[Federal Register Volume 70, Number 59 (Tuesday, March 29, 2005)]
[Rules and Regulations]
[Pages 16084-16093]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-6074]



[[Page 16083]]

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Part V





Department of Transportation





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Federal Aviation Administration



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14 CFR Part 93



Noise Limitations for Aircraft Operations in the Vicinity of Grand 
Canyon National Park; Rule

  Federal Register / Vol. 70, No. 59 / Tuesday, March 29, 2005 / Rules 
and Regulations  

[[Page 16084]]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 93

[Docket No. FAA-2003-14715; Amendment No. 93-83]
RIN 2120-AG34


Noise Limitations for Aircraft Operations in the Vicinity of 
Grand Canyon National Park

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: This action classifies aircraft used in commercial sightseeing 
flight operations over Grand Canyon National Park (GCNP) by the noise 
they produce. This amendment of 14 CFR part 93 is necessary to 
establish reasonably achievable requirements for aircraft operating in 
the GCNP to be considered as employing quiet aircraft technology. The 
FAA now refers to the designation as ``GCNP quiet aircraft technology'' 
rather than ``quiet technology'' to clarify that the scope of this rule 
is limited to aircraft operating in the GCNP. The FAA and NPS will use 
the GCNP quiet aircraft technology designation to consider establishing 
routes and corridors and in future actions to achieve substantial 
restoration of natural quiet and visitor experience in the GNCP. This 
rule does not require any action by commercial air tour operators, as 
it simply identifies which aircraft meet or do not meet the GCNP quiet 
aircraft technology designation. Further, this rule does not relieve 
GCNP commercial air tour operators of their operational limitations. 
Section 804(b) of the National Parks Air Tour Management Act directs 
the FAA, in consultation with the NPS and the Advisory Group (now known 
as the National Park Overflights Advisory Group Aviation Rulemaking 
Committee or NPOAG ARC) to consider establishing the GCNP quiet 
aircraft technology aircraft routes and corridors consistent with 
certain requirements.

EFFECTIVE DATE: March 29, 2005.

FOR FURTHER INFORMATION CONTACT: Thomas L. Connor; (AEE-100); Office of 
Environment and Energy; Federal Aviation Administration, 800 
Independence Ave., SW., Washington, DC 20591, (202) 267-8933.

SUPPLEMENTARY INFORMATION:

Availability of Rulemaking Documents

    You can get an electronic copy using the Internet by:
    (1) Searching the Department of Transportation's electronic Docket 
Management System (DMS) Web page (http://dms.dot.gov/search);
    (2) Visiting the Office of Rulemaking Web page at http://www.faa.gov/avr/arm/index.cfm; or
    (3) Accessing 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 
Ave., SW., Washington, DC 20591, or by calling (202) 267-9680. Make 
sure to identify the amendment number or docket number of this 
rulemaking.
    Anyone is able to search the electronic form of all comments 
received into any of our dockets by the name of the individual 
submitting the comment (or signing the comment, if submitted on behalf 
of an association, business, labor union, etc.). You may review DOT's 
complete Privacy Act statement in the Federal Register published on 
April 11, 2000 (Volume 65, Number 70; Pages 19477-78) or you may visit 
http://dms.dot.gov.

Small Business Regulatory Enforcement Fairness Act

    The Small Business Regulatory Enforcement Fairness Act (SBREFA) of 
1996 requires the FAA to comply with small entity requests for 
information or advice about compliance with statutes and regulations 
within its jurisdiction. If you are a small entity and have a question 
regarding this document, you may contact your local FAA official, or 
the person listed under FOR FURTHER INFORMATION CONTACT. You can find 
out more about SBREFA on the Internet at http://www.faa.gov/avr/arm/sbrefa.cfm.

Background

Regulatory History

    On December 31, 1996, the FAA published a notice of proposed 
rulemaking (NPRM) on Noise Limitations for Aircraft Operations in the 
Vicinity of Grand Canyon National Park (61 FR 69334; Notice 96-15), and 
a Notice of Availability of Proposed Commercial Air Tour Routes in the 
Federal Register (61 FR 69356). The FAA proposed to establish noise 
limitations for certain aircraft operating in the vicinity of GCNP. The 
proposed aircraft noise limitations rule generally would have 
categorized air tour aircraft according to each aircraft's noise 
efficiency and mandated a conversion date to aircraft meeting the GCNP 
quiet aircraft technology designation. Additionally, the FAA proposed 
an incentive flight corridor through Grand Canyon for quiet technology/
noise efficient aircraft. The NPRM sought to reduce the impact of air 
tour aircraft noise on GCNP and to make progress in achieving 
substantial restoration of natural quiet in GCNP. The FAA received many 
comments in opposition to this NPRM, primarily because of the impact of 
the mandatory conversion date. After the comment period closed on the 
1996 NPRM, the FAA and NPS began reconsidering GCNP quiet aircraft 
technology requirements and reaching consensus upon other steps that 
should be initiated to achieve the statutorily mandated goal of 
substantial restoration of natural quiet and to improve visitor 
experience in the GCNP. The FAA and NPS agreed to proceed with 
rulemakings to limit the number of commercial air tours in the GCNP and 
to modify the airspace and route system in the area. The agencies 
realized that the achievement of substantial restoration of natural 
quiet requires a multi-phased regulatory plan to control noise. 
Implementation of GCNP quiet aircraft technology alone would not 
suffice.
    The agencies concentrated their efforts upon resolving issues 
presented in comments on the 1996 NPRM and finalizing the GCNP quiet 
aircraft technology rulemaking, once the FAA issued the airspace and 
operations limitation final rules in April 2000.
    On April 5, 2000, the Wendell H. Ford Aviation Investment and 
Reform Act for the 21st Century was signed into law as Public Law 106-
181. Among other provisions the law enacted the National Parks Air Tour 
Management Act of 2000 (the Air Tour Act). Section 804(a) of the Air 
Tour Act directed the FAA Administrator to designate reasonably 
achievable quiet technology requirements for fixed-wing airplanes and 
helicopters for purposes of commercial air tour operations over the 
GCNP. If the FAA determined that it would not be able to make the 
designation within twelve months of the enactment of the Air Tour Act, 
then the FAA was required to transmit a report to Congress stating the 
reasons the FAA would not be able to make such a designation within 
that period and the expected date of such designation.
    Section 804(b) of the Air Tour Act also directed the FAA 
Administrator, in consultation with the NPS Director and the NPOAG ARC, 
to establish GCNP quiet aircraft technology routes or corridors for 
commercial air tour operations at GCNP, provided that such routes or 
corridors will not negatively impact tribal lands, safety, or the 
substantial restoration of natural quiet.

