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.
Source:
Docket No. 9337, 34 FR 18364, Nov. 18, 1969, unless otherwise noted.
(a) This part prescribes noise standards for the issue of the following certificates:
(1) Type certificates, and changes to those certificates, and standard airworthiness certificates, for subsonic transport category large airplanes, and for subsonic turbojet powered airplanes regardless of category.
(2) Type certificates and changes to those certificates, standard airworthiness certificates, and restricted category airworthiness certificates, for propeller-driven, small airplanes, and for propeller-driven, commuter category airplanes except those airplanes that are designed for "agricultural aircraft operations" (as defined in §137.3 of this chapter, as effective on January 1, 1966) or for dispersing fire fighting materials to which §36.1583 of this part does not apply.
(3) A type certificate and changes to that certificate, and standard airworthiness certificates, for Concorde airplanes.
(4) Type certificates, and changes to those certificates, for helicopters except those helicopters that are designated exclusively for "argicultural aircraft operations" (as defined in §137.3 of this chapter, as effective on January 1, 1966), for dispensing fire fighting materials, or for carrying external loads (as defined in §133.1(b) of this chapter, as effective on December 20, 1976).
(b) Each person who applies under Part 21 of this chapter for a type of airworthiness certificate specified in this part must show compliance with the applicable requirements of this part, in addition to the applicable airworthiness requirements of this chapter.
(c) Each person who applies under Part 21 of this chapter for approval of an acoustical change described in §21.93(b) of this chapter must show that the aircraft complies with the applicable provisions of §§36.7, 36.9, or 36.11 of this part in addition to the applicable airworthiness requirements of this chapter.
(d) Each person who applies for the original issue of a standard airworthiness certificate for a transport category large airplane or for a turbojet powered airplane under §21.183 must, regardless of date of application, show compliance with the following provisions of this part (including appendix C):
(1) The provisions of this part in effect on December 1, 1969, for subsonic airplanes that have not had any flight time before --
(i) December 1, 1973, for airplanes with maximum weights greater than 75,000 pounds, except for airplanes that are powered by Pratt & Whitney Turbo Wasp JT3D series engines;
(ii) December 31, 1974, for airplanes with maximum weights greater than 75,000 pounds and that are powered by Pratt & Whitney Turbo Wasp JT3D series engines; and
(iii) December 31, 1974, for airplanes with maximum weights of 75,000 pounds and less.
(2) The provisions of this part in effect on October 13, 1977, including the stage 2 noise limits, for Concorde airplanes that have not had flight time before January 1, 1980.
(3) December 31, 1974, for airplanes with maximum weights of 75,000 lbs. and less.
(e) Each person who applies for the original issue of a standard airworthiness certificate under §21.183, or for the original issue of a restricted category airworthiness certificate under §21.185, for propeller-driven, commuter category airplanes for a propeller driven small airplane that has not had any flight time before January 1, 1980, must show compliance with the applicable provisions of this part.
(f) For the purpose of showing compliance with this part for transport category large airplanes and turbojet powered airplanes regardless of category, the following terms have the following meanings:
(1) A "Stage 1 noise level" means a takeoff, sideline or approach noise level greater than the Stage 2 noise limits prescribed in section C36.5(a)(2) of appendix C of this part.
(2) A "Stage 1 airplane" means an airplane that has not been shown under this part to comply with the takeoff, sideline, and approach noise levels required for Stage 2 or Stage 3 airplanes.
(3) A "Stage 2 noise level" means a noise level at or below the Stage 2 noise limits prescribed in section C36.5(a)(2) of appendix C of this part but higher than the Stage 3 noise limits prescribed in section C36.5(a)(3) of appendix C of this part.
(4) A "Stage 2 airplane" means an airplane that has been shown under this part to comply with Stage 2 noise levels prescribed in section C36.5 of appendix C of this part (including use of the applicable tradeoff provisions) and that does not comply with the requirements for a Stage 3 airplane.
(5) A "Stage 3 noise level" means a noise level at or below the Stage 3 noise limits prescribed in section C36.5(a)(3) of appendix C of this part.
(6) A "Stage 3 airplane" means an airplane that has been shown under this part to comply with Stage 3 noise levels prescribed in section C36.5 of appendix C of this part (including use of the applicable tradeoff provisions).
(7) A "subsonic airplane" means an airplane for which the maximum operating limit speed, M (8) A "supersonic airplane" means an airplane for which the maximum operating limit speed, M (g) For the purpose of showing compliance with this part for transport category large airplanes and turbojet airplanes regardless of category, each airplane may not be identified as complying with more than one stage or configuration simultaneously.
(h) For the purpose of showing compliance with this part, for helicopters in the primary, normal, transport, and restricted categories, the following terms have the specified meanings:
(1) Stage 1 noise level means a takeoff, flyover, or approach noise level greater than the Stage 2 noise limits prescribed in section H36.305 of appendix H of this part, or a flyover noise level greater than the Stage 2 noise limits prescribed in section J36.305 of appendix J of this part.
(2) Stage 1 helicopter means a helicopter that has not been shown under this part to comply with the takeoff, flyover, and approach noise levels required for Stage 2 helicopters as prescribed in section H36.305 of appendix H of this part, or a helicopter that has not been shown under this part to comply with the flyover noise level required for Stage 2 helicopters as prescribed in section J36.305 of appendix J of this part.
(3) Stage 2 noise level means a takeoff, flyover, or approach noise level at or below the Stage 2 noise limits prescribed in section H36.305 of appendix H of this part, or a flyover noise level at or below the Stage 2 limit prescribed in section J36.305 of appendix J of this part.
(4) Stage 2 helicopter means a helicopter that has been shown under this part to comply with Stage 2 noise limits (including applicable tradeoffs) prescribed in section H36.305 of appendix H of this part, or a helicopter that has been shown under this part to comply with the Stage 2 noise limit prescribed in section J36.305 of appendix J of this part.
[Doc. No. 13243, Amdt. 36-4, 40 FR 1034, Jan. 6, 1975 as amended by Amdt. 36-7, 42 FR 12370, Mar. 3, 1977; Amdt. 36-10, 43 FR 28419, June 29, 1978; Amdt. 36-11, 45 FR 67066, Oct. 9, 1980; Amdt. 36-13, 52 FR 1836, Jan. 15, 1987; Amdt. 36-14, 53 FR 3540, Feb. 5, 1988; 53 FR 7728, Mar. 10, 1988; Amdt. 36-15, 53 FR 16366, May 6, 1988; Amdt. 36-20, 57 FR 42854, Sept. 16, 1992]
(a) Notwithstanding §21.17 of this chapter, each person who applies for a type certificate:
(1) For an airplane covered by this part, irrespective of the date of application for the type certificate, or
(2) For a helicopter covered by this part, on or after March 6, 1986,
must show compliance with the applicable provisions of this part.
(b) Notwithstanding §21.101(a) of this chapter, each person who applies for an acoustical change to a type design specified in §21.93(b) of this chapter must show compliance with the applicable provisions of this part.
[Doc. No. 9337, 34 FR 18364, Nov. 18, 1969, as amended by Amdt. 36-14, 53 FR 3540, Feb. 5, 1988]
It must be shown that the aircraft meets the airworthiness regulations constituting the type certification basis of the aircraft under all conditions in which compliance with this part is shown, and that all procedures used in complying with this part, and all procedures and information for the flight crew developed under this part, are consistent with the airworthiness regulations constituting the type certification basis of the aircraft.
[Doc. No. 9337, 34 FR 18364, Nov. 18, 1969, as amended by Amdt. 36-14, 53 FR 3540, Feb. 5, 1988]
Pursuant to 49 U.S.C. 1431(b)(4), the noise levels in this part have been determined to be as low as is economically reasonable, technologically practicable, and appropriate to the type of aircraft to which they apply. No determination is made, under this part, that these noise levels are or should be acceptable or unacceptable for operation at, into, or out of, any airport.
(a) General. This part prescribes certain standards and procedures which are not set forth in full text in the rule. Those standards and procedures are contained in published material which is reasonably available to the class of persons affected and has been approved for incorporation by reference by the Director of the Federal Register under 5 U.S.C. 552 (a) and 1 CFR Part 51.
(b) Incorporated matter. (1) Each publication, or part of a publication, which
is referenced but not set forth in full-text in this part and which is identified in paragraph (c) of this section is hereby incorporated by reference and made a part of Part 36 of this chapter with the approval of the Director of the Federal Register.
(2) Incorporated matter which is subject to subsequent change is incorporated by reference according to the specific reference and to the identification statement. Adoption of any subsequent change in incorporated matter is made under Part 11 of this chapter and 1 CFR Part 51.
(c) Identification statement. The complete title or description which identifies each published matter incorporated by reference in this part is as follows:
(1) International Electrotechnical Commission (IEC) Publications. (i) IEC Publication No. 179, entitled "Precision Sound Level Meters," dated 1973.
(ii) IEC Publication No. 225, entitled "Octave, Half-Octave, Third Octave Band Filters Intended for the Analysis of Sounds and Vibrations," dated 1966.
(iii) IEC Publication No. 651, entitled "Sound Level Meters," first edition, dated 1979.
(iv) IEC Publication No. 561, entitled "Electro-acoustical Measuring Equipment for Aircraft Noise Certification," first edition, dated 1976.
(v) IEC Publication No. 804, entitled "Integrating-averaging Sound Level Meters," first edition, dated 1985.
(2) Society of Automotive Engineers (SAE) Publications. (i) SAE ARP 866A, entitled "Standard Values at Atmospheric Absorption as a Function of Temperature and Humidity for Use in Evaluating Aircraft Flyover Noise," dated March 15, 1975.
(d) Availability for purchase. Published material incorporated by reference in this part may be purchased at the price established by the publisher or distributor at the following mailing addresses:
(1) IEC publications. (i) The Bureau Central de la Commission Electrotechnique, Internationale, 1, rue de Varembe, Geneva, Switzerland.
(ii) American National Standard Institute, 1430 Broadway, New York City, New York 10018.
(2) SAE publications. Society of Automotive Engineers, Inc., 400 Commonwealth Drive, Warrentown, Pennsylvania 15096.
(e) Availability for inspection. A copy of each publication incorporated by reference in this part is available for public inspection at the following locations:
(1) FAA Office of the Chief Counsel, Rules Docket, Room 916, Federal Aviation Administration Headquarters Building, 800 Independence Avenue, SW., Washington, DC.
(2) Department of Transportation, Branch Library, Room 930, Federal Aviation Administration Headquarters Building, 800 Independence Avenue, SW., Washington, DC.
(3) The respective Region Headquarters of the Federal Aviation Administration as follows:
(i) New England Region Headquarters, 12 New England Executive Park, Burlington, Massachusetts 01803.
(ii) Eastern Region Headquarters, Federal Building, John F. Kennedy (JFK) International Airport, Jamaica, New York 11430.
(iii) Southern Region Headquarters, 3400 Norman Berry Drive, East Point, Georgia 30344.
(iv) Great Lakes Region Headquarters, O'Hare Lake Office Center, 2300 East Devon Avenue, Des Plaines, Illinois 60018.
(v) Central Region Headquarters, Federal Building, 601 East 12th Street, Kanasa City Missouri 64106.
(vi) Southwest Region Headquarters, 4400 Blue Mound Road, Fort Worth, Texas 76193-0000.
(vii) Northwest Mountain Region Headquarters, 17900 Pacific Highway South, Seattle, Washington 98168.
(viii) Western-Pacific Region Headquarters, 15000 Aviation Boulevard, Hawthorne, California 92007.
(ix) Alaskan Region Headquarters, 701 C Street, Anchorage, Alaska 99513.
(x) European Office Headquarters, 15, Rue de la Loi (3rd Floor), B-1040 Brussels, Belgium. [Amdt. 36-9, 43 FR 8739, Mar. 3, 1978, as amended by Amdt. 36-16, 53 FR 47400, Nov. 22, 1988; Amdt. 36-20, 57 FR 42854, Sept. 16, 1992]
(a) Applicability. This section applies to all transport category large airplanes and turbojet powered airplanes for which an acoustical change approval is applied for under §21.93(b) of this chapter.
(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 Appendices A and B of this part.
(2) Compliance with the noise limits prescribed in section C36.5 of appendix C must be shown in accordance with the applicable provisions of sections C36.7 and C36.9 of appendix C of this part.
(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 C36.5(b) of appendix C 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 takeoff and sideline noise tests conducted before the change in type design, the quietest airworthiness approved configuration available for the highest approved takeoff weight must be used.
(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 turbojet engines. For an airplane that has turbojet 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 C36.5(b) of appendix C 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 takeoff and sideline 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 turbojet engines. For an airplane that does not have turbojet 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 takeoff and sideline noise tests conducted before the change in type design, the quietest airworthiness approved configuration available for the highest approved takeoff weight must be used.
(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.
[Amdt. 36-7, 42 FR 12371, Mar. 3, 1977; Amdt. 36-8, 43 FR 8730, Mar. 2, 1978; Amdt. 36-10, 43 FR 28420, June 29, 1978; Amdt. 36-12, 46 FR 33464, June 29, 1981; Amdt. 36-15, 53 FR 16366, May 6, 1988; 53 FR 18950, May 25, 1988; Amdt. 36-17, 54 FR 21042, May 15, 1989]
For propeller-driven small airplanes in the primary, normal, utility, acrobatic, transport, and restricted categories and for propeller-driven, commuter category airplanes for which an acoustical change approval is applied for under §21.93(b) of this chapter after January 1, 1975, the following apply:
(a) If the airplane was type certificated under this part prior to a change in type design, it may not subsequently exceed the noise limits specified in §36.501 of this part.
(b) If the airplane was not type certificated under this part prior to a change in type design, it may not exceed the higher of the two following values:
(1) The noise limit specified in §36.501 of this part, or
(2) The noise level created prior to the change in type design, measured and corrected as prescribed in §36.501 of this part.
[Amdt. 36-16, 53 FR 47400, Nov. 22, 1988; 53 FR 50157, Dec. 13, 1988; Amdt. 36-19, 57 FR 41369, Sept. 9, 1992]
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) 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 parts 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.
(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.
(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.
