Noise Certification Regulations for Helicopters

Note: EPA no longer updates this information, but it may be useful as a reference or resource.
 [Federal Register: June 2, 2004 (Volume 69, Number 106)]
[Rules and Regulations]
[Page 31225-31246]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr02jn04-17]
[[Page 31226]]

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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 36
[Docket No. FAA-2000-7958; Amendment No. 36-25]
RIN 2120-AH10
 
Noise Certification Regulations for Helicopters

AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.

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SUMMARY: The Federal Aviation Administration (FAA) is amending the 
noise certification regulations for helicopters. These changes are 
based on a joint effort by the FAA, the European Joint Aviation 
Authorities (JAA), and the Aviation Rulemaking Advisory Committee 
(ARAC), to harmonize the U.S. noise certification regulations with the 
European Joint Aviation Requirements (JAR) for helicopters. These 
changes will 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. Harmonizing 
the noise certification standards will simplify airworthiness approvals 
for imported and exported helicopters.

DATES: Effective July 2, 2004.

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 e-mail at sandy.liu@faa.gov.

SUPPLEMENTARY INFORMATION:

Availability of Rulemaking Documents

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following steps:
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or the Government Printing Office's Web page at 
http://www.gpoaccess.gov/fr/index.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 amendment number or docket number of this 
rulemaking.

Small Business Regulatory Enforcement Fairness Act

    The Small Business Regulatory Enforcement Fairness Act (SBREFA) of 
1996 requires FAA to comply with small entity requests for information 
or advice about compliance with statutes and regulations within its 
jurisdiction. Therefore, any small entity that has a question regarding 
this document may contact their local FAA official, or the person 
listed under FOR FURTHER INFORMATION CONTACT. You can find out more 
about SBREFA on the Internet at our site, http://www.faa.gov/avr/arm/
sbrefa.htm.  For more information on SBREFA, e-mail us 
9-AWA-SBREFA@faa.gov.

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 ongoing 
prototypical sets of aircraft noise standards that its member States, 
including the United States, are encouraged to adopt into their 
respective national regulations. Many ICAO member States have adopted 
the ICAO standards word for word. The United States has adopted noise 
certification regulations in title 14 of the Code of Federal 
Regulations (CFR) part 36. Although similar to the ICAO standard, the 
U.S. regulations contain substantive differences from the ICAO version. 
A third body, the 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 from its country of 
manufacture and certification. It became apparent to the manufacturers 
the differences among the three versions of the helicopter noise 
standards represent an undesirable burden. The manufacturers requested 
that the regulating agencies harmonize the three sets of regulations in 
order to minimize the costs for demonstrating compliance and facilitate 
international trade.
    These three aviation certification authorities, the United States, 
the JAA, and the ICAO, had 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 harmonizing U.S. regulations with those of the JAA and 
the ICAO.

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.'' In the United States, noise standards 
and regulations that apply to issuing type certificates, changes in 
type design, and airworthiness certificates for specified classes and 
categories of aircraft are contained in 14 CFR part 36. 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 published on February 5, 1988 (53 FR 3534). 
On September 16, 1992, the FAA published an alternative noise 
certification procedure, appendix J, for helicopters that do not exceed 
6,000 pounds maximum takeoff weight (57 FR 42846).

ICAO Helicopter Noise Certification Standards

    The ICAO has adopted a set of Standards and Recommended Practices 
for aircraft noise certification. These ICAO standards are similar to 
the U.S. regulations. The ICAO Annex 16 standards, which are not alone 
enforceable, 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,

[[Page 31227]]

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 Regulations, or 
JARs. One goal of the JARs is to minimize type certification 
differences on multinational European ventures and to facilitate the 
export and import of aviation products between European nations. 
Aviation authorities of participating European countries recognize the 
JARs as an acceptable basis for showing compliance with their national 
aviation laws. 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.

Aviation Rulemaking Advisory Committee

    In June 1990, at a meeting of the JAA Council, which consists of 
JAA members and the FAA, the FAA Administrator committed the FAA to 
support harmonizing the U.S. regulations with the JARs.
    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 facing the 
agency. The FAA tasked the ARAC with several noise certification 
issues. These issues involve harmonizing 14 CFR part 36 with JAR 36, 
harmonizing associated guidance material, and interpretations of the 
regulations. On May 3, 1994, the FAR/JAR Harmonization Working Group 
for Helicopters was established (59 FR 22883). The Helicopter 
Harmonization Working Group (HHWG), as it is known, 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 
recommend 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 it to the FAA for consideration in the 
form of a draft NPRM.
    On October 5, 2000, the FAA published Notice No. 00-11 entitled 
``Noise Certification Regulations for Helicopters'' (65 FR 59634). On 
October 16, 2000, a correction document was published (65 FR 61125) 
correcting the notice number from 00-11 to 00-12. The FAA solicited 
comments on the proposals, which are discussed below. This final rule 
is based on Notice No. 00-12.

Discussion of Comments

    Two commenters responded to Notice No. 00-12.
    Transport Canada reviewed the proposed rule and agrees with its 
content. Bell Helicopter Textron, Inc. (BHTI) also supports the 
amendment to harmonize the U.S. regulations with the European JARs.
    In its comment, BHTI suggests adopting changes that were 
recommended by the Helicopter Harmonization Working Group (HHWG). BHTI 
was a member of the HHWG that identified three items that were expected 
to be in the NPRM but were inadvertently omitted in the drafting 
process. These include clarification of test series requirements, the 
allowable weather data time window, and flight requirements relative to 
wind direction and minimal wind threshold.
    Specifically, BHTI made the following three comments:
    1. Section H36.101(c)(7): BHTI requests a change in the allowable 
timeframe for meteorological temperature and relative humidity 
measurements to be obtained relative to each noise test measurement. 
This change would increase the timeframe from 25 minutes to 30 minutes 
and results in a single international standard.
    2. Section H36.107(b)(2): BHTI states that the height tolerances of 
±30 ft (±9 meters) are not consistent with the 
JAR 36 glide slope tolerance limits. BHTI suggests that the FAA adopt 
the JAR standards. This change would conform to related requirements 
made in section H36.101(b)(7) and maintains technical consistency.
    3. Section J36.105(b): BHTI states the current flyover procedures 
require at least six flights over the noise measuring station, with an 
equal number in the opposite direction. BHTI suggests that relative 
wind effects (head versus tail winds) be accounted for during test 
series. This change would improve noise repeatability by further 
balancing directional wind effects over a test series and results in a 
balanced flight procedure that is the same as JAR 36 requirements.
    The FAA agrees with incorporating these harmonization changes in 
this final rule. These changes were agreed upon by the HHWG and do not 
change noise stringency, and provide further comprehensive technical 
uniformity of the noise certification requirements in the U.S. 
regulations, JAR requirements, and ICAO guidelines.

Corrections and Other Minor Changes to the Proposed Rule

    This final rule incorporates the BHTI comments. It also corrects 
typographical errors, and word omissions that appear in the proposed 
rule. In addition, we are correcting section and appendix designations, 
cross-references, symbol designations, equation changes, and 
terminology that will harmonize the rule more closely. The following is 
a list of the corrections and changes discussed above.
    (1) In section H36.3(d), the symbol ``D'' is changed to 
``D_r'' and the symbol ``J'' to ``J_r''; the word 
``reference'' is added before the word ``airspeed'' to indicate that 
the specifications are for reference flight conditions.
    (2) In section H36.3(f)(1)(i), the approach reference profile 
designation is changed from ``EK'' to ``E_rK_r'', 
and the angle measure is changed from ``6[deg]
+/-0.5 [deg]'' to 
``6[deg].''
    (3) In section H36.111(c)(2), the word ``engine'' is deleted.
    (4) In section H36.201(a)(1), the word ``Instantaneous'' is deleted 
to be consistent with the nomenclature and title used in section A36.6.