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Recommendations and requirements for use of GCNP quiet aircraft 
technology in air tour management plans for national parks other than 
the GCNP pursuant to other provisions of the Air Tour Act will be 
subject to separate rulemaking and are not addressed by this final rule 
for GCNP. For example, Section 805 of the Air Tour Act requires the 
NPOAG ARC to provide advice, information, and recommendations to the 
FAA and NPS on commonly accepted quiet aircraft technology for use in 
commercial air tour operations over a national park or tribal lands, 
which will receive preferential treatment in air tour management plans. 
While the NPOAG ARC may consider this final rule in making 
recommendations on commonly accepted quiet aircraft technology for use 
at other national parks, pursuant to Section 805 of the Air Tour Act, 
this final rule is limited to fulfilling the requirements under Section 
804 of the Air Tour Act for the GCNP.
    In October 2001, the FAA submitted a report to Congress on Quiet 
Aircraft Technology for the Grand Canyon, as required under Section 804 
of the Air Tour Act. The report indicated that, while substantive 
progress had been made on the GCNP quiet aircraft technology 
rulemaking, the FAA would not be able to make a designation within the 
12 months of enactment of the Air Tour Act because of the need to 
resolve some key technical issues. These issues included the then-
ongoing GCNP Noise Model Validation project, a study regarding the 
correlation between aircraft certification noise levels and aircraft 
audibility, and how changes to the GCNP SFRA affected substantial 
restoration of natural quiet. The report also stated that the FAA 
planned to issue a supplemental notice of proposed rulemaking (SNPRM) 
in early 2002. The FAA and the NPS required more time than expected to 
resolve the technical issues, which delayed the publication of the 
SNPRM for another year.
    On March 24, 2003, the FAA published the SNPRM Notice No. 03-05 
entitled ``Noise Limitations for Aircraft Operations in the Vicinity of 
Grand Canyon National Park'' (68 FR 14276). The FAA solicited comments 
on the proposal, which are discussed in the following section. This 
final rule is based on the SNPRM Notice No. 03-05.

Discussion of Comments

    Seventeen commenters responded to the supplemental Notice No. 03-05 
regarding the proposed designation for quiet technology aircraft 
operating in the GCNP (hereinafter GCNP quiet aircraft technology 
designation). While one commenter believes that the FAA should scrap 
the whole project, the other commenters offered a range of opinions and 
recommendations on the proposal. These comments and the FAA responses 
are discussed below. The docket also contains 111 comments that had 
been submitted to the original 1996 NPRM Notice No. 96-15. The FAA 
responded to these comments on the 1996 NPRM in the 2003 SNPRM.

Noise Efficiency

    Lighter than Air Solar International, LLC and an anonymous 
commenter recommended that the GCNP quiet aircraft technology 
designation should be based upon an absolute noise limit rather than a 
noise value as a function of the number of passenger seats. Operators 
should not be given an ``efficiency bonus'' for aircraft that are 
capable of carrying more passengers.

FAA Response

    The FAA finds that the noise efficiency concept (larger aircraft 
with more passenger seats are allowed to generate more noise per 
aircraft, but less noise per passenger) exhibits all of the desired 
attributes for the designation of reasonably achievable requirements 
for aircraft to be considered as employing GCNP quiet aircraft 
technology for purposes of Section 804(a) of the Air Tour Act. The 
concept is technically sound, as it takes into account aircraft design, 
flight configuration, acoustic characteristics, productivity, and 
economic reasonableness. The FAA believes that this GCNP quiet aircraft 
technology standard, used in conjunction with other future actions, 
will contribute towards substantial restoration of natural quiet at 
GCNP.

Helicopter Noise Annoyance

    The Sierra Club contends that helicopter noise is more annoying 
than noise from fixed-wing aircraft and recommends that such noise 
effects be considered.

FAA Response

    Given that the objective is not to have audible aircraft noise in 
large areas of the GCNP, the FAA finds the GCNP quiet aircraft 
technology designation appropriately reflects the audibility of 
commercial sightseeing operations using the different aircraft types. 
For example, low frequency pressure pulses created by the spinning 
motion of the rotor blades characterize helicopter noise. Audibility is 
the ability of the human observer to detect an acoustic signal in the 
presence of noise. For the GCNP setting, audibility is quantified by 
the summation of the signal-to-noise ratios over the entire bandwidth 
representing the range of human hearing. Thus, the method used to 
measure advancement towards the goal of substantial restoration of 
natural quiet is already very sensitive to the distinctive acoustic 
characteristics of different aircraft types.

Airships

    Lighter than Air Solar International, LLC recommends that the 
definition for ``quiet technology aircraft'' be expanded to include 
airships. An airship is defined in 14 CFR part 1 is ``an engine-driven 
lighter than air aircraft that can be steered.'' This commenter asks 
the FAA to afford airship operators the same opportunities as heavier-
than-air operators by enacting a more flexible and inclusive definition 
of GCNP quiet aircraft technology.

FAA Response

    The FAA sees no need to expand the definition, since it now simply 
refers to ``aircraft subject to Sec.  93.301'', which includes 
airships. Introducing airships for commercial air tour operations would 
raise issues related to both noise characterization and operational 
compatibility.
    While there are presently no airship tour operations being 
conducted over the Grand Canyon, the FAA does not intend to prohibit 
this category of aircraft from due consideration, provided such 
operations could be accommodated safely within the SFRA. As a matter of 
policy, the FAA encourages industry to pursue research and development 
of newer, innovative technology applications where possible. With 
regard to this proposal, the FAA acknowledges that the application of 
certain airship technologies might conceivably contribute toward the 
goal of restoring natural quiet in the Grand Canyon. Although special 
operational protocols would have to be developed to integrate airship 
operations in the GCNP SFRA, it is feasible that such operations could 
be safely accommodated in much the same manner as in other high-density 
environments.
    The FAA does not have noise certification requirements for 
airships. Thus, FAA-approved noise data for these aircraft types do not 
exist. The FAA has provided for this contingency both in the rule and 
in an Advisory Circular (AC) that will accompany the promulgation of 
this rule. The draft FAA AC-GCNP-1, ``Noise Levels for Aircraft used 
for Commercial Operations in Grand Canyon National Park Special Flight 
Rules Areas,'' states that where noise certification under 14 CFR part 
36 was not required due to applicability, the noise level could be 
provided to the FAA by the operator or

[[Page 16086]]

owner and considered to be an estimated noise certification level, as 
long as the FAA can sufficiently substantiate that the noise level is 
representative of the subject aircraft.
    The scope of this rule does not include issues associated with any 
potential change to commercial sightseeing flight protocols in the SFRA 
with the introduction of airships. The FAA would thoroughly investigate 
those operational issues if and when it receives an application for 
operational specifications for an airship.