[Doc. No. 26910, 57 FR 42854, Sept. 16, 1992]
For transport category large airplanes and turbojet powered airplanes the noise generated by the airplane must be measured under appendix A of this part or under an approved equivalent procedure.
[Doc. No. 9337, 34 FR 18364, Nov. 18, 1969, as amended by Amdt. 36-10, 43 FR 28420, June 29, 1968]
For transport category large airplanes and turbojet powered airplanes noise measurement information obtained under §36.101 must be evaluated under appendix B of this part or under an approved equivalent procedure.
[Doc. No. 9337, 34 FR 18364, Nov. 18, 1969, as amended by Amdt. 36-10, 43 FR 28420, June 29, 1978]
(a) For subsonic transport category large airplanes and subsonic turbojet powered airplanes compliance with this section must be shown with noise levels measured and evaluated as prescribed in Subpart B of this part, and demonstrated at the measuring points, and in accordance with the flight test conditions under sections C36.7 and C36.9 (or an approved equivalent procedure), prescribed under appendix C of this part.
(b) Type certification applications for subsonic transport category large airplanes and all subsonic turbojet powered airplanes must show that the noise levels of the airplane are no greater than the Stage 3 noise limits prescribed in section C36.5(a)(3) of appendix C of this part.
[Doc. No. 9337, 34 FR 18364, Nov. 18, 1969, as amended by Amdt. 36-7, 42 FR 12371, Mar. 3, 1977; Amdt. 36-8, 43 FR 8730, Mar. 2, 1978; Amdt. 36-10, 43 FR 28420, June 29, 1978; Amdt. 36-12, 46 FR 33464, June 29, 1981; Amdt. 36-15, 53 FR 16366, May 6, 1988]
(a) General. For the Concorde airplane, compliance with this subpart must be shown with noise levels measured and evaluated as prescribed in Subpart B of this part, and demonstrated at the measuring points prescribed in appendix C of this part.
(b) Noise limits. It must be shown, in accordance with the provisions of this part in effect on October 13, 1977, that the noise levels of the airplane are reduced to the lowest levels that are economically reasonable, technologically practicable, and appropriate for the Concorde type design.
[Amdt. 36-10, 43 FR 28420, June 29, 1978]
(a) Compliance with this subpart must be shown for --
(1) Propeller driven small airplanes for which application for the issuance of a new, amended, or supplemental type certificate in the normal, utility, acrobatic, transport, or restricted category is made on or after October 10, 1973; and propeller-driven, commuter category airplanes for which application for the issuance of a type certificate in the commuter category is made on or after January 15, 1987.
(2) Propeller driven small airplanes and propeller-driven, commuter category airplanes for which application is made for the original issuance of a standard airworthiness certificate or
restricted category airworthiness certificate, and that have not had any flight time before January 1, 1980 (regardless of date of application).
(3) Airplanes in the primary category:
(i) Except as provided in paragraph (a)(3)(ii) of this section, for an airplane for which application for a type certificate in the primary category is made, and that was not previously certificated under appendix F of this part, compliance with appendix G of this part must be shown.
(ii) For an airplane in the normal, utility or acrobatic category that (A) has a type certificate issued under this chapter, (B) has a standard airworthiness certificate issued under this chapter, (C) has not undergone an acoustical change from its type design, (D) has not previously been certificated under appendix F or G of this part, and (E) for which application for conversion to the primary category is made, no further showing of compliance with this part is required.
(b) For aircraft covered by this subpart for which certification tests are completed before December 22, 1988, compliance must be shown with noise levels as measured and prescribed in Parts B and C of appendix F, or under approved equivalent procedures. It must be shown that the noise level of the airplane is no greater than the applicable limit set in Part D of appendix F.
(c) For aircraft covered by this subpart for which certification tests are not completed before December 22, 1988, compliance must be shown with noise levels as measured and prescribed in Parts B and C of appendix G, or under approved equivalent procedures. It must be shown that the noise level of the airplane is no greater than the applicable limits set in Part D of appendix G.
[Doc. No. 13243, 40 FR 1034, Jan. 6, 1975, as amended by Amdt. 36-13, 52 FR 1836, Jan. 15, 1987; Amdt. 36-16, 53 FR 47400, Nov. 22, 1988; Amdt. 36-19, 57 FR 41369, Sept. 9, 1992] Source:
Amdt. 36-14, 53 FR 3540, Feb. 5, 1988; 53 FR 7728, Mar. 10, 1988, unless otherwise noted.
For primary, normal, transport, or restricted category helicopters for which certification is sought under appendix H of this part, the noise generated by the helicopter must be measured at the noise measuring points and under the test conditions prescribed in part B of appendix H of this part, or under an FAA-approved equivalent procedure. For those primary, normal, transport, and restricted category helicopters having a maximum certificated takeoff weight of not more than 6,000 pounds for which compliance with appendix J of this part is demonstrated, the noise generated by the helicopter must be measured at the noise measuring point and under the test conditions prescribed in part B of appendix J of this part, or an FAA-approved equivalent procedure.
[Doc. No. 26910, 57 FR 42854, Sept. 16, 1992]
The noise measurement data required under §36.801 and obtained under appendix H of this part must be corrected to the reference conditions contained in part A of appendix H of this part, and evaluated under the procedures of part C of appendix H of this part, or an FAA-approved equivalent procedure. The noise measurement data required under §36.801 and obtained under appendix J of this part must be corrected to the reference conditions contained in part A of appendix J of this part, and evaluated under the procedures of part C of appendix J of this part, or an FAA-approved equivalent procedure.
[Doc. No. 26910, 57 FR 42854, Sept. 16, 1992]
(a) Compliance with the noise levels prescribed under part D of appendix H of this part, or under part D of appendix J of this part, must be shown for helicopters for which application for issuance of a type certificate in the
primary, normal, transport, or restricted category is made on or after March 6, 1986.
(b) For helicopters covered by this section, except as provided in paragraph (c) or (d)(2) of this section, it must be shown either:
(1) For those helicopters demonstrating compliance under appendix H of this part, the noise levels of the helicopter are no greater than the applicable limits prescribed under section H36.305 of appendix H of this part, or
(2) For helicopters demonstrating compliance under appendix J of this part, the noise level of the helicopter is no greater than the limit prescribed under section J36.305 of appendix J of this part.
(c) For helicopters for which application for issuance of an original type certificate in the primary, normal, transport, or restricted category is made on or after March 6, 1986, and which the FAA finds to be the first civil version of a helicopter that was designed and constructed for, and accepted for operational use by, an Armed Force of the United States or the U.S. Coast Guard on or before March 6, 1986, it must be shown that the noise levels of the helicopter are no greater than the noise limits for a change in type design as specified in section H36.305(a)(1)(ii) of appendix H of this part for compliance demonstrated under appendix H of this part, or as specified in section J36.305 of appendix J of this part for compliance demonstrated under appendix J of this part. Subsequent civil versions of any such helicopter must meet the Stage 2 requirements.
(d) Helicopters in the primary category:
(1) Except as provided in paragraph (d)(2) of this section, for a helicopter for which application for a type certificate in the primary category is made, and that was not previously certificated under appendix H of this part, compliance with appendix H of this part must be shown.
(2) For a helicopter that:
(i) Has a normal or transport type certificate issued under this chapter,
(ii) Has a standard airworthiness certificate issued under this chapter,
(iii) Has not undergone an acoustical change from its type design,
(iv) Has not previously been certificated under appendix H of this part, and
(v) For which application for conversion to the primary category is made, no further showing of compliance with this part is required.
[Doc. No. 26910, 57 FR 42855, Sept. 16, 1992]
(a) All procedures, weights, configurations, and other information or data employed for obtaining the certified noise levels prescribed by this part, including equivalent procedures used for flight, testing, and analysis, must be developed and approved. Noise levels achieved during type certification must be included in the approved airplane (rotorcraft) flight manual.
(b) Where supplemental test data are approved for modification or extension of an existing flight data base, such as acoustic data from engine static tests used in the certification of acoustical changes, the test procedures, physical configuration, and other information and procedures that are employed for obtaining the supplemental data must be developed and approved.
[Amdt. 36-15, 53 FR 16366, May 6, 1988]
(a) If an Airplane Flight Manual or Rotorcraft Flight Manual is approved, the approved portion of the Airplane Flight Manual or Rotorcraft Flight Manual must contain the following information, in addition to that specified under §36.1583 of this part. If an Airplane Flight Manual or Rotorcraft Flight Manual is not approved, the procedures and information must be furnished in any combination of approved manual material, markings, and placards.
(1) For transport category large airplanes and turbojet powered airplanes, the noise level information must be
one value for each takeoff, sideline, and approach as defined and required by appendix C of this part, along with the maximum takeoff weight, maximum landing weight, and configuration.
(2) For propeller driven small airplanes the noise level information must be one value for flyover as defined and required by appendix F of this part, along with the maximum takeoff weight and configuration.
(b) If supplemental operational noise level information is included in the approved portion of the Airplane Flight Manual, it must be segregated, identified as information in addition to the certificated noise levels, and clearly distinguished from the information required under §36.1581(a).
(c) The following statement must be furnished near the listed noise levels:
No determination has been made by the Federal Aviation Administration that the noise levels of this aircraft are or should be acceptable or unacceptable for operation at, into, or out of, any airport. (d) For transport category large airplanes and turbojet powered airplanes, for which the weight used in meeting the takeoff or landing noise requirements of this part is less than the maximum weight established under the applicable airworthiness requirements, those lesser weights must be furnished, as operating limitations in the operating limitations section of the Airplane Flight Manual. Further, the maximum takeoff weight must not exceed the takeoff weight that is most critical from a takeoff noise standpoint.
(e) For propeller driven small airplanes and for propeller-driven, commuter category airplanes for which the weight used in meeting the flyover noise requirements of this part is less than the maximum weight by an amount exceeding the amount of fuel needed to conduct the test, that lesser weight must be furnished, as an operating limitation, in the operating limitations section of an approved Airplane Flight Manual, in approved manual material, or on an approved placard.
(f) For primary, normal, transport, and restricted category helicopters, if the weight used in meeting the takeoff, flyover, or approach noise requirements of appendix H of this part, or the weight used in meeting the flyover noise requirement of appendix J of this part, is less than the certificated maximum takeoff weight established under either §27.25(a) or §29.25(a) of this chapter, that lesser weight must be furnished as an operating limitation in the operating limitations section of the Rotorcraft Flight Manual, in FAA-approved manual material, or on an FAA-approved placard.
(g) Except as provided in paragraphs (d), (e), and (f) of this section, no operating limitations are furnished under this part.
[Doc. 13243, 40 FR 1035, Jan. 6, 1975 as amended by Amdt. 36-10, 43 FR 28420, June 29, 1978; Amdt. 36-11, 45 FR 67066, Oct. 9, 1980; Amdt. 36-13, 52 FR 1836, Jan. 15, 1987. Redesignated and amended by Amdt. 36-14, 53 FR 3540, Feb. 5, 1988; 53 FR 7728, Mar. 10, 1988; Amdt. 36-15, 53 FR 16366, May 6, 1988; 53 FR 18950, May 25, 1988; Amdt. 36-20, 57 FR 42855, Sept. 16, 1992]
(a) This section applies to propeller-driven, small airplanes that --
(1) Are designed for "agricultural aircraft operations" (as defined in §137.3 of this chapter, effective on January 1, 1966) or for dispensing fire fighting materials; and
(2) Have not been shown to comply with the noise levels prescribed under appendix F of this part --
(i) For which application is made for the original issue of a standard airworthiness certificate and that do not have any flight time before January 1, 1980; or
(ii) For which application is made for an acoustical change approval, for airplanes which have a standard airworthiness certificate after the change in the type design, and that do not have any flight time in the changed configuration before January 1, 1980.
(b) For airplanes covered by this section an operating limitation reading as follows must be furnished in the manner prescribed in §36.1581:
Noise abatement: This airplane has not been shown to comply with the noise limits
in FAR Part 36 and must be operated in accordance with the noise operating limitation prescribed under FAR §91.815. [Amdt. 36-11, 45 FR 67066, Oct. 9, 1980. Redesignated by Amdt. 36-14, 53 FR 3540, Feb. 5, 1988; Amdt. 36-18, 54 FR 34330, Aug. 18, 1989] A36.1 Noise certification test and measurement conditions.
A36.3 Measurement of aircraft noise received on the ground.
A36.5 Reporting and correcting measured data.
A36.7 Symbols and units.
A36.9 Atmospheric attenuation of sound.
A36.11 Detailed correction procedures.
Section A36.1 Noise certification test and measurement conditions.
(a) General. This section prescribes the conditions under which aircraft noise certification tests must be conducted and the measurement procedures that must be used to measure aircraft noise during each test conducted on or after April 3, 1978.
(b) Test site requirements. (1) Tests to show compliance with established aircraft noise certification levels must consist of a series of takeoffs and approaches (or stabilized flight path segments thereof) during which measurements must be taken at noise measuring stations located at the measuring points prescribed in section C36.3 of appendix C of this part. Each recorded segment must include measurements throughout the entire time period in which the recorded signal is within 10 dB of PNLTM.
(2) During each test takeoff, simultaneous measurements should be made at the sideline noise measuring stations on each side of the runway and also at the takeoff noise measuring station. However, if test site conditions make it impractical to simultaneously measure takeoff and sideline noise, and if each of the other sideline measurement requirements is met, independent measurements may be made of the sideline noise under simulated flight path techniques. If the reference flight path includes a power cutback before the maximum possible sideline noise level is developed, the reduced sideline noise level which is the maximum value developed by the simulated flight path technique must be the certificated sideline noise value.
(3) If the height of the ground at a noise measuring station differs from that of the nearest point on the runway by more than 20 feet, corrections must be made as prescribed in section A36.5(d) of this appendix.
(4) The location of each noise measuring station must be surrounded by relatively flat terrain having no excessive sound absorption characteristics, such as might be caused by thick, matted, or tall grass, shrubs, or wooded areas.
(5) An airport tower, or other facility, used to obtain required measurements of meteorological conditions at the test site must be approved in accordance with section A36.9(b)(1) of this appendix.
