Unless otherwise specified, the date to be used for determining the applicability of the appropriate part 36 standards for an aircraft type design is the date on which application for a type certificate was made. An application for type certification is effective for the time periods specified in §21.17(c) of part 21.
(2) Noise related type certification requirements See paragraph 7-8 of Reference G4.
(3) Supplemental type certificates See paragraph 7-8 of Reference G4.
(4) Definitions of terms Section 4 of the preamble of this AC provides definitions of terms (see Table 2) related to the aircraft types and categories within Items (1) – (4) of §36.1(a).
Table 2. Aircraft terminology and categories
AIRCRAFT TERMINOLOGY AIRCRAFT TERMINOLOGY Aircraft Large Aircraft Airplane Small Aircraft Jet Airplane Turboprop Airplane (Note 3) Propeller AIRCRAFT CATEGORIES (Note 1) AIRCRAFT CATEGORIES (Note 1) Airplane Helicopter Acrobatic Normal Commuter Transport Normal Primary Restricted (Note 2) Transport Utility Note 1.— Airplane Categories and Aircraft Classes: Part 1 recognizes a distinction between Airplane Categories (e.g., acrobatic , commuter, normal, primary, restricted , transport and utility) and Aircraft Classes
(e.g., Conventional Takeoff and Landing (CTOL), Vertical Takeoff and Landing (VTOL), Short Takeoff and Landing (STOL), Reduced Takeoff and Landing (RTO L), and Supersonic Transports (SST)). The noise certification requirements contained in part 36 are specified for several Airplane and Helicopter Categories but not for STOL, RTOL, SST (except for Concorde), or VTOL Aircraft Classes.
Note 2.— Restricted Category Propeller-Driven Large Airplanes: Propeller-driven large airplanes that have been type certificated in the restricted category (see §21.25 of part 21) are not required to demonstrate compliance with the requirements of part 36. In the absence of part 36 applicability, an Environmental Assessment is required (see paragraph 7-4 of Reference G4 for additional information).
Note 3.— Turboprop Airplanes: Turboprop-powered airplanes are included under the part 36 requirements applicable to propeller-driven airplanes (i.e., subsonic transport category large airplanes; propeller-driven small airplanes, including acrobatic, normal, restricted, and transport categories; or propeller-driven Page 33
201(a)(2) Aircraft configuration §36.1(b) An applicant’s proposal for an aircraft configuration to be certified under the requirements of part 36 must include any type design changes that may be a result of airworthiness standards testing and analysis, and which would result in acoustical changes. (See §36.1(c) for FAA criteria on when aircraft type design changes represent an acoustical change). If an applicant does not propose the appropriate ai rcraft configuration, additional noise certification testing and analysis may be required.
201(a)(3) Voluntary changes §36.1(c)
(1) Examples of voluntary changes in type design A voluntary change in the configuration of an aircraft means a change in the type design of that aircraft. Examples of voluntary changes in aircraft type design that may affect part 36 certificated noise levels are as follows:
a) increased engine thrust (powe r) to improve aircraft performance;
b) maximum gross weight changes;
c) limitations on operational flap settings related to noise;
d) hardware revisions (e.g., vortex generators, flap configuration, wing tip stabilizers, wing tip fuel tanks, etc.);
e) engine modifications to improve engine performance, accelera tion, deceleration, or surge margin protection;
f) addition of wing or body hardware to improve aerodynamics;
g) external nacelle changes to improve air flow patterns;
h) engine inlet changes to improve ice protection;
i) reduction of engine blade tip clearances to improve inlet flow characteristics, and;
j) modifications to engine /nacelle acoustic treatments.
(2) Acoustical change criteria A voluntary change in the type design of an aircraft that may result in an increase in its certificated noise levels is defined as an “acoustical change.” A type design change that does no t result in an “acoustical change” as defined in section§21.93(b) of part 21 is referred to as a “no acoustical change” (NAC). The numerical criteria used by the FAA in defining an acoustical change for airplanes and helicopters are provided in 101(d) and (e) of this AC and are established to limit the cumulative effects of multiple small changes.