Relationship Between Audibility and Certificated Noise Levels

    The NPS recommends that the FAA perform an analysis to ensure that 
aircraft that the FAA has classified as GCNP quiet aircraft technology 
based upon certificated noise levels are less audible than aircraft not 
so classified. The NPS included with its comment a technical 
memorandum, ``Relationship Between Audibility of Tour Aircraft and 
Certification Data,'' prepared by the aviation environmental consulting 
firm, Harris Miller Miller & Hanson, Inc. (HMM&H).

FAA Response

    To address the NPS concern, the FAA performed a comprehensive 
assessment of the subject relationship utilizing the capabilities of 
the FAA's Integrated Noise Model (INM) Version 6.2. The FAA finds that 
the designation of reasonably achievable GCNP quiet aircraft technology 
correlates sufficiently with audibility to assist the FAA and NPS in 
fulfilling the National Park Overflights Act (Pub. L. 100-91).
    INM 6.2 is the latest advancement in the FAA standard tool for the 
calculation of aircraft noise. The shortcomings of the previous INM 
version in predicting audibility became the impetus behind its 
development. These shortcomings were discovered in the joint FAA and 
NPS GCNP noise model validation study (``Aircraft Noise Validation 
Study,'' HMM&H Report No. 295860.29, January 2003). The validation 
study was described in the SNPRM Notice No. 03-05, and an electronic 
copy is available through the NPS Web page at http://www.nps.gov/grca/overflights/documents/anmvs/index.htm. The model improvements include: 
(1) More aircraft types that are used in commercial sightseeing 
operations; (2) spectral-based method for signal detection prediction; 
and (3) a high-resolution terrain database to better address the effect 
of terrain features on sound propagation. All of these improvements are 
intended to improve the accuracy of the audibility calculations.
    Audibility is defined as the ability for an attentive listener to 
hear aircraft noise. Detectability is based on signal detection theory, 
and depends on both the actual aircraft sound level (``signal'') and 
the ambient sound level (background or ``noise''). As such, audibility 
is based on many factors, including the listening environment one is 
in. Conversely, detectability is a theoretical formulation based on a 
significant body of research. For the purposes of INM modeling the 
terms ``audibility'' and ``detectability'' are used interchangeably. 
The detectability level (d') calculated in INM 6.2 is based on the 
signal-to-noise ratio within one-third octave-band spectra for both the 
signal and noise, using a 10log(d') value of 7 dB. There are three 
parts to the calculation of audibility in INM 6.2: (1) Calculate the 
detectability level for each one-third octave band of the signal for a 
single contributing flight path segment; (2) Calculate the 
detectability level for the overall signal for a single contributing 
flight path segment; and (3) Calculate absolute or percentage of time a 
signal is audible for a flight path.
    In addition to using the improved INM 6.2, this assessment used the 
aircraft operations from the aforementioned GCNP aircraft noise model 
validation study. Time audible predictions were generated for all 
aircraft types measured during the validation study, using operations 
and one-third octave band spectral data consistent with the validation 
study. The aircraft taken from the original validation study include 
the Aerospatiale AS350, Bell B206B and Bell B206L helicopters, as well 
as the Cessna C182, Cessna C207, and Vistaliner (DHC-6QP) propeller-
driven aircraft. For the purposes of this assessment, operational and 
acoustic data were added for some GCNP quiet aircraft technology 
designation helicopters not operating at the time of the model 
validation study. These include the MD600, MD900 and Eurocopter EC-130. 
Predictions were summarized for all validation study measurement sites 
and relationships between predicted time audible and noise 
certification levels derived.
    Just as was done by the consultant (HMM&H) for the preparation of 
the NPS comment to the SNPRM Notice No. 03-05, the FAA evaluated the 
ranking of aircraft audibility duration per available passenger seat 
against the ranking of the noise certification level in A-weighted 
decibels per available passenger seat. The FAA performed this 
evaluation at the 39 measurement sites in the GCNP noise model 
validation study (labeled as `1A', `2A', * * * to `9F' in the study). 
Similar to what the NPS's consultant had done, the FAA generated 
figures that compare the aircraft's margin of compliance with the GCNP 
quiet aircraft technology designation to the length of time the 
aircraft is audible, adjusting for the number of available passenger 
seats.
    The margin of compliance is the difference in decibels between the 
aircraft's certificated noise level and the GCNP quiet aircraft 
technology designation noise limit, using the appropriate equation in 
the proposed rule. A negative margin of compliance means that the 
certificated noise level is below the noise limit designating that 
aircraft as GCNP quiet aircraft technology. In this evaluation, the 
Vistaliner, EC-130, MD600 and MD900 all have negative margins of 
compliance (GCNP quiet aircraft technology designation); while the 
C182, C207, AS350, B206B, and B206L all have positive margins of 
compliance (not GCNP quiet aircraft technology designation).
    Figure 1 compares the margins of compliance to the average length 
of time audible for the sample of aircraft at validation measurement 
Site 7. While Site 7 has been singled out for display, the findings are 
comparable to the other validation measurement sites. Site 7 included 6 
microphone locations along Tanner Trail in the GCNP. The average 
audibility duration value at the 6 microphone locations is plotted for 
each of the aircraft types. The helicopters and fixed wing aircraft 
that meet the GCNP quiet aircraft technology designation are less 
audible than those aircraft that do not meet the designation.

