(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;
d) test description: test site location and characteristics (e.g., topography, ground cover and obstructions), location of noise measurement points, weather constraints, aircraft configuration including flap settings, airbrake and landing gear positions, APU Operation, conditions of pneumatic bleeds and power/takeoffs, test matrix, including weights, target altitudes, airspeeds, engine thrust (power), and test tolerances;
e) measurement system components and procedures including calibration procedures : acoustical, meteorological, time/space position, aircraft/engine performance;
f) data evaluation procedures including calibration and data processing : approval status of data processing software and version level, adjustment and normalization procedures (acoustical, meteorological, time/space position, and airplane engine performance);
g) aircraft certification schedule, including noise certification and TC dates: flight test plans should be submitted to FAA 60 days prior to start of testing. If new and novel equivalent procedures are proposed, or exemptions are required, then submittal of test plans earlier than 60 days prior to the start of testing may be necessary;
h) references;
i) a listing of all equivalent procedures utilized: for example, flight path intercept procedure;
(3) Noise compliance demonstration plans (airplane families) Noise certification of airplane families (derived versions) often require FAA approval of equivalent procedures involving measurement and evaluation of static engine noise test data as described in Chapter 4 of this AC (402(a)(2) for jets and 402(b)(2) for heavy props), in addition to the information listed in Item (2), above. These procedures include projection of static engine noise test data for development of flyover, lateral, and approach NPD plots that define differences between the airplanes used for the original noise certification flight test and a derived version (see Note 1). When use of static engine noise data is proposed, test plans must also be submitted to FAA and either integrated into the basic noise compliance demonstration plan, or submitted to FAA as separate plans and referenced in the basic plan.
Static engine noise test plans must include the following information:
a) engine description: type, model, test engine serial numbers, nacelle acoustic treatments, engine conformity requirements;
b) test description : test facility, engine installation, turbul ence control screen configuration, weather constraints, acoustical and meteorol ogical measurement points, bleed schedules, test run matrix and sequence including thrust (power) settings and test tolerances;
c) measurement system components and procedures including calibration procedures : acoustical, meteorological, engine performance;
d) data evaluation procedures including calibration, data processing, adjustment and normalization procedures: acoustical, meteorological, engine performance;
e) schedules: static noise test, noise certification and TC dates;
f) references; and
g) a listing of all equivalent procedures utilized.
Note.— Applicants may also generate separate static test plans in cases where development of airplane families is anticipated but not yet formalized and there is opportunity to obtain static engine noise data (because of engine availability) for future noise certification applications.
(4) Noise compliance demonstration plans (analytical methods) For certain aircraft type design changes (e.g., weight/thrust, airframe design changes and thrust (power) reduction distances or minor changes in engine components or acoustical treatments), applicants may propose using analytical equivalent procedures to derive noise increments to an aircraft’s certificated noise levels (see 402(a)(2) of this AC for jets and 402(b)(2) of this AC for heavy props) as applicable to the type of aircraft being certificated) or to demonstrate a no acoustical change (NAC) between the original certificated aircraft and the derived version.
Noise compliance demonstration plans must include the following information:
a) aircraft description: type, model, , engines, propellers/rotors;
b) description of type design changes;
c) noise certification methodology : overall concepts, description/substantiation of analytical equivalent procedures or methods of assessment of NAC aircraft reference conditions, methods for determination of EPNLr and 90% confidence limit values;
d) aircraft certification schedules; and
e) references.
(5) DER “raw data” reports FAA Order 8110.37E (Reference G6) specifies that Acoustical Designated Engineering Representatives (DERs) may, within the limits of their authority (defined in their letter of appointment) and with prior FAA approval, witness noise certification tests condu cted in accordance with FAA approv ed noise compliance demonstration plans.
In cases where tests are witnessed by DERs, the FAA may require the following information to validate that tests are being conducted in accordance with approved plans.
a) test event log: includes event times and conditions, nominal engine thrusts (powers) and thrust (power) stability, atmospheric conditions, airspeeds and deviations relative to target speeds, valid and invalid test points (including reasons for invalid points);
b) test measurement system components (type/model) and measurement/calibration procedures;
c) measurement system calibration events and results;
d) measurement system failures, malfunctions, non-standard operations, spurious signals and corrective actions taken;
e) report of test condition compliance with part 36 test site requirements;
f) field data: samples of measured and corrected noise spectra, acoustical, meteorological, time/space position, aircraft performance field data and data adjustments, EPNdB estimates, and DER notes; and
g) summary of meetings.
(6) Noise certification reports Noise certification reports must provide information, data, and procedures demonstrating compliance with the requirements of part 36 and FAA approved noise certification demonstration plans.
(7) Noise certification reports (aircraft flight test) These reports must include the following:
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 and part serial numbers, aircraft/engine conformity status, reference c onditions (MTOW/MLW, thrust (power), altitudes, airspeeds, takeoff profiles;
c) noise certification methodology : noise certification methodology elements of a noise certification demonstration compliance plan approved by FAA for the aircraft configuration that is being certified and the specific report sections in which implementation of each element is addressed;
d) test description: test site location and characteristics (e.g., topography, ground cover, and obstructions), location of noise measurement poin ts, test conditions fo r each noise measurement point (including weather), aircraft configuration (e.g., flap, airbrake, landing gear and CG positions, APU operation, conditions of pneumatic bleeds and power takeoffs, airc raft weights, altitudes, airspeeds, engine thrust (power)), engine spooldown measurement points and test conditions, airframe noise measurement points and test conditions, and valid and invalid measurements;
e) measurement system components and procedures including calibration procedures : acoustical, meteorological, time/space position, aircraft/engine performance equipment;
f) data evaluation procedures including calibration, data processing and adjustment procedures :
acoustical, meteorological, time/space position, aircraft/engine performance;
g) data analysis and normalization results : analysis results for height of maximum lateral noise, thrust (power) reduction distance, airframe noise adjustment s, engine spooldown characteristics, normalized aircraft data (e.g., noise, power, distance (NPD plots)), values of EPNLr and 90% confidence limits, and aircraft flight manual pages;
h) if test witnessing is delegated, then the witness l og or notes specified in section 5 above must be included;
and
i) references.
(8) Noise certification reports (airplane families) Noise certification reports involving airplane family plan concepts must include additional information on noise certification methodology and, if applicable, results of static engine noise tests as follows:
a) noise certification methodology: identify approved equivalent procedures for projection of static engine noise data to flight conditions in NPD plot format and methods for defining:
NPD plot differences between flight datum (originally certified airplanes) and derived versions, and Page 47
“Residual” NPD plot differences between flight test data and projected flight data for the originally certified airplane;
b) static engine noise test results
c) engine description: type, model, serial numbers, nacelle acoustic treatments, engine conformity status]
d) test description : test facility, engine installation, turbulence control screen, acoustical and meteorological measurement points, bleed schedules, valid and invalid test points, test conditions for each test point (weather, engine thrust (power);
e) measurement systems and procedures including calibration procedur es: acoustical, meteorological and engine performance;
f) data evaluation procedures: including calibration and data processing, and adjustment and normalization of acoustical, meteorological, and engine performance;
(9) Equivalent procedure applications, documentation and approval process An applicant proposes to use equivalent procedures must be included in aircraft noise compliance demonstration plans (see Note 1). Such proposals may involve new procedures or procedures that have been used previously.
However, applicants must be capable of implementing proposed procedures and such procedures must be applicable to the specific aircraft model for which a TC is requested (see Note 2). Equivalent procedures must be substantiated to yield the same noise levels as the procedures prescribed in part 36.
FAA Order 8110.4C (Reference G4), paragraph 7-5 specifies AEE as the FAA approving authority for Equivalent Procedures (see Note 3). However, as experience is gained with the application of a particular procedure, AEE may delegate approval of the procedure to ACO or NCS specialists (see Reference G8). For example, FAA policy currently permits NCS approval (or ACO approval when authority is delegated) of NPD equivalencies representing extensions of data used to demonstrate comp liance with part 36 for original certified aircraft. NCS (or ACO) approval authority is limited to cases where either the NPD curve fit is linear and the proposed extension is not greater than 5 percent, or the NPD curve fit is 2 nd order and the proposed extension is not greater than 2.5 percent. The NCS also has approval authority for use of existing NPD plots for amended type designs (excluding extrapolation and increments to NPD plots – see Note 4).
Although equivalent procedures may be submitted as proprietary property of an applicant, when several applicants propose closely related or similar procedures (e.g., Flight Path Intercepts), they may be considered to be common industry knowledge and may be described in this AC. Information on equivalent procedures is provided in this AC in Chapter 4, section 402 for subsonic jets, heavy props and helicopters, Chapter 5, section 502 for light props, and Chapter 6, section 602 or light helicopters.
Note 1.— Equivalent procedure proposals should be submitted to FAA early in an aircraft noise certification program because approval may require more than one year.
Note 2.— Prior to approving an e quivalent procedure, the FAA must assess an applicant’s capability to effectively implement the procedure as well as the appropriateness of the procedure for the specific type of aircraft for which certification is requested.
Note 3.— The FAA does not consider equivalencies that modifies reference flight conditions (see 201(a)(10) paragraph 2 of this AC) without following public process.
Note 4.— Data obtained during noise certification tests may support extrapolation of noise databases (e.g., for engine thrust (power) range extensions above and below what was tested). Guidance on extrapolation of NPD databases is provided in 402(a)(2)(B)) of this AC.