(3) NAC cumulative effects When type design changes result in reduced noise levels, an applicant may elect not to provide the full part 36 substantiation, but instead provide FAA with data a nd/or information to subs tantiate an NAC. However subsequent type design changes may require full part 36 certification because of cumulative acoustical effects.
Example: An applicant proposes a configuration change which will reduce the noise levels by approximately
2.1 dB for the flyover noise measurement point, 1.1 dB for the lateral noise measurement point, and with no Page 34
change in noise level at the approach noise measurement point. FAA verifies that the noise levels were reduced, and the applicant accepts the pre-change configuration certificated noise levels as published in the AFM to apply to this change in type design. The applicant may not make another type design change as an NAC that increases the flyover noise level and the lateral noise level without providing substantiation of the cumulative effects of this type design change on AFM noise certificated levels. Multiple type design changes must be evaluated on a cumulative basis (as a combined single configuration) for each noise measurement point for the purposes of determining whether there is an acoustical change.
(4) NAC approvals FAA may approve results of component laboratory demonstrations, back to-back noise comparisons from ground tests or flight tests of each configuration, acoustical analyses, etc as acceptable for substantiating that an applicant’s proposed changes to an aircraft type design is an NAC. The results from these evaluations must be applicable to an aircraft’s certificated noise levels at the part 36 reference noise measurement points.
(5) Non-standard jet airplane configurations Sections 21.93(b)(2)(i) and (ii) specify exceptions under which certain changes in jet airplane type design are not subject to compliance with part 36 requirements because such configurations are not intended for normal operations, but are typically required for maintenance ope rations (e.g., ferry flights, transporting engines to aircraft that cannot be ferried, etc.).
(6) Time-limited changes Time-Limited engine or nacelle chan ges on jet airplanes for periods of up to 90 days (as specified in §21.93(b)(2)(iii) of part 21) may be necessary for continued airplane operation until maintenance can be performed on the original engines or nacelles that were changed. These changes must comply with applicable airworthiness standards and the maintenance, preventa tive maintenance, rebuilding and alteration inspection requirements of part 43. Such changes do not require co mpliance with part 36 requirements even though they may result in an increase in airplane noise levels, relative to the certificated noise levels. FAA policy (see Federal Register Vol. 64, No. 225, Page 65655, dated November 23, 1999) permits the 90 day period allowed by §21.93(b)(2)(iii)of part 21 to continue to be used af ter December 31, 1999, but only for maintenance-related purposes. It cannot be used for meeting Stage 3 requirements due to lack of an adequate number of spare engines or nacelles, or insufficient number of engines or nace lles to operate a Stage 3 fleet at a given time. Section
21.93(b)(2)(iii) may only be us ed to intermix engines when maintenance is required and no conforming engine or nacelle for the configuration is available.
(7) Special purpose aircraft Type design changes to propeller-driven small airplanes and helicopters do not need to comply with the provisions of part 36 when they are operated for special purposes as specified in §§21.93(b)(3)(i-iv) and §21.93(b)(4) of part
21.
(8) Applicant’s responsibility Pursuant to §21.93(b), an applicant must identify type desi gn changes that affect an aircraft’s certificated noise levels by aircraft serial number and must demonstrat e part 36 compliance for those aircraft. The noise levels approved by the FAA for the modified aircraft must be documented in an FAA Approved AFM or RFM by either a revision to the AFM or RFM (typically an option only available to the aircraft manufacturer), an AFM or RFM Supplement (for Supplemental Type Certificates and Field Approvals), or a Supplemental AFM or RFM (for aircraft that do not have a FAA Approved AFM or RFM). Configurations and modifications for which noise approval is required must be found to comply with applicable airworthiness requirements specified in part 21 as well as the requirements of §36.3 of part 36.
