes the aircraft noise level 
threshold that must exceed the background level in each \1/3\ octave 
band from 5dB to 3dB. This change would bring appendix H in line with 
appendix B for transport category and turbojet powered airplanes.

Section H36.113  Atmospheric Attenuation of Sound

    Proposed section H36.113(b) would amend the current external 
reference to the revised section B36.7 proposed in the NPRM for 
subsonic jet, large airplanes and subsonic transports. Section B36.7 
describes the method to calculate atmospheric attenuation rates and 
completely documents them within the regulation under part 36. 
Documenting this section within U.S. regulations follows a similar ICAO 
practice and builds the harmonization between regulations.
    Proposed section H36.113(c)(1)(iii) is revised to specify that the 
10-meter temperature and relative humidity measurement values be used 
to adjust for the sound propagation path absorption. Noise 
certification data collected to date has demonstrated that EPNL values 
corrected using atmospheric data measured at 10 meters are acoustically 
identical to those corrected using averaged temperature and relative 
humidity data. There is no loss in accuracy by avoiding inherent 
aircraft measurement inaccuracies.

Section H36.205  Detailed Data Correction Procedures

    Proposed section H36.205(a)(1) is revised to allow negative value 
corrections. Such corrections are appropriate to accurately account for 
any difference between reference and test conditions. Currently, 
negative corrections resulted in no correction (essentially setting the 
value to zero). This change will consider all influences, whether 
negative or positive.
    Proposed sections H36.205(a)(1)(i) and H36.205(a)(ii) are revised 
to specify corrections based on ``differences'' from reference rather 
than conditions ``greater than'' or ``higher than'' reference. This 
change clarifies the requirement.
    Proposed section H36.205(a)(1)(iii) eliminates the correction to 
the EPNL calculated from measured data if the test weight is less than 
maximum certification weight. Based on past test data, such weight 
effects are difficult to isolate from other dominant parameters. Such 
corrections are unnecessary.
    Under this proposal, section H36.205(a)(2) is deleted. This 
material is no longer necessary given the allowance of negative 
correction values described in section H36.205(a)(1).
    Proposed section H36.205(a)(3)(iii) redefines in more accurate 
descriptive terms the distances applied for duration corrections. 
Instead of ``minimum'' distances, the existing rule requires that 
distances be based on the PNLTM (maximum PNLT) distance. This is a more 
accurate method for correcting for noise impact since it is based on 
the actual noise characteristics (peak PNLT) rather than a minimum 
distance along the flight path.
    Proposed section H36.205(a)(3)(iv) would replace the use of rotor 
rpm and test speed with the acoustically accurate term of Mach number 
that accounts for both rpm and test speed effects. This is a more 
concise and accurate variable to apply when addressing the acoustical 
effects of cumulative speed.
    Proposed section H36.205(b)(ii)(2) simplifies the takeoff airspeed 
range by designating as the minimal boundary the slowest climb speed 
allowed under the airworthiness requirements. The proposed language 
also removes the reference to rotor speed, since rotor speed is not 
needed in describing a flight profile for data correction purposes. 
This reference was included in error.
    Proposed section H36.205(b)(3) removes the minimal distance 
description from the paragraph. This description is no longer needed 
given the proposed change to section H36.205(a)(3)(iii).
    Proposed section H36.205(c)(1) removes text that describes speed 
criteria. It is not appropriate in a section describing data correction 
because the criteria are included elsewhere in part

[[Page 59639]]

36. The proposed language also removes a reference to rotor speed, 
since rotor speed is not needed in describing a flight profile for data 
correction purposes.
    Proposed section H36.205(d)(2) would eliminate the requirement that 
the test approach procedure be included in the Flight Manual. Such a 
procedure is never used in approach , and if included in the Flight 
Manual, could be confused with approved airworthiness approach 
procedures. The proposal also explains the term ``10 dB down period'' 
with ``10 dB-down time interval'' as the accepted nomenclature for this 
specific time segment. This ``harmonized'' term is being adopted in the 
regulations for jets, large turboprop, small airplanes, and 
helicopters.
    Proposed section H36.205(d)(3) removes the minimal distance 
description from the reference to figure H3. This description is no 
longer needed given the proposed change to section H36.205(a)(3)(iii).
    Proposed section H36.205(e)(1) removes the requirement that only 
the advancing blade tip Mach number be used when making source noise 
adjustments. It also adds an alternate procedure for off-reference tip 
Mach number adjustments. The proposal allows use of a more appropriate 
source noise adjustment parameter which would give results identical to 
that of the more complex current procedure while substantially reducing 
the amount of additional flyover passes necessary to generate 
statistically valid source noise sensitivity curves.
    Proposed section H36.205(f)(1)(i) corrects designations of measured 
takeoff sound propagation path and length, ``L<INF>r</INF>A'' to ``AL'' 
and ``LrA'' to ``ALr'' , respectively.
    Proposed section H36.205(f)(2) replaces incorrect designations of 
takeoff distances for measured and reference paths, ``AM'' to ``AN'' 
and AMr'' to ``ANr'' , respectively, and add ``i'' to the alpha in the 
second term.
    Proposed section H36.205(f)(3) removes the ``o'' and ``+'' symbol 
from the equation; they are incorrect.
    Proposed corrections for the designator ``K'' by flight condition 
are as follows: ``Ln'' to ``Lr'', ``M'' to ``N'', ``Mn'' to ``Nr'', and 
``N'' to ``M'', ``Nr'' to ``Mr'', respectively, within the paragraph 
text. This change also corrects a typographical error.
    Proposed section H36.205(f)(4) replaces incorrect designations of 
flyover distances for measured and reference paths, ``AN'' to ``AM'' 
and ``ANr'' to ``AMr'' , respectively, and adds a subscript ``i'' to 
the first alpha in the second term.
    Proposed sections H36.205(g)(1)(i), through (iv) correct the 
constant value ``-10'' to ``-7.5'' in front of the log term in each of 
the <greek-D><INF>2</INF> equations.
    Proposed section H36.205(g)(1)(i) corrects the term for measured 
and reference lengths, ``AT'' to ``AL'' and ``ATr'' to ``ALr'', 
respectively within the <greek-D><INF>2</INF> equation and paragraph 
text.
    Proposed section H36.205(g)(1)(ii) corrects the terms used for 
measured and reference lengths, ``AS'' to ``AN'' and ``ASr'' to 
``ANr'', respectively, within the <greek-D><INF>2</INF> equation and 
paragraph text.
    Proposed section H36.205(g)(1)(iii) corrects the terms used for 
measured and reference lengths at each of the flight condition, ``T'' 
to ``L'' , ``Tr'' to ``Lr'' , ``S'' to ``N'', ``Sr'' to ``Nr'', and 
``G'' to ``M'', ``Gr'' to ``Mr'', respectively, within the paragraph 
text.
    Proposed section H36.205(g)(1)(iv) corrects the terms used for 
measured and reference lengths, ``AG'' to ``AM'' and ``AGr'' to 
``AMr'', respectively within the <greek-D><INF>2</INF> equation and 
paragraph text. All of the corrections in section H36.205(g)(1) are of 
previous errors. No substantive changes are intended.