[[Page 31228]]

    (5) In sections H36.205(a)(1)(i) and H36.205(a)(ii), the range of 
correctional variation is changed to show that it can be less than 
zero.
    (6) In section H36.205(c)(1), the text that discusses operational 
speed is deleted because it is not applicable when describing flight 
profile criteria.
    (7) In section H36.205(e)(2), the range specification for Mach 
Number is changed from ``0.3'' to ``0.03.''
    (8) In section H36.205(f)(1)(i), the equation designations of 
measured takeoff sound propagation path and length are changed from, 
``L_r A'' to ``AL'' in the second sentence and from 
``L_r A'' to ``AL_r'' in the third sentence.
    (9) In section H36.205(f)(2)(i), the equation designations of 
takeoff distances for measured and reference paths are changed from 
``AM'' to ``AN'' and AM_r'' to ``AN_r''.
    (10) In section H36.205(f)(2)(ii), the paragraph reference is 
changed from (d)(1)(ii) to (f)(1)(ii) to cite the correct procedures.
    (11) In section H36.205(f)(4), the flyover distance designations 
for measured and reference paths are changed from, ``AN'' to ``AM'' and 
AN_r'' to ``AM_r''.
    (12) In sections H36.205(f)(1)(i), (f)(2)(i), (f)(3) and (f)(4), 
the symbols and units in the equation are corrected to be consistent 
with the definition of corrected maximum sound pressure level in 
appendix A to part 36.
    (13) In sections H36.205(g)(1)(i) through (iv), the constant value 
``-10'' in the first term is changed to ``-7.5'' for each of the 
[Delta]₂ equations.
    (14) In section H36.205(g)(1)(i), the word ``corrected'' is changed 
to ``reference'' throughout the section for consistent terminology 
between measured and reference conditions. The measured and reference 
length terms are changed from, ``AT'' to ``AL'' and from 
``AT_r'' to ``AL_r'', within the 
[Delta]₂ equation and paragraph text. Also, the words ``as 
the corrected and'' are deleted.
    (15) In section H36.205(g)(1)(ii), the approach designations of 
measured and reference lengths are changed from, ``AS'' to ``AN'' and 
from ``ASr'' to ``AN_r'', within the [Delta]₂ 
equation and paragraph text.
    (16) In section H36.205(g)(1)(iii), the sideline measured and 
reference length designations for each of the flight conditions is 
changed from, ``T'' to ``L'', from ``Tr'' to ``L_r'', from 
``S'' to ``M'', from ``S_r'' to ``M_r'', from ``G'' 
to ``N'', from ``G_r'' to ``N_r'', and from ``K'' 
to ``S''. The word ``approach'' is changed to ``flyover'' and 
``flyover'' is changed to ``approach'' to be consistent with the 
changed format.
    (17) In section H36.205(g)(1)(iv), the measured and reference 
length terms are changed from ``AG'' to ``AM'' and from 
``AG_r'' to ``AM_r'', within the 
[Delta]₂ equation and paragraph text.
    (18) In section J36.3(c), the term ``power on'' is removed to 
simplify and more accurately express the operating condition.
    Sections H36.205(f) and H36.205(g) are reordered to match the 
sequence of the flight conditions, and establishes format consistency 
throughout appendix H. These sections are reordered to follow the 
flight conditions order of takeoff, flyover, approach, and sideline 
measures. A related format change is made in section H36.205(f)(3) 
where the sideline station designations are changed from ``Ln'' to 
``L_r'', and from ``Mn'' to ``M_r''. Also, the word 
``approach'' is changed to ``flyover'' and ``flyover'' to ``approach'' 
to be consistent with the changed format.

Synopsis of the Final Rule

    Part 36 of 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 
certifying civil helicopters in the normal, transport, restricted, or 
primary category. This includes rules governing issuing original, 
amended, or supplemental type certificates for helicopters for which 
application is made on or after March 6, 1986.
    The FAA is amending some of the technical specifications included 
in appendices H and J, and adding a new definition of maximum normal 
operating RPM in Sec.  36.1. This final rule does not substantively 
alter the prescribed noise limits or 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 changes in 
this final rule can 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 exist; or (c) removing an existing part 36 
specification where there is no corresponding ICAO specification. The 
FAA has chosen to remove those part 36 specifications that are no 
longer technically appropriate and for which the practice is outdated.
    The FAA has examined the part 36 helicopter noise certification 
process and analyzed how the changes will affect previous helicopter 
noise certification projects. The cumulative positive and negative 
effect of the changes on a single certification would not typically 
exceed ± 0.1 decibels and would not be expected to exceed 
± 0.3 decibels under a worst-case combination of conditions. 
The FAA has determined that the changes will not substantively alter 
the noise certification levels or the finding of compliance for 
helicopters currently certificated under appendix H or appendix J.

Section-by-Section Discussion

    The following is a section-by-section discussion of the changes 
proposed in Notice No. 00-12 that are incorporated in this final rule.

Section 36.1 Applicability and Definitions

    A new definition for ``maximum normal operating RPM'' is added to 
Sec.  36.1(h)(5) of the final rule. Maximum normal operating RPM is 
defined as the highest rotor speed corresponding to the airworthiness 
limit imposed by the manufacturer and approved by the FAA. This term 
will cover instances where a tolerance on the highest rotor speed is 
specified, where the rotor speed is automatically linked to flight 
condition, or where the rotor speed can be changed by pilot action.

Section 36.11 Acoustical Change: Helicopters and Section 36.801 Noise 
Measurement

    The applicability of appendix J in the final rule is changed. It 
increases the maximum takeoff weight limit from 6,000 pounds to 7,000 
pounds. This change reflects a previous change to 14 CFR part 27 
airworthiness standards for normal category rotorcraft. The part 27 
revision, published on October 18, 1999, increased the maximum weight 
limitation for normal category rotorcraft to 7,000 pounds, increased 
the passenger seat limitation to nine, and updated the safety standards 
for airworthiness.

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. 
This final rule adds the word ``Documentation'' to the subpart title to 
better identify the subject matter of subpart O.
    In Sec.  36.1581(a)(2), the reference to appendix F is changed to 
appendix G. The noise certification requirement for propeller-driven 
small airplanes was moved to appendix G in Amendment 36-16 (53 FR 
47394, November 22, 1988), and this change was overlooked in the NPRM.

[[Page 31229]]

    In new Sec.  36.1581(a)(3), the requirement to include helicopter 
noise levels in the rotorcraft flight manual is added. This change 
includes noise certification documentation requirements and is similar 
to requirements for other types of aircraft. This change will provide 
uniform noise level documentation requirements for each aircraft 
category and will standardize documentation procedures.

Section H36.3 Reference Test Conditions

    Sea level pressure in metric units of hector Pascal (hPa) is added 
to section H36.3(a)(1) of this final rule. The English units of pounds 
per square foot (psf) that are specified in the current rule remain in 
the final rule. The outdated designation for inches of mercury is 
deleted. This change will prevent possible variations in measured data 
resulting from differing conversion factors made by applicants using 
metric units.
    The reference to rotor speed in section H36.3(d) is deleted in the 
final rule. The FAA has determined that it is unnecessary when 
describing a flight profile, since rotor speed is an operational 
procedure and not a flight profile description.
    Two new criteria for flyover reference airspeeds: 0.9V_NE 
and 0.45V_NE+65 knots are added to section H36.3(d) of the 
final rule. Currently, the reference airspeed required is the lesser of 
0.9V_H or 0.45_VH+65 knots. (Note: V_NE 
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 has resulted in helicopters that can 
have a V_H airspeed in excess of the power-on V_NE 
airspeed. The new noise certification airspeed criteria are needed to 
keep up with technological advances and still accommodate the 
airworthiness limitations imposed for safety. The value of 
V_NE is also added to section H36.3(e).
    Test approach angle tolerance limits between 5.5[deg]
and 6.5[deg]
are removed from section H36.3(f)(1)(ii) of the final rule. These 
limits are added to section H36.3(f)(1)(i). Since section 
H36.3(f)(1)(ii) defines approach profile requirements and section 
H36.3(f)(1)(i) defines operating procedures, paragraph (i) is the 
appropriate place for the tolerance limits.

Section H36.5 Symbols and units

    The symbols S_r, T, and T_r and their 
definitions are removed from in the ``Flight Profile Identification-
Positions'' table in section H36.5. The symbols AS, AS_r, AT, 
and AT_r and their definitions in the Flight Profile 
Distances table are also removed from section H36.5. Since the closest 
points of approach are not used for testing, these symbols are no 
longer addressed on the Figures.
    The description for the symbol S is revised and three new symbols 
and their definitions are added to the Flight Profile Identification 
Positions table in the final rule. The new symbols and their 
definitions are as follows:

F_r--Position on reference takeoff path directly above noise 
measuring Station A.
G_r--Position on reference flyover path directly above noise 
measuring Station A.
H_r--Position on reference approach path directly above noise 
measuring Station A.
S.--Sideline noise measuring station (note: a subscript denotes the 
aircraft orientation relative to the direction of flight). These 
changes and corrections make these tables consistent with revised 
Figures H1, H2, and H3.