201(a)(4) Airworth iness certificates §36.1(d)
(1) Requirements for Issuance of Airworthiness Certificates An airworthiness certificate is issued for each airplane produced, and is a means of distinguishing (by date of issuance) airplanes within a production run that comply with the noise certification requirements of part 36. Prior to the original issuance of a standard airworthiness certificate (see §21.183 of part 21) and regardless of the date of application for certification, compliance with the regulatory requirements of part 36 (including Appendix B) is required for a transport category large airplane, or for a jet airplane regardless of category (see paragraph 7-11(a) of Reference G4). The following table summarizes the requirements of §36.1(d) of part 36.
Table 3. Requirements of §36.1(d) of part 36 Maximum Airplane Weight Airplane Type Engine Configuration Effective Date of Part 36 Compliance Date for Airplanes With Initial Flight Time on or After 75,000 pounds or less Subsonic All engines December 1, 1969 December 31, 1974 Greater than 75,000 Subsonic Without Pratt &Whitney JT3D engines December 1, 1969 December 1, 1973 Greater than 75,000 Subsonic With Pratt & Whitney JT3D engines December 1, 1969 December 31, 1974 Concorde – all weights Supersonic All engines October 13, 1977 January 1, 1980
(2) “Grandfathered” airplanes Airplane types not identified above are “grandfathered” airplanes and are permitted to continue normal operations without showing compliance with the requirements of part 36. For example, the twin-engine propeller-driven Convair 580 or Douglas DC-3 airplanes that first logged flight time before December 31, 1974, did not have to comply with the noise provisions of part 36 and may have received a standard airworthiness certificate under the provisions of §21.183 of part 21, or may have received a standa rd airworthiness certificate under the provisions of the regulations in effect at the time of certification without compliance with part 36.
201(a)(5) Airworth iness certificates §36.1(e)
(1) Requirements for issuance of airworthiness certificates:
An applicant must show compliance of individual airplanes with the requirements of part 36 prior to issuance of airworthiness certificates, as prescribed in §21.183 or 21.185 of part 21 (see paragraph 7-11 of Reference G4).
2) Commuter category airplanes:
Since airworthiness standards for commuter category airplanes became effective February 17, 1987, (under part 21, Amendment 21-59) there are no airplanes in this category with initial flight time before January 1, 1980. All commuter category airplanes are thus required to show compliance with the noise certification requirements of part 36.
201(a)(6) One-Stage limit §36.1(g) Page 36
(1) In-flight configuration changes:
In-flight changes in an airplane configuration (including changes in maximum gross weight) that could result in multiple certificated noise levels for a given noise meas urement point or stage classification are not permitted.
They are changes in the airplane type design and therefore require a change in operating limitations. A change in maximum gross weight requires an applicant to remove an airplane from service, and comply with the approval procedures of part 43.5 and 43.7. The type design approval procedures under part 21 must be followed if the change does not have prior certification approval.
201(a)(7) Stage 1/ Stage 2 limits §36.1(h)
(1) The Stage 1 noise limits apply to all helicopters for whic h application for a type certificate or a change in type design was made prior to March 6, 1986.
(2) The Stage 2 noise levels apply to all helicopters for which application for a type certificate or a change in type design is made on or after March 6, 1986, with the following exception. For helicopters for which application for issuance of an original type certificate in the 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 which was designed and constructed for, and accepted for operational use by an Armed Force of the U.S. or the U.S. Coast Guard on or before March 6, 1986, it must be shown that the noise levels of the helicopter certificated under the provisions of Appendix H are no greater than Stage 2 levels pl us 2 EPNdB at each measuring point. There is no corresponding provision under Appendix J. The tradeoff provision of H36.305(b) of part 36 may not be used to show compliance with Stage 2 levels plus 2 EPNdB, nor may they be used to increase any noise level beyond these limits. Subsequent civil versions (acoustical changes) must meet the Stage 2 requirements without the extra 2 EPNdB at each measuring point. The tradeoff provisions of H36.305(b) of part 36 may be used in showing stage 2 compliance for these subsequent versions.