Figures H1, H2 and H3

    Proposed revision to Figure H1 deletes the designation of Positions 
Tr since the minimal distance designation is no longer needed and 
includes the height above measurement point in metric units; see the 
text of proposed section H36.205(b)(3) regarding the takeoff condition.
    Proposed revision to Figure H2 repositions the bullet-marker that's 
incorrectly positioned near label G due to a typographical error. The 
marker is repositioned in the proposed revised graphic image at the 
intersection of line Dr-Jr and line A-G.
    Proposed revision to Figure H3 deletes the designations of 
Positions S and Sr since the minimal distance designation is no longer 
needed and includes the height above measurement point in metric units; 
see the text of section H36.205(d)(3) regarding the approach condition.
    In proposed Figures H1, H2, and H3 the titles of the figures are 
changed to reflect the language of this proposal. The word 
``reference'' would replace the word ``corrected'' in each title.

Section H36.305  Noise Levels

    Proposed sections H36.305(a)(2)(i) through (iii) would revise the 
values for the noise/weight reduction rate, from ``3.01'' to ``3.0''. 
The proposed text also removes the phrase ``for maximum weight of 1,764 
pounds or less'' from the end of each paragraph and replaces it with 
the phrase ``after which the limit is constant.'' The existing text was 
found to be confusing; this proposed change would enhance clarity. No 
substantive change in the requirements is intended.

Section J36.1  General

    Proposed section J36.1 would increase the maximum takeoff weight 
requirement of appendix J from 6,000 pounds to 7,000 pounds. As 
explained previously, Part 27 was amended to increase the allowable 
passenger seat limit to nine; accordingly the weight limit was 
increased to 7,000 lbs. This proposal makes the corresponding changes 
in appendix J.

Section J36.3  Reference Test Conditions.

    Proposed section J36.3(c) would clarify that the stabilized 
airspeed be maintained throughout the measured portion of the flyover. 
Stabilized airspeed will insure the highest quality noise data by 
avoiding variability of advancing tip Mach number that effectively 
impacts noise.
    Proposed section J36.3(c)(1) would add the requirement airspeed 
V<INF>NE</INF> that must be included in the approved Flight Manual. 
These changes standardize the languages used in appendices H and J 
without substantive change.

Section J36.101  Noise Certification and Measurement Conditions

    Proposed section J36.101(c)(4) revises the location where 
meteorological data is measured. This change would harmonize this 
proposal with the JAR and adds flexibility without substantive change. 
It also makes the language of this section compatible with 
J36.101(c)(6).
    Proposed section J36.101(c)(6):
    1. Specifies that the physical location of meteorological 
instruments be representative of the atmospheric conditions existing 
near the surface over the geographical area where the helicopter noise 
measurements are made.
    2. Provides that a fixed meteorological station, such as those 
found at airports, may be used to meet the location requirement.
    3. Adds the requirement that a fixed meteorological station must be 
within 2,000 meters of the noise measurement area. The 2,000-meter 
distance limitation is a reasonable allowance when using a ``fixed 
meteorological station.''
    These proposed changes harmonize this proposal with the JAR and add 
flexibility without substantive change since part 36 requirements 
specify that

[[Page 59640]]

the meteorological measurements be made ``at the noise monitoring 
station,'' while JAR requirements specify that if the measurement site 
is within 2,000 meters of an aerodrome thermometer, the aerodrome 
reported temperature be used.