(6) During the period when the flyover noise/time record indicates the noise measurement is within 10 dB of PNLTM, no obstruction that significantly influences the sound field from the aircraft may exist --
(i) For a takeoff, approach, or sideline measuring station, within a conical space above the measuring position (the point on the ground vertically below the microphone), the cone being defined by an axis normal to the ground and by a half-angle 80 degrees from this axis; and
(ii) For a sideline noise measuring station, above the line of sight between the microphone and the aircraft.
(7) A minimum of two noise measuring stations, symmetrically positioned about the test flight track, must be used to define the maximum sideline noise with respect to location and level as required by section C36.3 of appendix C of this part. For turbojet powered aircraft, when approved by the FAA, the maximum sideline noise at takeoff thrust may be assumed to occur at the point (or its approved equivalent) along the extended centerline of the runway where the aircraft reaches 1000 feet (305 meters) altitude above ground level. A height of 1440 feet (439 meters) may be assumed for Stage 1 or Stage 2 four engine airplanes. The altitude of the aircraft as it passes the microphone stations must be within +500 to −0 feet (+150 to −0 meters) of the target altitude. For aircraft powered by other than turbojet engines, the altitude for maximum sideline noise must be determined experimentally.
(c) Weather restrictions. The tests must be conducted under the following atmospheric conditions:
(1) No rain or other precipitation.
(2) Ambient air temperature between 36 degrees F and 95 degrees F (2.2 degrees C and 35 degrees C), inclusively, over that portion of the sound propagation path between the aircraft and a point 10 meters above the ground at the noise measuring station.
(3) Relative humidity and ambient temperature over that portion of the sound propagation path between the aircraft and a point 10 meters above the ground at the noise measuring station is such that the sound attenuation in the one-third octave band centered a 8 kHz is not greater than 12 dB/100 meters and the relative humidity is between 20 and 95 percent, inclusively. However, if the dew point and dry bulb temperature used for obtaining relative humidity are measured with a device which is accurate to within ±0.5 °C, the sound attenuation rate
shall not exceed 14 dB/100 meters in the one-third octave band centered at 8kHz.
(4) Average wind velocity 10 meters above ground is not to exceed 12 knots and the crosswind velocity for the airplane is not to exceed 7 knots. The average wind velocity shall be determined using a thirty-second averaging period spanning the 10 dB down time interval. Maximum wind velocity 10 meters above ground is not to exceed 15 knots and the crosswind velocity is not to exceed 10 knots during the 10 dB down time interval.
(5) No anomalous wind conditions (including turbulence) which will significantly affect the noise level of the aircraft when the noise is recorded at each noise measuring station.
(d) Aircraft testing procedures. -- (1) The aircraft testing procedures and noise measurements must be conducted and processed in an approved manner which yields the noise evaluation measure designated as Effective Perceived Noise Level (EPNL) in units of EPNdB, as prescribed in appendix B of this part.
(2) The aircraft height and lateral position relative to the extended centerline of the runway must be determined by an FAA approved method which is independent of normal flight instrumentation, such as radar tracking, theodolite triangulation, laser trajectography, or photographic scaling techniques.
(3) The aircraft position along the flight path must be related to the noise recorded at the noise measuring stations by means of synchronizing signals at an approved sampling rate. The position of the aircraft must be recorded relative to the runway during the entire time period in which the recorded signal is within 10 dB of PNLTM. Measuring and sampling equipment must be approved by the FAA.
(4) Each takeoff test must meet the conditions of section C36.7 of appendix C of this part.
(5) If a takeoff test series is conducted at weights other than the maximum takeoff weight for which noise certification is requested, the following additional requirements apply:
(i) At least one takeoff test must be conducted at a weight at, or above, the maximum certification weight.
(ii) Each test weight must be within +5 percent or −10 percent of the maximum certification weight.
(6) Each approach test must be conducted with the aircraft stabilized and following a 3.0 degree (7) If an approach test series is conducted at weights other than the maximum landing weight for which certification is requested, the following additional requirements apply:
(i) At least one approach test must be conducted at a weight at, or above, the maximum landing weight.
(ii) Each test weight must exceed 90 percent of the maximum landing weight.
(8) Aircraft performance data sufficient to make the correction required under section A36.5 of this appendix must be recorded at an approved sampling rate using FAA approved equipment.
Section A36.3 Measurement of aircraft noise received on the ground.
(a) General. (1) The measurements prescribed in this section provide the data for determining the one-third octave band noise produced by aircraft during testing at specific noise measuring stations, as a function of time.
(2) Sound pressure level data for aircraft noise certification purposes must be obtained with approved acoustical equipment and measurement practices.
(3) Paragraphs (b), (c), and (d) of this section prescribe the required equipment specifications. Paragraphs (e) and (f) prescribe the calibration and measurement procedures required for each certification test series.
(b) Measurement system. The acoustical measurement system must consist of approved equipment equivalent to the following:
(1) A microphone system with frequency response and directivity which are compatible with the measurement and analysis system accuracy prescribed in paragraph (c) of this section.
(2) Tripods or similar microphone mountings that minimize interference with the sound energy being measured.
(3) Recording and reproducing equipment whose characteristics, frequency response, and dynamic range are compatible with the response and accuracy requirements of paragraph (c) of this section.
(4) Calibrators using sine wave, or pink noise, of known levels. When pink noise (defined in paragraph (e)(1) of this section) is used, the signal must be described in terms of its root-mean-square (rms) value.
(5) Analysis equipment with the response and accuracy which meets or exceeds the requirements of paragraph (d) of this section.
(6) Attenuators used for range changing in sensing, recording, reproducing, or analyzing aircraft sound must be capable of being operated in equal-interval decibel steps with no error between any two settings which exceeds 0.2 dB.
(c) Sensing, recording, and reproducing equipment. (1) The sound produced by the aircraft must be recorded in such a way that the complete information, including time history, is retained. A magnetic tape recorder is acceptable.
(2) The microphone must be a pressure sensitive capacitive type, or its approved equivalent, such as free field type with incidence corrector.
(i) After an adequate "warm-up" period, at least as long as that specified by the equipment manufacturer, the system output for constant acoustical input shall change by not more than 0.3 dB within any one hour nor by more than 0.4 dB within 5 hours.
(ii) The variation of microphone and preamplifier system sensitivity within an angle of ±30 degrees of grazing (60-120 degrees from the normal to the diaphragm) must not exceed the following values:
With the wind screen in place, the variation in sensitivity in the plane of the diaphragm of the microphone system shall not exceed 1.0 dB over the frequency range 45 to 11,200 Hz.
(iii) The free-field frequency response of the microphone system at the reference incidence direction shall lie within an envelope having the following values:
Note:
The requirements of this paragraph may be determined by a pressure response calibration (which may be obtained from an electrostatic calibrator in combination with manufacturer provided corrections) or an anechoic free-field facility. (iv) Specifications concerning sensitivity to environmental factors such as temperature, relative humidity, and vibration must in conformity with the recommendations of International Electrotechnical Commission (IEC) Publication No. 179, entitled "Precision Sound Level Meters" (as incorporated by reference under §36.6 of this part).
(v) If the wind speed exceeds 6 knots, a windscreen must be employed with the microphone during each measurement of aircraft noise. Correction for any insertion loss produced by the windscreen as a function of frequency, must be applied to the measured data and any correction applied must be reported.
(3) If a magnetic tape recorder is used to store data for subsequent analysis, the record/replay system (including tape) must conform to the following:
(i) The electric background noise produced by the system in each one-third octave must be at least 35 dB below the standand recording level, which is defined as that level which is either 10 dB below the 3 pecent harmonic distortion level for direct recording or ±40 percent deviation for frequency modulation (FM) recording.
(ii) At the standard recording level, the corrected frequency response in each selected one-third octave band between 44 Hz and 180 Hz must be flat within ±0.75 dB, and in each band between 180 Hz and 11,200 Hz must be flat within ±0.25 dB.
(iii) If the overall system satisfies the requirements of paragraph (c)(2)(ii) of this section, and if the limitations of the dynamic range of the equipment are insufficient to obtain adequate spectral information, high frequency pre-emphasis may be added to the recording channel with the converse de-emphasis on playback. If pre-emphasis is added, the instantaneously recorded sound pressure level between 800 Hz and 11,200 Hz of the maximum measured noise signal must not vary more than 20 dB between the levels of the maximum and minimum one-third octave bands.
(d) Analysis equipment. (1) A frequency analysis of the acoustic signal must be performed using one-third octave filters which conform to the recommendations of International Electrotechnical Commission (IEC) Publication No. 225, entitled "Octave, Half-Octave, and Third-Octave Band Filters Intended for Analysis of Sounds and Vibrations" (as incorporated by reference under §36.6 of this part).
(2) A set of 24 consecutive one-third octave filters must be used. The first filter of the set must be centered at a geometric mean frequency of 50 Hz and the last filter at 10,000 Hz.
(i) The output of each filter must contain less than 0.5 dB ripple.
(ii) The correction for effective bandwidth relative to the response at the center frequency response for each one-third octave band filter must be determined by measuring the filter response to sinusoidal signals at a minimum of 20 frequencies equally spaced between the two adjacent preferred one-third octave frequencies or by using an approved equivalent procedure.
(3) The analyzer indicating device may be either analog or digital, or a combination of both. The preferred sequence of signal processing is:
(i) Squaring the one-third octave filter outputs;
(ii) Averaging or intergrating; and
(iii) Coverting linear formulation to logarithmic.
(4) Each detector must operate over a minimum dynamic range of 60 dB and perform as
a true-mean-square device for sinusoidal tone bursts having crest factors of at least 3 over the following dynamic range:
(i) Up to 30 dB below full-scale reading must be accurate within (ii) Between 30 dB and 40 dB below full-scale reading must be accurate within (iii) In excess of 40 dB below full-scale reading must be accurate within (5) The averaging properties of the integrator must be tested as follows:
(i) White noise must be passed through the 200 Hz one-third octave band filter and the output fed in turn to each detector/integrator. The standard deviation of the measured levels must then be determined from a large number of samples of the filtered white noise taken at intervals of not less than 5 seconds. The value of the standard deviation must be within the interval 0.48±0.06 dB for a probability limit of 95 percent. (An approved equivalent method may be substituted for this test on those analyzers where the test signal cannot readily be fed directly to each detector/integrator.)
(ii) For each detector/integrator, the response to a sudden onset or interruption of a constant amplitude sinusoidal signal at the respective one-third octave band center, frequency must be measured at sampling times 0.5, 1.0, 1.5, and 2.0 seconds after the onset or interruption. The rising responses must be the following amounts before the steady-state level:
(iii) The falling response must be such that the sum of the decibel readings (below the initial steady-state level) and the corresponding rising response reading are 6.5±1.0 dB, at each sampling time.
(iv) Analyzers using true integration cannot meet the requirements of paragraphs (d)(5)(i), (ii), and (iii) of this section directly, because their overall average time is greater than the sampling interval. For these analyzers, compliance must be demonstrated in terms of the equivalent output of the data processor. Further, in cases where readout and resetting require a dead-time during acquisition, the percentage loss of the total data must not exceed one percent.
(6) The sampling interval between successive readouts shall not exceed 500 milliseconds and its precise value must be known to within ± one (1) percent. The instant in time by which a readout is characterized, shall be the midpoint of the average period. (The averaging period is defined as twice the effective time constant of the analyzer.)
(7) The amplitude resolution of the analyzer must be at least 0.25 dB.
(8) After all systematic errors have been eliminated, each output level from the analyzer must be accurate within (9) The dynamic range capability of the analyzer for display of a single aircraft noise event (in terms of the difference between full-scale output level and the maximum noise level of the analyzer equipment) must be at least 60 dB.
(e) Calibrations. (1) Within the five days before the beginning of each test series, the complete electronic system (as installed in the field, including cables) must be electronically calibrated for frequency and amplitude by the use of a pink noise signal of known amplitudes covering the range of signal levels furnished by the microphone. For purposes of this section, a "pink noise" means a noise whose noise-power/unit-frequency is inversely proportional to frequency at frequencies within the range of 44 Hz to 11,200 Hz. The signal used must be described in terms of its average root-mean-square (rms) values for a nonoverload signal level. This system calibration must be repeated within five days of the end of each test series, or as required by the FAA.
(2) Immediately before and after each day's testing, a recorded acoustic calibration of the system must be made in the field with an acoustic calibrator to check the system sensitivity and provide an acoustic reference level for the analysis of the sound level data. The performance of equipment in the system will be considered satisfactory if, during each day's testing, the variation does not exceed 0.5 dB.
(3) A normal incidence pressure calibration of the combined microphone/preamplifier must be performed with pure tones at each preferred one-third octave frequency from 50 Hz to 10,000 Hz. This calibration must be completed within the 90 days before the beginning of each test series.
(4) Each reel of magnetic tape must:
(i) Be pistonphone calibrated; and
(ii) At its beginning and end, carry a calibration signal consisting of at least a 15 second burst of pink noise, as defined in paragraph (e)(1) of this section.
(5) Data obtained from tape recorded signals are not considered reliable if the difference between the pink noise signal levels, before and after the tests in each one-third octave band, exceeds 0.75 dB.
(6) The one-third octave filters must have been demonstrated to be in conformity with the recommendations of IEC Publication 225 (as incorporated by reference under §36.6 of this part) during the six calendar months preceding the beginning of each test series.
However, the correction for effective bandwidth relative to the center frequency response may be determined for each filter --
(i) By measuring the filter response to sinusoidal signals at a minimum of twenty frequencies equally spaced between the two adjacent preferred one-third octave frequencies; or
(ii) By using an approved alternative technique.
(7) A performance calibration analysis of each piece of calibration equipment, including piston phones, reference microphones, and voltage insert devices, must have been made during the six calendar months preceding the beginning of each day's test series. Each calibration must be traceable to the National Bureau of Standards.
(f) Noise measurement procedures. (1) Each microphone must be oriented so that the diaphragm is substantially in the plane defined by the flight path of the aircraft and the measuring station. The microphone located at each noise measuring station must be placed so that its sensing element is approximately 4 feet above ground.
(2) Immediately before and immediately after each series of test runs and each day's testing, a recorded acoustic calibration of the system prescribed in section A36.3(e)(2) of this appendix must be made in the field to check the acoustic reference level for the analysis of the sound level data. Ambient noise must be recorded for at least 10 seconds and be representative of the acoustical background, including systemic noise, that exists during the flyover test run. During that recorded period, each component of the system must be set at the gain-levels used for aircraft noise measurement.
