Fort Worth, Texas 76193-0170
(x) Fort Worth Special Certification Office (ASW-190) Federal Aviation Administration 2601 Meacham Boulevard Fort Worth, Texas 76137-4298
(mailing address:
DOT FAA Fort Worth, Texas 76193-0190
(xi) Los Angeles Aircraft Certification Office (ANM-100L) Federal Aviation Administration 3960 Paramount Boulevard, Suite 100 Lakewood, California 90712-4137
(xii) New York Aircraft Certification Office (ANE-170) Federal Aviation Administration 10 Fifth Street, 3rd Floor Valley Stream, New York 11581-1200
(xiii) Seattle Aircraft Certification Office (ANM-100S) Federal Aviation Administration 1601 Lind Avenue Southwest Renton, Washington 98055-4056
(xiv) Wichita Aircraft Certification Office (ACE-115W) Federal Aviation Administration Mid-Continent Airport FAA Building, Room 100 1801 Airport Road Wichita, Kansas 67209
Note: An applicant must coordinate airworthiness and noise certification activities with the appropriate ACO Office. Assistance in selecting the appropriate ACO Office may be obtained from FAA Directorate, Regional or Noise Certification Specialist Offices.
c. Procedures
None
31. Section 36.7 Acoustical Change: Transport category large airplanes and jet airplanes
32. Section 36.7(a)
Applicability. This section applies to all transport category large airplanes and jet airplanes for which an acoustical change approval is applied for under § 21.93(b) of this chapter.
33. Section 36.7(b)
General requirements. Except as otherwise specifically provided, for each airplane covered by this section, the acoustical change approval requirements are as follows:
(1) In showing compliance, noise levels must be measured and evaluated in accordance with the applicable procedures and conditions prescribed in Appendix A of this part.
(2) Compliance with the noise limits prescribed in section B36.5 of Appendix B must be shown in accordance with the applicable provisions of section B36.7 and B36.8 of Appendix B of this part.
a. Explanation
This section specifies requirements for approval of acoustical changes applied for under part 21, section 21.93(b).
b. Supplemental Information
None
c. Procedures
None
34. Section 36.7(c)
Stage 1 airplanes. For each Stage 1 airplane prior to the change in type design, in addition to the provisions of paragraph (b) of this section, the following apply:
(1) If an airplane is a Stage 1 airplane prior to the change in type design, it may not, after the change in type design, exceed the noise levels created prior to the change in type design. The tradeoff provisions of section B36.6 of Appendix B of this part may not be used to increase the Stage 1 noise levels, unless the aircraft qualifies as a Stage 2 airplane.
(2) In addition, for an airplane for which application is made after September 17, 1971--
(i) There may be no reduction in power or thrust below the highest airworthiness approved power or thrust, during the tests conducted before and after the change in type design; and
(ii) During the flyover and lateral noise tests conducted before the change in type design, the quietest airworthiness approved configuration available for the highest approved takeoff weight must be used.
a. Explanation
None
b. Supplemental Information
(1) Quietest Airworthiness Approved Configuration: This requirement was established to show that an acoustical change resulting from an approved type design change must be determined consistently. The FAA policy does not require an applicant to determine the quietest airworthiness approved configuration at the flyover or lateral noise measurement points by noise measurement and evaluation. However, FAA requires consistent evaluations between derivative and originally certificated configurations. For example, an applicant might choose an approved takeoff flap setting of 5 degrees. Later a type design change may be requested that would increase the flyover and lateral noise levels (an acoustical change). The FAA may not require the applicant to measure and evaluate all airworthiness approved takeoff flap settings (e.g., 0, 1, 2, 5, 10 degrees) to determine the quietest configuration, but may, in this example, require appropriate evaluations for a flap setting of 5 degrees.
c. Procedures
None
35. Section 36.7(d)
Stage 2 airplanes. If an airplane is a Stage 2 airplane prior to the change in type design, the following apply, in addition to the provisions of paragraph (b) of this section:
(1) Airplanes with high bypass ratio jet engines. For an airplane that has jet engines with a bypass ratio of 2 or more before a change in type design--
(i) The airplane, after the change in type design, may not exceed either (A) each Stage 3 noise limit by more than 3 EPNdB, or (B) each Stage 2 noise limit, whichever is lower:
(ii) The tradeoff provisions of section B36.6 of Appendix B of this part may be used in determining compliance under this paragraph with respect to the Stage 2 noise limit or to the Stage 3 plus 3 EPNdB noise limits, as applicable; and
(iii) During the flyover and lateral noise test conducted before the change in type design, the quietest airworthiness approved configuration available for the highest approved takeoff weight must be used.