Section J36.109  Measurement of Helicopter Noise Received on the Ground

    Under this proposal, three references to section H36.109 are being 
changed to section B36.3. Section H36.109 was removed because the data 
appears in section B36.3. Note: The jet noise harmonization proposed 
rule (65 FR 42796, July 11, 2000) includes a proposal for amending the 
values in section B36.3. The proposed change would also apply to 
helicopter noise and tests but the proposal is not repeated in this 
NPRM to avoid confusion.
    Proposed section J36.305(a) would have the same correction as made 
in section H36.305(a) above.
    Proposed section J36.305(a) increases the upper weight limit from 
6,000 pounds to 7,000 pounds maximum gross weight. This is a conforming 
change for reasons already described.

Paperwork Reduction Act

    The Paperwork Reduction Act of 1995 (44 U.S.C. 3507(d)) requires 
that the FAA consider the impact of paperwork and other information 
collection burdens imposed on the public. We have determined that there 
are no new information collection requirements associated with this 
proposed rule.

International Compatibility

    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 two differences with these proposed 
regulations. These two differences are applicability provisions that 
already exist and do not represent substantive changes. If this 
proposal is adopted, the FAA will file these differences with ICAO.
    (1) Sections 36.11 and H36.305 of part 36 allow for higher than 
Stage 2 noise limits for helicopter changes in the type design of 
certain (Stage 1) helicopters certified before the ``grandfather'' 
clause date of March 6, 1986; and
    (2) Section 36.805(c) allows for higher than Stage 2 noise limits 
for helicopter changes in the type design of certain (Stage 1) 
helicopters that the FAA recognizes as the first civil version that was 
designed, constructed for and accepted for operational use by an Armed 
Force of the United States.

Economic Evaluation

    Proposed changes to Federal regulations must 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, FAA has determined this rule (1) has 
benefits which do justify its costs, is not a ``significant regulatory 
action'' as defined in the Executive Order and is not ``significant'' 
as defined in DOT's 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 on the 
private sector. These analyses, available in the docket, are summarized 
below.
    This notice of proposed rulemaking would provide nearly uniform 
noise certification standards for helicopters certificated in the 
United States, the JAA countries, and any other countries that have 
adopted as their national regulation either the United States 
regulation, the JAA regulation, or the ICAO standard.
    The proposals would more closely harmonize the flight test 
conditions, procedures, and reporting requirements mandated by the 
provisions of Subpart A and appendices H, and J of 14 CFR part 36 with 
the corresponding applicable provisions of the Joint Aviation 
Regulations (JAR) 36 and the International Civil Aviation Organization 
(ICAO) Annex 16. Specifically, the proposal would amend some of the 
technical specifications of appendices H and J and add a new definition 
to Subpart A of part 36.
    The FAA concludes that the proposed rule would be cost beneficial. 
The proposed rule would require fewer flyover passes, takeoffs, and 
microphone systems, would eliminate humidity and wind speed 
measurements and the requirements to process test data twice and issue 
separate reports for FAA and ICAO methods, and would extend the gross 
weight upper limit for the appendix J certification test procedure. The 
cost savings of the proposed rule are estimated to be $17.31 million 
($12.16 million, discounted) over a 10 year period. The one-time cost 
of this proposed rule would be $40,800 ($33,305 discounted) and would 
accrue to those manufacturers that need to obtain ICAO/JAA 
certification.

Initial Regulatory Flexibility Determination

    The Regulatory Flexibility Act of 1980 (RFA) establishes ``as a 
principle of regulatory issuance that agencies shall endeavor, 
consistent with the objective of the rule and of applicable statutes, 
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 
rationale for their actions. The Act covers a wide-range of small 
entities, including small businesses, not-for-profit organizations and 
small governmental jurisdictions.
    Agencies must perform a review to determine whether a proposed or 
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 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 a regulatory flexibility 
analysis is not required. The certification must include a statement 
providing the factual basis for this determination, and the reasoning 
should be clear.
    Small entities are firms employing 1,500 employees or less based on 
Small

[[Page 59641]]

Business Administration guidelines. Enactment of this proposal would 
impose a one-time cost of $10,200 per small entity, which would be 
incurred by two small helicopter manufacturers that met the criterion 
of small entity. The yearly cost-savings per small entity would be 
$265,000. In view of the substantial net cost-savings per small entity, 
the FAA has determined that this proposed rule would not have a 
significant adverse economic impact on a substantial number of small 
entities; therefore, a regulatory flexibility analysis is not required 
under the terms of the RFA. The FAA solicits comments with respect to 
this finding and determination and requests that all comments be 
accompanied by clear documentation.

International Trade Impact Assessment

    The Trade Agreement Act of 1979 prohibits Federal agencies from 
engaging in any standards or related activities 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 used as the basis for 
U.S. standards. In addition, consistent with this Administration's 
belief in the general superiority and desirability of free trade, it is 
the policy of this 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 United States.
    This proposed rule is a direct action to respond to this policy by 
increasing the harmonization of the U.S. Federal regulations with the 
European Joint Aviation Requirements. The results would facilitate 
international trade.

Unfunded Mandated Assessment

    The Unfunded Mandates Reform Act of 1995 (the Act), enacted as 
Public Law 104-4 on March 22, 1995, is intended, among other things, to 
curb the practice of imposing unfunded Federal mandates on State, 
local, and tribal governments. Title II of the Act requires each 
Federal agency to prepare a written statement assessing the effects of 
any Federal mandate in a proposed or final agency rule that may result 
in a $100 million or more expenditure (adjusted annually for inflation) 
in any one year by State, local, and tribal governments, in the 
aggregate, or by the private sector; such a mandate is deemed to be a 
``significant regulatory action.''
    This proposed rule does not contain such a mandate. Therefore, the 
requirements of Title II of the Unfunded Mandates Reform Act of 1995 do 
not apply.