(3) The mean background noise spectrum must contain the sound pressure levels, which, in each preferred third octave band in the range of 50 Hz to 10,000 Hz, are the averages of the energy of the sound pressure levels in every preferred third octave. When analyzed in PNL, the resulting mean background noise level must be at least 20 PNdB below the maximum PNL of the aircraft.
(4) Corrections for recorded levels of background noise are allowed, within the limits prescribed in §A36.5(d)(3) of this appendix.
Section A36.5 Reporting and correcting measured data.
(a) General. Data representing physical measurements, or corrections to measured data, including corrections to measurements for equipment response deviations, must be recorded in permanent form and appended to the record. Each correction must be reported and is subject to FAA approval. An estimate must be made of each individual error inherent in each of the operations employed in obtaining the final data.
(b) Data reporting. (1) Measured and corrected sound pressure levels must be presented in one-third octave band levels obtained with equipment conforming to the standards prescribed in section A36.3 of this appendix.
(2) The type of equipment used for measurement and analysis of all acoustics, aircraft performance, and meteorological data must be reported.
(3) The atmospheric environmental data required to demonstrate compliance with section A36.1(c) of this appendix, measured throughout the test period under section A36.9(b)(3) of this appendix, must be reported.
(4) Conditions of local topography, ground cover, or events which may interfere with sound recording must be reported.
(5) The following aircraft information must be reported:
(i) Type, model, and serial numbers (if any) of aircraft engines.
(ii) Gross dimensions of aircraft and location of engines.
(iii) Aircraft gross weight for each test run.
(iv) Aircraft configuration, including flap and landing gear positions.
(v) Airspeed in knots.
(vi) Engine performance parameters relevant to noise generation, such as net thrust, engine pressure ratio, exhaust temperatures, and fan or compressor rotational speeds.
(vii) Aircraft flight path (above ground level in feet) determined by an FAA approved method which is independent of normal flight instrumentation, such as radar tracking, theodolite triangulation, laser trajectography, or photographic scaling techniques.
(6) Aircraft speed and position, and engine performance parameters must be recorded at an approved sampling rate sufficient to correct to the noise certification reference conditions prescribed in paragraph (c) of this section. Lateral position relative to the extended centerline of the runway, configuration, and gross weight must be reported.
(c) Noise certification reference conditions. (1) Meteorological conditions. Aircraft position and performance data and the noise measurements must be corrected to the following homogeneous noise certification reference atmospheric conditions:
(i) Sea level pressure of 2116 psf (76 cm mercury).
(ii) Ambient temperature of 77 degrees F (25 degrees C).
(iii) Relative humidity of 70 percent.
(iv) Zero wind.
(2) Aircraft conditions. The reference condition for takeoff is the maximum weight, except as provided in §36.1581(b) of this part. The reference conditions for approach tests consist of --
(i) Maximum landing weight, except as provided in §36.1581(d) of this part;
(ii) Approach angle of 3 degrees; and
(iii) Aircraft height of 394 feet above the ground at the noise measuring station.
(d) Data corrections. (1) Aircraft position and performance data and the noise measurement must be corrected to the noise certification reference conditions as prescribed in paragraph (c) of this section. The measured atmospheric conditions must be those obtained in accordance with section A36.1(c) of this appendix and paragraph (b)(3) of this section. Atmospheric attenuation sound corrections must be made under section A36.9 of this appendix.
(2) The measured flight path must be corrected by an amount equal to the difference between the applicants predicted flight path for the certification reference conditions and the measured flight path at the test conditions. Necessary corrections relating to aircraft flight path or performance may be derived from approved data other than certification test data. The source noise must be corrected from approved data for the difference between measured and reference engine conditions, together with appropriate allowances for sound attenuation with distance. The Effective Perceived Noise Level (EPNL) correction must be less than 2.0 EPNdB for any combination of the following:
(i) The aircraft's not passing vertically above the measuring station.
(ii) Any difference between 394 feet and the actual minimum distance of the aircraft's ILS antenna from the approach measuring station.
(iii) Any difference between the actual approach angle and the noise certification reference approach flight path.
(iv) Any correction of the measured noise levels which accounts for any difference between the test engine thrust or power and the reference engine thrust or power.
Detailed correction requirements are prescribed in section A36.11 of this appendix.
(3) Aircraft sound pressure levels within the 10 dB-down points (described in section B36.9 of appendix B) must exceed the mean background sound pressure levels determined under section A36.3(f)(3) by at least 3 dB in each one-third octave band (or be corrected under an FAA approved method) to be included in the computation of the overall noise level of the aircraft. An EPNL may not be computed or reported from data from which more than four one-third octave bands in any spectrum within the 10 dB-down points have been excluded under this paragraph.
(4) Where more than seven one-third octaves are within 3 dB of the ambient noise levels, a time/frequency interpolation of the noise data shall be performed using an approved procedure.
(5) If equivalent test procedures, different from the reference procedures, are used, the test procedures and all methods for adjusting the results to the reference procedures must be approved by the FAA. The amounts of adjustments must not exceed 16 EPNdB on takeoff and 8 EPNdB on approach, and if the adjustments are more than 8 EPNdB and 4 EPNdB respectively, the resulting numbers must not be within 2 EPNdB of the appropriate appendix C noise levels including tradeoffs.
(e) Validity of results. (1) The test results must produce three mean EPNL values within the 90 percent confidence limits, each value consisting of the arithmetic mean of the corrected noise measurements for all valid test runs at the takeoff, approach, and sideline measuring stations, respectively. If more than one noise measurement system is used at any single measuring station, the resulting data for each test run (after correction) must be averaged as a single measurement. If more than one test site or noise measuring station location is used, each valid test run must be included in the computation of the mean EPNL values and their confidence limits.
(2) The minimum sample size acceptable for each of the three certification measurements (takeoff, approaches, and sideline) is six. The number of samples must be large enough to establish statistically for each of the three mean noise certification levels a 90 percent confidence limit which does not exceed (3) The mean EPNL values and their 90 percent confidence limits obtained by the procedure described in this paragraph must be those by which the noise emission of the aircraft is assessed against the noise certification criteria, and must be reported.
(4) If equivalent procedures are to be used to certificate several airplane configurations of the same type from noise tests of a single airplane, the test procedures and analysis methods must be approved by the FAA. The request for approval must identify the noise measurement test procedures and data base, the airplane configurations, procedures and analysis methods, the method for establishing the 90 percent confidence limit for each noise certification level, and the proposed equivalent procedures.
Section A36.7 Symbols and units.
(a) General. The symbols used in appendixes A and B of this part have the following meanings.
Section A36.9 Atmospheric attenuation of sound.
(a) General. The measured values of the one-third octave band spectra must conform, or be corrected, to the reference-day conditions listed in section A36.5(c) of this appendix. Each correction must account for any differences in the atmospheric attenuation of sound between the test-day conditions and the reference-day conditions along the sound
propagation path between the aircraft and the microphone. Unless the meteorological conditions conform to those prescribed in section A36.1(c) of this appendix, the test data are not acceptable.
(b) Meteorological measurements. (1) The wind velocity, temperature and relative humidity measurements required under this part must be measured in the vicinity of the noise measuring stations. The location of the meteorological measurements must be approved by the FAA as representative of those atmospheric conditions existing near the surface over the geographical area in which aircraft noise measurements are made. In some cases, a fixed meteorological station (such as those found at airports or other facilities) may meet this requirement.
(2) The temperature and relative humidity must be measured from a point 10 meters above the surface at the measuring stations to the altitude of the aircraft, using previously approved equipment and methods.
(3) Meteorological measurements must be obtained within 25 minutes of each noise test measurement. Meteorological data must be interpolated to actual times of each noise measurement.
(c) Attenuation rates. The atmospheric attenuation rates of sound with distance for each one-third octave band from 50Hz to 10,000 Hz must be determined in accordance with the formulations and tabulations of SAE ARP 866A, entitled "Standard Values of Atmospheric Absorption as a Function of Temperatures and Humidity for Use in Evaluating Aircraft Flyover Noise" (as incorporated by reference under §36.6 of this part).
(d) Correction for atmospheric attenuation. (1) EPNL values calculated for measured data must be corrected by the methods prescribed in section A36.11(d) of this appendix whenever --
(i) The ambient atmospheric conditions of temperature and relative humidity do not conform to the reference conditions (77 degrees F. and 70 percent, respectively), or
(ii) The measured takeoff and approach flight paths do not conform to the reference flight paths.
(2) If the atmospheric absorption coefficients do not vary over the PNLTM sound propagation path by more than ± 1.6 dB/1000 ft (± 0.5 dB/100 meters) in the 3150 Hz one-third octave band from the value of the absorption coefficient derived from the meteorological measurement obtained at 10 meters above the surface, the mean of the values of the atmospheric absorption coefficients at 10 meters above the surface and at the altitude of the aircraft at PNLTM may be used to determine the atmospheric attenuation rates for each one-third octave band. The resulting atmospheric attenuation rate may be used to compute the PNLTM correction under section A36.11(d) of this appendix.
(3) If the conditions do not conform to those prescribed in paragraph (d)(2) of this section, the corrections for atmospheric attenuation must be determined by the following layered-atmosphere procedure:
(i) The sound propagation path must be divided into increments no greater than 100 feet in altitude, and the average temperature and relative humidity that exists within each increment at the time of the test must be calculated from the meteorological data required under paragraph (b) of this section.
(ii) Atmospheric attenuation rates must be determined under paragraph (c) of this section for each one-third octave band in each altitude increment.
(iii) The mean attenuation rate over the complete sound propagation path from the aircraft to the microphone must be computed for each one-third octave band from 50 Hz to 10,000 Hz. These rates must be used in computing the corrections required in section A36.11(d) of this appendix.
Section A36.11 Detailed correction procedures.
(a) General. If the test conditions do not conform to those prescribed as noise certification reference conditions under section A36.5 of this appendix, the following correction procedure and requirements apply:
(1) If a positive value results from any difference between reference and test conditions, and appropriate positive correction must be made to the EPNL calculated from the measured data. Conditions which can result in a positive value include:
(i) Atmospheric absorption of sound under test conditions which is greater than the reference;
(ii) Test flight path at an altitude which is higher than the reference; or
(iii) Test weight which is less than maximum certification weight.
(2) If a negative value results from any difference between reference and test conditions, no correction may be made to the EPNL calculated from the measured data, unless the difference results from:
(i) An atmospheric absorption of sound under test conditions which is less than the reference; or
(ii) A test flight path at an altitude which is lower than the reference.
(3) The following correction procedures may produce one or more possible correction values which must be added algebraically to the EPNL calculated as if the tests were conducted completely under the noise certification reference conditions:
(i) The flight profiles must be determined for both takeoff and approach, and 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; however, for approach, the reference profile is prescribed under paragraph (c)(2) of this section.
(ii) The sound propagation paths to the microphone from the aircraft position corresponding to PNLTM are 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 change in sound propagation path length; and
(C) Inverse square law on the change in sound propagation path length. The corrected values of SPL are then converted to PNLT from which must be subtracted PNLTM. The resulting difference represents the correction which must be added algebraically to the EPNL calculated from the measured data.
(iii) The minimum distances from both the test and reference profiles to the noise measuring station must be calculated and used to determine a noise duration correction due to any change in the altitude of aircraft flyover. The duration correction must be added algebraically to the EPNL calculated from the measured data.
(iv) From approved data in the form of curves or tables giving the variation of EPNL with engine thrust or test speed, corrections are determined and must be added to the EPNL (which is calculated from the measured data) to account for noise level changes due to differences between test conditions and reference conditions.
(v) From approved data corrections are determined and must be added algebraically to the EPNL (which is calculated from measured data) to account for noise level changes due to differences between 3 degrees and the test approach angle.
(b) Takeoff profiles. (1) Figure A1 illustrates a typical takeoff profile.
(i) The aircraft begins the takeoff roll at point A, lifts off at point B, and initiates the first constant climb at point C at an angle (ii) The takeoff profile is defined by five parameters -- (A) AB, the length of takeoff roll; (B) (2) If the test conditions do not conform to those prescribed as reference conditions under section A36.5 of this appendix, the corresponding test and reference profile parameters will be different, as shown in Figure A2. The profile parameter changes, identifies as Note:
Under reference atmospheric conditions and with maximum takeoff weight, the gradient of the second constant climb angle ( (3) Figure A3 illustrates portions of the measured and corrected takeoff flight paths including the significant geometrical relationships influencing sound propagation. EF represents the measured second constant flight path with climb angle (c) Approach profiles. (1) Figure A4 illustrates a typical approach profile.
(i) The beginning of the noise certification approach profile is represented by aircraft position G whose vertical projection on the flight track (extended centerline of the runway) is point P. The position of the aircraft should be recorded for a distance OP from the runway threshold O to ensure recording of the entire interval during which the measured aircraft noise is within 10 dB of PNLTM.
(ii) The aircraft approaches at an angle passes vertically over the noise measuring station N at a height of NH, begins the level off at position I, and touches down at position J. The distance ON is prescribed as 6,562 feet (2,000 meters).
(iii) The approach profile is defined by the approach angle and the height NH which are functions of the aircraft operating conditions controlled by the pilot. If the measured approach profile parameters do not conform to the corresponding reference approach parameters (3 degrees and 394 feet, respectively, as shown in Figure A5), corrections, if positive, must be applied to the EPNL calculated from the measured data.
(2) Figure A6 illustrates portions of the measured and reference approach flight paths, including the significant geometrical relationships influencing sound propagation. GI represents the measured approach path with approach angle -- , and GrIr represents the reference approach flight path at lower altitude and approach angle of 3 degrees. Position S represents the aircraft location on the measured approach flight path for which PNLTM is observed at the noise measuring station N, and Sr is the corresponding position on the reference approach flight path. The measured and corrected sound propagation paths are NS and NSr, respectively, which form the same angle λ with their flight paths. Position T represents the point on the measured approach flight path nearest the noise measuring station N, and Tr is the corresponding point on the reference approach flight path. The minimum distances to the measured and reference flight paths are indicated by the lines NT and NTr, respectively, which are normal to their flight paths. NOTE: The reference approach flight path is defined by -- =3 degrees and NH=394 feet. Consequently NTr can also be defined; NTr=393 feet to the nearest foot and is, therefore, considered to be one of the reference parameters.