Section H36.101 Noise Certification Test and Measurement Conditions

    The requirement that flyover test conditions be at, or above the 
maximum certification weight are added to section H36.101(b)(6)(i) of 
the final rule. Requiring the maximum certification weight limit for at 
least three flight conditions, eliminates the necessity for requiring 
separate comprehensive weight test series. In accounting for the 
maximum noise due to weight effects, it reduces test cost by minimizing 
the number of flights previously necessary. This change also harmonizes 
the flight condition weight criteria necessary to be consistent with 
JAR 36 requirements.
    Section H36.101(b)(6)(iii) is deleted. The requirement for 
additional flight test data to determine the variation of EPNL with 
weight for the takeoff condition is unnecessary because takeoff noise 
generation is a function of torque (power) to the rotor systems, not 
weight.
    The requirement for approach test weight in section 
H36.101(b)(8)(ii) is changed from a ``maximum of 90 percent'' to 
``between 90 percent and 105 percent'' of the rotorcraft's maximum 
certification weight. This change makes this section consistent with 
section H36.101(b)(6)(ii), and simplifies the weight requirements for 
the three flight conditions.
    Section H36.101(b)(8)(iii) is deleted. The requirement for 
additional flight test data that is used to determine the variation of 
EPNL with weight for the approach condition is unnecessary. During 
approach, noise generation is predominantly a function of complex 
aeroacoustic sources associated with main rotor blade vortex 
interaction, not weight. This change will further harmonize measurement 
procedures and streamline certification testing.
    The minimum test temperature in section H36.101(c)(2) is changed 
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. The temperature limit for noise 
measuring equipment in part 36 is unchanged.
    Section H36.101(c)(2) of the final rule specifies that the 
atmospheric test window be based on the 10-meter temperature values and 
relative humidity values instead of the average temperature between the 
aircraft and the 10-meter tower above the ground. The final rule also 
specifies that the atmospheric test window be used to adjust the sound 
propagation path for propagation path absorption. Noise certification 
data collected to date demonstrate that EPNL values corrected using 
atmospheric data measured at 33 feet (10 meters) are acoustically 
identical to the previous correction standard. The previous correction 
standard used both averaged aircraft altitude temperature and relative 
humidity data, and ground based temperature and relative humidity data. 
This change makes the part 36 requirements the same as JAR 36 
requirements.
    Section H36.101(c)(3) of the current rule requires relative 
humidity and ambient temperature values to be measured at the 10-meter 
measurement station for allowable sound attenuation in the one-third 
octave band centered at 8 kHz. The final rule eliminates the 
requirement that the sound attenuation determination use aircraft 
measurements. This change is supported by years of noise certification 
data demonstrating that atmospheric measurements at 33 feet (10 meters) 
satisfy the sound attenuation determination. Analysis has indicated 
minimal differences between humidity measured at the helicopter 
altitude and the 10-meter measurement position. Corrections have been 
no greater than 0.1 dB, except under extreme conditions that would be 
considered an anomalous meteorological condition under which a test 
could not be conducted.
    Section H36.101(c)(5) of the final rule expands the testing 
limitations under anomalous conditions to account for other 
meteorological factors such as temperature and relative humidity. The 
current criterion specifies only the

[[Page 31230]]

anomalous test condition for wind effects. As an example, the typical 
desert test environment provides acceptable wind conditions but also 
develops complex temperature and relative humidity gradients that 
highly influence and distort noise measurements. Additional limitations 
on anomalous conditions of meteorological factors to maintain noise 
repeatability are added in the final rule. FAA-approved procedures are 
to be used to determine compliance. This change results in harmonizing 
the testing limitations with that in JAR 36.
    As discussed previously in this document, the allowable timeframe 
for meteorological temperature and relative humidity measurements that 
must be obtained relative to each noise test measurement in section 
H36.101(c)(7) is included in the final rule. The timeframe is increased 
from 25 minutes to 30 minutes and results in a single international 
standard. This change harmonizes the testing procedures in part 36 with 
those in JAR 36.
    Sections H36.101(d)(2) and (d)(3) currently require that the 
helicopter height and lateral position be determined relative to the 
reference flight track, rather than the centerline or runway. The final 
rule, allows the use of a differential global positioning system 
(DGPS), as an alternate, acceptable independent method for determining 
helicopter position.

Section H36.103 Takeoff Test Conditions

    Section H36.103(b)(1) of the final rule adds the requirement to 
establish the takeoff procedure airspeed before entering the 10dB-down 
time interval of the climb out. The current rule requires only that the 
takeoff procedure airspeed be established during the horizontal portion 
of the takeoff test procedure. Adding this requirement clarifies that 
portion of the takeoff flight profile for which the required airspeed 
must be maintained. This revised takeoff procedure allows the pilot to 
establish and stabilize required power settings at the time the climb 
is started. This procedure simplifies and shortens the pilot's workload 
by requiring one less parameter (power) that must be adjusted from 
horizontal flight to the time the climb is initiated. This method is 
satisfactory only if the initial 10 dB-down time interval occurs during 
the climb portion of the profile. If this does not occur during the 
climb portion of the flight, the test run is invalid and must be repeated.
    An alternate criterion of maximum takeoff power corresponding to 
minimum installed engine power is added to section H36.103(b)(3). The 
current rule only allows for the use of torque limit at the minimum 
installed power available. The final rule adds the use of maximum 
takeoff power available as an alternate takeoff test condition. As 
amended, the lower of the two limits (gearbox torque limit or maximum 
takeoff power) will be used to satisfy the takeoff condition 
requirement. This change makes the requirements in part 36 the same as 
in JAR 36.
    The current takeoff airspeed requirement in section H36.103(b)(4) 
states that either the best rate of climb airspeed, or the lowest 
airworthiness approved takeoff speed, be maintained during the 10db 
down time interval. The language used to describe takeoff airspeed 
requirements has caused confusion between the FARs and the JARs in the 
past. This final rule harmonizes the language used to explain takeoff 
airspeed requirements; the requirement has not changed.
    A definition of the highest rotor speed used in takeoff is added to 
section H36.103(b)(5). The current rotor speed criterion specifies 
normal operating RPM. The term ``normal'' is being removed. The average 
rotor speed is required to be within ±1.0 percent of maximum 
normal operating RPM during the 10 dB-down time interval. A complete 
discussion of this change can be found in the discussion of section 
36.1(h)(5) of this preamble.
    A new alternate allowable altitude criteria of a wider zenith 
tolerance, in meters, for low altitudes near the start point of the 10 
dB-down time interval is added to section H36.103(b)(6). The current 
permitted zenith tolerance defined in degrees throughout the 10 dB-down 
time interval is still allowed. This change harmonizes the part 36 
criteria with those used in JAR 36.
    A new paragraph (b)(7) is added to section H36.103. This new 
paragraph requires that a constant takeoff configuration be maintained, 
and permits the landing gear to be retracted when establishing the best 
rate-of-climb speed, V_y. Both conditions must be consistent 
with aircraft airworthiness standards. This change makes the 
requirements in part 36 the same as the requirements in JAR 36.