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.

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 has determined 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) Public Law 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 36

    Aircraft, Noise control.

The Proposed Amendment

    In consideration of the foregoing the Federal Aviation 
Administration proposes to amend 14 CFR part 36, as follows:

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.

    2. Section 36.1 is amended by adding a new paragraph (h)(5) to read 
as follows:


Sec. 36.1  Applicability and definitions.

* * * * *
    (h) * * *
    (5) Maximum normal operating RPM means the highest rotor speed for 
each reference procedure corresponding to the airworthiness limit 
imposed by the manufacturer and approved by the FAA. Where a tolerance 
on the highest rotor speed is specified, the maximum normal operating 
rotor speed is the highest rotor speed for which that tolerance is 
given. If the rotor speed is automatically linked with flight 
condition, the maximum normal operating rotor speed corresponding with 
that flight condition must be used during the noise certification 
procedure. If rotor speed can be changed by pilot action, the highest 
normal operating rotor speed specified in the flight manual limitation 
section for power-on conditions must be used during the noise 
certification procedure.
    3.-4. Section 36.11 is amended by revising the introductory text 
and by removing ``6,000'' and adding ``7,000'' in its place in 
paragraph (a)(1) to read as follows:


Sec. 36.11  Acoustical change: Helicopters.

    This section applies to all helicopters in the primary, normal, 
transport, and restricted categories for which an acoustical change 
approval is applied for under Sec. 21.93(b) of this chapter on or after 
March 6, 1986. Compliance with the requirements of this section must be 
demonstrated under appendix H of this part, or, for helicopters having 
a maximum certificated takeoff weight of not more than 7,000 pounds, 
compliance with this section may be demonstrated under appendix J of 
this part.


Sec. 36.801  [Amended]

    5. Section 36.801 is revised by removing the term ``6,000'' in the 
second sentence and adding the term ``7,000'' in its place.

Subpart O--Documentation, Operating Limitations and Information

    6. Revise the heading of Subpart O to read as set forth above:
    7. In Sec. 36.1581 paragraph (a)(2) is revised and paragraph (a)(3) 
is added to read as follows:

[[Page 59642]]

Sec. 36.1581  Manuals, markings, and placards.

* * * * *
    (2) For propeller driven small airplanes the noise level 
information must be one value for takeoff as defined and required by 
appendix G of this part, along with the maximum takeoff weight and 
configuration.
    (3) For rotorcraft the noise level information must be one value 
for each takeoff, flyover, and approach as defined and required by 
appendix H of this part or one value for flyover as defined and 
required by appendix J of this part along with the maximum takeoff 
weight, maximum landing weight (for appendix H), and configuration.
* * * * *

Appendix H [Amended]

    8. In appendix H, section H36.3 is amended by revising paragraphs 
(a)(1), (c)(2), (d), (e), (f)(1)(i), and (f)(1)(ii) to read as follows:

    Section H36.3  Reference test conditions.
    (a) * * *
    (1) Sea level pressure of 2,116 psf (76 cm mercury, 1,013.25 
hPa).
    (c) * * *
    (2) The reference flight path is defined as a straight line 
segment inclined from the starting point (1,640 feet prior to the 
center microphone location at 65 feet above ground level) at an 
constant climb angle <greek-b> defined by the certificated best rate 
of climb and V<INF>y</INF> for minimum engine performance. The 
constant climb angle <greek-b> is derived from the manufacturer's 
data (approved by the FAA) to define the flight profile for the 
reference conditions. The constant climb angle <greek-b> is drawn 
through C<INF>r</INF> and continues, crossing over station A, to the 
position corresponding to the end of the type certification takeoff 
path represented by position I<INF>r.</INF>
    (d) Level flyover reference profile. The beginning of the level 
flyover reference profile is represented by helicopter position Dr 
(Figure H2). The helicopter approaches position Dr in level flight 
492 feet above ground level as measured at Station A. Reference 
airspeed must be either 0.9V<INF>H</INF>; 0.9V<INF>NE</INF>; 
0.45V<INF>H</INF>+65 kts (0.45V<INF>H</INF>+120km/h); or 
0.45V<INF>NE</INF>+65kts (0.45V<INF>NE</INF>+120 km/h), whichever of 
the four speeds is least. The helicopter crosses directly overhead 
station A in level flight and proceeds to position Jr.
    (e) For noise certification purposes, V<INF>H</INF> is defined 
as the airspeed in level flight obtained using the minimum 
specification engine torque corresponding to maximum continuous 
power available for sea level, 25 deg.C ambient conditions at the 
relevant maximum certificated weight. V<INF>NE</INF> is the never-
exceed airspeed. The value of V<INF>H</INF> and V<INF>NE</INF> used 
for noise certification must be included in the approved Flight 
Manual.
    (f) * * *
    (1) * * *
    (i) The beginning of the approach profile is represented by 
helicopter position E. The position of the helicopter is recorded 
for a sufficient distance (EK) to ensure recording of the entire 
interval during which the measured helicopter noise level is within 
10 dB of Maximum Tone Corrected Perceived Noise Level (PNLTM), as 
required. ErKr represents a stable flight condition in terms of 
torque, rpm, indicated airspeed, and rate of descent resulting in a 
6 deg. approach angle.
    (ii) The test approach profile is defined by the approach angle 
<greek-ee> passing directly over the station A at a height of AH, to 
position K, which terminates the approach noise certification 
profile. The test approach angle <greek-ee> must be between 5.5 deg. 
and 6.5 deg..
* * * * *