(3) Helicopters excepted Helicopters that are designated exclusively for agricultural aircraft operations, as defined in §137.3 of part 137, for dispensing firefighting materials, or for carrying external loads, as defined in §133.1(b) of part 133, are excluded from the noise certification requirements.
(4) Stage 1/Stage 2 A helicopter, with a maximum takeoff weight of 7000 lb (3175 kg) or less, that fails to comply with the Stage 2 noise limit prescribed in J36.305 of part 36 has the alternative to comply with the Stage 2 noise limit of H36.305 of part 36.
Note.— The Appendix J noise limit us es a sound exposure level (SEL) that was defined more stringent by approximately 2 dB than the corresponding average of the three Appendix H noise limits in EPNL. However, this is no guarantee that subsequent Appendix H noise ce rtification testing will comply, especially for a military helicopter seeking civil certification.
201(a)(8) Date of application §36.2
(1) Requirements
a) Section 36.2 specifies the applicable part 36 requirements to be those in effect on the date of application for the a) aircraft type certificate or b) change in type design. If the time interval between application for the type certificate (or change in type design ) and the issuance of the type certif icate (or amended or supplemental Page 37
type certificate) exceeds 5 years, the applicable part 36 requirements are those in effect, on a date to be selected by the applicant, not earlier than 5 years before the date of issuance of the type certificate, amended type certificate, or supplemental type certificate.
b) Section 36.2(c) permits the applicant to elect to demonstrate compliance with a later part 36 standard than is required by §36.2(a) or (b). For the purposes of §36.2, “standard” refers to any of the requirements contained in part 36. As specified in §§36.2(c)(1) and (2), an applicant’s election of a later standard is subject to FAA approval, and the election must include standards adopted between the date of application and the effective date of the standard that the applicant has elected to comply with. Thus, an applicant’s election to demonstrate compliance with a particular later standard would also require that compliance be demonstrated with all other part 36 standards (applicable to the aircraft type) ad opted between the date of application and the effective date of the standard that the appli cant has elected to comply with. Furt her, in accordance with §36.2(c)(3), the FAA may require compliance with other standards that were adopted after the date of the elected standard.
For the purposes of §36.2(c)(3), “other standards” refers to other part 36 standards. For example, if the compliance standard elected under §36 .2(c)(3) had later been revised, the FAA may determine that it is appropriate for compliance to be demonstrated with the revised standard. Such a determination would also require that compliance be demonstrated with all other part 36 standards (applicable to the aircraft type) adopted between the date of application and the effective date of the standard that the FAA has determined to be the appropriate compliance basis.
201(a)(9) Airworth iness compatibility §36.3
(1) Requirements Aircraft certification tests and analyses must be conducted using configurations, procedures and information that are consistent with the airworthiness re gulations applicable to that aircraft. For example, noise tests or analyses may not be conducted with landing flap settings that could not meet the applicable airworthiness regulation requirements.
201(a)(10) Limitations of part §36.5
(1) Scope of part 36 regulation Part 36 requires compliance with U.S. Government noise standards for aircraft type and airworthiness certification but does not include noise standards related to aircraft operations, such as is provided in part 91. Part 36 certificated noise levels are achieved using procedures that can be duplicated practicably in normal operations by flight crews with safe reserves of thrust (power) and speed. Public Law 103-272 (Reference G2), mandates that the Administrator of the FAA prescribe standards to measure and evaluate aircraft noise. Under this law, an original type certificate may be issued for an aircraft for which substantial noise abatement can be achieved only after the FAA Administrator prescribes standards and regulations that apply to that aircraft. Consideration must be given to relevant information on aircraft noise, consultations with appropriate US and State authorities, whether the standards or regulations are consistent with the highest degree of safety and are economically reasonable, technologically practical, and appropriate for the type of aircraft to which they apply.