(2) Airplanes that do not have high bypass ratio jet engines. For an airplane that does not have jet engines with a bypass ratio of 2 or more before a change in type design-
(i) The airplane may not be a Stage 1 airplane after the change in type design; and
(ii) During the flyover and lateral noise tests conducted before the change in type design, the quietest airworthiness approved configuration available for the highest approved takeoff weight must be used. .
a. Explanation
None
b. Supplemental Information
See section 36.7(c), Supplemental Information, Item (1)
c. Procedures
None
36. Section 36.7(e)
Stage 3 airplanes. If an airplane is a Stage 3 airplane prior to the change in type design, the following apply, in addition to the provisions of paragraph (b) of this section:
(1) If compliance with Stage 3 noise levels is not required before the change in type design, the airplane must-- (I) Be a Stage 2 airplane after the change in type design and compliance must be shown under the provisions of paragraph (d)(1) or (d)(2) of this section, as appropriate; or
(ii) Remain a Stage 3 airplane after the change in type design. Compliance must be shown under the provisions of paragraph (e)(2) of this section.
(2) If compliance with Stage 3 noise levels is required before the change in type design, the airplane must be a Stage 3 airplane after the change in type design.
(3) Applications on or after [August 14, 1989.] The airplane must remain a Stage 3 airplane after the change in type design.
a. Explanation
None
b. Supplemental Information
(1) “Dual-Stage” Certificated Airplanes: Some older airplane models have been certificated to Stage 2 for one configuration and to Stage 3 for another configuration (e.g., airplane takeoff flap setting or maximum allowable gross weights). These airplanes are classified as “Dual-Stage” certificated airplanes. No new dual certifications will be considered.
c. Procedures
None
37. Section 36.9 Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category airplanes [To be completed later]
38. Section 36.9(a) [To be completed later]
39. Section 36.9(b) [To be completed later]
40. Section 36.11 Acoustical Change: Helicopters
This section applies to all helicopters in the primary, normal, transport, and restricted categories for which an acoustical change approval is applied for under § 21.93(b) of this chapter on or after March 6, 1986. Compliance with the requirements of this section must be demonstrated under appendix H of this part, or, for helicopters having a maximum certificated takeoff weight of not more than 6,000 pounds, compliance with this section may be demonstrated under Appendix J of this part.
a. Explanation
None
b. Supplementary Information
(1) Modifications excluded from compliance with part 36, as listed in part 21, section 21.93(b)(4)(ii) Classification of Changes in Type Design:
(i) Addition or removal of external equipment; (This means any instrument, mechanism, part, apparatus, appurtenance, or accessory that is attached to or extends from the helicopter exterior but is not used nor is intended to be used in operating or controlling a helicopter in flight and is not part of an airframe or engine).
(ii) Changes in the airframe made to accommodate the addition or removal to facilitate the use of external equipment, to provide for an external load attaching means, to facilitate the safe operation of the helicopter with external equipment mounted to, or external loads carried by, the helicopter;
(iii) Reconfiguration of the helicopter by the addition or removal of floats and skis;
(iv) Flight with one or more doors and/or windows removed or in an open position; or
(v) Any changes in the operational limitations on the helicopter as a consequence of the addition or removal of external equipment, floats, and skis, or flight operations with doors and/or windows removed or in an open position.
c. Procedures
None
41. Section 36.11(a)
General requirements. Except as otherwise provided, for helicopters covered by this section, the acoustical change approval requirements are as follows:
(1) In showing compliance with the requirements of appendix H of this part, noise levels must be measured, evaluated, and calculated in accordance with the applicable procedures and conditions prescribed in parts B and C of appendix H of this part. For helicopters having a maximum certificated takeoff weight of not more than 6,000 pounds that alternatively demonstrate compliance under appendix J of this part, the flyover noise level prescribed in appendix J of this part must be measured, evaluated, and calculated in accordance with the applicable procedures and conditions prescribed in part s B and C of appendix J of this part.
(2) Compliance with the noise limits prescribed in section H36.305 of appendix H of this part must be shown in accordance with the applicable provisions of part D of appendix H of this part. For those helicopters that demonstrate compliance with the requirements of appendix J of this part, compliance with the noise levels prescribed in section J36.305 of appendix J of this part must be shown in accordance with the applicable provisions of part D of appendix J of this part.
a. Explanation
None
b. Supplementary Information
(1) Equivalent Procedures: Subject to prior approval by the FAA, equivalent procedures may be used to measure, evaluate and calculate noise levels. Some commonly used equivalent procedures relating to helicopter noise certification will be included in a future revision to this AC.