    9. In appendix H, section H36.5, the Flight Profile Identification-
Positions table is amended by removing the symbols S, S<INF>r,</INF> T 
and T<INF>r</INF> and their descriptions; the Flight Profile Distances 
table is amended by removing the symbols AS<INF>r,</INF> AT, and 
AT<INF>r</INF> and their meanings. The Flight Profile Identification-
Positions table is revised by adding three new symbols and their 
descriptions in alphabetical order to read as follows:

    Section H36.5  Symbols and units.

F<INF>r</INF>--Position on reference takeoff path directly above 
noise measuring Station A.
G<INF>r</INF>--Position on reference flyover path directly above 
noise measuring Station A.
H<INF>r</INF>--Position on reference approach path directly above 
noise measuring Station A.


    10. In appendix H, Section H36.101 is revised by removing 
paragraphs (b)(6)(iii) and (b)(8)(iii); by redesignating paragraph 
(b)(9) as (d)(4); and by revising paragraphs (b)(8)(ii), (c)(2), 
(c)(3), (c)(5), (d)(2), (d)(3) and newly redesignated paragraph (d)(4) 
to read as follows:

    Section H36.101  Noise certification test and measurement 
conditions.
    (b) * * *
    (8) * * *
    (ii) Each test weight must be within +5 percent and -10 percent 
of the maximum certification weight.
    (c) * * *
    (2) Ambient air temperature between 14 deg.F and 95 deg.F 
(-10 deg.C and 35 deg.C), inclusively, at a point 10 meters above 
the ground at the noise measuring station. The temperature and 
relative humidity measured at a point 10 meters above the ground at 
the noise measuring station must be used to adjust for propagation 
path absorption.
    (3) Relative humidity and ambient temperature at a point 10 
meters above the ground at the noise measuring station is such that 
the sound attenuation in the one-third octave band centered at 8 kHz 
is not greater than 12 dB/100 meters and the relative humidity is 
between 20 percent and 95 percent, inclusively.
* * * * *
    (5) No anomalous meteorological conditions (including 
turbulence) that will significantly affect the noise level of the 
aircraft when the noise is recorded at each noise measuring station.
* * * * *
    (d) * * *
    (2) The helicopter height and lateral position relative to the 
reference flight track (which passes through the flight track noise 
measuring station) must be determined using an FAA-approved method. 
The equipment used to make the determination must be independent of 
normal flight instrumentation, such as radar tracking, theodolite 
triangulation, laser trajectography, photo scaling, or differential 
global positioning system.
    (3) The helicopter position along the flight path must be 
related to the noise recorded at the noise measuring stations by 
means of synchronizing signals at an approved sampling rate. The 
position of the helicopter must be recorded relative to the 
reference flight track during the entire time interval in which the 
recorded signal is within 10 dB of PNLTM. Measuring and sampling 
equipment must be approved by the FAA.
    (4) Aircraft performance data sufficient to make the corrections 
required under section H36.205 of this appendix must be recorded at 
an FAA-approved sampling rate using FAA approved equipment.

    11. In appendix H, Section H36.103 is amended by revising 
paragraphs (b)(1), (b)(3), (b)(4), (b)(5), and (b)(6), and by adding 
new paragraph (b)(7) to read as follows:

    Section H36.103  Takeoff test conditions.
* * * * *
    (b) * * *
    (1) An airspeed of either V<INF>y</INF> <plus-minus>5 knots or 
the lowest approved speed <plus-minus>5 knots for the climb after 
takeoff, whichever speed is greater, must be established and 
maintained throughout the 10 dB-down time interval.
    (2) * * *
    (3) Upon reaching a point 1,640 feet (500 meters) from the noise 
measuring station, the helicopter must be stabilized at the maximum 
take-off power that corresponds to minimum installed engine(s) 
specification power available for the reference ambient conditions 
or gearbox torque limit, whichever is lower.
    (4) The helicopter must be maintained throughout the 10 dB-down 
time interval at the best rate of climb speed V<INF>y</INF> 
<plus-minus>5 knots, or the lowest approved speed for climb after 
takeoff, whichever is greater, for an ambient temperature at sea 
level of 25 deg.C.
    (5) The average rotor speed must not vary from the maximum 
normal operating rotor RPM by more than <plus-minus>1.0 percent 
during the 10 dB-down time interval.
    (6) The helicopter must stay within <plus-minus>10 deg. or 
<plus-minus>20 m, whichever is greater, from the vertical above the 
reference track throughout the 10dB-down time interval.
    (7) A constant takeoff configuration selected by the applicant 
must be maintained throughout the takeoff reference procedure with 
the landing gear position consistent with the airworthiness 
certification tests for establishing Best Rate-of-Climb and Speed 
for Best Rate-of-Climb.