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[GRAPHIC] [TIFF OMITTED] TR29MR05.004

    The FAA analysis found that the GCNP quiet aircraft technology 
designation aircraft are less audible at all of the other model 
validation measurements sites. Table 1 summarizes the findings. The 
column on the far left of Table 1 contains the identity of the site 
groups used in the model validation study. That study grouped the 39 
microphone locations according to common geographic characteristics 
that could lead to common levels of aircraft noise exposure. The 
remaining columns group the average time audible values by aircraft 
category (fixed wing or helicopter) and by compliance with the GCNP 
quiet aircraft technology designation. A range of average audible 
duration values is given when there is more than one aircraft model in 
that specific category. For example, this analysis includes 2 fixed 
wing aircraft that would not meet the GCNP quiet aircraft technology 
designation (C182 and C207), 3 helicopters that would not meet the 
designation (AS350, B206B, and B206L), 3 GCNP quiet aircraft technology 
designation helicopters (EC130, MD600, and MD900), and one GCNP quiet 
aircraft technology designation fixed wing aircraft (Vistaliner or 
DHC6QP).

                Table 1.--Comparison of Average Time Audible Per Seat (Minutes, Minimum-Maximum)
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                                                            Fixed wing                      Helicopters
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                                                    GCNP quiet                      GCNP quiet
                                                     aircraft                        aircraft
                   Site group                       technology         Other        technology         Other
                                                    designation                     designation
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1All............................................                        No aircraft audible
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2All............................................                        No aircraft audible
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3North..........................................             0.0         0.5-0.8         0.0-0.0         0.0-0.1
3South..........................................             0.0         0.3-0.5         0.0-0.1         0.0-0.2
4North..........................................             0.1         0.7-1.4         0.5-0.6         0.6-1.0
4South..........................................             0.0         0.6-1.1         0.3-0.4         0.4-1.1
5Rim............................................             0.3         1.9-3.6         1.1-1.4         1.4-2.6
5Interior.......................................             0.1         1.0-2.0         0.2-0.5         0.2-1.4
6All............................................             0.2         1.2-2.2         0.9-1.0         1.2-1.6
7All............................................             0.2         1.2-2.1         0.9-1.0         1.2-1.8
8Mtn............................................             0.1         1.3-2.3         0.8-0.9         0.9-1.7
8Ridge..........................................             0.2         0.9-1.6         0.6-0.6         0.8-1.3
-------------------------------------------------

[[Page 16088]]

 
9Far............................................                        No aircraft audible
-------------------------------------------------
9Near...........................................             0.3         1.8-3.2         1.0-1.2         1.4-2.2
----------------------------------------------------------------------------------------------------------------

    The NPS's consultant also expressed concern that the A-weighting 
used for the certification and the GCNP quiet aircraft technology 
designation may not correlate with time audible. The FAA examination 
indicates there is some validity to this concern. In particular, the 
Cessna 182 aircraft (C182), which has a relatively low certification 
level but a high audible duration, seems to be an exception to the 
relationships derived between time audible and certification level. 
This is especially the case when considering the time audible on a per 
seat basis. A possible reason for this is that the C182 has a lower 
Blade Passage Frequency (BPF) than the other fixed wing aircraft. The 
BPF of the C182 is 80 Hz, the BPF of the C207 is 125 Hz, and the BPF of 
the DHC-6QP is 100 Hz. These low frequency tones have little influence 
on the A-weighted levels, but propagate through the atmosphere without 
significant reduction from atmospheric attenuation.
    Since the helicopters in this evaluation have dominant main rotor 
BPF tones even lower in frequency than does the C182, one would expect 
to find a lack of correlation between the A-weighted noise levels for 
these helicopters and their values of audibility duration. However this 
does not seem the case as shown in the linear relationships derived by 
the NPS's consultant. The reason is likely the auditory masking of 
these lower frequency tones by the threshold of human hearing, which 
slopes up significantly in the lower frequencies. Thus, even though the 
helicopters generate a substantial amount of energy at the very low 
frequencies, a large amount of that energy is below the threshold of 
hearing.
    The FAA concludes that while the correlation between ranking of 
certification noise levels and ranking of audibility duration is 
inexact, aircraft that meet the GCNP quiet aircraft technology 
designation are consistently less audible than those that do not. 
Therefore it is reasonable to expect that replacing non-compliant 
aircraft with larger, GCNP quiet aircraft technology designation 
aircraft (e.g., replace a Cessna 207 with a Vistaliner or replace a 
B206L with an EC-130) should produce marked improvement toward 
substantial restoration of natural quiet.

Addressing Selectable Noise Reduction Technologies

    The Aerospace Industries Association (AIA) raised concerns that 
since the FAA first proposed basing the GCNP quiet aircraft technology 
designation upon noise certification data, manufacturers have 
introduced new selectable (or automated) helicopter noise reduction 
technologies. AIA is concerned that exclusive use of only the reference 
noise conditions will discourage the application of helicopter noise 
reduction innovations gained through these new selectable technologies.

FAA Response

    The FAA envisions that it could accept noise levels derived from 
selectable noise reduction technologies in the event that the noise 
certification regulations are amended to accommodate such a concept. 
The noise certification regulations, 14 CFR part 36, are based on 
standard reference conditions designed to acquire noise levels 
representing the noisiest flight configurations. Technical procedures 
do not currently exist that address selectable noise reduction 
technologies. A technical working group on aircraft noise under the 
International Civil Aviation Organization (ICAO) is addressing 
selectable noise reduction technology. This technical group, which is 
made up of international regulators, aircraft manufactures and the 
airline industry, will explore concepts that may lead to changes in the 
noise certification scheme. The work program for such an activity under 
ICAO usually takes 3-6 years to bring to fruition.

Economic Consequences to Indirect Entities

    AIA and the Helicopter Association International (HAI) expressed a 
concern that the proposed rule applies to a very narrow application of 
commercialized air tour operators in the GCNP, but that it has broader 
implications upon helicopter manufacturing and operating industries. 
AIA and HAI claims that local jurisdictions, both domestic and foreign, 
could attempt to apply the quiet technology designation as criteria for 
use restriction. Such restrictions could result in significant costs to 
aircraft operators not linked in any way to the air tour industry. AIA 
and HAI recommend that the FAA should assess these costs. 
Alternatively, AIA and HAI recommend that the FAA adopt terminology 
that specifically narrows the quiet technology designation to that 
subset of aircraft for which it is intended. Both recommend replacing 
``quiet technology designation'' with ``GCNP aircraft quiet air tour 
designation.'' AIA suggests that without this terminology change the 
potential for economic implications could be ``both substantial and 
adverse to the helicopter manufacturing and operating industries.''