(2) Noise Level Tradeoffs: Tradeoffs between the adjusted noise levels for flyover, takeoff and approach defined in H36.305(b) may be used to show compliance with the maximum noise levels (noise limits) of Appendix H. Since Appendix J only includes a flyover procedure, no tradeoff is possible.
c. Procedures
(1) Compliance: The procedure used to show compliance under Appendix H or Appendix J must follow the applicable parts of the regulation. Compliance with the maximum noise levels (noise limits) prescribed in section H36.305 of Appendix H or J36.305 of Appendix J must be shown.
42. Section 36.11(b)
Stage 1 helicopters. Except as provided in § 36.805(c), for each Stage 1 helicopter prior to a change in type design, the helicopter noise levels may not, after a change in type design, exceed the noise levels specified in section H36.305(a)(1) of appendix H of this part where the demonstration of compliance is under appendix H of this part. The tradeoff provisions under section H36.305(b) of appendix H of this part may not be used to increase any Stage 1 noise level beyond these limits. If an applicant chooses to demonstrate compliance under appendix J of this part, for each Stage 1 helicopter prior to a change in type design, the helicopter noise levels may not, after a change in type design, exceed the Stage 2 noise levels specified in section J36.305(a) of Appendix J of this part.
a. Explanation
None
b. Supplementary Information
(1) The maximum noise levels (noise limits) associated with a Stage 1 helicopter certificated under Appendix H after a change in type design are dependent on the noise levels of the original Stage 1 helicopter.
Unless the Stage 1 helicopter after the change meets the Stage 2 maximum noise levels (noise limits), or Stage 2+ 2 EPNdB levels at each measuring point, it will be necessary to show that the helicopter has no increase in the noise levels at any of the measuring points. This will require determination of the noise levels associated with the original Stage 1 helicopter using Appendix H procedures. If this is not possible an applicant must obtain FAA approval for another procedure.
c. Procedures
None
43. Section 36.11(c)
Stage 2 helicopters. For each helicopter that is Stage 2 prior to a change in type design, the helicopter must be a Stage 2 helicopter after a change in type design
a. Explanation
None
b. Supplementary Information
(1) Helicopter under 6000 lbs (2727 kg): If after a change in type design a helicopter previously certificated under Appendix J, fails to meet the Appendix J Stage 2 maximum noise levels (noise limits) prescribed in J36.305 an applicant may attempt to show compliance by electing the use of Appendix H procedures and the Appendix H Stage 2 maximum noise levels (noise limits) specified in H36.305.
(2) Noise Levels: Section 36.11 requirements apply to helicopters certificated under both Appendix H and Appendix J.
c. Procedures
None
44. – 50. RESERVED
a. Explanation
Subpart B specifies part 36 requirements for measurement and evaluation of airplane noise certification data, and maximum noise levels for Stage 1, Stage 2 and Stage 3 airplanes.
b. Procedures
None
c. Procedures
None
51. Section 36.101 Noise measurement and evaluation
For transport category large airplanes and jet airplanes the noise generated by the airplane must be measured and evaluated under Appendix A of this part or under an approved equivalent procedure
a. Explanation
None
b. Supplemental Information
(1) Appendix A: Appendix A prescribes methodologies for conducting noise certification tests and for measurement and evaluation of noise data for comparison with maximum noise levels specified in Appendix B (see Note A). Specific requirements include:
(i) Specifications of various physical and environmental conditions under which airplane noise certification measurements are permitted. These conditions are related to the noise test site, wind velocity/direction and atmospheric sound attenuation.
(ii) Procedures for measurement of atmospheric parameters.
(iii) Methods for synchronization of airplane position and performance measurements with noise measurements.
(iv) Specifications for noise certification measurement and analysis systems (See Note B).
(v) Methods to calculate atmospheric sound attenuation coefficients and Effective Perceived Noise Level (in units of EPNdB).
(vi) Methods for adjustment of measured flight test data to reference conditions.
(vii) Nomenclature for symbols and units.
(viii) Specification of data to be reported to FAA.
Notes:
III. SUBPART B— TRANSPORT CATEGORY LARGE AIRPLANES AND JET AIRPLANES
(A) Appendix A requirements are nearly identical to those of Appendix 2 of Annex 16 Volume 1, Amendment 7 (See reference 11 of this AC).
(B) Some provisions of Appendix A may also apply to the noise certification of helicopters as prescribed in Appendix H of part 36.
(2) Equivalent Procedures: Equivalent Procedures, as referred to in this AC, are aircraft measurement, flight test, analytical or evaluation methods that differ from the methods specified in the text of part 36 Appendices A and B, but yield essentially the same noise levels. Equivalent procedures must be approved by the FAA. Some equivalent procedures may be the same for all types of aircraft but others may be unique to specific types of aircraft or be proprietary to a particular aircraft manufacturer.