(2) Compatability with ICAO Annex 16 Standards Part 36 does not contain the Annex allowance to depart from the required reference procedures specified in Annex chapters. For example, §3.6.1.4 of Chapter 3 of Annex 16 permits the certificating authority to approve reference procedures that are different from those contained in §§ 3.6.2 and 3.6.3 of Annex 16, when design characteristics of an airplane would prevent flight from being conducted in accordance with §§ 3.6.2 and 3.6.3 of Annex 16. The FAA recognizes that there may be a need for changes to the specified reference procedures when part 36 may not be appropriate for a particular airplane when design characteristics of an airplane would prevent flight from being Page 38
conducted in accordance with the reference procedures described in part 36. In cases where part 36 is not appropriate, the rulemaking process, which includes a public comment period, would be followed to develop an appropriate noise certification standard . Thus, the main difference between th e U.S. and ICAO requirements is that under part 36, the reference procedures would be changed through the rulemaking process rather than solely at the discretion of the certificating authority.
201(a)(11) Configuration consistency §36.7(c)
(1) Quietest airworthiness approved configuration This requirement was established to show that an acoustical change resulting from an approved type design change must be determined consistently. The FAA policy does not require an applicant to determine the quietest airworthiness approved configuration at the flyover or lateral noise measurement points by noise measurement and evaluation. However, FAA requires consistent evaluations between derivative and originally certificated configurations. For example, an applicant might choose an approved takeoff flap setting of 5 degrees. Later a type design change may be requested that would increase the flyover and lateral noise levels (an acoustical change).
The FAA may not require the applicant to measure and evaluate all airworthiness approved takeoff flap settings
(e.g., 0, 1, 2, 5, 10 degrees) to determine the quietest configuration, but may, in this example, require appropriate evaluations for a flap setting of 5 degrees.
201(a)(12) Dual stage certification §36.7(e)
(1) “Dual-Stage” certificated airplanes Some older airplane models have been certificated to Stage 2 for one configuration and to Stage 3 for another configuration (e.g., airplane takeoff flap setting or maximum allowable gross weights). These airplanes are classified as “Dual-Stage” certificated airplanes. No new dual certifications will be considered.
201(a)(13) Exempt helic opter modifications §36.11 Modifications excluded from compliance with part 36, as listed in part 21, §21.93(b)(4)(ii) “Classification of Changes in Type Design” include:
a) addition or removal of external equipment (This means any instrument, mechanism, part, apparatus, appurtenance, or accessory that is att ached to or extends from the helicopter exterior but is not used nor is intended to be used in operating or controlling a helicopter in flight and is not part of an airframe or engine.);
b) changes in the airframe made to accommodate the addition or removal to fac ilitate the use of external equipment, to provide for an external load attaching m eans, to facilitate the safe operation of the helicopter with external equipment mounted to, or external loads carried by, the helicopter;
c) reconfiguration of the helicopter by the addition or removal of floats and skis;
d) flight with one or more doors and/or windows removed or in an open position; or
e) any changes in the operational limitations on the helicopter as a consequence of the addition or removal of external equipment, floats, and skis, or flight operations with doors and/or windows removed or in an open position.
201(a)(14) Helicopter compliance with part 36 §36.11(a) Page 39
(1) Equivalent procedures Subject to prior approval by the FAA, equivalent procedures may be used to measure, evaluate and calculate noise levels (see 1(c) of the preamble of this AC). Some commonly used equivalent procedures relating to helicopter noise certification are included in Chapters 4 and 6 of this AC.
(2) Noise level tradeoffs Tradeoffs between the adjusted noise levels for flyover, takeoff and approach defined in H36.305(b) of part 36 may be used to show compliance with the maximum noise levels (noise limits) of Appendix H of part 36. Since Appendix J of part 36 only includes a flyover procedure, no tradeoff is possible.
(3) Compliance The procedure used to show compliance under Appendix H or Appendix J of part 36 must follow the applicable parts of the regulation. Compliance with the maximum noise levels (noise limits) prescribed in H36.305 or J36.305 of part 36 must be shown.