FAA Response

    The FAA appreciates the concerns expressed by AIA and HAI, but 
questions the likelihood that non-airport proprietor State and local 
governments would assert such authority. It is well settled that the 
FAA has exclusive sovereignty over and authority to regulate use of the 
navigable air space. Actions by State and local governments to use 
their police powers to regulate aircraft overflights would be federally 
preempted. Nonetheless, to minimize any possible unintended adverse 
consequences that could result from the proposed ``quiet technology 
designation'' terminology the FAA has changed the phrase ``quiet 
technology designation'' to ``GCNP quiet aircraft technology 
designation'' in all places that it is used in the rule. This 
terminology change will correctly limit the scope of the rule to air 
tour aircraft operating over GCNP, in accordance with the plain 
language of Section 804 of the Air Tour Act, and eliminate any need to 
analyze the costs of possible unintended adverse consequences. This 
more precise terminology will also help to emphasize the scope of this 
final rule

[[Page 16089]]

and its relationship to quiet technology requirements at other national 
parks under other provisions of the Air Tour Act.

Helicopter Quiet Air Tour Designation Correspondence to the Flyover 
Condition

    AIA states that the U.S. helicopter industry is disadvantaged by 
the exclusive use of the flyover certification condition as the flight 
profile for gauging the GCNP quiet aircraft technology. AIA claims that 
U.S. noise research has not concentrated on this flight condition for 
achieving noise reduction and thus makes this approach inappropriate.

FAA Response

    The FAA finds the use of the flyover condition from noise 
certification best matches the primary flight operation by helicopters 
in commercial sightseeing operations in the Grand Canyon. The flyover 
condition is the most basic reference flight profile for helicopters as 
defined in both 14 CFR part 36 Appendix H and Appendix J (equivalent to 
ICAO Annex 16 Chapters 8 and 11 helicopter noise certification 
standards, respectively). Since the establishment of the Appendix J 
(Chapter 11) noise certification procedures for helicopters under 7000 
pounds, numerous helicopters have been certificated at only the flyover 
condition, including most U.S. manufactured small helicopters. 
Therefore, the FAA believes it is appropriate that such an openly 
available and highly reliable noise data source be utilized and 
incorporated into the GCNP quiet aircraft technology designation 
helicopter limits.

Definition of ``Passenger Seat''

    AIA and HAI find that the proposed rule does not define ``number of 
passenger seats.'' These commenters recommend that FAA define the 
number of passenger seats to mean the maximum number of passenger seats 
for which the individual aircraft is certified.

FAA Response

    The FAA agrees to define the number of passenger seats as the 
``number of passenger seats for which an individual aircraft is 
configured.''

Helicopter Weight Scaling

    AIA, HAI, and AgustaWestland state that the proposed helicopter 
noise limit does not appropriately reflect the scaling of noise levels 
with weight when considering helicopter technology that is reasonably 
achievable. These commenters recommend that the slope of 12 log should 
be incorporated rather than the 10 log to account for higher seating 
capacity and growth versions of existing helicopter designs.

FAA Response

    The FAA finds the proposed GCNP quiet aircraft technology 
designation for helicopters to be appropriate. It was derived from the 
generally accepted common scaling with maximum gross weight, such that 
noise level increases 3 decibels for every doubling of aircraft weight 
(equating to 10 log slope). For example, the ICAO and FAA helicopter 
noise certification requirements for the takeoff, flyover, and approach 
noise conditions all use 3 decibels per doubling of weight to define 
the noise limits. The commenters' proposal to change it to 12 log seems 
designed to classify a certain helicopter, which is not currently used 
for commercial sightseeing, as meeting the GCNP quiet aircraft 
technology designation. Although the AgustaWestland EH-101 helicopter 
may have been built with some noise reduction technology, there is no 
evidence to show that it was built with the aim of meeting the rigorous 
standard needed to assist in the substantial restoration of natural 
quiet in GCNP. As such, the FAA rejects the recommendation, as it would 
weaken the effort towards the restoration of natural quiet.

Noise Limits for Fixed Wing Aircraft

    AIA noted that the GCNP quiet aircraft technology limits for fixed 
wing aircraft do not account for changes to the small propeller-driven 
airplane noise certification scheme as found in the latest amendments 
to Appendix F and Appendix G of 14 CFR part 36.

FAA Response

    The FAA agrees with AIA to update the appropriate rule language to 
reflect the technical changes made in 14 CFR part 36 amendment 22 
(October 13, 1999). Amendment 22 replaced the 4-foot height microphone 
with a ground plane installation for small propeller-driven airplane 
noise certification tests. The change in microphone height affects the 
signal received. As such, the rule language of Part 93, Appendix A 
should be revised to account for the part 36 amendment noise level and 
to read as follows (added text is underlined):
    ``D. In the event that a flyover noise level is not available in 
accordance with Appendix F of 14 CFR part 36, the noise limit for 
propeller-driven airplanes with a takeoff noise level obtained in 
accordance with the measurement procedures prescribed in Appendix G is 
74 dB or 77 dB, depending on the 14 CFR part 36 amendment noise level, 
for airplanes having two or fewer passenger seats, increasing at 3 dB 
per doubling of the number of passenger seats for airplanes having 
three or more passenger seats. The noise limit for propeller-driven 
airplanes with three or more passenger seats can be calculated by the 
formula:

LAmax(G) = 74 + 10log( PAX seats/2) dB for certifications 
obtained under 14 CFR part 36 Amendment 21 or earlier;

LAmax(G) = 77 + 10log( PAX seats/2) dB for certifications 
obtained under 14 CFR part 36 Amendment 22 or later.''