Section H36.105 Flyover Test Conditions

    Current section H36.105(b) requires that an even number of flights 
be conducted to assure a balanced measurement of any directional 
effects related to flight path orientation. As previously discussed in 
this document, relative wind effects (head versus tail winds) must also 
be accounted for during test series. After further analysis, the FAA 
has determined that the suggested change to add the relative wind 
effects will improve noise repeatability by further balancing 
directional wind effects over a test series. This final rule 
incorporates this change because it is a technically sound approach 
that results in a balanced flight procedure. Adding this requirement 
harmonizes part 36 with JAR 36 requirements.
    The requirement that a constant cruise configuration be maintained 
is added to section H36.105(b)(1). This change adopts the commonly 
understood term ``cruise configuration'' to clarify the requirement for 
steady, controlled-piloting, constant speed operations during flyover 
test conditions.
    Two alternative flyover reference airspeed criteria are added to 
the current requirement of continuous power (VH ) in section 
H36.105(c)(1). The two alternative level flyover reference airspeeds 
are 90 percent of the never-exceed airspeed, V_NE, and 45 
percent of the never-exceed airspeed plus 65 knots. The least of the 
three airspeeds is required to be used as the reference airspeed. The 
advent of more powerful engines and improved gearboxes has resulted in 
helicopters that can have a V_H airspeed in excess of the 
power-on V_NE airspeed. These new noise certification 
airspeed criteria are needed to keep up with technological advances 
while accommodating the airworthiness limitations imposed for safety. 
This addition makes the airspeed criteria in part 36 the same as the 
criteria in JAR 36.
    A definition of the highest rotor speed used in flyover is added to 
section H36.105(c)(2). The current rotor speed criterion specifies 
normal operating RPM. The average rotor speed is required to be within 
±1.0 percent of maximum normal operating RPM during the 10 
dB-down time interval. This change is being made for the same reasons 
previously discussed for section 36.1(h)(5) of this final rule.

Section H36.107 Approach Test Conditions

    As previously discussed in this document, the height tolerance of 
±30 ft (±9 meters) in current section 
H36.107(b)(2) is not consistent with the JAR 36 glide slope tolerance 
limits. The height tolerance in section H36.107(b)(2) is changed to 
±33 ft (±10 meters) in order to be accurate and 
consistent with the 6[deg]
±0.5 [deg]
glide slope 
requirement of section H36.101(b)(7). This change conforms to related 
requirements made in section

[[Page 31231]]

H36.101(b)(7) and maintains technical consistency.
    A new fixed-distance-lateral-tolerance at low altitudes is added to 
section H36.107(b)(3). This new tolerance adds flexibility to 
operations conducted near the end of the approach test condition. The 
current vertical ground convergent zenith tolerance was overly strict 
for approach flight operations. The upper altitude zenith tolerance 
criterion must still be met beyond the altitude range where the two 
criteria overlap or converge. This change makes the requirements in 
part 36 the same as the requirements in JAR 36. The use of expanded 
tolerances in JAR 36 has had no impact to noise acquisition and has 
reduced the number of approach test flights required.
    A definition for the highest rotor speed used in approach is added 
to section H36.107(b)(5). The current rotor speed criterion specifies 
normal operating RPM. The average rotor speed is required to be within 
±1.0 percent of maximum normal operating RPM during the 10 
dB-down time interval. This change is made for the same reasons 
discussed at section 36.1(h)(5) in the preamble.
    A new paragraph (b)(6) is added to section H36.107 of the final 
rule. This paragraph requires that a constant approach configuration be 
maintained and permits the landing gear to be extended when 
establishing the best rate-of-climb or the lowest approved speed for 
the approach. Both conditions must be consistent with aircraft 
airworthiness standards. This change makes the requirements for 
approach configuration in part 36 the same as the requirements in JAR 36.

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

    In the final rule, the text in section H36.109 is being replaced 
with a reference to the procedures for measurements of helicopter noise 
received on the ground in section A36.3 of Appendix A. In the current 
rule, the procedures are listed in section H36.109 and A36.3. The final 
rule removes the text in section H36.109 because it is not necessary to 
have the same text repeated in part 36.

Section H36.111 Reporting and Correcting Measured Data

    An allowable EPNL correction for takeoff flight condition is added 
to section H36.111(c)(2). The amount of this allowable correction is 
limited to 4.0 EPNdB. This change is intended to reduce the number of 
takeoff flights required during testing by allowing a greater range of 
acceptable data.
    The description of the corrective conditions for reporting 
corrected measured noise data in section H36.111(c)(2) of the final 
rule is revised. This revised description is more general, and removes 
an outdated reference specifying the use of the ILS antenna position, 
which is not applicable to most other positioning methods. Paragraph 
(c)(2)(iii) is revised to include a reference to the detailed 
corrections specified in H36.205. Paragraph (c)(2)(iv) is deleted 
because we no longer correct for engine thrust or power for flyover 
noise levels. The major source of noise comes from the rotor systems; 
the engine thrust or power is a secondary noise effect. These changes 
make the requirements in part 36 the same as the requirements in JAR 36.
    In section H36.111(c)(3), the aircraft noise level measurement 
required in each 1/3 octave band is changed from an allowance threshold 
of 5dB over the background noise to an allowance threshold of 3dB over 
the background noise. This change to appendix H adopts the same noise 
analysis change made in appendix B for transport category and turbojet 
powered airplanes. This amendment also replaces the term ``10 dB down 
points'' with ``10 dB-down time interval'' as the accepted nomenclature 
for this specific time segment. This harmonized background noise 
analysis threshold limit and the ``10 dB-down time interval'' term are 
in the final rule, ``Noise Certification Standards for Subsonic Jet 
Airplanes and Subsonic Transport Category Large Airplanes,'' published 
in the Federal Register on July 8, 2002 (67 FR 45196).

Section H36.113 Atmospheric Attenuation of Sound

    In section H36.113(c)(1)(iii) of the final rule, the adjustment for 
the sound propagation path absorption is revised to require the use of 
the 10-meter temperature and relative humidity measurement values. The 
current sound propagation path absorption was based upon the average of 
temperature and relative humidity measurements made at aircraft 
altitude and at the 10-meter measurement stations. Noise certification 
data voluntarily collected by industry to date have demonstrated that 
EPNL values corrected using atmospheric data measured at 33 feet (10 
meters) are acoustically identical to those corrected using averaged 
temperature and relative humidity.

Section H36.205 Detailed Data Correction Procedures

    Section H36.205(a)(1) of the final rule is revised to include the 
addition of negative value corrections to the test data measurements. 
Currently, negative differences are assigned a zero value. The FAA has 
determined that negative value corrections are appropriate to account 
accurately for any differences between reference and test conditions. 
This change more accurately reflect the effects of noise reduction in 
the measurements.
    In section H36.205(a)(1)(iii) of the final rule, the criteria for 
maximum certification weight for corrections are deleted. The effect of 
weight on EPNL is better accounted for by limiting the allowable test 
weight to be between 90 and 105 percent of the maximum certification 
weight.
    In section H36.205(a)(2) of the final rule, the negative value 
correction procedures for reference and test conditions are revised. As 
discussed above, negative corrections are now included in paragraph 
(a)(1) of this section. Accordingly, section H36.205(a)(3) is 
redesignated as H36.205(a)(2).
    In sections H36.205(a)(3)(iii), (b)(3) and (d)(3) of the final 
rule, the distance criterion used to calculate the duration corrections 
between measured and reference altitudes is revised. The new distance 
criterion is the distance between the measuring station and helicopter 
when the maximum PNLT (PNLTM) noise value is measured. The current 
distance criterion uses the simplified geometric closest point of 
approach (CPA). This change in distance criterion to the PNLTM-measured 
value is a more accurate method for computing noise duration 
corrections because it is based on the actual peak noise source 
characteristics.
    The final rule amends section H36.205(a)(3)(iv) to permit the use 
of more general source noise data in flyover, when submitted for FAA 
approval prior to testing. The current formats require that the data be 
expressed in the form of EPNL curves or tables for variation of RPM and 
test speed. This final rule permits the use of more general source 
noise data, and alternative data formats.
    In section H36.205(b)(ii)(2) of the final rule, the takeoff 
airspeed criteria is simplified by designating the slowest climb speed 
allowed under the aircraft airworthiness requirements as the minimum 
boundary. This final rule also removes the reference to rotor speed, 
because rotor speed is not needed in

[[Page 31232]]

describing a flight profile for data correction purposes.
    As discussed previously in this document, a conforming change to 
section H36.105(b) and an associated harmonization issue were 
inadvertently omitted from proposed section H36.205(c)(1). The current 
flyover procedures require subsequent flyovers in reverse direction 
with a minimal of three flights in each direction. The FAA has 
determined that the suggested change to add the relative wind effects 
(head versus tail winds) will improve noise repeatability by further 
balancing directional wind effects over a test series. This final rule 
incorporates this additional effect of head versus tail wind because it 
is a technically sound approach, and results in a balanced flight 
procedure that is the same as JAR 36 requirements.
    Section H36.205(d)(2) of the final rule eliminates the requirement 
that the noise test approach procedure be included in the Flight 
Manual. Noise test approach procedures are more appropriate for noise 
certification test reports. Including the procedures in the Flight 
Manual could be confused with approved airworthiness approach 
procedures. This final rule will also replace the term ``10 dB down 
period'' with ``10 dB-down time interval'' in section H36.205(d)(2), as 
the accepted nomenclature for this specific time segment.
    Section H36.205(e)(1) of the final rule removes the requirement 
that only the advancing blade tip Mach number can be used when making 
source noise adjustments. The revised section allows the use of an 
alternate procedure for off-reference tip Mach number adjustments. The 
alternate procedure is expected to yield 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. The flexibility of offering an 
alternative procedure is consistent with ICAO practices.

