No technical guidance has been developed for the following sections:
58. Section 36.501 Noise Limits
59. Section 36.501(a)
60. Section 36.501(b)
61. Section 36.501(c) VII. SUBPART F--PROPELLER-DRIVEN SMALL AIRPLANES AND PROPELLER-DRIVEN, COMMUTER
CATEGORY AIRPLANES
62. -65 [RESERVED]
VIII. SUBPART G--[RESERVED]
66. Section 36.801 Noise measurement [To be completed later]
67. Section 36.803 Noise evaluation and calculation [To be completed later]
68. Section 36.805 Noise limits [To be completed later]
69. Section 36.805(a) [To be completed later]
70. Section 36.801(b) [To be completed later]
71. Section 36.805(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.
a. Explanation
(1) Stage 1 helicopters: The provision applicable to a helicopter based on a military design is defined. Reference is included to Appendix J but the rule does not provide the “Stage 2 + 2 dB (SEL)” or “no noisier than the parent” provision similar to the limits under Appendix H provided in section H36.305. Thus, the noise compliance discussed is essentially related to certification under the provision of Appendix H.
b. Supplemental Information
(1) Stage 1 Helicopter: If section 36.805(c) applies, then noise testing will lead to one of the following:
a) The helicopter is demonstrated to be a Stage 2 helicopter: The tradeoff provisions in section H36.305(b) may be used to demonstrate compliance with the Stage 2 noise level requirement. 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 section H36.305(a)(1)(ii) and is consequently designated as the first civil version. The trade provisions in section H36.305(b) 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 section H36.305(a)(1)(ii): 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 otherwise meet the Stage 2 limits (note: a helicopter may exceed the Stage 1 limit for a given flight procedure and yet achieve Stage 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 section 21.93) would be less noisy or no noisier than the (parent) first civil version IX. SUBPART H--HELICOPTERS
helicopter, no additional demonstration of compliance with part 36 is required. The derivative helicopter remains a first civil version. The applicant may elect to: (1) carry forward the parent’s noise numbers to the rotorcraft flight manual of the derived version; or (2) voluntarily noise test the derivative helicopter in order 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 section 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 section 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 sufficient to require a new type certificate (as provided in section
21.19). As specified in section 36.805(c), a subsequent civil version must comply with the Stage 2 noise limits.
72. Section 36.805(d) [To be completed later]
73. –75 [RESERVED]
X. SUBPARTS I--N [RESERVED]
XI. SUBPART E--RESERVED
76. Section 36.1501 Procedures, noise levels and other information
77. Section 36.1501(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.
a. Explanation
This section specifies various types of information that must be developed and approved in the course of an aircraft (airplane or rotorcraft) noise certification process.
b. Supplemental Information
Noise Certification Compliance Documentation: The following types of documentation may be required in implementation of an aircraft (airplane of 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; JAR 36- See references 5 and 11 of this AC). An example would be aircraft certified under FAA/JAA Concurrent and Cooperative Programs (see Note).
Noise certification plans must include the following types of information:
(i) An overview of the contents of a forthcoming noise compliance demonstration plan and noise certification report;
(ii) Description of applicable noise certification regulations and the tests, reports, data submittals and flight manual pages planned to complete an aircraft noise certification process;
(iii) Description of conformity requirements;
(iv) DERs and other cognizant personnel to be involved in the aircraft noise certification process;
(v) Milestone schedule of key events;
(vi) Miscellaneous information (e.g. acronyms, organizational codes, etc. ).