(d) PNLT corrections. If the ambient atmospheric conditions of temperature and relative humidity are not those prescribed as reference conditions under §A36.5(c) of 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 A3, the spectrum of PNLTM observed at station K for the aircraft at position Q is decomposed into its individual SPLi values.
(i) Step 1. A set of corrected values are then computed as follows:
where SPLi and SPLic are the measured and corrected sound pressure levels, respectively, in the i-th one-third octave band. The first correction term accounts for the effects of change in atmospheric sound absorption where αi and αio are the sound absorption coefficients for the test (determined under section A36.9(d)) and reference atmospheric conditions, respectively, for the i-th one-third octave band and KQ is the measured takeoff sound propagation path. The second correction term accounts for the effects of atmospheric sound absorption on the change in the sound propagation path length where KQc is the corrected takeoff sound propagation path. The third correction term accounts for the effects of the inverse square law on the change in the sound propagation path length.
(ii) Step 2. The corrected values of SPLic are then converted to PNLT and a correction term calculated as follows:
Δ1=PNLT−PNLTM
which represents the correction to be added algebraically to the EPNL calculated from the measured data.
(2) Approach flight path.
(i) The procedure prescribed in paragraph (d)(1) of this section for takeoff flight paths is also used for the approach flight path, except that the value for SPLic relate to the approach sound propagation paths shown in Figure A6 as follows:
where NS and NSr are the measured and reference approach sound propagation paths, respectively.
(ii) The remainder of the procedure is the same as that prescribed in paragraph (d)(1)(ii) of this section, regarding takeoff flight path.
(3) Sideline flight path. The procedure prescribed in paragraph (d)(1) of this section for takeoff flight paths is also used for the sideline flight path, except that the values of SPLic relate only to the measured sideline sound propagation path as follows:
where LX is the measured sideline sound propagation path from station L (Figure A1) to position X of the aircraft for which PNLTM is observed at station L and LXc is the corrected sideline sound propagation path.
(e) Duration corrections. If the measured takeoff and approach flight paths do not conform to those prescribed as the corrected and reference flight paths, under section A36.11 (b) and (c) respectively, it will be necessary to apply duration corrections to the EPNL values calculated from the measured data. Such corrections must be calculated as follows:
(1) Takeoff flight path. For the takeoff flight path shown in Figure A3, the correction term is calculated using the formula --
Δ2 = −7.5 log (KR/KRc)
which represents the correction which must be added algebraically to the EPNL calculated from the measured data. The lengths KR and KRc are the measured and corrected takeoff minimum distances from the noise measuring station K to the measured and the corrected flight paths respectively. A negative sign indicates that, for the particular case of a duration correction, the EPNL calculated from the measured data must be reduced if the measured flight path is at a greater altitude than the corrected flight path.
(2) Approach flight path. For the approach flight path shown in Figure A6, the correction term is calculated using the formula --
Δ 2 = −7.5 log (NT/393)
where NT is the measured approach minimum distance from the noise measuring station N to the measured flight path and 393 feet is the minimum distance from station N to the reference flight path.
(3) Sideline flight path. For the sideline flight path, the correction term is calculated using the formula --
Δ 2 = −7.5 log (LX/LXc)
where LX and LXc are the measured and corrected sideline noise measuring distances, respectively, from the noise measuring station L to the aircraft position X or X (f) Nonstandard location correction. When takeoff and approach noise measurements are conducted at points other than those prescribed in section C36.1 of appendix C, the EPNL value computed from these measurements must be corrected to the value that would have occurred at the prescribed measuring points under one of the following procedures:
(1) Simplified procedure. Unless the amount of adjustment exceeds 8 dB on takeoff or 4 dB on approach, or the correction results in a final EPNL value which is within 1.0 dB of the noise levels prescribed in appendix C of this part, the correction procedures prescribed in paragraphs (d) and (e) of this section may be used. Since this procedure accounts for extrapolation of PNLTM from the close-in measurement station to the prescribed measuring point, the remaining corrections for differences between test and reference conditions, including thrust and airspeed, must be made afterward.
(2) Integrated procedure. If the correction factor exceeds 8 dB on takeoff or 4 dB on approach, or the correction results in a final EPNL value which is within 1.0 dB of the noise levels prescribed in appendix C of this part, the following correction procedure must be used:
(i) Each
(ii) After the measured one half (
[Amdt. 36-9, 43 FR 8739, Mar. 2, 1978, as amended at 44 FR 3031, Jan. 15, 1979; Amdt. 36-15, 53 FR 16367, May 6, 1988; 53 FR 18835, May 25, 1988; 53 FR 51087, Dec. 19, 1988] Sec.
B36.1 General.
B36.3 Perceived noise level.
B36.5 Correction for spectral irregularities.
B36.7 Maximum tone corrected perceived noise level.
B36.9 Duration correction.
B36.11 Effective perceived noise level.
B36.13 Mathematical formulation of noy tables.
Section B36.1 General. The procedures in this appendix must be used to determine the noise evaluation quantity designated as effective perceived noise level, EPNL, under §§36.103 and 36.803. These procedures, which use the physical properties of noise measured as prescribed by appendix A of this part, consist of the following:
(a) The 24 one-third octave bands of sound pressure level are converted to perceived noisiness by means of a noy table. The noy values are combined and then converted to instantaneous perceived noise levels, PNL(k).
(b) A tone correction factor, C(k), is calculated for each spectrum to account for the subjective response to the presence of the maximum tone.
(c) The tone correction factor is added to the perceived noise level to obtain tone corrected perceived noise levels, PNLT(k), at each one-half second increment of time. The instantaneous values of tone corrected perceived noise level are noted with respect to time and the maximum value, PNLTM, is determined.
PNLT(k)=PNL(k)+C(k)
(d) A duration correction factor, D, is computed by integration under the curve of tone corrected perceived noise level versus time.
(e) Effective perceived noise level, EPNL, is determined by the algebraic sum of the maximum tone corrected perceived noise level and the duration correction factor.
EPNL=PNLTM+D
Section B36.3 Perceived noise level. Instantaneous perceived noise levels, PNL(k), must be calculated from instantaneous one-third octave band sound pressure levels, SPL(i,k), as follows:
(a) Step 1. Convert each one-third octave band SPL(i,k), from 50 to 10,000 Hz, to perceived noisiness, n(i,k), by reference to Table B1, or to the mathematical formulation of the noy table given in §B36.13 of this appendix.
(b) Step 2. Combine the perceived noisiness values, n(i,k), found in step 1 by the following formula:
N(k)=n(k)+0.15 [[ n(i,k)]−n (k)]=0.85
n(K)+0.15 where n(k) is the largest of the 24 values of n(i,k) and N(k) is the total perceived noisiness.
(c) Step 3. Convert the total perceived noisiness, N(k), into perceived noise level, PNL(k), by the following formula:
PNL(k)=40.0+33.22 log N(k)
which is plotted in Figure B1. PNL(k) may also be obtained by choosing N(k) in the 1,000 Hz column of Table B1 and then reading the corresponding value of SPL(i,k) which, at 1,000 Hz, equals PNL(k).
Section B36.5 Correction for spectral irregularities. Noise having pronounced irregularities in the spectrum (for example, discrete frequency components or tones), must be adjusted by the correction factor C(k) calculated as follows:
(a) Step 1. Starting with the corrected sound pressure level in the 80 Hz one-third octave band (band number 3), calculate the changes in sound pressure level (or "slopes") in the remainder of the one-third octave bands as follows:
(b) Step 2. Encircle the value of the slope, s(i,k), where the absolute value of the change in slope is greater than 5; that is, where
(c) Step 3. (1) If the encircled value of the slope s(i,k) is positive and algebraically greater than the slope s[(i−1),k], encircle SPL(I,K).
(2) If the encircled value of the slope s(1,k) is zero or negative and the slope s[i−1),k] is positive, encircle (SPL[(i−1),k])
(3) For all other cases, no sound pressure level value is to be encircled.
(d) Step 4. Omit all SPL(i,k) encircled in Step 3 and compute new sound pressure levels SPL'prime;(i,k) as follows:
(1) For nonencircled sound pressure levels, let the new sound pressure levels equal the original sound pressure levels,
SPL'(i,k)=SPL(i,k)
(2) For encircled sound pressure levels in bands 1-23, let the new sound pressure level equal the arithmetic average of the preceding and following sound pressure levels.
SPL'(i,k)=(
(3) If the sound pressure level in the highest frequency band (i=24) is encircled, let the new sound pressure level in that band equal
SPL'(24,k)=SPL(23,k+s(23,k).
(e) Step 5. Recompute new slopes s' (i,k), including one for an imaginary 25-th band, as follows:
(f) Step 6. For i from 3 to 23, compute the arithmetic average of the three adjacent slopes as follows: (g) Step 7. Compute final adjusted one-third octave-band sound pressure levels, SPL' (i,k), by beginning with band number 3 and proceeding to band number 24 as follows:
(h) Step 8. Calculate the differences, F(i,k), between the original and the adjusted sound pressure levels as follows:
F(i,k)=SPL(i,k)−SPL'(i,k)
and note only value greater than one and a half.
(i) Step 9. For each of the 24 one-third octave bands, determine tone correction factors from the sound pressure level differences F(i,k) and Table B2.
(j) Step 10. Designate the largest of the tone correction factors, determined in Step 9, as C(k). An example of the tone correction procedure is given in Table B3.
(k) Tone corrected perceived noise levels PNLT(k) are determined by adding the C(k) values to corresponding PNL(k) values, that is,
PNLT(k)=PNL(k)+C(k)
(l) For any i-th one-third octave band, at any k-th increment of time, for which the tone correction factor is suspected to result from something other than (or in addition to) an actual tone (or any special irregularity other than aircraft noise), an additional analysis may be made using a filter with a bandwidth narrower than one-third of an octave. If the narrow band analysis corroborates that suspicion, then a revised value for the background sound pressure level, SPL'(i,k) may be determined from the analysis and used to compute a revised tone correction factor, F(i,k), for that particular one-third octave band.
(m) Tones resulting from ground-plane reflections in the 800 Hz and lower one-third octave bands may be excluded from the calculation of corrections for spectral irregularities. To qualify for this exclusion, the pseudotones must be clearly identified as not being related to the engine noise. This identification may be made either by comparing measured data with data from a flush
mounted microphone, or by observing the Doppler shift characteristics of the tone during the flyover-noise/time history. Since pseudotones are related to ground reflections, a microphone mounted flush to the ground will yield a spectral shape which can be distinguished from that produced by the 4-foot high microphone at those frequencies which can be related to ground reflection's geometrical relationships. Identification through Doppler shifting (the symmetric variation of frequency with time) can be made because the Doppler frequency variation yields a frequency increase for an approaching signal and a frequency decrease for a receding signal. Pseudotones at frequencies above 800 Hz generally should not yield significant tone corrections. However, for consistency, each tone correction value must be included in the computation for spectral irregularities. While the tone corrections below 800 Hz may be ignored for the spectral irregularity correction, the SPL values must be included in the noy calculation prescribed in section B36.13 of this appendix.
(n) After the value of PNLTM for each flyover-noise/time history, is identified, the frequency for the largest tone correction factor (C(k)) must be identified for the two preceding and the two succeeding, 500-milli-second time intervals, to identify possible tone suppression at PNLTM as a result of band sharing of the tone. If the value of C(k) for PNLTM is less than the average value of C(k) for those five consecutive time intervals, that average value of C(k) must be used to compute a new value for PNLTM.
Section B36.7 Maximum tone corrected perceived noise level. (a) The maximum tone corrected perceived noise level, PNLTM, is the maximum calculated value of the tone corrected perceived noise level, PNLT(k), calculated in accordance with the procedure of section B36.5 of this appendix. Figure B2 is an example of a flyover noise time history where the maximum value is clearly indicated. Half-second time intervals, (b) If there are no pronounced irregularities in the spectrum, then the procedure of §B36.5 of this appendix would be redundant since PNLT(k) would be identically equal to PNL(k). For this case, PNLTM would be the maximum value of PNL(k) and would equal PNLM.
Section B36.9 Duration correction. The duration correction factor D is determined by the integration technique defined by the expression:
[TOP]
§36.1
Applicability and definitions.
[TOP]
§36.2
Special retroactive requirements.
[TOP]
§36.3
Compatibility with airworthiness requirements.
[TOP]
§36.5
Limitation of part.
[TOP]
§36.6
Incorporation by reference.
[TOP]
§36.7
Acoustical change: Transport category large airplanes and turbojet powered airplanes.
[TOP]
§36.9
Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category airplanes.
[TOP]
§36.11
Acoustical change: Helicopters.
[TOP]
§36.101
Noise measurement.
[TOP]
§36.103
Noise evaluation.
[TOP]
§36.201
Noise limits.
[TOP]
§36.301
Noise limits: Concorde.
[TOP]
§36.501
Noise limits.
[TOP]
§36.801
Noise measurement.
[TOP]
§36.803
Noise evaluation and calculation.
[TOP]
§36.805
Noise limits.
[TOP]
§36.1501
Procedures, noise levels and other information.
[TOP]
§36.1581
Manuals, markings, and placards.
[TOP]
§36.1583
Noncomplying agricultural and fire fighting airplanes.
------------------------------------------------------------------------
Frequency (HZ) Change in sensitivity (dB)
------------------------------------------------------------------------
45 to 1,120............................ 1.0
1,120 to 2,240......................... 1.5
2,240 to 4,500......................... 2.5
4,500 to 7,100......................... 4.0
7,100 to 11,200........................ 5.0
------------------------------------------------------------------------
------------------------------------------------------------------------
Frequency (HZ) Change in Tolerance (dB)
------------------------------------------------------------------------
45 to 4,500............................ <plus-minus>1.0
4,500 to 5,600......................... <plus-minus>1.5
5,600 to 7,100......................... +1.5 to -2.0
7,100 to 9,000......................... +1.5 to -3.0
9,000 to 11,200........................ +2.0 to -4.0
------------------------------------------------------------------------
------------------------------------------------------------------------
Symbol Unit Meaning
------------------------------------------------------------------------
ant................... ...................... Antilogarithm to the
Base 10.