Figures H1, H2 and H3

    In Notice No. 00-12, the FAA proposed to revise Figures H1 and H3 
to include the height above measurement points in metric units and to 
delete the closest point of approach (CPA) distance designations. The 
FAA received no comments on this proposal and it is being adopted as 
proposed.
    Although Figure H2 changes were not addressed in the NPRM, for 
accuracy and completeness, the FAA is making corrections to 
typographical errors and replacing incomplete designations. The word 
``corrected'' is replaced with the word ``reference'' in the titles of 
Figures H1, H2 and H3 in the final rule. This change keeps the language 
in the final rule consistent throughout Appendix H.

Section H36.305 Noise Levels

    Sections H36.305(a)(2)(i) through (iii), are revised by removing 
the phrase ``for maximum weight of 1,764 pounds or less'' from the end 
of each paragraph and replacing it with the phrase ``after which the 
limit is constant'' to adopt the same language used by ICAO standards.

Section J36.1 General

    The maximum takeoff weight requirement of appendix J is increased 
from 6,000 pounds to 7,000 pounds in section J36.1 of the final rule. 
In the final rule, ``Normal Category Rotorcraft Maximum Weight and 
Passenger Seat Limitation,'' published in the Federal Register on 
August 18, 1999, (64 FR 45092), the allowable passenger seat limit for 
part 27 rotorcraft was increased to nine and the corresponding weight 
limit was increased to 7,000 pounds. The weight limit change is made in 
part 36, appendix J in this final rule.

Section J36.3 Reference Test Conditions

    Section J36.3(c) of the final rule adds the phrase ``maintained 
throughout the measured portion of the flyover'' to clarify the 
requirement for stabilized airspeed. Stabilized airspeed will minimize 
the likelihood of variability of advancing tip Mach number. Section 
J36.3(c)(1) of the final rule adds the requirement that airspeed VNE 
must be included in the approved Flight Manual. This change 
standardizes the language used in appendices H and J. This section is 
also amended by replacing the term ``10 dB down time period'' with ``10 
dB-down time interval'' as the accepted nomenclature for this specific 
time segment, as discussed previously.

Section J36.101 Noise Certification and Measurement Conditions

    Section J36.101(c)(4) of the final rule revises the criterion by 
which meteorological data is collected. The current rule requires 
measurements to be made at the noise measuring station. The revision 
removes this requirement. This change and the following related changes 
to the final rule are harmonized with the JARs and add flexibility in 
the use of meteorological station requirements. The requirements of 
section J36.101(c)(6) are amended as follows:
    1. The physical location of meteorological instruments must be 
representative of the atmospheric conditions existing near the surface 
over the geographical area where the helicopter noise measurements are 
made.
    2. A fixed meteorological station, such as those found at airports, 
may be used to meet the location requirement.
    3. A fixed meteorological station, if used, must be within 2,000 
meters of the noise measurement area. The 2,000-meter distance 
limitation is a reasonable allowance when conducting tests relative to 
a ``fixed meteorological station,'' such as those found at airport 
sites or other facilities.
    These changes harmonize this final rule with the JARs and do not 
pose a known increase in noise levels.

Section J36.105 Flyover Test Conditions

    As previously stated in this document, an associated harmonization 
issue was inadvertently omitted in proposed section J36.105(b). The 
current flyover procedures require at least six flights over the noise 
measuring station, with an equal number in opposite direction. The FAA 
has determined the suggested change to add the relative wind effects 
(head versus tail winds) will improve noise repeatability by further 
balancing directional wind effects over a test series. This final rule 
incorporates this additional effect of head versus tail wind because it 
is a technically sound approach, and results in a balanced flight 
procedure that is the same as JAR 36 requirements.
    The maximum weight limit is increased from 6,000 pounds to 7,000 
pounds in section J36.305(a) of the final rule. This is a conforming 
change made for the reasons discussed above at section J36.1. The final 
rule also revises the value for the noise/weight reduction rate from 
``3.01'' to ``3.0''. The effect of this change is so minimal that it 
has no effect on noise limit calculations.

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 
final 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

[[Page 31233]]

Standards and Recommended Practices and has identified the following 
two differences with this final rule. The FAA filed these differences 
with ICAO in 1999.
    (1) In sections 36.11 and H36.305 of part 36, helicopters 
certificated before March 6, 1986 are permitted to amend their type 
certificates to reflect acoustical changes. The measured levels at 
recertification must meet either Stage 2 noise limits plus 2 EPNdB, or 
be no greater than the noise levels of the parent helicopter after a 
change in type design; and
    (2) In Sec.  36.805(c) of part 36, helicopters of the United States 
Armed Forces that operated on or before March 6, 1986 are permitted to 
amend their type certificates to reflect acoustical changes. The 
measured levels at recertification must meet either Stage 2 noise 
limits, or be no greater than the noise levels of the parent helicopter 
after a change in type design.

Economic Evaluation

    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. Sec.  2531-2533) prohibits agencies 
from setting standards that create unnecessary obstacles to the foreign 
commerce of the United States. In developing U.S. standards, the Trade 
Act also requires agencies to consider international standards and, 
where appropriate, use them as the basis of U.S. standards. 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 this final 
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 final rule will 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.
    This final rule will more closely harmonize the flight test 
conditions, procedures, and documentation mandated by Appendices H and 
J of 14 CFR part 36 with the corresponding applicable provisions of the 
JAR 36 and the ICAO Annex 16. Specifically, this final rule will amend 
the technical specifications embodied in Appendix H and Appendix J of 
part 36 along with a minor technical change to Appendix B, and add a 
new definition to Sec.  36.1.
    The FAA concludes that this final rule will be cost beneficial. 
This final rule will lessen the certification test burden by (1) 
requiring fewer takeoffs and approaches; (2) eliminating aircraft 
humidity and temperature measurements and the requirements to process 
test data twice and to issue separate reports for FAA and ICAO methods 
and; (3) extending the upper gross weight limit for rotorcraft using 
the Appendix J certification test procedure. The expected cost savings 
of the final rule will be $6.6 million ($4.6 million, discounted) over 
a 10 year period. The one-time cost of this final rule will be $40,800 
($33,300 discounted) and will accrue to those manufacturers that also 
need to obtain ICAO/JAA certification.

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 final 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 RFA requires agencies 
to solicit and consider flexible regulatory proposals and to explain 
the rationale for their actions. The RFA covers a wide-range of small 
entities, including small businesses, not-for-profit organizations and 
small governmental jurisdictions.
    Agencies must perform a review to determine whether a proposed 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 RFA.
    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 RFA provides that the 
head of the agency may so certify and that a regulatory flexibility 
analysis is not required. The certification must include a statement 
providing the factual basis for this determination, and its reasoning 
should be clear.
    Small entities are firms employing 1,500 employees or less, based 
on Small Business Administration guidelines. Enactment of this final 
rule will impose a one-time cost of $10,200 per test for a small 
entity, which would be incurred by two small helicopter manufacturers 
that met the criterion of small entity. The expected cost savings per 
test for a small entity could be at least $85,000. In view of the net 
cost savings per small entity, the FAA has determined that this final 
rule will 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.

International Trade Impact Assessment

    The Trade Agreement Act of 1979 prohibits Federal agencies from 
engaging in any related activities to develop standards 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 accordance with the above statute, the FAA has assessed the 
potential effect of this final rule and has determined that it will 
reduce trade barriers by reducing the differences between U.S. and 
European regulations.

Unfunded Mandates Assessment

    The Unfunded Mandates Reform Act of 1995 (the Act), enacted as Pub. 
L. 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;

[[Page 31234]]

such a mandate is deemed to be a ``significant regulatory action.''
    This final 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 final rule under the principles and 
criteria of Executive Order 13132, Federalism. The FAA has determined 
that this action will 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 final rule will not have federalism implications.

