
[Federal Register: June 8, 2009 (Volume 74, Number 108)]
[Rules and Regulations]               
[Page 27076]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr08jn09-2]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 36

 
Calculation of Noise Levels Published in Advisory Circular 36-3

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Statement of policy.

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SUMMARY: This action clarifies the Federal Aviation Administration's 
(FAA) policy on the calculation of derived noise levels submitted for 
publication in Advisory Circular (AC) 36-3, Estimated Airplane Noise 
Levels in A-Weighted Decibels. This action is intended to provide 
guidance on calculating the derived levels used in that publication.

FOR FURTHER INFORMATION CONTACT: Mr. James Skalecky, Office of 
Environment and Energy (AEE-100), Federal Aviation Administration, 800 
Independence Avenue, SW., Washington, DC 20591; telephone (202) 267-
3699; facsimile (202) 267-5594; e-mail James.Skalecky@faa.gov.

Background

    Paragraph 3 of AC 36-3 states that ``14 CFR part 36 requires the 
reporting of turbojet and large transport category aircraft 
certificated noise levels in units of Effective Perceived Noise Level 
in decibels (EPNdB). Many airport and other community noise analyses 
utilize a noise rating scale that is based upon A-weighted decibels. 
For this reason, A-weighted noise levels for aircraft under 14 CFR part 
36 conditions have been estimated to provide a reference source for 
aircraft noise levels that is consistent with the many noise rating 
scales having A-weighted noise level as the basic measure.'' The noise 
levels published in AC 36-3 for turbojet and large transport category 
airplanes are usually submitted to the FAA by the airplane type 
certificate (or supplemental type certificate) holder. The entity 
submitting the noise levels for publication is responsible for deriving 
the A-weighted level from the EPNdB levels submitted for certification.
    Recently, we received an inquiry requesting a clarification of 
those reference procedures, data analysis procedures, and data 
corrections that are to be used in deriving A-weighted noise levels for 
publication in AC 36-3. The question and our policy stated in this 
document apply only to noise levels for turbojet and large transport 
category airplanes.

Policy Statement

    In order to ensure that all airplane noise levels submitted for 
publication in AC 36-3 are derived in a consistent manner, it is the 
FAA's policy that the noise levels be derived using the same reference 
procedures, data analysis procedures, and data corrections/adjustments 
that were used in deriving the 14 CFR part 36 certificated noise 
levels. The only exceptions are for deviations necessitated by (1) 
differences between the effective perceived noise level and A-weighted 
sound level metrics, or (2) inclusion of approach noise levels 
corresponding to use of less than the maximum flap setting, as 
permitted under AC 36-3, paragraph 4.a. In the case of number 2, the 
deviation is limited to the use of an approach configuration other than 
the noise-critical configuration that is required for the noise 
certification approach reference procedure by part 36, Appendix B, 
paragraph B36.7(c)(5). Such deviations must be identified to the FAA 
when the data are submitted for inclusion in the AC. No other 
deviations will be accepted.
    When an airplane model that is already listed in AC 36-3 is 
recertificated from 14 CFR part 36 Stage 3 to Stage 4, the noise levels 
corresponding to the Stage 3 configuration are not automatically 
replaced. The Stage 3 noise levels will remain in AC 36-3, unless noise 
levels corresponding to the Stage 4 configuration are submitted for 
publication. If Stage 4 noise levels are submitted, the FAA will remove 
the Stage 3 noise levels from AC 36-3 for that model and replace them 
with the Stage 4 noise levels when the AC is updated.
    Noise levels submitted for Stage 4 configurations must conform to 
this policy for deriving noise levels submitted for publication in AC 
36-3.

    Issued in Washington, DC, on June 2, 2009.
Lourdes Q. Maurice,
Acting Director of Environment and Energy.
[FR Doc. E9-13333 Filed 6-5-09; 8:45 am]

BILLING CODE 4910-13-P