201(a)(15) Noise limits §36.11(b)
(1) Stage 1 helicopters The maximum noise levels (noise limits) associated with a Stage 1 helicopter certificated under Appendix H of part 36 after a change in type design are dependent on the noise levels of the original Stage 1 helicopter. Unless the Stage 1 helicopter after the change meets the Stage 2 maximum noise levels (noise limits), or Stage 2+ 2 EPNdB levels at each measurement point, it will be necessary to show that the helicopter has no increase in the noise levels at any of the measurement points. This will require determination of the noise levels associated with the original Stage 1 helicopter using Appendix H procedures. If this is not possible an applicant must obtain FAA approval for another procedure.
201(a)(16) Stage 2 helicopters §36.11(c)
(1) Helicopter under 7000 lb (3175 kg) If after a change in type design a helicopter previously certificated under Appendix J of part 36, fails to meet the Appendix J Stage 2 maximum noise levels (noise limits) prescribed in J36.305 of part 36 an applicant may attempt to show compliance by electing the use of Appendix H procedures and the Appendix H Stage 2 maximum noise levels (noise limits) specified in H36.305 of part 36.
(2) Noise levels Section 36.11 requirements apply to helicopters certificated under both Appendix H and Appendix J of part 36.
201(b) Subpart B- Transport Category Large Airplanes and Jet Airplanes 201(b)(1) Noise measur ement and evaluation §36.101
(1) Appendix A Page 40
Appendix A prescribes methodologies for conducting airplane noise certification tests and for measurement and evaluation of noise data for comparison with maximum noise levels specified in Appendix B (see Note 1). Specific requirements include:
a) specifications of various physical and environmental conditions under which airplane noise certification measurements are permitted; these conditions are related to the noise test site, wind velocity/direction and atmospheric sound attenuation;
b) procedures for measuremen t of atmospheric parameters;
c) methods for synchronization of airplane position and performance measurements with noise measurements;
d) specifications for noise certification measurement and analysis systems (see Note 2);
e) methods to calculate atmospheric sound attenuation coefficients and effective perceived noise level (in units of EPNdB);
f) methods for adjustment of measured flight test data to reference conditions;
g) nomenclature for symbols and units; and
h) specification of data to be reported to FAA.
Note 1.— Part 36 Appendix A requirements are nearly identical to those of Appendix 2 of Annex 16 Volume 1, Amendment 7. Subsequent changes to Annex 16 Volume 1 after Amendment 7 have not created any significant differences between the requirements of part 36 Appendix A and Annex 16 Volume 1 Appendix 2 at the time of publication of this AC.
Note 2.— Some provisions of Appendix A may also apply to the noise certification of helicopters as prescribed in Appendix H of part 36.
(2) Equivalent procedures Equivalent Procedures are described in 1(c) of the introductory purpose section of this AC. Section 402 of this AC identifies several potential applications of equivalent procedures for jet and heavy prop airplanes. The ICAO ETM (Reference G5) also provides general and technical guidance on equivalent procedures that have been accepted as a technical means for demonstrating complian ce with the noise certificatio n requirements of ICAO Annex 16, Volume 1. Equivalent procedures provided in the ICAO ETM are incorporated into this AC to the extent applicable to the U.S. regulations.. FAA has not approved these procedures for any current or future aircraft noise certification actions. (See Suppl emental Information Items in Subpart O, §1501, regarding the FAA’s approval process for equivalent procedures).
(3) Applicant’s responsibility Applicants must prepare noise compliance demonstration plans for FAA approval that include proposed methods for compliance with the requirements of B36.1 of part 36. Equivalent procedure proposals in these plans must include substantiation of their technical validity and feasibility of application to the airplane type for which noise certification is requested. (See Subpart O §1501, Supplem ental Information, of part 36 for noise compliance demonstration plan documentation requirements.)