Environmental Analysis

    In accordance with the provisions of regulations issued by the 
Council on Environmental Quality (40 CFR parts 1500-1508), FAA Order 
1050.1D identifies certain FAA actions that may be categorically 
excluded from preparing an Environmental Assessment or an Environmental 
Impact Statement. Pursuant to FAA Order 1050.1D, appendix 4, paragraph 
4(j), this rulemaking action qualifies for a categorical exclusion 
because no significant impacts to the environment are expected to 
result from its finalization or implementation and no extraordinary 
circumstances exist as prescribed under paragraph 32 of Order 1050.1D.

Regulations That Significantly Affect Energy Supply, Distribution, or Use

    The FAA has analyzed this NPRM under Executive Order 13211, Actions 
Concerning Regulations that Significantly Affect Energy Supply, 
Distribution, or Use (May 18, 2001). We have determined that it is not 
a ``significant energy action'' under the executive order because it is 
not a ``significant regulatory action'' under Executive Order 12866, 
and it is not likely to have a significant adverse effect on the 
supply, distribution, or use of energy.

List of Subjects in 14 CFR Part 36

    Aircraft, Noise control.

The Amendment

? In consideration of the foregoing the FAA amends part 36 of title 14 
Code of Federal Regulations, 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 
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.

Sec.  36.11  [Amended]

? 3. Section 36.11 is amended by removing the term ``6,000'' and adding 
the term ``7,000'' in its place in the introductory text and paragraph 
(a)(1).

Sec.  36.801  [Amended]

? 4. Section 36.801 is amended by removing the term ``6,000'' and adding 
the term ``7,000'' in its place.

Subpart O--Documentation, Operating Limitations and Information

? 5. Revise the heading of Subpart O to read as set forth above.

? 6. In Sec.  36.1581 paragraph (a)(2) is revised and a new paragraph 
(a)(3) is added to read as follows:

Sec.  36.1581  Manuals, markings, and placards

    (a) * * *
    (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, at the maximum takeoff weight and 
configuration.
* * * * *

? 7. In appendix H to part 36, section H36.3 is amended by revising 
paragraphs (a)(1), (c)(2), (d), (e), and (f)(1)(i) and (ii) to read as 
follows:

Appendix H to Part 36--Noise Requirements for Helicopters Under Subpart H

* * * * *

Section H36.3 Reference test conditions.

    (a) * * *
    (1) Sea level pressure of 2,116 psf (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 (500 meters) from the 
center microphone location and 65 feet (20 meters) above ground level) 
at a constant climb angle [beta]
defined by the certificated best rate 
of climb and V_y for minimum engine performance. The constant 
climb angle [beta]
is derived from the manufacturer's data (approved by 
the FAA) to define the flight profile for the reference conditions. The 
constant climb angle [beta]
is drawn through C_r and 
continues, crossing over station A, to the position corresponding to 
the end of the type certification takeoff path represented by position 
I_r.
    (d) Level flyover reference profile. The beginning of the level 
flyover reference profile is represented by helicopter position 
D_r (Figure H2). The helicopter approaches position 
D_r in level flight 492 feet above ground level as measured 
at Station A. Reference airspeed must be either 0.9V_H; 
0.9V_NE; 0.45V_H + 65 kts (0.45V_H + 
120km/h); or 0.45V_NE + 65kts (0.45V_NE + 120 km/
h), whichever of the four speeds is least. The helicopter crosses 
directly overhead station A in level flight and proceeds to position 
J_r.
    (e) For noise certification purposes, V_H is defined as 
the airspeed in level flight obtained using the minimum specified 
engine torque corresponding to maximum continuous power available for 
sea level pressure of 2,116 psf (1,013.25 hPa) at 77[deg]F (25[deg]C) 
ambient conditions at the relevant maximum certificated weight. The 
value of V_NE is the never-exceed airspeed. The values of 
V_H and V_NE that are used for

[[Page 31235]]

noise certification must be listed in the approved Rotorcraft 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). The reference 
flight path, E_rK_r 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 [eta]
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 [eta] must be between 5.5[deg] and 6.5[deg].
* * * * *

? 8. In appendix H to part 36, section H36.5, the Flight Profile 
Identification--Positions table is amended by removing the symbols 
S_r, T and T_r and their descriptions; the Flight 
Profile Distances table is amended by removing the symbols AS, 
AS_r, AT, and AT_r and their descriptions; and the 
Flight Profile Identification--Positions table is amended by adding in 
alphabetical order three new symbols (F_r, G_r, 
H_r), with their descriptions and revising the entry for S to 
read as follows:
* * * * *

Section H36.5 Symbols and Units

                Flight Profile Identification--Positions
------------------------------------------------------------------------
             Position                            Description
------------------------------------------------------------------------

                                * * * * *
Fr................................  Position on reference takeoff path
                                     directly above noise measuring
                                     Station A.

                                * * * * *
Gr................................  Position on reference flyover path
                                     directly above noise measuring
                                     Station A.

                                * * * * *
Hr................................  Position on reference path directly
                                     above noise measuring Station A.

                                * * * * *
S.................................  Sideline noise measuring station
                                     (note: a subscript denotes the
                                     aircraft orientation relative to
                                     the direction of flight).

                                * * * * *
------------------------------------------------------------------------

? 9. In appendix H to part 36, section H36.101 is amended by removing 
paragraphs (b)(6)(iii), (b)(8)(iii), and (b)(9); by revising paragraphs 
(b)(6)(i), (b)(8)(ii), (c)(2), (c)(3), (c)(5), (c)(7), (d)(1), (d)(2), 
(d)(3); and by adding a new paragraph (d)(4) to read as follows:
* * * * *

Section H36.101 Noise Certification Test and Measurement Conditions

* * * * *
    (b) * * *
    (6) * * *
    (i) At least one takeoff test and one flyover test must be 
conducted at, or above, the maximum certification weight.
* * * * *
    (8) * * *
    (ii) Each test weight must be between +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 33 feet (10 meters) 
above the ground at the noise measuring station and at the aircraft. 
The temperature and relative humidity measured at a point 33 feet (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 33 feet 
(10 meters) above the ground at the noise measuring station and at the 
aircraft, 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.
* * * * *
    (7) Temperature and relative humidity measurements must be obtained 
within 30 minutes of each noise test.
    (d) Aircraft testing procedures. (1) The aircraft testing 
procedures and noise measurements must be conducted and processed in a 
manner that yields the noise evaluation measure designated as Effective 
Perceived Noise Level (EPNL) in units of EPNdB, as prescribed in 
Appendix A of this part.
    (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. Applicable independent systems are 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 
synchronized signals recorded at an approved sampling rate. The 
helicopter position 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 before testing.
    (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.
* * * * *

? 10. In appendix H to part 36, section H36.103 is amended by revising 
paragraphs (b)(1), (3), (4), (5), and (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_y ± 5 knots or the 
lowest approved speed ± 5 knots for the climb after takeoff, 
whichever speed is greater, must be established and maintained 
throughout the 10 dB-down time interval.
* * * * *
    (3) Upon reaching a point 1,640 feet (500 meters) from the noise 
measuring station, the helicopter must be stabilized at the maximum 
takeoff 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_y 
± 5 knots, or the lowest approved speed for climb after takeoff, 
whichever is greater, for an ambient temperature of 25[deg]C at sea level.

[[Page 31236]]

    (5) The average rotor speed must not vary from the maximum normal 
operating rotor RPM by more than ±1.0 percent during the 10 
dB-down time interval.
    (6) The helicopter must stay within ±10[deg] or ±65 
feet (±20 meters), 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 speed, V_y.
* * * * *

? 11. In appendix H to part 36, 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 consists of at least six flights. The number of 
level flights made with a headwind component must be equal to the 
number of level flights made with a tailwind component with 
simultaneous measurements at all three noise measuring stations--
    (1) In level flight cruise configuration;
* * * * *
    (3) The helicopter must fly within ±10[deg] or ±65 
feet (±20 meters), 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_H; 0.9V_NE; 
0.45V_H + 65 kts (0.45V_H + 120 km/h); or 
0.45V_NE + 65 kts (0.45V_NE + 120 km/h), whichever 
speed is least, to be 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 ±1.0 percent during 
the 10 dB-down time interval.
* * * * *

? 12. In appendix H to part 36, Section H36.107 is amended by revising 
paragraphs (b)(2), (3) and (5) and adding new paragraph (b)(6) to read 
as follows:
* * * * *

Section H36.107 Approach Test Conditions.