Comments on Implementation

    Through this action, the FAA designates a standard for GCNP quiet 
aircraft technology that applies to certain aircraft in commercial air 
tour operations over GCNP. Under the provisions of Section 804 of the 
Air Tour Act, the FAA will address the establishment of routes or 
corridors for commercial air tour operations that employ quiet aircraft 
technology in subsequent rulemaking in consultation with the NPS and 
the NPOAG ARC. Since the ultimate objective is to determine the role of 
the GCNP quiet aircraft technology designation in achieving substantial 
restoration of natural quiet, the FAA requested specific comments to 
six questions. This section summarizes the specific comments made in 
response to each question below. These comments will be considered in 
subsequent rulemaking in consultation with the NPS and the NPOAG ARC, 
as provided in Section 804.
    1. How reasonable is the noise efficiency approach (larger aircraft 
with more passenger seats are allowed to generate proportionally more 
noise) to define quiet technology and how appropriate is the use of 
certificated noise level as the basis?
    The NPS believes that the implementation of noise efficient 
aircraft alone will not achieve substantial restoration of natural 
quiet. Achieving the goal will require some type of use restriction. 
Since audibility is the measure of natural quiet in GCNP, the NPS 
recommends that the sound levels produced by quiet technology aircraft 
be analyzed in terms of audibility, rather than certificated noise 
levels, to ensure that the aircraft is less audible than non-quiet 
technology aircraft.
    Lighter Than Air Solar International, LLC suggests that an absolute 
noise level be used rather than noise efficiency.

[[Page 16090]]

    AIA, HAI, and the United States Air Tour Association (USATA) 
support the proposed noise efficiency approach and the use of 
certificated noise levels. AIA and HAI also recommended some technical 
changes to this aspect of the rule. The FAA addressed these technical 
recommendations in the previous section of this document.
    The Sierra Club acknowledges that the noise efficiency approach 
makes sense, i.e. to allow aircraft that give more passengers tour 
rides to make more noise, as long as larger quieter aircraft lead to 
fewer flights. The Sierra Club also acknowledges that certificated 
noise levels are the most readily available substantiated data but 
questions whether the ranking of certification noise data will give the 
same results in the rank of audibility.
    The Friends of Grand Canyon support the proposed noise efficiency 
approach only if it will substantially reduce the number of flights.
    2. What provisions should be made for changes in technology that 
result in source noise reduction and/or increased noise efficient 
aircraft designs?
    Lighter Than Air Solar International, LLC suggests that the 
definition of quiet technology aircraft be expanded to include airships 
to accommodate for future innovations in both noise reduction 
technology and noise efficient aircraft designs.
    AIA, HAI, and USATA recommend that incentives for research and 
development into source noise reduction technologies be made available 
to both manufacturers and others for developing Supplemental Type 
Certificates (STC). The incentives could take the form of research 
grants or directed appropriations to the National Aeronautics and Space 
Administration (NASA). As modifications and STCs are developed that 
reduce source noise and/or increase noise efficient aircraft designs, 
operators of the modified aircraft would be allowed increased 
operations within the GCNP.
    The Sierra Club comments that some incentive is appropriate for 
retrofitting existing aircraft if it does not compromise the 
restoration of natural quiet.
    3. What economic and operational incentives should be considered in 
order to achieve the transition to quieter aircraft and how should be 
the quiet technology designation be used in the establishment of 
incentives?
    AIA favors direct U.S. government support for research and 
development of flyover source noise reduction technologies to assist 
U.S. manufacturers in developing new helicopters or modifying current 
helicopters.
    HAI recommends tax incentive to operators who purchased quiet 
technology equipment, exemption to all caps and curfews, and route 
expansions for all quiet technology aircraft. Similarly, USATA and 
Lighter Than Air Solar International, LL recommend relief from all caps 
and curfews, incentive routes, low-cost federal loans, over fee rebates 
or investment tax credits or elimination of overflight fees altogether.
    The Sierra Club opposes opening incentive routes through existing 
flight free zones. This commenter supports operational incentives that 
allocate larger numbers of flights to aircraft that have lower noise 
signatures without increasing the overall number of flights, unless the 
flights are substantially quieter.
    The Grand Canyon National Park Service (GCNPS) opposes any increase 
in the total number of operations as an incentive for conversion to 
noise-efficient aircraft. Such an incentive would be counterproductive 
to the efforts to achieve the mandate of substantial restoration of 
natural quiet.
    4. Should incentives include a ``flexible'' cap that would permit 
increasing operations of aircraft based upon the acquisition of 
leading-edge noise efficient technology by operators?
    USATA and Lighter Than Air Solar International, LLC support a 
``flexible'' cap that would include no cap for quiet technology 
designation aircraft. USATA also suggests that the cap should be raised 
for operators who use approved noise abatement flight procedures.
    The Sierra Club objects to the idea of ``flexible'' cap that may 
allow an increase in number of flights with the introduction of quiet 
technology designation aircraft. This commenter does not believe there 
is any reason to treat the GCNP overflights differently from other park 
limits, such as number of rooms, parking places, modes of 
transportation, access to trails, and boating permits, which are all 
capped.
    The GCNPS endorses noise budgets as one form of ``flexible'' cap. 
Under a noise budget, operators would be allocated a quantity of noise 
(``decibel-minutes'') equivalent to the amount and duration of noise 
each operation created during the 1997-98 base year, which they can use 
according to their operational needs.
    One commenter suggested that rather than phasing out louder 
aircraft, the FAA should let the operators phase in the quieter ones.
    5. Should growth be tied to an incentive system for existing 
operators to convert their fleet to quiet technology?
    Grand Canyon Trust (The Trust) and Friends of the Grand Canyon do 
not support the use of incentives, nor do they believe that there 
should be any allowances for air tour operational growth. The Trust 
opposes duplicate routes connecting the same two points (with one 
incentive route and one non-incentive route), as this would spread the 
noise over a wider area.
    Sierra Club supports growth tied to conversion to quiet aircraft as 
long as aircraft noise continues to fall below the 1975 levels.
    HAI and USATA believe that the mechanisms they had suggested in 
response to Question 4 should provide the affected operators with the 
necessary incentives to convert to quieter aircraft.
    Lighter Than Air Solar International, LLC favors incentives for 
operators' investment in quiet technology in the form of expanded 
operational rewards (allocations). The criteria for such rewards should 
also be based on decreased noise levels and not other, non-related 
criteria, such as seniority or company size.
    The NPS and GCNPS both believe that growth incentives at the 
expense of substantial restoration of natural quiet are contrary to the 
mandate. Some limited growth in number of operations might be possible 
under a system of partial redistribution of reverted allocations.
    6. What operational limitations (phase-out, expanded curfews, noise 
budgets, quota system, etc.) should be considered, and how should the 
quiet technology designation be used in the setting of the limitations?
    The Trust and the Sierra Club support phase-out, expanded curfews, 
and an added noise cap approach for operational limitations. The Trust 
recommends that the caps for the number of aircraft should also apply 
to the number of flights. The Trust suggests that the annual number of 
flights decline until they are stabilized at the 1975 levels. This 
could be achieved by a 5% decline in flights per year over the next 15 
or 20 years in the Dragon Corridor. The Trust supports the quiet 
technology designation as the noise standard to be applied to all 
commercial tour aircraft at the Grand Canyon. The Trust wants it 
instituted for the east end of the GCNP by 2007 and the entire GCNP by 
2010. The Trust seeks to abolish the Dragon Corridor and asks that the 
Zuni Corridor become ``quiet aircraft only.'' In addition, the Sierra 
Club suggests a sliding scale