C(k).................. dB.................... Tone Correction. The
factor to be added to
PLN(k) to account for
the presence of
spectral irregularities
such as tones at the k-
th increment of time.
d..................... Sec................... Duration Time. The
length of the
significant noise time
history being the time
interval between the
limits of t(1) and t(2)
to the nearest second.
D..................... dB.................... Duration Correction. The
factor to be added to
PNLM to account for the
duration of the noise.
EPNL.................. EPNdB................. Effective Perceived
Noise Level. The value
of PNL adjusted for
both the presence or
discrete frequencies
and the time history.
(The unit EPNdB is used
instead of the unit
dB.)
f(i) or fi............ Hz.................... Frequency. The
geometrical mean
frequency for the i-th
one-third octave band.
F(i,k)................ dB.................... Delta-dB. The difference
between the original
and background sound
pressure levels in the
i-th one-third octave
band at the k-th
interval of time.
h..................... dB.................... dB-Down. The level to be
subtracted from PNLTM
that defines the
duration of the noise.
H..................... %..................... Relative Humidity. The
ambient atmospheric
relative humidity.
(i) or i.............. ...................... Frequency Band Index.
The numerical indicator
that denotes any one of
the 24 one-third octave
bands with geometrical
mean frequencies from
50 to 10,000 Hz.
(k)................... ...................... Time Increment Index.
The numerical indicator
that denotes the number
of equal time
increments that have
elapsed from a
reference zero.
log................... ...................... Logarithm to the Base
10.
log n (a)............. ...................... Noy discontinuity
Coordinate. The log n
value of the
intersection point of
the straight lines
representing the
variation of SPL with
log n.
M(b), M(c)............ ...................... Noy Inverse Slope. The
reciprocals of the
slopes of the straight
lines representing the
variation of SPL with
log n.
n..................... noy................... Perceived Noisiness. The
perceived noisiness at
any instant of time
that occurs in a
specified frequency
range.
n(i, k)............... noy................... Perceived Noisiness. The
perceived noisiness at
the k-th instant of
time that occurs in the
i-th one-third octave
band.
n(k).................. noy................... Maximum Perceived
Noisiness. The maximum
value of all of the 24
values of n(i) that
occurs at the k-th
instant of time.
N(k).................. noy................... Total Perceived
Noisiness. The total
perceived noisiness at
the k-th instant of
time calculated from
the 24-instantaneous
values of n(i, k).
p(b), p(c)............ ...................... Noy Slope. The slopes of
the straight lines
representing the
variation of SPL with
log n.
PNL................... PNdB.................. Perceived Noise Level.
The perceived noise
level at any instant of
time (the unit PNdB is
used instead of the
unit dB).
PNL(k)................ PNdB.................. Perceived Noise Level.
The perceived noise
level calculated from
the 24 values of SPL
(i, k) at the k-th
increment of time. (The
unit PNdB is used
instead of the unit
dB.)
PNLM.................. PNdB.................. Maximum Perceived Noise
Level. The maximum
value of PNL(k) that
occurs during the
aircraft flyover. (The
unit PNdB is used
instead of the unit
dB.)
PNLT.................. PNdB.................. Tone Corrected Perceived
Noise Level. The value
of PNL adjusted for the
presence of spectral
irregularities
(discrete frequencies)
at any instant of time.
(The unit PNdB is used
instead of the unit
dB.)
PNLT(k)............... PNdB.................. Tone Corrected Perceived
Noise Level. The value
of PNL(k) adjusted for
the presence of
discrete frequencies
that occurs at the k-th
increment of time. (The
unit PNdB is used
instead of the unit
dB.)
PNLTM................. PNdB.................. Maximum tone Corrected
Perceived Noise Level.
The maximum value of
PNLT(k) that occurs
during the aircraft
flyover. (The unit PNdB
is used instead of the
unit dB.)
s(i, k)............... dB.................... Slope of Sound Pressure
Level. The change in
level between adjacent
one-third octave band
sound pressure levels
at the i-th band for
the k-th instant of
time.
Δ s(i, k)....... dB.................... Change in Slope of Sound
Pressure Level.
s'(i, k).............. dB.................... Adjusted Slope of Sound
Pressure Level. The
change in level between
adjacent adjusted one-
third octave band sound
pressure levels at the
i-th band for the k-th
instant of time.
s(i, k)............... dB.................... Average Slope of Sound
Pressure Level.
SPL................... dB re 0.0002 microbar. Sound Pressure Level.
The sound pressure
level at any instant of
time that occurs in a
specified frequency
range.
SPL(a)................ dB re 0.002 microbar.. Noy Discontinuity
Coordinate. The SPL
value of the
intersection point of
the straight lines
representing the
variation of SPL with
log n.
SPL(b)................ dB re 0.002 microbar.. Noy Intercept. The
SPL(c)................ intercepts on the SPL-
axis of the straight
lines representing the
variation of SPL with
log n.
SPL(l, k)............. dB re 0.002 microbar.. Sound Pressure Level.
The sound pressure
level at the k-th
instant of time that
occurs in the i-th one-
third octave band.
SPL'(l, k)............ dB re 0.002 microbar.. Adjusted Sound Pressure
Level. The first
approximation to
background level in the
i-th one-third octave
band for the k-th
instant of time.
SPL'(l, k)............ dB re 0.002 microbar.. Background Sound
Pressure Level. The
final approximation to
background level in the
i-th one-third octave
band for the k-th
instant of time.
SPLi.................. dB re 0.002 microbar.. Maximum Sound Pressure
Level. The sound
pressure level that
occurs in the i-th one-
third octave band of
the spectrum for PNL-
TM.
SPLic................. dB re 0.002 microbar.. Corrected Maximum Sound
Pressure Level. The
sound pressure level
that occurs in the i-th
one-third octave band
of the spectrum for
PNLTM corrected for
atmospheric sound
absorption.
t..................... Sec................... Elapsed Time. The length
of time measured from a
reference zero.
t(1), t(2)............ Sec................... Time Limit. The
beginning and end of
the significant noise
time history defined by
h.
Δ t............. Sec................... Time Increment. The
equal increments of
time for which PNL(k)
and PNLT (k) are
calculated.
T..................... Sec................... Normalizing Time
Constant. The length of
time used as a
reference in the
integration method for
computing duration
corrections.
T..................... deg.F................ Temperature. The ambient
atmospheric temperature
α i............. dB/ft................. Test Atmospheric
α i'............ dB/1000 ft............ Absorption. The
atmospheric attenuation
of sound that occurs in
the i-th one-third
octave band for the
measured atmospheric
temperature and
relative humidity.
α io............ dB/ft................. Reference Atmospheric
α io'........... dB/1000 ft............ Absorption. The
atmospheric attenuation
of sound that occurs in
the i-th one-third
octave band for the
reference atmospheric
temperature and
relative humidity.
β................ Degrees............... First Constant Climb
Angle.
ψ................. Degrees............... Second Constant Climb
Angle.
δ............... Degrees............... Thrust Cutback Angles.
ε............. Degrees............... The angles defining the
points on the takeoff
flight path at which
thrust reduction is
started and ended
respectively.
η................. Degrees............... Approach Angle.
θ............... Degrees............... Takeoff Noise Angle. The
angle between the
flight path and noise
path for takeoff
operation. It is
identical for both
measured and corrected
flight paths.
μ.................. Degrees............... Approach Noise Angle.
The angle between the
flight path and the
noise path for approach
operation. It is
identical for both
measured and corrected
flight paths.
Δ l............. EPNdB................. PNLT Correction. The
correction to be added
to the EPNL calculated
from measured data to
account for noise level
changes due to
differences in
atmospheric absorption
and noise path length
between reference and
test conditions.
Δ2.............. EPNdB................. Noise Path Duration
Correction. The
correction to be added
to the EPNL calculated
from measured data to
account for noise level
changes due to the
noise duration because
of differences in
flyover altitude
between reference and
test condition.
Δ3.............. EPNdB................. Weight Correction. The
correction to be added
to the EPNL calculated
from measured data to
account for noise level
changes due to
differences between
maximum and test
aircraft weights.
Δ4.............. EPNdB................. Approach Angle
Correction. The
correction to be added
to the EPNL calculated
from measured data to
account for noise level
changes due to
differences between 3
deg. and the test
approach angle.
Δ AB............ Feet.................. (\1\)
Δβ......... Degrees............... (\1\)
Degrees............... (\1\)
Δγ........
Δδ........ Degrees............... (\1\)
Δα........ Degrees............... (\1\)
Δε...... Degrees............... (\1\)
------------------------------------------------------------------------
\1\Takeoff Profile Changes. The changes in the basic parameters defining
the takeoff profile due to differences between reference and test
conditions.
Flight Profile Identification Positions
------------------------------------------------------------------------
Position Description
------------------------------------------------------------------------
A................................. Start of takeoff roll.
B................................. Liftoff.
C................................. Start of first constant climb.
D................................. Start of thrust reduction.
E................................. Start of second constant climb.
Ec................................ Start of second constant climb on
corrected flight path.
F................................. End of noise certification takeoff
flight path.
Fc................................ End of second constant climb on
corrected flight path.
G................................. Start of noise certification
approach flight path.
Gr................................ Start of noise certification
approach on reference flight path.
H................................. Position on approach path directly
above noise measuring station.
I................................. Start of level off.
Ir................................ Start of level off on reference
approach flight path.
J................................. Touchdown.
K................................. Takeoff noise measuring station.
L................................. Sideline noise measuring station
(not on flight track).
M................................. End of noise type certification
takeoff flight track.
N................................. Approach noise measuring station.
O................................. Threshold of approach end of runway.
P................................. Start of noise type certification
approach flight track.
Q................................. Position on measured takeoff flight
path corresponding to PNLTM at
station K.
Qc................................ Position on corrected takeoff flight
path corresponding to PNLTM at
station K.
R................................. Position on measured takeoff flight
path nearest to station K.
Rc................................ Position on corrected takeoff flight
path nearest to station K.
S................................. Position on measured approach flight
path corresponding to PNLTM at
station N.
Sr................................ Position on reference approach
flight path corresponding to PNLTM
at station N.
T................................. Position on measured approach flight
path nearest to station N.
Tr................................ Position on reference approach
flight path nearest to station N.
X................................. Position on measured takeoff flight
path corresponding to PNLTM at
station L.
Xc................................ Position on corrected takeoff flight
path corresponding to PNLTM at
station L.
------------------------------------------------------------------------
Flight Profile Distances
------------------------------------------------------------------------
Distance Unit Meaning
------------------------------------------------------------------------
AB..................... feet................ Length of Takeoff Roll.
The distance along the
runway between the start
of takeoff roll and lift
off.
AK..................... feet................ Takeoff Measurement
Distance. The distance
from the start of roll
to the takeoff noise
measurement station
along the extended
centerline of the
runway.
AM..................... feet................ Takeoff Flight Track
Distance. The distance
from the start of roll
to the takeoff flight
track position along the
extended centerline of
the runway for which the
position of the aircraft
need no longer be
recorded.
KQ..................... feet................ Measured Takeoff Noise
Path. The distance from
station K to the
measured aircraft
position Q.
KQc.................... feet................ Corrected Takeoff Noise
Path. The distance from
station K to the
corrected aircraft
position Qc.
KR..................... feet................ Measured Takeoff Minimum
Distance. The distance
from station K to point
R on the measured flight
path.
KRc.................... feet................ Corrected Takeoff Minimum
Distance. The distance
from station K to point
Rc on the corrected
flight path.
LX..................... feet................ Measured Sideline Noise
Path. The distance from
station L to the
measured aircraft
position X.
LXc.................... feet................ Corrected Sideline Noise
Path. The distance from
station L to the
corrected aircraft
position Xc.
NH..................... feet................ Aircraft Approach Height.
The vertical distance
between the aircraft and
the approach measuring
station.
NS..................... feet................ Measured Approach Noise
Path. The distance from
station N to the
measured aircraft
position S.
NSr.................... feet................ Reference Approach Noise
Path. The distance from
station N to the
reference aircraft
position Sr.
NT..................... feet................ Measured Approach Minimum
Distance. The distance
from station N to point
T on the measured flight
path.
NTr.................... feet................ Reference Approach
Minimum Distance. The
distance from station N
to point Tr on the
corrected flight path;
it equals 393 feet.
ON..................... feet................ Approach Measurement
Distance. The distance
from the runway
threshold to the
approach measurement
station along the
extended centerline of
the runway.
OP..................... feet................ Approach Flight Track
Distance. The distance
from the runway
threshold to the
approach flight track
position along the
extended centerline of
the runway for which the
position of the aircraft
need no longer be
recorded.
------------------------------------------------------------------------







Table B1--Perceived Noisiness (NOYs) as a Function of Sound Pressure Level
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1/3\ Octave Band Center Frequencies in Hz (c/s)
SPL -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
50 63 80 100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000 6300 8000 10000
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
4 .... .... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... 0.10 ...... 0.10 ...... ...... ......
1 1
1 5 .... .... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... 0.10 0.11 0.10 ...... ...... ...... ......
6 .... .... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... 0.11 0.12 0.11 ...... ...... ...... ......
7 .... .... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... 0.13 0.14 0.13 0.10 ...... ...... ......
8 .... .... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... 0.14 0.16 0.14 0.11 ...... ...... ......
9 .... .... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... 0.10 0.16 0.17 0.16 0.14 ...... ...... ......
10 .... .... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... 0.11 0.17 0.19 0.18 0.16 0.10 ...... ......
11 .... .... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... 0.13 0.19 0.22 0.21 0.18 0.12 ...... ......
12 .... .... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... 0.10 0.14 0.22 0.24 0.24 0.21 0.14 ...... ......
12 .... .... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... 0.11 0.16 0.24 0.27 0.27 0.24 0.16 ...... ......
14 .... .... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... 0.13 0.18 0.27 0.30 0.30 0.27 0.19 ...... ......
15 .... .... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... ...... 0.10 0.14 0.21 0.30 0.33 0.33 0.30 0.22 ...... ......