* * * * *
    (b) * * *
    (2) At a height of 394 ± 33 feet (120 ± 10 
meters)
    (3) The helicopter must fly within ±10[deg] or ±65 feet (±20 meters) 
lateral deviation tolerance, whichever is greater, from the vertical 
above the reference track throughout the 10 dB-down time interval;
* * * * *
    (5) At average rotor speed, which may not vary from the maximum 
normal operating rotor RPM by more than ±1.0 percent during 
the 10 dB-down time interval; and
    (6) The constant approach configuration used in airworthiness 
certification tests, with the landing gear extended, must be maintained 
throughout the approach reference procedure.
* * * * *

? 13. In Appendix H to part 36, 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.

? 14. In Appendix H to part 36, section H36.111 is amended by revising 
paragraphs (c)(2) and (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 helicopter flight 
path or performance may be derived from FAA-approved data for the 
difference between measured and reference conditions, together with 
appropriate allowances for sound attenuation with distance. The 
Effective Perceived Noise Level (EPNL) correction may not exceed 2.0 
EPNdB except for takeoff flight condition, where the correction may not 
exceed 4.0 EPNdB, of which the arithmetic sum of [Delta]₁ 
(described in section H36.205(f)(1)) and the term -7.5 log (AL/
AL_r) from [Delta]₂ term (described in section 
H36.205(g)(1)(i)) may not exceed 2.0 EPNdB, for any combination of the 
following:
    (i) The helicopter not passing vertically above the measuring 
station.
    (ii) Any difference between the reference flight track and the 
actual test flight track; and
    (iii) Detailed correction requirements prescribed in section 
H36.205 of this appendix.
    (3) Helicopter 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 must be corrected under an FAA-approved method.
* * * * *

? 15. In Appendix H to part 36, 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 determined in accordance with Society of 
Automotive Engineering (SAE) ARP 866A. The atmospheric attenuation 
equations are provided in both the International and English system of 
units in section A36.7 of this part.
    (c) * * *
    (1) * * *
    (iii) The temperature and relative humidity measured at 33 feet (10 
meters) above the ground must be used to adjust for propagation path 
absorption.
* * * * *

? 16. In appendix H to part 36, section H36.201 is amended by removing 
the term ``appendix B'' and adding the term ``appendix A'' in paragraph 
(a) introductory text and by removing the term ``instantaneous'' in 
paragraph (a)(1).

? 17. In Appendix H to part 36, section H36.205 is amended by removing 
paragraph (a)(3); by revising paragraphs (a)(1), (a)(2), (b)(2), 
(b)(3), (c)(1), (d)(2), (d)(3), (e), (f), and (g)(1)(i) through (iv) 
and by revising Figures H1, H2, and H3 to read as follows:
* * * * *

Section H36.205 Detailed Data Correction Procedures

    (a) * * *
    (1) If there is any difference between measured test and reference 
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 measured test conditions 
that are different from the reference test conditions; or

[[Page 31237]]

    (ii) Measured flight path that is different from the reference 
flight path.
    (2) The following correction procedures may produce one or more 
possible correction values which must be added algebraically to the 
calculated EPNL to bring it to reference conditions:
    (i) The flight profiles must be determined for both reference and 
test conditions. The procedures require noise and flight path recording 
with a synchronized time signal from which the test profile can be 
delineated, including the aircraft position for which PNLTM is observed 
at the noise measuring station. For takeoff, the flight profile 
corrected to reference conditions may be derived from FAA approved 
manufacturer's data.
    (ii) The sound propagation paths to the microphone from the 
aircraft position corresponding to PNLTM must be determined for both 
the test and reference profiles. The SPL values in the spectrum of 
PNLTM must then be corrected for the effects of--
    (A) Change in atmospheric sound absorption;
    (B) Atmospheric sound absorption on the linear difference between 
the two sound path lengths; and
    (C) Inverse square law on the difference in sound propagation path 
length. The corrected values of SPL must then be converted to a 
reference condition PNLTM value from which PNLTM must be subtracted. 
The resulting difference represents the correction which must be added 
algebraically to the EPNL calculated from the measured data.
    (iii) As observed at the noise measuring station, the measured 
PNLTM distance is different from the reference PNLTM distance and 
therefore the ratio must be calculated and used to determine a noise 
duration correction factor. Effective perceived noise level, EPNL, is 
determined by the algebraic sum of the maximum tone corrected perceived 
noise level (PNLTM) and the duration correction factor.
    (iv) For aircraft flyover, alternative source noise corrections 
require FAA approval and must be determined and adjusted to account for 
noise level changes caused by the differences between measured 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_y ±5 
knots or the lowest approved speed for the climb after takeoff, 
whichever speed is greater.
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[[Page 31238]]
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[TIFF OMITTED]
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[[Page 31239]]

    (3) Figure H1 illustrates the significant geometrical relationships 
influencing sound propagation. Position L represents the helicopter 
location on the measured takeoff path from which PNLTM is observed at 
station A, and L_r is the corresponding position on the 
reference sound propagation path. Propagation paths AL and 
AL_r both form the same angle [thetas]
(theta) relative to 
their respective flight paths.
    (c) Level flyover profiles. (1) The noise type certification level 
flyover profile is shown in Figure H2. Airspeed must be stabilized 
within ±5 knots of the reference airspeed determined using 
the procedures in section H36.3(d). The number of level flights made 
with a headwind component must be equal to the number of level flights 
made with a tailwind component.

[[Page 31240]]
[GRAPHIC]
[TIFF OMITTED]
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[[Page 31241]]

* * * * *
    (d) * * *
    (2) The helicopter approaches position H along a 6[deg]
(< ±0.5[deg]) average approach slope throughout the 10dB-down time 
interval. Deviation from the 6[deg] average approach slope must be 
approved by the FAA before testing.

[[Page 31242]]
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[TIFF OMITTED]
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[[Page 31243]]

    (3) Figure H3 illustrates portions of the measured and reference 
approach flight paths including the significant geometrical 
relationships influencing sound propagation. The measured approach path 
is represented by segment EK with an approach allowable angle [thetas]. 
Reference positions, E_r and K_r, define an 
idealized reference approach angle of 6[deg]. Position N represents the 
helicopter location on the measured approach flight path for which 
PNLTM is observed at measuring station A, and N_r is the 
corresponding position on the reference approach flight path. The 
measured and reference noise propagation paths are AN and 
AN_r, respectively, both of which form the same angle, 
[thetas]_APP, corresponding to PNLTM relative to their 
approach flight paths.

[[Page 31244]]
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[TIFF OMITTED]
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[[Page 31245]]

    (e) Correction of noise at source during level flyover. (1) For 
level overflight, if any combination of the following three factors, 
airspeed deviations from reference, rotor speed deviations from 
reference, and temperature deviations from reference, results in a 
noise correlating parameter whose value deviates from the reference 
value of this parameter, then source noise adjustments must be 
determined from the manufacturer's data that is approved by the FAA.
    (2) Off-reference tip Mach number adjustments must be based upon a 
sensitivity curve of PNLTM versus advancing blade tip Mach number, 
deduced from overflights performed at different airspeeds surrounding 
the reference airspeed. If the test aircraft is unable to attain the 
reference value, then an extrapolation of the sensitivity curve is 
permitted if data cover at least a range of 0.03 Mach units. The 
advancing blade tip Mach number must be computed using true airspeed, 
onboard outside air temperature, and rotor speed. A separate PNLTM 
versus advancing blade tip Mach number function must be derived for 
each of the three certification microphone locations, i.e., centerline, 
sideline left, and sideline right. Sideline left and right are defined 
relative to the direction of flight for each run. PNLTM adjustments are 
to be applied to each microphone datum using the appropriate PNLTM 
function.
    (f) PNLT corrections. If the measured ambient atmospheric 
conditions of temperature and relative humidity differ from those 
prescribed as reference conditions under this appendix (77 degrees F 
and 70 percent, respectively), corrections to the EPNL values must be 
calculated from the measured data under paragraph (a) of this section 
as follows:
    (1) Takeoff flight path. For the takeoff flight path shown in 
Figure H1, the spectrum of PNLTM observed at station A for the aircraft 
at position L is decomposed into its individual SPL(i) values.
    (i) Step 1. A set of corrected values are then computed as follows:

SPL(i)_r = SPL(i) + C[_[alpha](i) - 
_[alpha](i)_o]AL + 
C_[alpha](i)_o (AL - AL_r) + 20 log (AL/
AL_r)

where SPL(i) and SPL(i)_r are the measured and corrected 
sound pressure levels, respectively, in the i-th one-third octave band. 
The first correction term adjusts for the effect of change in 
atmospheric sound absorption where [alpha](i) and 
[alpha](i)_o are the sound attenuation coefficients for the 
test and reference atmospheric conditions, respectively, for the i-th 
one-third octave band, and AL is the measured takeoff sound propagation 
path. The conversion factor constant, C, is 0.001 for English System of 
Units and is 0.01 for International System of Units. The second 
correction term adjusts for the effects of atmospheric attenuation due 
to the difference in the sound propagation path length where 
AL_r is the Reference takeoff sound propagation path. The 
third correction term, known as the ``inverse square'' law, adjusts for 
the effect of the difference in the sound propagation path lengths.
    (ii) Step 2. The corrected values of the SPL(i)_r are 
then converted to reference condition PNLT and a correction term 
calculated as follows:

[Delta]₁ = PNLT - PNLTM

which represents the correction to be added algebraically to the EPNL 
calculated from the measured data.
    (2) Level flyover flight path. (i) The procedure described in 
paragraph (f)(1) of this section for takeoff paths is also used for the 
level flyover paths, with the values of SPL(i)_r relating to 
the flyover sound propagation paths shown in Figure H2 as follows:

SPL(i)_r = SPL(i) + C[_[alpha](i) - 
_[alpha](i)_o]AM + 
C_[alpha](i)_o (AM - AM_r) + 20 log (AM/
AM_r)

where the lines AM and AM_r are the measured and reference 
level flyover sound propagation paths, respectively.
    (ii) The remainder of the procedure is the same for the flyover 
condition as that prescribed in the paragraph (f)(1)(ii) of this 
section regarding takeoff flight path.
    (3) Approach flight path. (i) The procedure described in paragraph 
(f)(1) of this section for takeoff paths is also used for the approach 
paths, with the values of SPL(i)_r relating to the approach 
sound propagation paths shown in Figure H3 as follows:

SPL(i)_r = SPL(i) + C[_[alpha](i) - 
_[alpha](i)_o]AN + 
C_[alpha](i)_o (AN - AN_r) + 20 log (AN/
AN_r)

where the lines AN and AN_r are the measured and reference 
approach sound propagation paths, respectively.
    (ii) The remainder of the procedure is the same for the approach 
condition as that prescribed in the paragraph (f)(1)(ii) of this 
section regarding takeoff flight path.
    (4) Sideline microphones. (i) The procedure prescribed in paragraph 
(f)(1) of this section for takeoff paths is also used for the 
propagation to the sideline locations, with the values of 
SPL(i)_r relating as follows to the measured sideline sound 
propagation path shown in Figure H3 as follows:

SPL(i)_r = SPL(i) + C[_[alpha](i) - 
_[alpha](i)_o]SX + 
C_[alpha](i)_o (SX - SX_r) + 20 log (SX/
SX_r)

where S is the sideline measuring station and, based upon the flight 
condition, the helicopter positions, X and X_r, correspond to:

    X = L, and X_r = L_r for takeoff
    X = M, and X_r = M_r for flyover
    X = N, and X_r = N_r for approach

    (ii) The remainder of the procedure is the same for the sideline 
paths as that prescribed in the paragraph (f)(1)(ii) of this section 
regarding takeoff flight paths.
    (g) * * *
    (1) * * *
    (i) Takeoff flight path. For the takeoff path shown in Figure H1, 
the correction term is calculated using the formula--

[Delta]₂ = -7.5 log (AL/AL_r) + 10 log (V/
V_r)

which represents the correction that must be added algebraically to the 
EPNL calculated from the measured data. The lengths AL and 
AL_r are the measured and reference takeoff distances from 
the noise measuring station A to the measured and the reference takeoff 
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 takeoff path is at greater 
altitude than the reference takeoff path.
    (ii) Level flyover flight paths. For the level flyover flight path, 
the correction term is calculated using the formula--

[Delta]₂ = -7.5 log (AM/AM_r) + 10 log (V/
V_r)

where AM is the measured flyover distance from the noise measuring 
station A to the measured flyover path, and AM_r is the 
reference distance from station A to the reference flyover path.
    (iii) Approach flight path. For the approach path shown in Figure 
H3, the correction term is calculated using the formula--

[Delta]₂ = -7.5 log (AN/AN_r) + 10 log (V/
V_r)

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

[Delta]₂ = -7.5 log (SX/SX_r) + 10 log (V/
V_r)

where S is the sideline measuring station and based upon the flight 
condition, the helicopter positions, X and X_r, correspond to:

X = L, and X_r = L_r for takeoff
X = M, and X_r = M_r for flyover
X = N, and X_r = N_r for approach
* * * * *

[[Page 31246]]

? 18. In Appendix H to part 36, 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 (80,000 kg) or more, reduced by 3.01 
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 (80,000 kg) or more, reduced by 3.01 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 (80,000 kg) or more, reduced by 3.01 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 to part 36 and section J36.1 
introductory text by removing the term ``6,000'' and adding ``7,000'' 
in its place.

? 20. In Appendix J to part 36, section J36.3 is amended by revising 
paragraph (c) introductory text and paragraph (c)(1) to read as 
follows:

Appendix J to Part 36--Alternative Noise Certification Procedure for 
Helicopters Under Subpart H Having a Maximum Certificated Takeoff 
Weight of Not More Than 7,000 Pounds

* * * * *

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_H; 0.9V_NE; 
0.45V_H + 65 kts (120 km/h); or 0.45V_NE + 65 kts 
(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 maximum normal operating RPM throughout the 10 dB-
down time interval.
    (1) For noise certification purposes, V_H is defined as 
the airspeed in level flight obtained using the minimum specification 
engine power corresponding to maximum continuous power available for 
sea level pressure of 2,116 psf (1,013.25 hPa) at 77[deg]F (25[deg]C) 
ambient conditions at the relevant maximum certificated weight. The 
value of V_H and V_NE used for noise certification 
must be included in the Flight Manual.
* * * * *

? 21. In Appendix J to part 36, 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) above the ground. 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 6560 feet (2,000 meters) of a 
fixed meteorological station (such as those found at airports or other 
facilities) the weather measurements reported for temperature, relative 
humidity and wind velocity may be used, if approved by the FAA.
* * * * *

? 22. In Appendix J in part 36, section J36.105 is amended by revising 
paragraph (b) introductory text to read as follows:
* * * * *

Section J36.105 Flyover Test Conditions

* * * * *
    (b) A test series must consist of at least six flights. The number 
of level flights made with a headwind component must be equal to the 
number of level flights made with a tailwind component over the noise 
measurement station:
* * * * *

? 23. In Appendix J to part 36, section J36.109 is amended in paragraph 
(d)(1)(ii) by removing the words ``section H36.109(c)(3) of appendix 
H'' and adding the words ``section A36.3.6 of appendix A'' in its 
place; in paragraph (e)(1) by removing the words ``section H36.109(e) 
of appendix H'' and adding the words ``section A36.3.6 of appendix A'' 
in its place; and by revising paragraph (c)(4) to read as follows:
* * * * *

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

* * * * *
    (c) * * *
    (4) The calibration and checking of measurement systems must use 
the procedures described in Section A36.3.9.
* * * * *

? 24. In Appendix J to part 36, 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 that are 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_AE (limit) = 82 + 3.0 [log₁₀ (MTOW/1737)/
log₁₀(2)]
dB, where MTOW is the maximum takeoff weight, in 
pounds, for which certification under this appendix is requested.
* * * * *

    Issued in Washington, DC, on May 24, 2004.
Marion C. Blakey,
Administrator.
[FR Doc. 04-12069 Filed 6-1-04; 8:45 am]
BILLING CODE 4910-13-P
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