[[Page 16091]]

incentive to reward incremental noise reduction efforts.
    The Friends of the Grand Canyon seek a cap on the number of 
passengers to assure the noise benefit and gains from reduced flights 
materialize. Such visitor caps have existed for 3 decades for ground 
visitors.
    HAI and USATA endorse the elimination of all caps and curfews for 
quiet technology operators. HAI finds that a phase-out is unnecessary, 
as other operational incentives will cause an increase in quiet 
technology aircraft. HAI supports tax relief for the development of 
noise abatement techniques and low noise operational techniques that 
can be incorporated into the aircraft flight manual.
    Lighter Than Air Solar International, LLC (11) support a 
``gradual'' phase-out and continuing periodic FAA noise reviews.
    The NPS and GCNPS have concluded that substantial restoration of 
natural quiet requires supplemental operational limitations, i.e., 
reduced flights, quieter equipment for the total passenger carrying 
capability and accountability for number of flights. The NPS and GCNPS 
support a market-based flight allocation system for the benefit of 
natural quiet.

Economic Summary

    Proposed changes to Federal regulations must undergo several 
economic analyses. First, Executive Order 12866 directs that each 
Federal agency shall propose or adopt a regulation only upon a reasoned 
determination that the benefits of the intended regulation justify its 
costs. Second, the Regulatory Flexibility Act of 1980 requires agencies 
to analyze the economic impact of regulatory changes on small entities. 
Third, the Trade Agreements Act (19 U.S.C. section 2531-2533) prohibits 
agencies from setting standards that create unnecessary obstacles to 
the foreign commerce of the United States. In developing U.S. 
standards, this Trade Act requires agencies to consider international 
standards and, where appropriate, that they be 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, in any one year (adjusted for inflation).
    In conducting these analyses, FAA has determined that this rule: 
(1) Has benefits that justify its costs, is not economically 
significant under Executive Order 12866, and is significant as defined 
in DOT's Regulatory Policies and Procedures; (2) will not have a 
significant economic impact on a substantial number of small entities; 
(3) will not reduce barriers to international trade; and (4) does not 
impose an unfunded mandate on State, local, or tribal governments, or 
on the private sector.
    However, for regulations with an expected minimal impact the above-
specified analyses are not required. The Department of Transportation 
Order DOT 2100.5 prescribes policies and procedures for simplification, 
analysis, and review of regulations. If it is determined that the 
expected impact is so minimal that the proposal does not warrant a full 
evaluation, a statement to that effect and the basis for it is included 
in the regulation.
    This final rule does not require any action by operators, as it 
simply identifies which aircraft meet or do not meet the GCNP quiet 
aircraft technology designation. Further, this rule does not relieve 
operators of the currently established operational limitations. The 
expected outcome is to have a minimal impact.

Comments

    Two commenters, AIA and HAI, submitted comments on the economic 
consequences to the proposal that have been discussed earlier in this 
final rule.
    The FAA agrees with AIA and HAI and has changed the phrase ``quiet 
technology designation'' to ``GCNP quiet aircraft technology 
designation'' in all places that it is used in the rule. This change 
will eliminate any need to analyze the costs of possible unintended 
adverse consequences to entities not subject to this action and clarify 
how this final rule relates to quiet technology requirements under 
Section 805 and other sections of the Air Tour Act applicable to 
national parks other than GCNP.

Regulatory Flexibility Determination

    The Regulatory Flexibility Act of 1980 (RFA) establishes ``as a 
principle of regulatory issuance that agencies shall endeavor, 
consistent with the objective of the rule and of applicable statutes, 
to fit regulatory and informational requirements to the scale of the 
business, organizations, and governmental jurisdictions subject to 
regulation.'' To achieve that principle, the 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 a regulatory flexibility 
analysis is not required. The certification must include a statement 
providing the factual basis for this determination, and the reasoning 
should be clear.
    This action merely defines quiet technology designation for 
aircraft use in GCNP air tour operations but does not impose any 
requirements. This action does not impose any requirements to use 
aircraft that meet the GCNP quiet aircraft technology designation. This 
action does not grant any relief from current GCNP air tour 
requirements if an operator uses aircraft that meets the designation. 
Therefore, the FAA does not expect this rule to have any cost impact on 
small entities that provide GCNP air tours. Consequently, the FAA 
certifies that the rule will not have a significant economic impact on 
a substantial number of small entity GCNP air tour operators.

International Trade Impact Analysis

    The Trade Agreement Act of 1979 prohibits Federal agencies from 
engaging in any standards or related activities that create unnecessary 
obstacles to the foreign commerce of the United States. Legitimate 
domestic objectives, such as safety, are not considered unnecessary 
obstacles. The statute also requires consideration of international 
standards and, where appropriate, that they be the basis for U.S. 
standards.
    In accordance with the above statute, the FAA has determined that 
this action will have a minimal impact and, therefore, has determined 
that this rule will not result in any unnecessary obstacles to the 
foreign commerce of the United States.

Unfunded Mandates Reform Act

    The Unfunded Mandates Reform Act of 1995 (the Act), enacted as 
Public Law 104-4 on March 22, 1995, is intended, among other things, to 
curb the practice of imposing unfunded Federal mandates

[[Page 16092]]

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 an expenditure of $100 million or more (adjusted annually 
for inflation) in any one year by State, local, and tribal governments, 
in the aggregate, or by the private sector; such a mandate is deemed to 
be a ``significant regulatory action.'' The FAA currently uses an 
inflation-adjusted value of $120.7 million in lieu of $100 million.
    This action does not contain such a mandate. Therefore, the 
requirements of Title II of the Unfunded Mandates Reform Act of 1995 do 
not apply.