16 .... .... ...... ...... ...... ...... ...... ...... ...... 0.10 0.10 0.10 0.10 0.10 0.11 0.16 0.24 0.33 0.35 0.35 0.33 0.26 ...... ......
17 .... .... ...... ...... ...... ...... ...... ...... ...... 0.11 0.11 0.11 0.11 0.11 0.13 0.18 0.27 0.35 0.38 0.38 0.35 0.30 0.10 ......
18 .... .... ...... ...... ...... ...... ...... ...... 0.10 0.13 0.13 0.13 0.13 0.13 0.15 0.21 0.30 0.38 0.41 0.41 0.38 0.33 0.12 ......
19 .... .... ...... ...... ...... ...... ...... ...... 0.11 0.14 0.14 0.14 0.14 0.14 0.17 0.24 0.33 0.41 0.45 0.45 0.41 0.36 0.14 ......
20 .... .... ...... ...... ...... ...... ...... ...... 0.13 0.16 0.16 0.16 0.16 0.16 0.20 0.27 0.36 0.45 0.49 0.49 0.45 0.39 0.17 ......
21 .... .... ...... ...... ...... ...... ...... 0.10 0.14 0.18 0.18 0.18 0.18 0.18 0.23 0.30 0.39 0.49 0.53 0.53 0.46 0.42 0.21 0.10
22 .... .... ...... ...... ...... ...... ...... 0.11 0.16 0.21 0.21 0.21 0.21 0.21 0.26 0.33 0.42 0.53 0.57 0.57 0.53 0.46 0.25 0.11
23 .... .... ...... ...... ...... ...... ...... 0.13 0.18 0.24 0.24 0.24 0.24 0.24 0.30 0.36 0.46 0.57 0.62 0.62 0.57 0.50 0.30 0.13
24 .... .... ...... ...... ...... ...... 0.10 0.14 0.21 0.27 0.27 0.27 0.27 0.27 0.33 0.40 0.50 0.62 0.67 0.67 0.62 0.55 0.33 0.15
25 .... .... ...... ...... ...... ...... 0.11 0.16 0.24 0.30 0.30 0.30 0.30 0.30 0.35 0.43 0.55 0.67 0.73 0.73 0.67 0.60 0.36 0.17
26 .... .... ...... ...... ...... ...... 0.13 0.18 0.27 0.33 0.33 0.33 0.33 0.33 0.38 0.48 0.60 0.73 0.79 0.79 0.73 0.65 0.39 0.20
27 .... .... ...... ...... ...... 0.10 0.14 0.21 0.30 0.35 0.35 0.35 0.35 0.35 0.41 0.52 0.65 0.79 0.85 0.85 0.79 0.71 0.42 0.23
28 .... .... ...... ...... ...... 0.11 0.16 0.24 0.33 0.38 0.38 0.38 0.38 0.38 0.45 0.57 0.71 0.85 0.92 0.92 0.85 0.77 0.46 0.26
29 .... .... ...... ...... ...... 0.13 0.18 0.27 0.35 0.41 0.41 0.41 0.41 0.41 0.49 0.63 0.77 0.92 1.00 1.00 0.92 0.84 0.50 0.30
30 .... .... ...... ...... 0.10 0.14 0.21 0.30 0.38 0.45 0.45 0.45 0.45 0.45 0.53 0.69 0.84 1.00 1.07 1.07 1.00 0.92 0.55 0.33
31 .... .... ...... ...... 0.11 0.16 0.24 0.33 0.41 0.49 0.49 0.49 0.49 0.49 0.57 0.76 0.92 1.07 1.15 1.15 1.07 1.00 0.60 0.37
32 .... .... ...... ...... 0.13 0.18 0.27 0.36 0.45 0.53 0.53 0.53 0.53 0.53 0.62 0.83 1.00 1.15 1.23 1.23 1.15 1.07 0.65 0.41
33 .... .... ...... ...... 0.14 0.21 0.30 0.39 0.49 0.57 0.57 0.57 0.57 0.57 0.67 0.91 1.07 1.23 1.32 1.32 1.23 1.15 0.71 0.45
34 .... .... ...... 0.10 0.16 0.24 0.33 0.42 0.53 0.62 0.62 0.62 0.62 0.62 0.73 1.00 1.15 1.32 1.41 1.41 1.32 1.23 0.77 0.50
35 .... .... ...... 0.11 0.18 0.27 0.36 0.46 0.57 0.67 0.67 0.67 0.67 0.67 0.79 1.07 1.23 1.41 1.51 1.51 1.41 1.32 0.84 0.55
36 .... .... ...... 0.13 0.21 0.30 0.40 0.50 0.62 0.73 0.73 0.73 0.73 0.73 0.85 1.15 1.32 1.51 1.62 1.62 1.51 1.41 0.92 0.61
37 .... .... ...... 0.15 0.24 0.33 0.43 0.55 0.67 0.79 0.79 0.79 0.79 0.79 0.92 1.23 1.41 1.62 1.74 1.74 1.62 1.51 1.00 0.67
38 .... .... ...... 0.17 0.27 0.37 0.48 0.60 0.73 0.85 0.85 0.85 0.85 0.85 1.00 1.32 1.51 1.74 1.86 1.86 1.74 1.62 1.10 0.74
39 .... .... 0.10 0.20 0.30 0.41 0.52 0.65 0.79 0.92 0.92 0.92 0.92 0.92 1.07 1.41 1.62 1.86 1.99 1.99 1.86 1.74 1.21 0.82
40 .... .... 0.12 0.23 0.33 0.45 0.57 0.71 0.85 1.00 1.00 1.00 1.00 1.00 1.15 1.51 1.74 1.99 2.14 2.14 1.99 1.86 1.34 0.90
41 .... .... 0.14 0.26 0.37 0.50 0.63 0.77 0.92 1.07 1.07 1.07 1.07 1.07 1.23 1.62 1.86 2.14 2.29 2.29 2.14 1.99 1.48 1.00
42 .... .... 0.16 0.30 0.41 0.55 0.69 0.84 1.00 1.15 1.15 1.15 1.15 1.15 1.32 1.74 1.99 2.29 2.45 2.45 2.29 2.14 1.63 1.10
43 .... .... 0.19 0.33 0.45 0.61 0.76 0.92 1.07 1.23 1.23 1.23 1.23 1.23 1.41 1.86 2.14 2.45 2.63 2.63 2.45 2.29 1.79 1.21
44 .... 0.10 0.22 0.37 0.50 0.67 0.83 1.00 1.15 1.32 1.32 1.32 1.32 1.32 1.52 1.99 2.29 2.63 2.81 2.81 2.63 2.45 1.99 1.34
45 .... 0.12 0.26 0.42 0.55 0.74 0.91 1.08 1.24 1.41 1.41 1.41 1.41 1.41 1.62 2.14 2.45 2.81 3.02 3.02 2.81 2.63 2.14 1.48
46 .... 0.14 0.30 0.46 0.61 0.82 1.00 1.16 1.33 1.52 1.52 1.52 1.52 1.52 1.74 2.29 2.63 3.02 3.23 3.23 3.02 2.81 2.29 1.63
47 .... 0.16 0.34 0.52 0.67 0.90 1.08 1.25 1.42 1.62 1.62 1.62 1.62 1.62 1.87 2.45 2.81 3.23 3.46 3.46 3.23 3.02 2.45 1.79
48 .... 0.19 0.38 0.58 0.74 1.00 1.17 1.34 1.53 1.74 1.74 1.74 1.74 1.74 2.00 2.63 3.02 3.46 3.71 3.71 3.46 3.23 2.63 1.98
49 0.10 0.22 0.43 0.65 0.82 1.08 1.26 1.45 1.64 1.87 1.87 1.87 1.87 1.87 2.14 2.81 3.23 3.71 3.97 3.97 3.71 3.46 2.81 2.18
50 0.12 0.26 0.49 0.72 0.90 1.17 1.36 1.56 1.76 2.00 2.00 2.00 2.00 2.00 2.30 3.02 3.46 3.97 4.26 4.26 3.97 3.71 3.02 2.40
51 0.14 0.30 0.55 0.80 1.00 1.26 1.47 1.68 1.89 2.14 2.14 2.14 2.14 2.14 2.46 3.23 3.71 4.26 4.56 4.56 4.26 3.97 3.23 2.63
52 0.17 0.34 0.62 0.90 1.08 1.36 1.58 1.80 2.03 2.30 2.30 2.30 2.30 2.30 2.64 3.46 3.97 4.56 4.89 4.89 4.56 4.26 3.46 2.81
53 0.21 0.39 0.70 1.00 1.18 1.47 1.71 1.94 2.17 2.46 2.46 2.46 2.46 2.46 2.83 3.71 4.26 4.69 5.24 5.24 4.89 4.56 3.71 3.02
54 0.25 0.45 0.79 1.09 1.28 1.50 1.85 2.09 2.33 2.64 2.64 2.64 2.64 2.64 3.03 3.97 4.56 5.24 5.61 5.61 5.24 4.89 3.97 3.23
55 0.30 0.51 0.89 1.18 1.39 1.71 2.00 2.25 2.50 2.83 2.83 2.83 2.83 2.83 3.25 4.26 4.89 5.61 6.01 6.01 5.61 5.24 4.26 3.46
56 0.34 0.59 1.00 1.29 1.50 1.85 2.15 2.42 2.69 3.03 3.03 3.03 3.03 3.03 3.48 4.56 5.24 6.01 6.44 6.44 6.01 5.61 4.56 3.71
57 0.39 0.67 1.09 1.40 1.63 2.00 2.33 2.61 2.88 3.25 3.25 3.25 3.25 3.25 3.73 4.89 5.61 6.44 6.90 6.90 6.44 6.01 4.89 3.97
58 0.45 0.77 1.18 1.53 1.77 2.15 2.51 2.81 3.10 3.48 3.48 3.48 3.48 3.48 4.00 5.24 6.01 6.90 7.39 7.39 6.90 6.44 5.24 4.26
59 0.51 0.87 1.29 1.66 1.92 2.33 2.71 3.03 3.32 3.73 3.73 3.73 3.73 3.73 4.29 5.61 6.44 7.39 7.92 7.92 7.39 6.90 5.61 4.56
60 0.59 1.00 1.40 1.81 2.08 2.51 2.93 3.26 3.57 4.00 4.00 4.00 4.00 4.00 4.59 6.01 6.90 7.92 8.49 8.49 7.92 7.39 6.01 4.89
61 0.67 1.10 1.53 1.97 2.26 2.71 3.16 3.51 3.83 4.29 4.29 4.29 4.29 4.29 4.92 6.44 7.39 8.49 9.09 9.09 8.49 7.92 6.44 5.24
62 0.77 1.21 1.66 2.15 2.45 2.93 3.41 3.79 4.11 4.59 4.59 4.59 4.59 4.59 5.28 6.90 7.92 9.09 9.74 9.74 9.09 8.49 6.90 5.61
63 0.87 1.32 1.81 2.34 2.65 3.16 3.69 4.06 4.41 4.92 4.92 4.92 4.92 4.92 5.66 7.39 8.49 9.74 10.4 10.4 9.74 9.09 7.39 6.01
64 1.00 1.45 1.97 2.54 2.88 3.41 3.98 4.39 4.73 5.28 5.28 5.28 5.28 5.28 6.06 7.52 9.09 10.4 11.2 11.2 10.4 9.74 7.92 6.44
65 1.11 1.60 2.15 2.77 3.12 3.69 4.30 4.71 5.08 5.66 5.66 5.66 5.66 5.66 6.50 8.49 9.74 11.2 12.0 12.0 11.2 10.4 8.49 6.90
66 1.22 1.75 2.34 3.01 3.39 3.99 4.64 5.07 5.45 6.06 6.06 6.06 6.06 6.06 6.96 9.09 10.4 12.0 12.8 12.8 12.0 11.2 9.09 7.39
67 1.35 1.92 2.54 3.28 3.68 4.30 5.01 5.46 5.85 6.50 6.50 6.50 6.50 6.50 7.46 9.74 11.2 12.8 13.8 13.8 12.8 12.0 9.74 7.92
68 1.49 2.11 2.77 3.57 3.99 4.64 5.41 5.88 6.27 6.96 6.96 6.96 6.96 6.96 8.00 10.4 12.0 13.8 14.7 14.7 13.8 12.8 10.4 8.49
69 1.65 2.32 3.01 3.80 4.33 5.01 5.84 6.33 6.73 7.46 7.46 7.46 7.46 7.46 8.57 11.2 12.8 14.7 15.8 15.8 14.7 13.8 11.2 9.09
70 1.82 2.59 3.28 4.23 4.69 5.41 6.31 6.81 7.23 8.00 8.00 8.00 8.00 8.00 9.19 12.0 13.8 15.8 16.9 16.9 15.8 14.7 12.0 9.74
71 2.02 2.79 3.57 4.60 5.09 5.84 6.81 7.33 7.75 8.57 8.57 8.57 8.57 8.57 9.85 12.8 14.7 16.9 18.1 18.1 16.9 15.8 12.8 10.4
72 2.23 3.07 3.88 5.01 5.52 6.31 7.36 7.90 8.32 9.19 9.19 9.19 9.19 9.19 10.6 13.8 15.8 18.1 19.4 19.4 18.1 16.9 13.8 11.2
73 2.46 3.37 4.23 5.45 5.99 6.81 7.94 8.50 8.93 9.85 9.85 9.85 9.85 9.85 11.3 14.7 16.9 19.4 20.8 20.8 19.4 18.1 14.7 12.0
74 2.72 3.70 4.60 5.94 6.50 7.36 8.57 9.15 9.59 10.6 10.6 10.6 10.6 10.6 12.1 15.8 18.1 20.8 22.3 22.3 20.8 19.4 15.8 12.8
75 3.01 4.06 5.01 6.46 7.05 7.94 9.19 9.85 10.3 11.3 11.3 11.3 11.3 11.3 13.0 16.9 19.4 22.3 23.9 23.9 22.3 20.8 16.9 13.8
76 3.32 4.46 5.45 7.03 7.65 8.57 9.85 10.6 11.0 12.1 12.1 12.1 12.1 12.1 13.9 18.1 20.8 23.9 25.6 25.6 23.9 22.3 18.1 14.7
77 3.67 4.89 5.94 7.66 8.29 9.19 10.6 11.3 11.8 13.0 13.0 13.0 13.0 13.0 14.9 19.4 22.3 25.6 27.4 27.4 25.6 23.9 19.4 15.8
78 4.06 5.37 6.46 8.33 9.00 9.85 11.3 12.1 12.7 13.9 13.9 13.9 13.9 13.9 16.0 20.8 23.9 27.4 29.4 29.4 27.4 25.6 20.8 16.9
79 4.49 5.90 7.03 9.07 9.76 10.6 12.1 13.0 13.6 14.9 14.9 14.9 14.9 14.9 17.1 22.3 25.6 29L4 31.5 31.5 29.4 27.4 22.3 18.1
80 4.96 6.48 7.66 9.85 10.6 11.3 13.0 13.9 14.6 16.0 16.0 16.0 16.0 16.0 18.4 23.9 27.4 31.5 33.7 33.7 31.5 29.4 23.9 19.4
81 5.48 7.11 8.33 10.6 11.3 12.1 13.9 14.9 15.7 17.1 17.1 17.1 17.1 17.1 19.7 25.6 29.4 33.7 36.1 36.1 33.7 31.5 25.6 20.8
82 6.06 7.81 9.07 11.3 12.1 13.0 14.9 16.0 16.9 18.4 18.4 18.4 18.4 18.4 21.1 27.4 31.5 36.1 38.7 38.7 36.1 33.7 27.4 22.3
83 6.70 8.57 9.87 12.1 13.0 13.9 16.0 17.1 18.1 19.7 19.7 19.7 19.7 19.7 22.6 29.4 33.7 38.7 41.5 41.5 38.7 36.1 29.4 23.9