Note: The FAA/JAA Concurrent and Cooperative Programs are intended to establish (to the extent possible) commonality in compliance methods and reduce program costs. Commonality may be achieved by obtaining approval from certificating authorities to use the most stringent requirements specified by the regulations involved, or by substantiating that the requirements of the regulations involved produce equivalent noise levels (in this case an applicant may choose a method of compliance from only one regulation)
(2) NOISE COMPLIANCE DEMONSTRATION PLANS (Aircraft Flight Test): Noise compliance demonstration plans contain the specific methodology (including equivalent procedures) by which an applicant XII. SUBPART O--OPERATING LIMITATIONS AND INFORMATION
proposes to establish compliance of a specific aircraft configuration 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:
(i) Introduction (Identify Applicable part 36 Requirements – Aircraft Noise Certification Basis);
(ii) Aircraft Description (Type, Model/Serial Numbers, Engines or Propellers Type, Model/Serial Numbers, Engine Ratings, Engine Nacelle Acoustic Treatments, Aircraft Gross Dimensions (including propeller and/or rotor diameter), Engine and ILS Antenna Locations, Aircraft/Engine Conformity);
(iii) Noise Certification Methodology (Test Concepts and Equivalent Procedures - See sections
1.3, 2, 3, 4, or 5 of the appended ICAO TM), Plans for Determining Engine Spooldown Characteristics and Airframe Noise, Aircraft/Engine Performance Substantiation, Estimated Reference Conditions including Airspeeds, Thrust (Power) Reduction Distances, Altitudes, Thrust (Power) Settings, Methods for determination of EPNLr Values and 90% Confidence Limits, and Flight Manual Format;
(iv) 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/Take-Offs, Test Matrix, including Weights, Target Altitudes, Airspeeds, Engine Thrust (Power), and Test Tolerances;
(v) Measurement System Components and Procedures including Calibration Procedures:
(Acoustical, Meteorological, Time/Space Position, Aircraft/Engine Performance);
(vi) Data Evaluation Procedures including Calibration and Data Processing (e.g., Approval Status of Data Processing Software and Version Level), Adjustment and Normalization Procedures: (Acoustical, Meteorological, Time/Space Position, and Airplane Engine Performance);
(vii) Aircraft Certification Schedule, including Noise Certification and TC Dates. Noise compliance 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;
(viii) References;
(ix) A listing of all Equivalent Procedures utilized (e.g., 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 section 2.3 of the appended ICAO TM, 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 airplane 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:
(i) Engine Description (Type/Model and Serial Numbers, Nacelle Acoustic Treatments, Engine Conformity Requirements);
(ii) Test Description (Test Facility, Engine Installation, Turbulence Control Screen Configuration, Weather Constraints, Acoustical and Meteorological Measurement Points, Bleed Schedules, Test Run Matrix and Sequence including Thrust (Power) Settings and Test Tolerances);
(ii) Measurement System Components and Procedures including Calibration Procedures:
(Acoustical, Meteorological, Engine Performance);
(iii) Data Evaluation Procedures including Calibration, Data Processing, Adjustment and Normalization Procedures (Acoustical, Meteorological, Engine Performance);
(v) Schedules (Static Noise Test, Noise Certification and TC dates);
(vi) References;
(vii) A listing of all Equivalent Procedures utilized.
Note 1: 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 section 2.2, 3.2 or 5.13 of the appended ICAO TM) 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:
(i) Aircraft Description (Type/Model, Engines or Propellers) Type, Model/Serial Numbers;
(ii) Description of Type Design Changes;
(iii) 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;
(iv) Aircraft Certification Schedules;
(v) References.
(5) DER “RAW DATA” REPORTS: FAA Order 8110.37C (reference 10 of this AC) 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 conducted in accordance with FAA approved 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.
(i) 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);
(ii) Test Measurement System Components (Type/Model) and Measurement/Calibration Procedures;
(iii) Measurement System Calibration Events and Results;
(iv) Measurement System Failures, Malfunctions, Non-Standard Operations, Spurious Signals and Corrective Actions Taken;
(v) Report of Test Condition Compliance with part 36 Test Site Requirements;
(vi) 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);
(vii) 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:
(i) Introduction: Identify Applicable 14 CFR part 36 Requirements -- Aircraft Noise Certification Basis;
(ii) Aircraft Description: Type/Model/Serial Numbers, Engines or Propellers and Type, Model/Serial Numbers, Engine Ratings, Engine Nacelle Acoustical Treatments, Aircraft Gross Dimensions (including Propeller and/or Rotor diameter), Engine and ILS Antenna Locations, Aircraft/Engine Conformity Status, Reference Conditions (MTOW/MLW, Thrust (Power), Altitudes, Airspeeds, Takeoff Profiles);
(iii) 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;
(iv) Test Description: Test Site Location and Characteristics (e.g. Topography, Ground Cover, and Obstructions), Location of Noise Measurement Points, Test Conditions for 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, Aircraft 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;
(v) Measurement System Components and Procedures including Calibration Procedures:
Acoustical, Meteorological, Time/Space Position, Aircraft/Engine Performance Equipment;
(vi) Data Evaluation Procedures including Calibration, Data Processing and Adjustment Procedures: Acoustical, Meteorological, Time/Space Position, Aircraft/Engine Performance;
(vii) Data Analysis and Normalization Results: Analysis Results for Height of Maximum Lateral Noise, Thrust (Power) Reduction Distance, Airframe Noise Adjustments, Engine Spooldown Characteristics, Normalized Aircraft Data (e.g. Noise, Power, Distance Plots), Values of EPNLr and 90 % Confidence limits, and Aircraft Flight Manual Pages;
(viii) If test witnessing is delegated, then the witness log or notes specified in section 5 above must be included;
(ix) References.