[[Page 59643]]


    12. In appendix H, Section H36.105 is amended by revising 
paragraphs (b), introductory text, (b)(1), (b)(3), (c)(1), and (c)(2) 
to read as follows:

    Section H36.105  Flyover test conditions.
* * * * *
    (b) A test series must consist of at least six flights with an 
equal number of runs in each direction, over the flight-track noise 
measuring station (with simultaneous measurements at all three noise 
measuring stations)--
    (1) In level flight cruise configuration;
    (2) * * *
    (3) The helicopter must stay within <plus-minus>10 deg. or 
<plus-minus>20 m, whichever is greater, from the vertical above the 
reference track throughout the 10 dB-down time interval.
    (c) * * *
    (1) At a speed of 0.9V<INF>H</INF>; 0.9V<INF>NE</INF>; 
0.45V<INF>H</INF> + 65 kts (0.45V<INF>H</INF> + 120 km/h); or 
0.45V<INF>NE</INF> + 65 kts (0.45V<INF>NE</INF> + 120 km/h), 
whichever speed is less, maintained throughout the measured portion 
of the flyover;
    (2) At average rotor speed which must not vary from the maximum 
normal operating rotor RPM by more than <plus-minus>1.0 percent 
during the 10 dB-down time interval.
* * * * *

    13. In appendix H, Section H36.107 is amended by revising 
paragraphs (b)(3) and (b)(5) and adding new paragraph (b)(6) to read as 
follows:

    Section H36.107  Approach test conditions.
* * * * *
    (b) * * *
    (3) The helicopter must stay within <plus-minus>10 deg. or 
<plus-minus>20 m, whichever is greater, from the vertical above the 
reference track throughout the 10 dB-down time interval;
* * * * *
    (4) * * *
    (5) At average rotor speed which must not vary from the maximum 
normal operating rotor RPM by more than <plus-minus>1.0 percent 
during the 10 dB-down time interval; and
    (6) A constant approach configuration used in airworthiness 
certification tests, with the landing gear extended, must be 
maintained throughout the approach reference procedure.
* * * * *

    14. In appendix H, Section H36.109 is revised to read as follows:

    Section H36.109  Measurement of helicopter noise received on the 
ground.
    The measurement system and the measurement, calibration and 
general analysis procedures to be used are provided in Appendix A, 
section A36.3 of this part.

    15. In appendix H, Section H36.111 is amended by revising paragraph 
(c)(2), by removing paragraph (c)(2)(iv) and the undesignated text 
following (c)(2)(iv), by revising paragraphs (c)(2)(i), (c)(2)(ii) and 
(c)(2)(iii), and by revising paragraph (c)(3) to read as follows:

    Section H36.111  Reporting and correcting measured data.
* * * * *
    (c) * * *
    (2) The measured flight path must be corrected by an amount 
equal to the difference between the applicant's predicted flight 
path for the certification reference conditions and the measured 
flight path at the test conditions. Necessary corrections relating 
to aircraft flight path or performance may be derived from FAA-
approved data for the difference between measured and reference 
engine conditions, together with appropriate allowances for sound 
attenuation with distance. The Effective Perceived Noise Level 
(EPNL) correction must be less than 2.0 EPNdB except for take-off 
flight condition, where the correction must not exceed 4.0 EPNdB, of 
which the arithmetic sum of <greek-D><INF>1</INF> (described in 
section H36.205(f)(1)) and the term -7.5 log (AL/AL<INF>r</INF>) 
from <greek-D><INF>2</INF> term (described in section 
H36.205(g)(1)(i)) must not exceed 2.0 EPNdB, for any combination of 
the following:
    (i) The aircraft is not passing vertically above the measuring 
station.
    (ii) Any difference between the reference flight track and the 
actual test flight track.
    (iii) Detailed correction requirements prescribed in section 
H36.205 of this appendix.
    (3) Aircraft sound pressure levels within the 10 dB-down time 
interval must exceed the mean background sound pressure levels 
determined under section B36.3.9.11 by at least 3 dB in each one-
third octave band or be corrected under an FAA approved method to be 
included in the computation of the overall noise level of the 
aircraft. An EPNL may not be computed or reported from data from 
which more than four one-third octave bands in any spectrum within 
the 10 dB-down time interval have been excluded under this 
paragraph.
* * * * *

    16. Section H36.113 is amended by revising paragraphs (b) and 
(c)(1)(iii) to read as follows:

    Section H36.113  Atmospheric attenuation of sound.
* * * * *
    (b) Attenuation rates. The procedure for determining the 
atmospheric attenuation rates of sound with distance for each one-
third octave bands must be in accordance with Society of Automotive 
Engineering (SAE) ARP 866A included in section A36.7.
    (c) * * *
    (1) * * *
    (iii) The temperature and relative humidity measured at 10 
meters above the ground must be used to adjust for propagation path 
absorption.
* * * * *

    17. In appendix H, Section H36.205 is amended by removing 
paragraphs (a)(1)(iii), (a)(2), and (a)(3)(v); removing the last two 
sentences in paragraph (b)(3) and (d)(3); by revising paragraphs 
(a)(1)(i), (a)(1)(ii), (a)(3)(iii), (a)(3)(iv), (b)(2), (c)(1), (d)(2), 
(e), (f)(1)(i), (f)(2)(i), (f)(3), (f)(4), and (g)(1)-(i)-(iv), and by 
revising Figures H1, H2, and H3 to read as follows:

    Section H36.205  Detailed data correction procedures.
* * * * *
    (a) * * *
    (1) If a positive or negative value results from any difference 
between reference and test conditions, an appropriate correction 
must be made to the EPNL calculated from the measured noise data. 
Conditions that can result in a different value include:
    (i) Atmospheric absorption of sound under test conditions that 
are different than the reference; or
    (ii) Test flight path at an altitude that is different than the 
reference
    (3) * * *
    (iii) The distances for which PNLTM is observed from both the 
test and reference profiles to the noise measuring station must be 
calculated and used to determine a noise duration correction due to 
any change in the altitude of aircraft flyover. The duration 
correction must be added algebraically to the EPNL calculated from 
the measured noise data.
    (iv) For aircraft flyover, from FAA-approved data in the form of 
curves or tables giving the variation of EPNL with Mach Number, 
source noise corrections are determined and must be added to the 
EPNL, to account for noise level changes due to differences between 
test conditions and reference conditions.
    (b) * * *
    (2) For the actual takeoff, the helicopter approaches position C 
in level flight at 65 feet (20 meters) above ground level at the 
flight track noise measuring station and at either V<INF>y</INF> 
<plus-minus>5 knots or the lowest approved speed for the climb after 
takeoff, whichever speed is greater.
* * * * *
    (c) Level flyover profiles. (1) The noise type certification 
level flyover profile is shown in Figure H2. Airspeed must be 
stabilized within <plus-minus>5 knots of the reference airspeed 
given in section H36.3(d). If the test requirements are otherwise 
met, flight direction may be reversed for each subsequent flyover, 
to obtain three test runs in each direction.
* * * * *
    (d) * * *
    (2) The helicopter approaches position H along a 6 deg. 
(<plus-minus>0.5 deg.) average approach slope throughout the 10dB-
down time interval. The approach procedure must be acceptable to the 
FAA.
* * * * *
    (e) Correction of noise at source during level flyover. (1) For 
level overflight, if any combination of the following factors, 
airspeed deviations from reference, rotor speed deviations from 
reference, and temperature deviations from reference, results in a 
noise
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correlating parameter whose value deviates from the reference value 
of this parameter, then source noise adjustments must be determined 
from the manufacturer's data approved by the FAA.
    (f) * * *
    (1) * * *
    (i) Step 1. A set of corrected values are then computed as 
follows:

SPLic = SPLi + (<greek-a> i--<greek-a> io) (AL-ALr) + 20 log (AL/
ALr)

where SPLi and SPLic are the measured and corrected sound pressure 
levels, respectively, in the -ith one-third octave band. The first 
correction term accounts for the effects of change in atmospheric 
sound absorption where <greek-a>i and <greek-a>io are the sound 
absorption coefficients for the test and reference atmospheric 
conditions, respectively, for the -ith one-third octave band, and AL 
is the measured takeoff sound propagation path. The second 
correction term accounts for the effects of atmospheric sound 
absorption on the change in the sound propagation path length where 
ALr is the corrected takeoff sound propagation path. The third 
correction term accounts for the effects of the inverse square law 
on the change in the sound propagation path length.
* * * * *
    (2) Approach flight path. (i) The procedure described in 
paragraph (f)(1) of this section for takeoff flight paths is also 
used for the approach flight path, except that the value for SPLic 
relate to the approach sound propagation paths shown in Figure H3 as 
follows:

SPLic = SPLi + (<greek-a> i--<greek-a> io) AN + <greek-a> io 
(AN-ANr) + 20 log (AN/ANr)


[[Page 59647]]


where the lines AN and ANr are the measured and reference approach 
sound propagation paths, respectively.
* * * * *
    (3) Sideline microphones. The procedure prescribed in paragraph 
(f)(1) of this section for takeoff flight paths is also used for the 
propagation to the sideline microphones, except that the values of 
SPLic relate only in the measured sideline sound propagation path as 
follows:

SPLic = SPLi + (<greek-a> i-<greek-a> io)KX + <greek-a> io (KX-KXr) 
+ 20 log (KX/KXr)

K is the sideline measuring station where:

X = L and Xr = Lr for takeoff
X = M and Xr = Mr for flyover
X = N and Xr = Nr for approach

    (4) Level flyover flight path. The procedure described in 
paragraph (f)(1) of this section for takeoff flight paths is also 
used for the level flyover flight path, except that the values of 
SPLic relate only to the flyover sound propagation paths as follows:

SPLic = SPLi + (<greek-a> i-<greek-a> io)AM + <greek-a> io (AM-AMr) 
+ 20 log (AM/AMr)

    (g) * * *
    (1) * * *
    (i) Takeoff flight path. For the takeoff flight path shown in 
Figure H1, the correction term is calculated using the formula--

<greek-D><INF>2</INF> = -7.5 log (AL/ALr) + 10 log (V/Vr)

which represents the correction that must be added algebraically to 
the EPNL calculated from the measured data. The lengths AL and ALr 
are the measured and corrected takeoff distances from the noise 
measuring station A to the measured and the corrected flight paths, 
respectively. A negative sign indicates that, for the particular 
case of a duration correction, the EPNL calculated from the measured 
data must be reduced if the measured flight path is at greater 
altitude than the corrected flight path.
    (ii) Approach flight path. For the approach flight path shown in 
Figure H3, the correction term is calculated using the formula--

<greek-D><INF>2</INF> = -7.5 log (AN/ANr) + 10 log (V/Vr)

where AN is the measured approach distance from the noise measuring 
station A to the measured flight path and 394 feet is the overhead 
distance from station A to the reference flight path.
    (iii) Sideline microphones. For the sideline flight path, the 
correction term is calculated using the formula--