The appended ICAO TM provides both general and technical guidance on equivalent procedures that have been accepted as a technical means for demonstrating compliance with the noise certification requirements of ICAO Annex 16, Volume 1. Section 1 provides guidance material of a general nature including the purpose of the TM, its framework, information on incorporation of equivalent procedures and type design changes into compliance plans and changes to noise levels for derived versions. Section 2 contains technical guidance on equivalent and analytical procedures for subsonic jet airplanes, sections 3 and 4 contain similar guidance for propeller driven airplanes, and section 5 for helicopters. Technical guidance on evaluation procedures is given in section 6. The guidance material provided by the ICAO TM on equivalent procedures that have been approved in the past neither implies that they are the only acceptable ones, nor that they are limited for current noise certification applications, nor that FAA has approved their application for any current or future aircraft noise certification actions (See Supplemental Information Items in Subpart O, section 1501, regarding the FAA’s approval process for equivalent procedures).
Notes:
(A) Flight test equivalent procedures have been used to acquire a sufficient number of noise measurements at various engine thrusts (powers) to develop generalized noise databases often referred to as Noise-Power-Distance (NPD) plots. (See section 2.1.2 and 3.1.2 of the appended ICAO TM). These NPD plots may be particularly useful for applicants to determine values of EPNLr for derived versions of an aircraft type.
(B) Equivalent procedures involving the use of static engine noise test data projected to flight conditions to account for changes to an airplane engine configuration or to an installation of an acoustically similar engine on the same airframe have been used for comparison to measured flight noise levels of the airplane with engines as originally certified. This type of data has also been used to demonstrate “no acoustical change” resulting from minor modifications to engine components. (See section 2.3 and 3.3 of the appended ICAO TM).
(C) Equivalent procedures involving analytical methods have been used to determine changes in airplane certificated noise levels resulting from thrust (power) reduction, modifications of airplane maximum takeoff or landing weights, engine thrust (power) rating changes, engine or nacelle configuration or acoustic treatment changes, and airplane performance changes resulting from airframe design changes. (See sections
2.2 and 3.2 of the appended ICAO TM).
c. Procedures
(1) Applicant’s Responsibility: Applicants must prepare noise compliance demonstration plans for FAA approval that include proposed methods for compliance with the requirements of Appendix B (See section B36.1). Equivalent procedure proposals in these plans must include substantiation of their technical validity and feasibility of application to the airplane type for which noise certification is requested. (See Subpart O section 1501, Supplemental Information, for noise compliance demonstration plan documentation requirements).
52. Section 36.103 Noise limits
53. Section 36.103(a)
For subsonic transport category large airplanes and subsonic jet airplanes compliance with this section must be shown with noise levels measured and evaluated as prescribed in Appendix A of this part and demonstrated at the measuring points, and in accordance with the test procedures under section B36.8 (or an approved equivalent procedure), stated under Appendix B of this part
a. Explanation
This section specifies part 36 requirements for determination of EPNLr values.
b. Supplemental Information
(1) Noise Measurement Points: The locations of test noise measurement points frequently do not coincide with the reference noise measurement point locations specified in section B36.3. For example, locations of flyover noise measurement points may be subject to test site anomalies that would make it impractical to set up microphones at the reference locations. An applicant that has an approved equivalent procedure to measure airplane noise data for generation of NPD plots using the Flight Path Intercept procedure may select test noise measurement points (particularly the flyover point) so as to optimize the noise recording system signal-to-noise ratios.
(2) Equivalent Procedures: The FAA is not authorized to approve equivalencies for reference procedures.
(3) Flight Test Guide: General approved flight test procedures, principles, methods and flight crew operational practices are included in AC 25-7A, Flight Test Guide (See reference 6 of this AC).
c. Procedures
None
54. Section 36.103(b)
Type certification applications for subsonic transport category large airplanes and all subsonic jet airplanes must show that the noise levels of the airplane are no greater than the Stage 3 noise limits stated in section B36.5(c) of Appendix B of this part.
a. Explanation
None
b. Supplemental Information
(1) Stage 3 Compliance: Transport category large airplanes and turbojet-powered airplanes, for which application for a type certificate was made on or after November 5, 1975, are required to show compliance with Stage 3 maximum noise levels (noise limits) including tradeoffs. (See sections B36.5 and B36.6)
c. Procedures
None
IV. SUBPART C—RESERVED
No technical guidance has been developed for the following sections:
55. Section 36.301 Noise limits: Concorde
56. Section 36.301(a)
57. Section 36.301(b) V. SUBPART D—NOISE LIMITS FOR SUPERSONIC TRANSPORT CATEGORY AIRPLANES
VI. SUBPART E--[RESERVED]