201(b)(2) Noise measurement constraints §36.103(a) Page 41
(1) Noise measurement points The locations of test noise measurement points frequently do not coincide with the reference noise measurement point locations specified in B36.3 of part 36. For example, locations of flyover noise measurement points may be subject to test site anomalies that would make it impractical to set up microphones at the reference locations. An applicant that has an approved equivalent procedure to measure airplane noise data for generation of NPD plots using the Flight Path Intercept procedure may select test noise measurement points (particularly the flyover point) so as to optimize the noise recording system signal-to-noise ratios.
(2) Equivalent procedures The FAA does not consider equivalencies that modifies reference flight conditions (see 201(a)(10) paragraph 2 of this AC) without following public process.
(3) General approved flight test procedures, principles, methods and flight crew operational practices are included in AC 25-7A, Flight Test Guide (Reference G3).
201(b)(3) Flight manual statement of Chapter 4 or Chapter 5 equivalency §36.105, §36.106 The FAA is not authorized to approve aircraft co mpliance with Annex 16, Volume 1 Noise Standards.
(Reference G7). This is the responsibility of the foreign airworthiness authority involved. FAA participation is limited to witnessing tests and reviewing data. For the cases where Stage 3 compliance has been demonstrated it is permissible, but not a requirement, to insert the statement in 201(d) s ection 36.1581(a)(8) of this AC. In those cases where Stage 4 compliance has been demonstrated, the following statement must be included in the AFM or operations manual:
“Certification Noise Levels The following noise levels comply with part 36, Appendix B, Stage 4 maximum noise level requirements and were obtained by analysis of approved data from noise tests conducted under the provisions of part 36, Amendment 36-XX (insert part 36 amendment to which the airplane was certificated). The noise measurement and evaluation procedures used to obtain these noise levels are considered by the FAA to be equivalent to the Chapter 4 noise level required by the International Civil Aviation Organization (ICAO) in Annex 16, Volume I, Appendix 2, Amendment 7, effective March 21, 2002.”
Similarly, if the compliance demonstration has been demonstarted for Stage 5, the following statement must be included in the AFM or operations manual:
“Certification Noise Levels:
The following noise levels comply with part 36, Appendix B, Stage 5 maximum noise level requirements and were obtained by analysis of approved data from noise tests conducted under the provisions of part 36, Amendment [insert part 36 amendment number to which the airplane was certificated]. The noise measurem ent and evaluation procedures used to obtain these noise levels are considered by the FAA to be equivalent to the Chapter 14 noise levels required by the International Civil Aviation Organization (ICAO) in Annex 16, Volume 1, Appendix 2, Amendment 11-B, applicable January 1, 2015.” [Incorporated by reference, see § 36.6].
201(c) Subpart H – Helicopters 201(c)(1) Noise limits §36.805(c) Page 42
(1) Stage 1 helicopter If §36.805(c) applies, then noise testing will lead to one of the following:
a) The helicopter is demonstrated to be a Stage 2 helicopt er: the tradeoff provisions in H36.305(b) of part 36 may be used to demonstrate compliance with the Stage 2 noise level requir ement. The certificated helicopter is not designated as a first civil version, instead the certificated helicopter is designated as a Stage 2 helicopter;
b) The helicopter is demonstrated to be a Stage 1 helicopter via the “Stage 2 + 2 EPNdB” noise limits specified in H36.305(a)(1)(ii) of part 36 and is consequently designated as the first civil version. The trade provisions in H36.305(b) of part 36 may not be used for a first civil version; or
c) The helicopter fails to demonstrate compliance with the (Stage 2 + 2) noise limits specified in H36.305(a)(1)(ii) of part 36: The helicopter will be denied a type certificate until such time that the helicopter, modified as necessary, successfully demonstrates compliance with at least the requirements for a first civil version outlined above in outcome (b). The helicopter fails to demonstrate compliance if one or more of the demonstrated Appendix H noise levels exceeds the corresponding noise level limit or that flight procedure and the helicopter does not ot herwise meet the Stage 2 limits (note: a helicopter may exceed the Stage 1 limit for a given flight procedure and yet achieve St age 2 compliance through the use of tradeoffs).