<greek-D><INF>2</INF> = -7.5 log (KX/KXr) + 10 log (V/Vr)

K is the sideline measuring station

where X = L and Xr = Lr for takeoff
where X = M and Xr = Mr for flyover
where X = N and Xr = Nr for approach
    (iv) Level flyover flight paths. For the level flyover flight 
path, the correction term is calculated using the formula--

<greek-D><INF>2</INF> = -7.5 log (AM/AMr) + 10 log (V/Vr)

where AM is the measured flyover distance from the noise measuring 
station A to the measured flight path and 492 feet is the overhead 
distance from station A to the reference flight path.
* * * * *

    18. I appendix H, Section H36.305(a)(2) is revised to read as 
follows:

    Section H36.305  Noise levels. 
    (a) * * *
    (2) Stage 2 noise limits are as follows:
    (i) For takeoff calculated noise levels--109 EPNdB for maximum 
takeoff weights of 176,370 pounds or more, reduced by 3.0 EPNdB per 
halving of the weight down to 89 EPNdB, after which the limit is 
constant.
    (ii) For flyover calculated noise levels--108 EPNdB for maximum 
weights of 176,370 pounds or more, reduced by 3.0 EPNdB per halving 
of the weight down to 88 EPNdB, after which the limit is constant.
    (iii) For approach calculated noise levels--110 EPNdB for 
maximum weights of 176,370 pounds or more, reduced by 3.0 EPNdB per 
halving of the weight down to 90 EPNdB, after which the limit is 
constant.
* * * * *

Appendix J [Amended]

    19. Amend the title of Appendix J and section J36.1 introductory 
text by removing the reference ``6,000'' and adding ``7,000'' in its 
place
    20. In appendix J, Section J36.3 is amended by revising paragraph 
(c) introductory text and paragraph (c)(1) to read as follows:

    Section J36.3  Reference test conditions.
* * * * *
    (c) Level flyover reference profile. The reference flyover 
profile is a level flight 492 feet (150 meters) above ground level 
as measured at the noise measuring station. The reference flyover 
profile has a linear flight track and passes directly over the noise 
monitoring station. Airspeed is stabilized at 0.9V<INF>H</INF>; 
0.9V<INF>NE</INF>; 0.45V<INF>H</INF> + 65 kts (0.45V<INF>H</INF> + 
120 km/h); or 0.45V<INF>NE</INF> + 65 kts (0.45V<INF>NE</INF> + 120 
km/h), whichever of the four airspeeds is least, and maintained 
throughout the measured portion of the flyover. Rotor speed is 
stabilized at the power on maximum normal operating RPM throughout 
the 10 dB-down time interval.
    (1) For noise certification purposes, V<INF>H</INF> is defined 
as the airspeed in level flight obtained using the minimum 
specification engine power corresponding to maximum continuous power 
available for sea level, 77 deg.F (25 deg.C) ambient conditions at 
the relevant maximum certificated weight. The value of V<INF>H</INF> 
and V<INF>NE</INF> used for noise certification must be included in 
the Flight Manual.
* * * * *

    21. In appendix J, Section J36.101 is amended by revising paragraph 
(c)(4) and (c)(6) to read as follows:

    Section J36.101  Noise certification test and measurement 
conditions.
* * * * *
    (c) * * *
    (4) Measurements of ambient temperature, relative humidity, wind 
speed, and wind direction must be made between 4 feet (1.2 meters) 
and 33 feet (10 meters). Unless otherwise approved by the FAA, 
ambient temperature and relative humidity must be measured at the 
same height above the ground.
* * * * *
    (6) If the measurement site is within 2,000 meters of an 
airport's weather measurement equipment, the airport reported 
temperature, relative humidity and wind velocity may be used. A 
fixed meteorological station (such as those found at airports or 
other facilities), within 2,000 meters of the noise measuring 
station, may meet this requirement.
* * * * *

    22. In appendix J, Section J36.109 is amended by revising 
paragraphs (d)(1)(ii) and (e)(1) by removing the reference to ``section 
H36.109(c)(3) of appendix H'' and adding the reference ``section 
A36.3.6 of appendix B'' in its place and revising paragraph (c)(4) to 
read as follows:

    Section J36.109  Measurement of helicopter noise received on the 
ground
* * * * *
    (c)(4) Procedures for calibration and checking of system used 
must follow those described in Section A36.3.9.
* * * * *

    23. Section J36.305 is amended by revising paragraph (a) to read as 
follows:

    Section J36.305  Noise Limits.
    (a) For primary, normal, transport, and restricted category 
helicopters having a maximum certificated takeoff weight of not more 
than 7,000 pounds and noise tested under this appendix, the Stage 2 
noise limit is 82 decibels SEL for helicopters up to 1,737 pounds 
maximum certificated takeoff weight at which the noise certification 
is requested, and increasing at a rate of 3.0 decibels per doubling 
of weight thereafter. The limit may be calculated by the equation: 
L<INF>AE</INF> (limit) = 82 + 3.0 [log<INF>10</INF> (MTOW/1737)/
log<INF>10</INF>(2)] dB, where MTOW is the maximum takeoff weight, 
in pounds, for which certification under this appendix is requested.


    Issued in Washington, DC, on September 19, 2000.
James D. Erickson,
Director of Environment and Energy.
[FR Doc. 00-24634 Filed 10-4-00; 8:45 am]
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