84 7.41 9.41 10.7 13.0 13.9 14.9 17.1 18.4 19.4 21.1 21.1 21.1 21.1 21.1 24.3 31.5 36.1 41.5 44.4 44.4 41.5 38.7 31.5 25.6
85 8.19 10.3 11.7 13.9 14.9 16.0 18.4 19.7 20.8 22.6 22.6 22.6 22.6 22.6 26.0 33.7 38.7 44.4 47.6 47.6 44.4 41.5 33.7 27.4
86 9.05 11.3 12.7 14.9 16.0 17.1 19.7 21.1 22.4 24.3 24.3 24.3 24.3 24.3 27.9 36.1 41.5 47.6 51.0 51.0 47.6 44.4 36.1 29.4
87 10.0 12.1 13.9 16.0 17.1 18.4 21.1 22.6 24.0 26.0 26.0 26.0 26.0 26.0 29.9 38.7 44.4 51.0 54.7 54.7 51.0 47.6 38.7 31.5
88 11.1 13.0 14.9 17.1 18.4 19.7 22.6 24.3 25.8 27.9 27.9 27.9 27.9 27.9 32.0 41.5 47.6 54.7 58.6 58.6 54.7 51.0 41.5 33.7
89 12.2 13.9 16 .0 18.4 19.7 21.1 24.3 26.0 27.7 29.9 29.9 29.9 29.9 29.9 34.3 44.4 51.0 58.6 62.7 62.7 58.6 54.7 44.4 36.1
90 13.5 14.9 17.1 19.7 21.1 22.6 26.0 27.9 29.7 32.0 32.0 32.0 32.0 32.0 36.8 47.6 54.7 62.7 67.2 67.2 62.7 58.6 47.6 38.7
91 14.9 16.0 18.4 21.1 22.6 24.3 27.9 29.9 31.8 34.3 34.3 34.3 34.3 34.3 39.4 51.0 58.6 67.2 72.6 72.0 67.2 62.7 51.0 41.5
92 16.0 17.1 19.7 22.6 24.3 26.0 29.9 32.0 34.2 36.8 36.8 36.8 36.8 36.8 42.2 54.7 62.7 72.0 77.2 77.2 72.0 67.2 54.7 44.4
93 17.1 18.4 21.1 24.3 26.0 27.9 32.0 34.3 36.7 39.4 39.4 39.4 39.4 39.4 45.3 58.6 67.2 77.2 82.7 82.7 77.2 72.0 58.6 47.6
94 18.4 19.7 22.6 26.0 27.9 29.9 34.3 36.8 39.4 42.2 42.2 42.2 42.2 42.2 48.5 62.7 72.0 82.7 88.6 88.6 82.7 77.2 62.7 51.0
95 19.7 21.1 24.3 27.9 29.9 32.0 36.8 39.4 42.2 45.3 45.3 45.3 45.3 45.3 52.0 67.2 77.2 88.6 94.9 94.9 88.6 82.7 67.2 54.7
96 21.1 22.6 26.0 29.9 32.0 34.3 39.4 42.2 45.3 48.5 48.5 48.5 48.5 48.5 55.7 72.0 82.7 94.9 102 102 94.9 88.6 72.0 58.6
97 22.6 24.3 27.9 32.0 34.3 36.8 42.2 45.3 48.5 52.0 52.0 52.0 52.0 52.0 59.7 77.2 88.6 102 109 109 102 94.9 77.2 62.7
98 24.3 26.0 29.9 34.3 36.8 39.4 45.3 48.5 52.0 55.7 55.7 55.7 55.7 55.7 64.0 82.7 94.9 109 117 117 105 102 82.7 67.2
99 26.0 27.9 32.0 36.8 39.4 42.2 48.5 52.0 55.7 59.7 59.7 59.7 59.7 59.7 68.6 88.6 102 117 125 125 117 109 88.6 72.0
100 27.9 29.9 34.3 39.4 42.2 45.3 52.0 55.7 59.7 64.0 64.0 64.0 64.0 64.0 73.5 94.9 109 125 134 134 125 117 94.9 77.2
101 29.9 32.0 36.8 42.2 45.3 48.5 55.7 59.7 64.0 68.6 68.6 68.6 68.6 68.6 78.8 102 117 134 144 144 134 125 102 82.7
102 32.0 34.3 39.4 45.3 48.5 52.0 59.7 64.0 68.6 73.5 73.5 73.5 73.5 73.5 84.4 109 125 144 154 154 144 134 109 88.6
103 34.3 36.8 42.2 48.5 52.0 55.7 64.0 68.6 73.5 78.8 78.8 78.8 78.8 78.8 90.5 117 134 154 165 165 154 144 117 94.9
104 36.8 39.4 45.3 52.0 55.7 59.7 68.6 73.5 78.8 84.4 84.4 84.4 84.4 84.4 97.0 125 144 165 177 177 165 154 125 102
105 39.4 42.2 48.5 55.7 59.7 64.0 73.5 78.8 84.4 90.5 90.5 90.5 90.5 90.5 104 134 154 177 189 189 177 165 134 109
106 42.2 45.3 52.0 59.7 64.0 68.6 78.8 84.4 90.5 97.0 97.0 97.0 97.0 97.0 111 144 165 189 203 203 189 177 144 117
107 45.3 48.5 55.7 64.0 68.6 73.5 84.4 90.5 97.0 104 104 104 104 104 119 154 177 203 217 217 203 109 154 125
108 48.5 52.0 59.7 68.6 73.5 78.8 90.5 97.0 104 111 111 111 111 111 128 165 189 217 233 233 217 203 165 134
109 52.0 55.7 64.0 73.5 78.8 84.4 97.0 104 111 119 119 119 119 119 137 177 203 233 249 249 233 217 177 144
110 55.7 59.7 68.6 78.8 84.4 90.5 104 111 119 128 128 128 128 128 137 189 217 249 267 267 249 233 189 154
111 59.7 64.0 73.5 84.4 90.5 97.0 111 119 128 137 137 137 137 137 158 203 233 267 286 286 267 249 203 165
112 64.0 68.6 78.8 90.4 97.0 104 119 128 137 147 147 147 147 147 169 217 249 286 307 307 286 267 217 177
113 64.6 73.5 84.4 97.0 104 111 128 137 147 158 158 158 158 158 181 233 267 307 329 329 307 286 233 189
114 73.5 78.8 50.5 104 111 119 137 147 158 169 169 169 169 169 194 249 286 329 352 352 329 307 249 203
115 78.8 84.4 97.0 111 119 128 147 158 169 181 181 181 181 181 208 267 307 352 377 377 352 329 267 217
116 84.4 90.5 104 119 128 137 158 169 181 194 194 194 194 194 223 286 329 377 404 404 377 352 286 233
117 90.5 97.6 111 128 137 147 169 181 194 208 208 208 208 208 239 307 352 404 433 433 404 377 307 249
118 97.0 104 119 137 147 158 181 194 208 223 223 223 223 223 256 329 377 433 464 464 433 404 329 267
119 104 111 128 147 158 169 194 208 223 239 239 239 239 239 274 352 404 464 497 497 464 433 352 286
120 111 119 137 158 169 181 208 223 239 256 256 256 256 256 294 377 433 497 533 533 497 464 377 307
121 119 128 147 169 181 194 223 239 256 274 274 274 274 274 315 404 464 533 571 571 533 497 404 329
122 128 137 158 181 194 208 239 256 274 294 294 294 294 294 338 433 497 571 611 611 571 533 433 352
123 137 147 169 194 208 223 256 274 294 315 315 315 315 315 362 464 533 611 655 655 611 571 464 377
124 147 158 181 208 223 239 274 294 315 338 338 338 338 338 388 497 571 655 702 702 655 611 497 404
125 158 169 194 223 239 256 294 315 338 362 362 362 362 362 416 533 611 702 752 752 702 655 533 433
126 169 181 208 239 256 274 315 338 362 388 388 388 388 388 446 571 655 752 806 806 752 702 571 464
127 181 194 223 256 274 294 338 362 388 416 416 416 416 416 479 611 702 806 863 863 606 732 611 497
128 194 208 239 274 294 315 362 388 416 446 446 446 446 446 512 655 752 863 925 925 863 806 655 533
129 208 223 256 294 315 338 388 416 446 478 478 478 478 478 549 702 806 925 991 991 925 863 702 571
130 223 239 274 315 338 362 416 446 478 512 512 512 512 512 588 752 863 991 1062 1062 991 925 752 611
131 239 256 294 338 362 388 446 478 512 549 549 549 549 549 630 806 925 1062 1137 1137 1062 991 606 655
132 256 274 315 362 388 416 478 512 549 588 588 588 588 588 676 863 991 1137 1219 1219 1137 1062 863 702
133 274 294 338 388 416 446 512 549 588 630 630 630 630 630 724 925 1062 1219 1306 1306 1219 1137 925 752
134 294 315 362 416 446 478 549 588 630 676 676 676 676 676 776 991 1137 1306 1399 1399 1306 1219 991 606
135 315 338 388 446 478 512 588 630 676 724 724 724 724 724 832 1062 1219 1399 1499 1499 1399 1306 1062 863
136 338 362 416 478 512 549 630 676 724 776 776 776 776 776 891 1137 1306 1499 1606 1606 1499 1399 1197 925
137 362 388 446 512 549 588 676 724 776 832 832 832 832 832 955 1219 1399 1606 1721 1721 1606 1499 1219 991
138 398 416 478 549 588 630 724 776 832 891 891 891 891 891 1024 1306 1499 1721 1844 1844 1721 1606 1306 1062
139 416 446 512 588 630 676 776 832 891 955 955 955 955 955 1098 1399 1606 1844 1975 1975 1844 1721 1399 1137
140 446 478 549 630 676 724 832 891 955 1024 1024 1024 1024 1024 1176 1499 1721 1975 ...... ...... 1975 1844 1499 1219
141 478 512 588 676 724 776 891 955 1024 1098 1098 1098 1098 1098 1261 1606 1844 ...... ...... ...... ...... 1975 1606 1306
142 512 549 630 724 776 832 955 1024 1098 1176 1176 1176 1176 1176 1351 1721 1975 ...... ...... ...... ...... ...... 1721 1399
143 549 588 676 776 832 891 1024 1098 1176 1261 1261 1261 1261 1261 1448 1844 ...... ...... ...... ...... ...... ...... 1844 1499
144 588 630 724 832 891 955 1098 1176 1261 1351 1351 1351 1351 1351 1552 1975 ...... ...... ...... ...... ...... ...... 1975 1606
145 630 676 776 891 955 1024 1176 1261 1351 1448 1448 1448 1448 1448 1664 ...... ...... ...... ...... ...... ...... ...... ...... 1721
146 676 724 832 955 1024 1098 1261 1351 1448 1552 1552 1552 1552 1552 1783 ...... ...... ...... ...... ...... ...... ...... ...... 1844
147 724 776 891 1024 1098 1176 1351 1448 1552 1664 1664 1664 1664 1664 1911 ...... ...... ...... ...... ...... ...... ...... ...... 1975
148 776 832 955 1098 1176 1261 1448 1552 1664 1783 1783 1783 1783 1783 2048 ...... ...... ...... ...... ...... ...... ...... ...... ......
149 832 891 1024 1176 1261 1351 1552 1664 1783 1911 1911 1911 1911 1911 ...... ...... ...... ...... ...... ...... ...... ...... ...... ......
150 891 955 1098 1261 1351 1448 1664 1783 1911 2048 2048 2048 2048 2048 ...... ...... ...... ...... ...... ...... ...... ...... ...... ......
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

------------------------------------------------------------------------
Level difference Tone correction C,
Frequency f, Hz F, dB dB
------------------------------------------------------------------------
50<ls-thn-eq> f500.............. 1\1/2\*<ls-thn-eq> F/3-\1/2\
F3.
3<ls-thn-eq> F20.. F/6
20<ls-thn-eq> F... 3\1/2\
---------------------------------------
500<ls-thn-eq> f<ls-thn-eq>5,000 1\1/2\*<ls-thn-eq> 2 F/3-1
F3.
3<ls-thn-eq> F20.. F/3
20<ls-thn-eq> F... 6\2/3\
---------------------------------------
5,000 f<ls-thn-eq>10,000........ 1\1/2\*<ls-thn-eq> F/3-\1/2\
F3.
3<ls-thn-eq> F20.. F/6
20<ls-thn-eq> F... 3\1/3\
------------------------------------------------------------------------
*See Step 8.