(2) Change in type design If an applicant has substantiated that a proposed change in type design (as designated in §21.93) would be less noisy or no noisier than the (parent) first civil version helicopter, no additional demonstration of compliance with part 36 is required. The derivative helicopter remains a first civil version. The applicant may elect to:
a) carry forward the parent’s noise numbers to the rotorcraft flight manual of the derived version; or
b) voluntarily noise test the derivative helicopter in or der to substantiate lower noise certification levels.
However, if the derivative helicopter is found to be a Stage 2 helicopter as a result of the voluntary noise test, and if the applicant chooses to certify the derivative helicopter as a Stage 2 helicopter, that derivative helicopter is no longer classified as a first civil version.
(3) Subsequent civil version The §36.805(c) requirement for a subsequent civil version applies only to a helicopter previously designated as a first civil version. A subsequent civil version (unless otherwise excepted under §21.93(b)(4) from the acoustical change requirements) is:
a) any change in type design of the first civil version that would result in one or more of the noise certification levels of the subsequent civil version that are greater than the corresponding noise certification levels of the first civil version; or
b) any change in the first civil version that is suffic ient to require a new type certificate (as provided in §21.19).
As specified in §36.805(c), a subsequent civil version must comply with the Stage 2 noise limits.
201(d) Subpart 0 – Operating Li mitations; and Information Page 43
201(d)(1) Procedures, noise levels, and other information §36.1501 The following types of documentation may be required in implementation of an aircraft (airplane or rotorcraft) noise certification process.
(1) Noise certification plans Applicant noise certification plans should be provided to FAA in the early stages of an aircraft program and contain specific types of information including proposals for the methodology an applicant intends to use to certify a given type of aircraft. These plans, when approved, establish an aircraft’s noise certification basis under part
36. When an aircraft program involves agreements between FAA and foreign certificating authorities, these plans may specify an aircraft’s noise certification basis under both part 36 and the noise regulation used by the foreign authority (e.g., ICAO Annex 16, Volume 1).
Noise certification plans must include the following types of information:
a) an overview of the contents of a forthcoming noise compliance demonstration plan and noise certification report;
b) description of applicable noise certification regulati ons and the tests, reports, data submittals and flight manual pages planned to complete an aircraft noise certification process;
c) description of conformity requirements;
d) DERs and other cognizant personnel to be involved in the aircraft noise certification process;
e) milestone schedule of key events; and
f) miscellaneous information (e.g., acronyms, organizational codes, etc.).
2) Noise compliance demonstration plans (aircraft flight test) Noise compliance demonstration plans contain the specific methodology (including equivalent procedures) by which an applicant proposes to establis h compliance of a specific aircraft conf iguration with applicable part 36 requirements. These plans must define the information, data, and procedures that an applicant proposes in order to comply with the requirements of part 36. After approval by FAA, flight tests specified in this plan are included as a part of the Type Inspection Authorization (TIA) used to fulfill requirements for TC, STC, and amended TC certification.
Noise compliance demonstration plans must include the following types of information:
a) introduction: identify applicable part 36 requirements and aircraft noise certification basis, including part 36 amendment level;
b) aircraft description: type, model, engines, propellers/rotors, test aircraft serial numbers, engine ratings, engine nacelle acoustic treatments, aircraft gross dimensions (including propeller and/or rotor diameter), airplane engine and ILS antenna locations, aircraft/engine conformity);
c) noise certification methodology: test concepts and equivalent procedures, plans for determining airplane engine spooldown characteristics and airframe noise, aircraft/engine performance substantiation, estimated reference conditions including airspeeds, th rust (power) reduction distances, altitudes, thrust (power) settings, methods for determination of EPNL r values and 90% confidence limits, and flight manual format;