Federalism Implications

    The regulations herein would not have substantial direct effects on 
the States, on the relationship between the National Government and the 
States, or on the distribution of power and responsibilities among the 
various levels of government. Therefore, in accordance with Executive 
Order 13132, it is determined that this rule does not have sufficient 
federalism implications to warrant the preparation of a federalism 
assessment.

Environmental Review

    In accordance with FAA Order 1050.1E, the FAA has determined that 
this action is categorically excluded from environmental review under 
section 102(2)(C) of the National Environmental Policy Act (NEPA). This 
action was categorically excluded under FAA Order 1050.1D, Appendix 4, 
Paragraph 4.j (now Paragraph 312d in FAA Order 1050.1E), which covers 
regulations ``excluding those which if implemented may cause a 
significant impact on the human environment.'' This rule establishes 
quiet technology designations for aircraft operating in GCNP. It does 
not impose a phase-out or any alteration of any air tour operator's 
fleet of aircraft. It does not lift the operations limitation, alter 
any flight corridors through the park, or make any change to the SFRA. 
Finally, the FAA notes that this action alone has no impact on 
substantial restoration of natural quiet in the GCNP. Any environmental 
and economic impacts will depend on other future actions yet to be 
defined. Accordingly, this action will not individually or cumulatively 
have a significant effect on the human environment. In addition, the 
FAA has determined that there are no ``extraordinary circumstances'' 
associated with the proposed action that would otherwise require the 
preparation of an EA or EIS.

Consultation With Tribal Governments

    Executive Order 13084 provides for consultation and coordination 
with Indian tribal governments in certain circumstances that are set 
forth in the executive order. The SNPRM Notice No. 03-05 described 
consultations with Indian tribal governments about this rule and taken 
their concerns into account. The FAA determined that additional 
consultations were not necessary because this action is required by 
statute and would not impose any substantial direct compliance costs on 
the communities of Indian tribal governments.

Paperwork Reduction Act

    In accordance with the Paperwork Reduction Act of 1995 (Pub. L. 
104-13), there are no requirements for information collection 
associated with this action. An agency may not conduct or sponsor and a 
person is not required to respond to a collection of information unless 
it displays a currently valid Office of Management and Budget (OMB) 
control number.

List of Subjects in 14 CFR Part 93

    Air traffic control, Airports, Navigation (Air), Reporting and 
recordkeeping requirements.

The Amendment

0
For reasons set forth above, the Federal Aviation Administration amends 
part 93, in chapter I of Title 14, Code of Federal Regulations, as 
follows:

PART 93--SPECIAL AIR TRAFFIC RULES AND AIRPORT TRAFFIC PATTERNS

0
1. The authority citation for part 93 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40103, 40106, 40109, 40113, 44502, 
44514, 44701, 44719, 46301.

0
2. Section 93.303 is amended to add the definitions in alphabetical 
order to read as follows:


Sec.  93.303  Definitions.

* * * * *
    GCNP quiet aircraft technology designation means an aircraft that 
is subject to Sec.  93.301 and has been shown to comply with the noise 
limit specified in appendix A of this part.
    Number of passenger seats means the number of passenger seats for 
which an individual aircraft is configured.
* * * * *

0
3. Appendix A is added to read as follows:

Appendix A to Subpart U of Part 93--GCNP Quiet Aircraft Technology 
Designation

    This appendix contains procedures for determining the GCNP quiet 
aircraft technology designation status for each aircraft subject to 
Sec.  93.301 determined during the noise certification process as 
prescribed under part 36 of this chapter. Where no certificated 
noise level is available, the Administrator may approve an 
alternative measurement procedure.
    Aircraft Noise Limit for GCNP Quiet Aircraft Technology 
Designation
    A. For helicopters with a flyover noise level obtained in 
accordance with the measurement procedures prescribed in Appendix H 
of 14 CFR part 36, the limit is 80 dB for helicopters having a 
seating configuration of two or fewer passenger seats, increasing at 
3 dB per doubling of the number of passenger seats for helicopters 
having a seating configuration of three or more passenger seats. The 
noise limit for helicopters with three or more passenger seats can 
be calculated by the formula:

EPNL(H) = 80 +10log( PAX seats/2) dB

    B. For helicopters with a flyover noise level obtained in 
accordance with the measurement procedures prescribed in Appendix J 
of 14 CFR part 36, the limit is 77 dB for helicopters having a 
seating configuration of two or fewer passenger seats, increasing at 
3 dB per doubling of the number of passenger seats for helicopters 
having a seating configuration of three or more passenger seats. The 
noise limit for helicopters with three or more passenger seats can 
be calculated by the formula:

SEL(J) = 77 + 10log( PAX seats/2) dB

    C. For propeller-driven airplanes with a measured flyover noise 
level obtained in accordance with the measurement procedures 
prescribed in Appendix F of 14 CFR part 36 without the performance 
correction defined in Sec. F35.201(c), the limit is 69 dB for 
airplanes having a seating configuration of two or fewer passenger 
seats, increasing at 3 dB per doubling of the number of passenger 
seats for airplanes having a seating configuration of three or more 
passenger seats. The noise limit for propeller-driven airplanes with 
three or more passenger seats can be calculated by the formula:

LAmax(F) = 69 + 10log( PAX seats/2) dB

    D. In the event that a flyover noise level is not available in 
accordance with Appendix F of 14 CFR part 36, the noise limit for 
propeller-driven airplanes with a takeoff noise level obtained in 
accordance with the measurement procedures prescribed in Appendix G 
is 74 dB or 77 dB, depending on 14 CFR part 36 amendment level, for 
airplanes having a seating configuration of two or fewer passenger 
seats, increasing at 3 dB per doubling of the number of passenger 
seats for airplanes having a seating configuration of three or more 
passenger seats. The noise limit for propeller-driven airplanes with 
three or more passenger seats can be calculated by the formula:


[[Page 16093]]


LAmax(G) = 74 + 10log( PAX seats/2) dB for certifications 
obtained under 14 CFR part 36, Amendment 21 or earlier;

LAmax(G) = 77 + 10log( PAX seats/2) dB for certifications 
obtained under 14 CFR part 36, Amendment 22 or later.

    Issued in Washington, DC on March 22, 2005.
Marion C. Blakey,
Administrator.
[FR Doc. 05-6074 Filed 3-28-05; 8:45 am]
BILLING CODE 4910-13-P