(8) NOISE CERTIFICATION REPORTS (AIRPLANE FAMILIES): Noise certification reports involving airplane family concepts must include additional information on noise certification methodology and, if applicable, results of static engine noise tests as follows:
(i) 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: 1) NPD Plot Differences between Flight Datum (Originally Certified Airplanes) and Derived Versions, and 2) “ Residual” NPD Plot Differences between Flight Test Data and Projected Flight Data for the Originally Certified Airplane;
(ii) Static Engine Noise Test Results;
(A) Engine Description (Type/Model/Serial Number, Nacelle Acoustic Treatments, Engine Conformity Status);
(B) 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);
(C) Measurement Systems and Procedures Including Calibration Procedures: Acoustical, Meteorological and Engine Performance;
(D) Data Evaluation Procedures Including Calibration and Data Processing, Adjustment and Normalization Procedures: Acoustical, Meteorological, and Engine Performance.
(9) EQUIVALENT PROCEDURES: Applicants’ proposals to use equivalent procedures must be included in aircraft noise compliance demonstration plans (See Note A). 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 B). Equivalent procedures must be substantiated to yield the same noise levels as the procedures prescribed in part 36.
FAA Order 8110.4 B (reference 7 of this AC), paragraph 6-3(e)(3) specifies AEE as the FAA approving authority for Equivalent Procedures (See Note C). 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 FAA AEE Memorandum “ Required Approval Level for Part 36 Subpart B and C Equivalent Procedures”, dated August 19, 1998). 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 compliance 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 2nd 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 D).
Although equivalent procedures are usually treated by the FAA 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 FAA Advisory Circular and/or the appended ICAO TM (See sections 2 through 6 of the appended ICAO TM).
Notes:
A. Equivalent procedure proposals should be submitted to FAA early in an aircraft noise certification program because approval may require more than one year.
B. Prior to approving an equivalent 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.
C. The FAA is not authorized to approve alternate procedures or conditions as equivalent to the reference procedures (e.g., 3o approach glide path) or conditions specified in part 36.
D. 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 section 2.2.2 of the appended ICAO TM. Engine or aircraft designs that may cause transition to sonic fan tip velocity; mid-span fan shrouds interaction; fan exit guide vane choking;
surge bleed valve operation; stator vane interaction; choked primary compressor entrance; increased inlet bypass airflow; change in aircraft configuration interaction, etc., may change the nature of the noise signature of the engine or aircraft and prevent an ordered extension of noise data. Static engine noise tests may not provide adequate proof that an extension of the noise database is valid. Guidance on generating increments to NPD databases is presented in section 2.2.2(c) of the appended ICAO TM based upon development of analytical noise models validated by certificating authorities.
(10) NO ACOUSTICAL CHANGE (NAC) DOCUMENTATION: Aircraft type design changes that are categorized as NAC require FAA approval under the provisions of part 21 rather than part 36. Applicants’ proposals for approval of NAC must be submitted to the FAA in writing. The written submittal must define the planned changes in aircraft type design, and must include information, data and analyses that will substantiate that the specified type design change will not result in an “Acoustical Change” (See Subpart A, section 36.1(c), Supplemental Information (3).
NAC Substantiation documentation must include:
(i) Introduction (Concepts and Requirements)
(ii) Description of Aircraft Baseline and Proposed Type Design Changes
(iii) Methodology for Substantiating an NAC
(iv) Description of Tests and/or Analyses performed
(v) Test and/or Analyses Results Relating to Compliance with FAA NAC Criteria (See Subpart A section 36.1(c) Supplemental Information Item 3).
Notes:
(A) Part 21.93(b) states that, “…any voluntary change in the type design of an aircraft that may increase the noise levels of that aircraft is an ‘acoustic change’.” Therefore NAC is determined on an aircraft by aircraft basis rather than just on the basis of the type certificate data sheet (TCDS) information for the aircraft model.
(B) Part 183 section 183.29(i) specifies that Acoustic DERs may not determine that a type design change is an NAC. As such, Acoustic DERs may not make recommendations for approval of NACs under form 8110-3.
(11) OTHER NOISE RELATED DOCUMENTATION: FAA is required to develop noise related documentation other than that required of applicants under part 36, Subpart O, section 1501 as follows:
a. FINDINGS REQUIRED BY PUBLIC LAW 103-272 (reference 2 of this AC): Compliance with Public Law 103-272 requires that FAA, before issuing an original TC for any aircraft of any category, regardless of whether part 36 applies to the aircraft, must make a finding to determine whether: