PROPOSTA DE CRITÉRIOS DE RUÍDO PARA AERONAVE DE CLASSE ESPECIAL 

Aeronave Modelo EVE-100

da EVE Soluções de Mobilidade Aérea Urbana LTDA

Proposed NOISE CERTIFICATION criteria

Applicability

These noise certification criteria, established under the provisions of RBAC 21.17(b)-I, are applicable to the Model EVE-100.

TEST PROCEDURE

(1) General: The requirements and limitations of RBAC 36.3 e 36.6 apply to the EVE Air Mobility model EVE-100 aircraft, except as described herein.

(a) Limitations: The noise levels specified in these Noise Certification Criteria have been determined to be as low as is economically reasonable, technologically practicable, and appropriate for this aircraft. No determination is made, however, that these noise levels are, or should be, acceptable or unacceptable for operation at, into, or out of any airport, landing or takeoff site, community, or other noise-sensitive environment.

(b) Acoustical Change: If, after type certification using the requirements stated herein, the aircraft incorporates a change in type design, the changed design is subject to an acoustical change analysis and approval in accordance with RBAC 21.93(b). After such change in design, the aircraft may not subsequently exceed the noise limits specified in this rule.

(2) Noise Measurement (Reference § 36.801, as modified): The noise generated by the aircraft must be measured at the noise measuring points and under the test conditions prescribed in sections (8) through (23) of this rule, or using an equivalent procedure approved by the ANAC before testing. Any procedure not approved by the ANAC before a test is performed is subject to disapproval and may require the aircraft to be retested using an approved procedure.

(3) Noise Evaluation (Reference § 36.803, as modified): The noise measurement data required by section (2) of this rule and obtained under sections (5) through (32) of this rule must be:

(a) Corrected to the reference conditions contained in sections (5) and (6) of this rule; and

(b) Evaluated using the procedures of sections (24) through (32) of this rule, or using an ANAC-approved equivalent procedure. Any procedure not approved by the ANAC before a test is performed is subject to disapproval and may require the aircraft to be retested using an approved procedure.

(4) Noise Limits (Reference § 36.805, as modified): Compliance with the noise limits prescribed in section (34) of this rule must be shown for this aircraft for which application for issuance of a type certificate in the special class is made under RBAC 21.

(5) Reference Conditions - General (Reference RBAC 36 appendix H, section H36.1, as modified): Sections (5) through (35) of this rule prescribe the noise certification requirements for this aircraft including:

(a) The conditions under which each noise certification test must be conducted and the measurement procedures that must be used under section (2) of this rule to measure the aircraft noise during the test;

(b) The procedures that must be used under section (3) of this rule to correct the measured data to the reference conditions, and to calculate the noise evaluation quantity designated as the Effective Perceived Noise Level (EPNL); and

(c) The noise limit with which compliance must be shown under section (4) of this rule.

(6) Reference Conditions – Test (Reference RBAC 36 appendix H, section H36.3, as modified):

(a) Meteorological Conditions – Aircraft position, performance data and noise measurements must be corrected to the following noise certification reference atmospheric conditions, which are assumed to exist from the surface to the aircraft altitude:

i. Sea level pressure of 2,116 pounds per square foot (1,013.25 hPa, 76 centimeters of mercury);

ii. Ambient temperature of 77 degrees Fahrenheit (25 degrees Celsius);

iii. Relative humidity of 70 percent; and

iv. Zero wind.

(b) Reference test site. The reference test site is flat and without line-of-sight obstructions, including any area across the flight path that encompass the 15 dB down points.

(c) Takeoff Reference Profile

i. Figure 8 illustrates a typical takeoff profile, including reference conditions.

ii. The reference flight path is defined as a straight line segment inclined from the starting point 1,640 feet (500 meters) from (before) the center microphone location and 65 feet (20 meters) above ground level at a constant climb angle (β) and the best rate of climb speed (VY), lowest approved speed, or scheduled best rate of climb speed (VYT), as defined by section (14) of this rule. The climb angle β is derived from the manufacturer's data (approved by the ANAC) to define the flight profile for the reference conditions. The flight path starts at Cr, crosses over station Ar, and continues to position Ir, ending the takeoff reference profile.

(d) Level Flyover Reference Profile

i. Figure 9 illustrates a level flyover profile, including reference conditions.

ii. The beginning of the level flyover reference profile is represented by aircraft position Dr. The aircraft approaches position Dr in level flight at 492 feet AGL, crosses directly overhead station A at position Gr, and proceeds to position Jr, completing the level flyover reference profile. Throughout the measurement period, the aircraft must be at the reference airspeed, VH or 0.9VNE, in accordance with section (15) of this rule.

(e) Approach Reference Profile

i. Figure 10 illustrates the approach profile, including reference conditions.

ii. The approach reference profile is defined as a straight line segment at approach angle η which passes over station A at 492 feet. The aircraft starts at position Er, passes directly over station A at position Hr, and continues to position Kr, which terminates the approach reference profile. The aircraft must follow the best rate of climb speed (VY), lowest approved airspeed for approach, or lowest scheduled speed for approach (VYA), in accordance with section (16) of this rule.

(7) Symbols and Units – Flight Profile Positions (Reference RBAC 36, appendix H, section H36.5, as modified):

Table 1: Flight Profile Positions

Table 2: Flight Profile Distances

(8) Noise Certification Test and Measurement Conditions – General (Reference RBAC 36, appendix H, section H36.101(a), as modified): Sections (8) through (12) of this rule prescribe the conditions under which the aircraft noise certification tests must be conducted, and the measurement procedures that must be used to measure the aircraft’s noise during each test.

(9) Noise Measurement Conditions (Reference: RBAC 36, appendix H, section H36.101(b), as modified):

(a) Tests to show compliance with this rule must consist of a series of takeoffs, level flyovers, and approaches during which measurements must be taken at noise measuring stations located at the measuring points prescribed subsection (9)(b) of this section.

(b) Each takeoff, flyover, and approach test includes simultaneous measurements at the flight-track noise measuring station vertically below the reference flight path and at two sideline noise measuring stations, one on each side of the reference flight track 492 feet (150m) from, and on a line perpendicular to, the flight track of the noise measuring station.

(c) The difference between the elevation of either sideline noise measuring station may not differ from the flight-track noise measuring station by more than 20 feet.

(d) If a takeoff or flyover test series is conducted at weights other than the maximum takeoff weight for which noise certification is requested, the following additional requirements apply:

i. At least one takeoff test and one flyover test must be conducted at, or above, the maximum certification weight.

ii. Each test weight must be within + 5 percent or −10 percent of the maximum certification weight.

(e) If an approach test series is conducted at weights other than the maximum landing weight for which certification is requested, the following additional requirements apply:

i. At least one approach test must be conducted at a weight at, or above, the maximum landing weight.

ii. Each test weight must be between + 5 percent and −10 percent of the maximum certification weight.

(10) Test Environment conditions (Reference: RBAC 36, appendix H, section H36.101(b), as modified):

(a) Each noise measuring station must be surrounded by terrain having no excessive sound absorption characteristics, such as might be caused by thick, matted, or tall grass, shrubs, wooded areas, or loose soil. Grass is acceptable if mowed to 3 inches or less in a 25 foot radius around all sound measuring stations.

(b) During the period when the takeoff, flyover, or approach noise measurement is within 15 dB of PNLTM, no obstruction that significantly influences the sound field from the aircraft may exist-

i. For any measurement station, within a conical space above the noise measuring positions (the point on the ground vertically below the microphone). The cone is defined by an axis normal to the ground and by half-angle 80 degrees from this axis; and

ii. For any sideline noise measuring station, above the line of sight between the microphone and the aircraft.

(11) Weather restrictions (Reference: RBAC 36, appendix H, section H36.101(c) as modified): Each test must be conducted under the following atmospheric conditions:

(a) No rain or other precipitation.

(b) Ambient air temperature between 14 degrees and 95 degrees Fahrenheit (-10 degrees and 35 degrees Celsius), inclusively, and relative humidity between 20 percent and 95 percent inclusively, except that testing may not take place where combinations of temperature and relative humidity result in a rate of atmospheric attenuation greater than 12 dB per 100 meters (36.6 dB per 1,000 feet) in the one-third octave band, centered at 8 kilohertz (kHz).

(c) Wind velocity that does not exceed 10 knots (19 km/h) and a crosswind component that does not exceed 5 knots (9 km/h). The wind must be determined using a continuous thirty-second averaging period spanning the 10dB down time interval.

(d) Measurements of ambient temperature, relative humidity, wind speed, and wind direction must be made at an ANAC approved position 33 feet (10 meters) above the ground.

(e) No anomalous wind conditions (including turbulence) or other anomalous meteorological conditions that could significantly affect the noise level of the aircraft when the noise is recorded at the noise measuring station.

(f) Temperature and relative humidity vs altitude measurements must be obtained within 30 minutes of each noise test.

(12) Aircraft Data requirements (Reference RBAC 36, appendix H, section H36.101(d), as modified):

(a) The aircraft testing procedures and noise measurements must be conducted and processed in a manner that yields the noise evaluation measure designated as Effective Perceived Noise Level (EPNL) in units of EPNdB, in accordance with the procedures described in RBAC 36, Appendix A.

(b) The aircraft’s height and lateral position relative to the reference flight track (which passes through the flight track noise measuring station) must be determined using an ANAC-approved method. The equipment used to make the determination must be independent of normal flight instrumentation. Applicable independent systems are radar tracking, theodolite triangulation, laser trajectography, photo scaling, or differential global positioning system. A description of the aircraft location system and its accuracy must be included as part of the noise test plan required by section (34) of this rule, and approved by the ANAC before use.

(c) The aircraft’s position along the flight path must be related to the noise recorded at the noise measuring stations by means of synchronized signals recorded at an approved sampling rate. The aircraft’s position must be recorded relative to the reference flight track during the entire time interval in which the recorded signal is within 10 dB of PNLTM. Measuring and sampling equipment must be approved by the ANAC before testing.

(d) Aircraft performance data sufficient to make the corrections required under section (21) of this rule must be recorded at an ANAC-approved sampling rate using ANAC-approved equipment.

(e) If an applicant demonstrates that the design characteristics of the aircraft would prevent flight from being conducted in accordance with the reference test conditions prescribed in sections (14) through (16) of this rule, then the applicant may request a variance in reference test conditions to be used. Any variance from standard reference test conditions is limited to that required for the subject aircraft design characteristics that make compliance with the reference test conditions impossible.

(13) Flight Test Conditions (Reference RBAC 36, appendix H, section H36.103 through H36.107, as modified): Sections (14) through (19) of this rule prescribe the flight test conditions and allowable random deviations for noise tests conducted to demonstrate compliance with this rule. All requirements and associated tolerances must be met while within 10 dB of PNLTM. Sections (14) through (19), in addition to the applicable requirements of sections (8) through (12) and (27) of this rule, apply to all noise tests conducted under this rule to show compliance with this rule.

(14) Takeoff Test Conditions (Reference RBAC 36, appendix H, section H36.103, as modified): A test series must consist of at least six stable flights over the flight-track noise measuring station (with simultaneous measurements at the three noise measuring stations)–

(a) While in accordance with paragraphs (14)(a)i through (14)(a)iii of this subsection and the associated takeoff flight path prescribed in section (6)(c), the aircraft must create the maximum noise level:

i. The aircraft must follow an airspeed of either VY or the lowest approved speed for the climb after takeoff, whichever speed is greater. If a constant airspeed takeoff is not possible within the test constraints due to the aircraft’s design, scheduled best rate of climb speed (VYT) within the aircraft’s design constraints (physical or software) must be used (VYT is to be reported as the average airspeed within the 10 dB down points);

ii. The aircraft must be stabilized on the maximum, constant or scheduled takeoff power level [average of all rotors/propellers/proprotors (rotating airfoils), consistent with paragraph (14)(a)i of this rule; and

iii. The aircraft must takeoff in accordance with AFM takeoff procedures before beginning the reference profile. The aircraft must enter the measurement period on a stabilized and repeatable takeoff path, pass over the flight path reference point, and continue as if to climb to cruise altitude.

(b) The aircraft must fly –

i. Within ±10° or ±65 feet (±20 meters), whichever is greater, from the vertical above the reference track;

ii. In a constant or scheduled takeoff configuration throughout the takeoff reference procedure, with the landing gear position consistent with the airworthiness certification tests for establishing the reference airspeed selected in paragraph (14)(a)i of this rule; and

iii. At the maximum takeoff weight requested for noise certification.

(c) Each takeoff noise test must be conducted –

i. With the airspeed not deviating from the constant or scheduled airspeed, consistent with paragraph (14)(a)i of this rule, by more than ±5 knots (9 km/hr); and

ii. With the RPM not deviating from the RPM necessitated by subsection (14)(a) of this rule by more than ±1.0 % for rotating airfoils providing thrust for wing-borne lift and ±15 % for rotating airfoils providing significant aircraft control.

(15) Flyover Test Condition (Reference RBAC 36, appendix H, section H36.105, as modified): A test series consists of at least six stable flights (with simultaneous measurements at the three noise measuring stations). The number of level flights made with a headwind component does not need to be equal to the number of level flights made with a tailwind component.

(a) While in accordance with paragraph (15)(a)i of this subsection and the associated flyover flight path prescribed in section (6)(d), the aircraft must create the maximum noise level:

i. At the applicable reference airspeed, which is defined as the maximum allowable airspeed in level flight within the aircraft’s type design, whether limited by physical or software constraints (VH), without exceeding 0.9VNE (VNE is defined as the never-exceed airspeed);

(b) The aircraft must fly –

i. In a constant level flight cruise configuration;

ii. At a height of 492 feet ±30 feet (150 ±9 meters) above the ground level at the flight-track noise measuring station;

iii. Within ±10° or ±65 feet (±20 meters), whichever is greater, from the vertical above the reference track; and

iv. At the maximum takeoff weight requested for noise certification.

(c) Each flyover noise test must be conducted –

i. With the airspeed not deviating from the reference airspeed by more than ±5 knots (9 km/hr);

ii. With the RPM not deviating from the RPM necessitated by subsection (15)(a) of this rule by more than ±1.0 % for rotating airfoils providing thrust for wing-borne lift and ±15 % for rotating airfoils providing significant aircraft control; and

iii. With the power stabilized.

(16) Approach Test Condition (Reference RBAC 36, appendix H, section H36.107, as modified): A test series must consist of at least six stable flights over the flight-track noise measuring station (with simultaneous measurements at the three noise measuring stations) –

(a) While in accordance with paragraphs (16)(a)i and (16)(a)ii of this subsection and the associated flight path prescribed in section (6)(e), the aircraft must create the maximum noise level:

i. The aircraft must follow the best rate of climb speed, VY, or lowest approved airspeed for the approach, whichever is greater. If a constant airspeed approach is not possible within the test constraints due to the aircraft’s design, the aircraft must maintain the lowest airworthiness approved scheduled airspeed (VYA) within the aircraft’s design constraints (physical or software) (VYA is to be reported as the average airspeed within the 10 dB down points); and

ii. The aircraft must follow AFM approach procedures before beginning the reference profile. The aircraft must enter the measurement period on a stabilized and repeatable approach path, pass over the flight path reference point, and continue as if to land.

(b) The aircraft must fly –

i. Over the flight-track noise measuring station at a height of 394 ±33 feet (120 ±10 meters);

ii. Within ±10° or ±65 feet (±20 meters) lateral deviation tolerance, whichever is greater, from the vertical above the reference track;

iii. Within ±0.5° of the approved flight path angle (slope);

iv. At the maximum landing weight requested for noise certification; and

v. In a constant or scheduled approach configuration, with the landing gear extended.

(c) Each approach noise test must be conducted –

i. With the airspeed not deviating from the constant or scheduled airspeed, consistent with paragraph (16)(a)i of this rule, by more than ±5 knots (±9 km/hr); and

ii. With the RPM not deviating from the RPM necessitated by subsection (16)(a)i of this rule, by more than ±1.0 % for rotating airfoils providing thrust for wing-borne lift and ±15 % for rotating airfoils providing significant aircraft control.

(17) Supplemental operational test conditions – The following are supplemental tests to collect data for assessment of community noise impacts of takeoff, landing, and hover conditions to inform later general noise and test standards for eVTOLs. These supplemental tests do not require compliance with a noise limit and do not affect the noise certification findings for the subject aircraft.

The aircraft must perform a takeoff, landing and hover within its normal operating range in accordance with subsections (17)(a) through (17)(c) of this section. The measurements must be made with the same consideration as noise certification measurements.

(a) Takeoff and Landing Condition

i. The microphone must be located 200 ft away from the landing (touch down) or takeoff position along the eVTOL flight path to capture noise exposures near the landing pad/vertiport (Figure 5, 6). A full landing or takeoff must be completed for the purpose of these supplemental measurements. These supplemental tests may take place concurrently with the certification approach and takeoff tests.

ii. The measurements must be recorded with a ground plane microphone setup in accordance with RBAC 36 appendix G, section G36.107(a).

iii. A complete test condition series must consist of at least 3 valid passes over the microphone.

(b) Hover Condition

i. The aircraft must be stabilized in hover at headings of 0, 90, 180 and 270 degrees in each the following locations. At least one continuous 30 second recording must be measured at each respective heading to produce recordings at the following directivities (Figure 7):

1. 0 degrees – The aircraft maintains a hover condition at 125 feet AGL and hold centered within a 15-foot radius over the microphone location.

2. 30 degrees – The aircraft maintains a hover condition at a lateral distance of 72 feet to the microphone position and at 125 feet AGL.

3. 60 degrees – The aircraft maintains a hover condition at a lateral distance of 216 feet to the microphone and at 125 feet above ground level.

ii. The aircraft must be at MTOW;

iii. The tolerance of the hover height or lateral distance is within +/−15 ft, and the tolerance of the headings is within +/−5 degrees; and

iv. The measurements must be recorded with a 4 ft pole (certification) microphone and a collocated ground plane microphone, setup in accordance with RBAC 36 appendix G, section G36.107(a).

(c) For all supplemental test conditions, the full spectral time history and audio recordings are expected to be provided to the ANAC at the same time as the certification test report.

(18) Measurement of aircraft noise received on the ground – General (Reference: RBAC 36, appendix H, section H36.109, as modified): The measurement system and the measurement, calibration and general analysis procedures to be used are provided in RBAC 36, appendix A, section A36.3.

(19) Reporting and Correcting Measured Data – General (Reference RBAC 36, appendix H, section H36.111(a), as modified): Data representing physical measurements, and corrections to measured data, including corrections to measurements for equipment response deviations, must be recorded in permanent form and appended to the record. Each correction must be reported and is subject to ANAC approval. An estimate must be made of each individual error inherent in each of the operations employed in obtaining the final data.

(20) Data Reporting (Reference RBAC 36, appendix H, section H36.111(b), as modified): After the completion of all certification tests required by this rule, the following must be submitted to the ANAC in a test report:

(a) Measured and corrected sound pressure levels must be presented in one-third octave band levels obtained with equipment conforming to the standards prescribed in section (18) of this rule;

(b) A description of the equipment and systems used for measurement and analysis of all acoustic, aircraft performance, flight path, and meteorological data;

(c) The atmospheric environmental data required to demonstrate compliance with this rule, as measured throughout the test period;

(d) Conditions of local topography, ground cover, or events that may have interfered with a sound recording;

(e) The following aircraft information:

i. Type, model, and serial numbers, if any, of aircraft, engine(s), and rotor(s)/propeller(s)/proprotor(s) tested;

ii. Gross dimensions of aircraft, location of engines or motors, rotor(s)/propeller(s)/proprotor(s), number of blades for each rotating airfoil, and the range of rotational speeds of the rotating airfoils;

iii. The MTOW and MLW requested for noise certification;

iv. Aircraft configuration, including landing gear positions;

v. Applicable target reference speeds from sections (14) through (16) of this rule;

vi. Aircraft gross weight for each test run;

vii. True airspeed for each test run; and

viii. Aircraft engine performance as determined from aircraft instruments and manufacturer's data;

(f) Aircraft position (in three dimension space) and performance data, at an approved sampling rate, necessary to make the adjustments prescribed in section (26) through (32) of this rule and to demonstrate compliance with the performance and position restrictions prescribed in section (6) of this rule;

(g) All of the recorded audio data from all phases of all flight tests used to demonstrate compliance with this rule; and

(h) All recordings and data collected during the supplemental testing specified in section (17) of this rule. These data will not affect the outcome of this certification finding and may be submitted separately from data that affects certification.

(21) Data corrections – (Reference RBAC 36, appendix H, section H36.111(c), as modified): Aircraft position, performance data and noise measurement must be corrected to the noise certification reference conditions as prescribed in sections (6) and (14) through (16) of this rule.

(a) The measured flight path must be corrected by an amount equal to the difference between the certification reference conditions and the measured flight path at the test conditions. Necessary corrections relating to aircraft’s flight path or performance may be derived from ANAC-approved data for the difference between measured and reference conditions, together with appropriate allowances for sound attenuation with distance. The Effective Perceived Noise Level (EPNL) correction may not exceed 2.0 EPNdB except for takeoff flight condition, where the correction may not exceed 4.0 EPNdB, of which the arithmetic sum of Δ1 (described in RBAC 36, appendix H, section H36.205(f)(1)) and the term −7.5 log (AL/ALr) from Δ2 term (described in RBAC 36, appendix H, section H36.205(g)(1)(i)) may not exceed 2.0 EPNdB, for any combination of the following:

i. The aircraft not passing vertically above the measuring station;

ii. Any difference between the target test flight track and the actual test flight track; or

iii. Detailed correction requirements prescribed in section (26) through (32) of this rule.

(b) For the flyover test series, the helical tip Mach corrections found in RBAC 36, appendix G, section G36.201 must be applied if any propeller/proprotor tip Mach number exceeds 0.70. Tip corrections are applied once to the propeller/proprotor with the highest average tip Mach number.

(c) Aircraft sound pressure levels within the 10 dB-down time interval must exceed the mean background sound pressure levels determined under RBAC 36, appendix A, section A36.3.10 by at least 3 dB in each one-third octave band, or must be corrected under an ANAC-approved method.

(22) Validity of results (Reference RBAC 36, appendix H, section H36.111(d), as modified):

(a) The test results must produce three average EPNL values within the 90 percent confidence limits, each value consisting of the arithmetic average of the corrected noise measurements for all valid test runs at the takeoff, level flyovers, and approach conditions. The 90 percent confidence limit applies separately to takeoff, flyover, and approach.

(b) The minimum sample size acceptable for each takeoff, approach, and flyover certification measurements is six. The number of samples must be large enough to establish statistically for each of the three average noise certification levels a 90 percent confidence limit which does not exceed ±1.5 EPNdB. No test result may be omitted from the averaging process, unless otherwise specified by the ANAC.

(c) To comply with this rule, a minimum of six takeoffs, six approaches, and six level flyovers is required. To be counted toward this requirement, each flight event must be validly recorded at all three noise measuring stations.

(d) The approved target reference airspeed values used in calculating test conditions, reference conditions, and flight profiles must be reported along with measured and corrected sound pressure levels.

(23) Atmospheric attenuation of sound (Reference RBAC 36, appendix H, section H36.113, as modified):

(a) The values of the one-third octave band spectra measured during aircraft noise certification tests under this rule must conform, or be corrected, to the reference conditions prescribed in sections (6) of this rule. Each correction must account for any differences in the atmospheric attenuation of sound between the test-day conditions and the reference-day conditions along the sound propagation path between the aircraft and the microphone. Unless the meteorological conditions are within the test window prescribed in section (11) of this rule, the test data are not acceptable.

(b) Attenuation rates. The procedure for determining the atmospheric attenuation rates of sound with distance for each one-third octave bands must be determined in accordance with SAE ARP 866A (Incorporated by reference, see RBAC 36 section 36.6). The atmospheric attenuation equations are provided in both the International and English systems of units in RBAC 36, appendix A, section A36.7.

(c) Correction for atmospheric attenuation. EPNL values calculated for measured data must be corrected whenever—

i. The ambient atmospheric conditions of temperature and relative humidity do not conform to the reference conditions, 77 °F and 70%, respectively;

ii. The measured flight paths do not conform to the reference flight paths; or

iii. The temperature and relative humidity measured at 33 feet (10 meters) above the ground must be used to adjust for propagation path absorption.

(d) The mean attenuation rate over the complete sound propagation path from the aircraft to the microphone must be computed for each one-third octave band from 50 Hz to 10,000 Hz. These rates must be used in computing the corrections required in section (21) of this rule.

(24) Noise Evaluation in EPNdB (Reference RBAC 36, appendix H, section H36.201, as modified):

(a) Effective Perceived Noise Level (EPNL), in units of effective perceived noise decibels (EPNdB), shall be used for evaluating noise level values under section (4) of this rule. Except as provided in subsection (24)(b) of this section, the procedures in RBAC 36, appendix A, section A36.3 must be used for computing EPNL. When the requirements of sections (14) and/or (16) necessitate a variable speed throughout the measurement period, adjustments to the measured noise values must be made using the “integrated” method of adjustment, described in section A36.9.4.

Appendix A includes requirements governing determination of noise values, including calculations of:

i. Perceived noise levels;

ii. Corrections for spectral irregularities;

iii. Tone corrections;

iv. Duration corrections;

v. Effective perceived noise levels; and

vi. Mathematical formulation of noy tables.

(b) For noise certification of the subject aircraft, corrections for spectral irregularities shall start with the corrected sound pressure level in the 50 Hz one-third octave band.

(25) Calculation of Noise Levels (Reference RBAC 36, appendix H, section H36.203, as modified):

(a) To demonstrate compliance with the noise level limits of (34) of this rule, the noise values measured simultaneously at the three noise measuring points must be arithmetically averaged to obtain a single EPNdB value for each flight.

(b) The calculated noise level for each noise test series, i.e., takeoff, flyover, or approach must be the numerical average of at least six separate flight EPNdB values. The 90 percent confidence limit for all valid test runs under section (22) of this rule applies separately to the EPNdB values for each noise test series.

(26) Detailed data Correction Procedures – General (Reference RBAC 36, appendix H, section H36.205(a), as modified): If the test conditions do not conform to those prescribed as noise certification reference conditions under sections (6) or (14) through (16) of this rule, the following correction procedure shall apply. When the requirements of sections (14) and/or (16) necessitate a variable speed throughout the measurement period, adjustments to the measured noise values must be made using the “integrated” method of adjustment, described in section A36.9.4.

(a) If there is any difference between measured test and reference conditions, an appropriate correction must be made to the EPNL calculated from the measured noise data. Conditions that can result in a different value include:

i. Atmospheric absorption of sound under measured test conditions that are different from the reference test conditions; and/or

ii. Measured flight path that is different from the reference flight path.

(b) The following correction procedures may produce one or more possible correction values which must be added algebraically to the calculated EPNL to bring it to reference conditions:

i. The flight profiles must be determined for both reference and test conditions. The procedures require noise and flight path recording with a synchronized time signal from which the test profile can be delineated, including the aircraft position for which PNLTM is observed at the noise measuring station. For takeoff, the flight profile corrected to reference conditions may be derived from ANAC approved manufacturer's data.

ii. The sound propagation paths to the microphone from the aircraft position corresponding to PNLTM must be determined for both the test and reference profiles. The SPL values in the spectrum of PNLTM must then be corrected for the effects of—

1. Change in atmospheric sound absorption;

2. Atmospheric sound absorption on the linear difference between the two sound path lengths; and

3. Inverse square law on the difference in sound propagation path length. The corrected values of SPL must then be converted to a reference condition PNLTM value from which PNLTM must be subtracted. The resulting difference represents the correction which must be added algebraically to the EPNL calculated from the measured data.

iii. As observed at the noise measuring station, the measured PNLTM distance is different from the reference PNLTM distance and therefore the ratio must be calculated and used to determine a noise duration correction factor. Effective perceived noise level, EPNL, is determined by the algebraic sum of the maximum tone corrected perceived noise level (PNLTM) and the duration correction factor.

iv. For aircraft flyover, alternative source noise corrections require ANAC approval and must be determined and adjusted to account for noise level changes caused by the differences between measured test conditions and reference conditions.

(27) Detailed data Correction Procedures – Takeoff Profiles (Reference RBAC 36, appendix H, section H36.205(b), as modified):

(a) Figure 8 illustrates a typical takeoff profile, including reference conditions.

i. The reference takeoff flight path is described in section (14) of this rule.

ii. The test parameters are functions of the aircraft's performance and weight and the atmospheric conditions of temperature, pressure, wind velocity and direction.

(b) For the actual takeoff, the aircraft approaches position C in level flight at 65 feet (20 meters) above ground level at the flight track noise measuring station and at the airspeed specified in section (14) of this rule.

(c) Figure 8 illustrates the significant geometrical relationships influencing sound propagation. Position L represents the aircraft location on the measured takeoff path from which PNLTM is observed at station A, and Lr is the corresponding position on the reference sound propagation path. Propagation paths AL and ALr both form the same angle θ (theta) relative to their respective flight paths.

(28) Detailed data Correction Procedures – Flyover Profiles (Reference RBAC 36, appendix H, section H36.205(c), as modified):

(a) The noise type certification level flyover profile is shown in Figure 9. Airspeed must be stabilized within ±5 knots of the reference airspeed specified in section (15) of this rule. The number of level flights made with a headwind component does not need to be equal to the number of level flights made with a tailwind component.

(b) Figure 9 illustrates comparative flyover profiles when test conditions do not conform to prescribed reference conditions. The position of the aircraft shall be recorded for a distance (DJ) sufficient to ensure recording of the entire interval during which the measured aircraft noise level is within 10 dB of PNLTM, as required. The flyover profile is defined by the height AG which is a function of the operating conditions controlled by the pilot. Position M represents the aircraft location on the measured flyover flight path for which PNLTM is observed at station A, and Mr is the corresponding position on the reference flight path.

(29) Detailed data Correction Procedures – Approach Profiles (Reference RBAC 36, appendix H, section H36.205(d), as modified):

(a) Figure 10 illustrates a typical approach profile, including reference conditions.

(b) The aircraft approaches position H along the approved flight path angle (η), from section (16) of this rule, throughout the 10dB-down time interval.

(c) Figure 10 illustrates portions of the measured and reference approach flight paths including the significant geometrical relationships influencing sound propagation. The measured approach path is represented by segment EK with an approach allowable angle θ. Reference positions, Er and Kr, define an idealized reference approach angle. Position N represents the aircraft location on the measured approach flight path for which PNLTM is observed at measuring station A, and Nr is the corresponding position on the reference approach flight path. The measured and reference noise propagation paths are AN and ANr, respectively, both of which form the same angle, θ, corresponding to PNLTM relative to their approach flight paths.

(30) Detailed data Correction Procedures – Correction of noise at source during level flyover (Reference RBAC 36, appendix H, section H36.205(e), as modified): For the flyover test series, the helical tip Mach corrections found in RBAC 36, appendix G, section G36.201 must be applied if any propeller/proprotor tip Mach number exceeds 0.70. Tip corrections are applied once to the propeller/proprotor with the highest average tip Mach number.

(31) Detailed data Correction Procedures – PNLT corrections (Reference RBAC 36, appendix H, section H36.205(f), as modified): If the measured ambient atmospheric conditions of temperature and relative humidity differ from those prescribed as reference conditions under section (11) of this rule, (77 degrees F and 70 percent, respectively), corrections to the EPNL values must be calculated from the measured data under section (26) of this rule as follows:

(a) Takeoff flight path. For the takeoff flight path shown in Figure 8, the spectrum of PNLTM observed at station A for the aircraft at position L is decomposed into its individual SPL(i) values.

i. Step 1. A set of corrected values are then computed as follows:

SPL(i)r = SPL(i) + C[α(i) −α(i)o]AL + Cα(i)o (AL − ALr) + 20 log (AL/ALr)

Where SPL(i) and SPL(i)r are the measured and corrected sound pressure levels, respectively, in the i-th one-third octave band. The first correction term adjusts for the effect of change in atmospheric sound absorption where α(i) and α(i)o are the sound attenuation coefficients for the test and reference atmospheric conditions, respectively, for the i-th one-third octave band, and AL is the measured takeoff sound propagation path. The conversion factor constant, C, is 0.001 for English System of Units and is 0.01 for International System of Units. The second correction term adjusts for the effects of atmospheric attenuation due to the difference in the sound propagation path length where ALr is the Reference takeoff sound propagation path. The third correction term, known as the “inverse square” law, adjusts for the effect of the difference in the sound propagation path length.

ii. Step 2. The corrected values of the SPL(i)r are then converted to reference condition PNLT and a correction term calculated as follows:

Δ1 = PNLT − PNLTM

Which represents the correction to be added algebraically to the EPNL calculated from the measured data.

(b) Level flyover flight path.

i. The procedure described in subsection (31)(a) of this section for takeoff paths is also used for the level flyover paths, with the values of SPL(i)r relating to the flyover sound propagation paths shown in Figure 9 as follows:

SPL(i)r = SPL(i) + C[α(i) −α(i)o]AM + Cα(i)o (AM − AMr) + 20 log (AM/AMr)

where the lines AM and AMr are the measured and reference level flyover sound propagation paths, respectively.

ii. The remainder of the procedure is the same for the flyover condition as that prescribed in paragraph (31)(a)ii of this section regarding takeoff flight path.

(c) Approach flight path.

i. The procedure described in subsection (31)(a) of this section for takeoff paths is also used for the approach paths, with the values of SPL(i)r relating to the approach sound propagation paths shown in Figure 10 as follows:

SPL(i)r = SPL(i) + C[α(i) −α(i)o]AN + Cα(i)o (AN − ANr) + 20 log (AN/ANr)

where the lines AN and ANr are the measured and reference approach sound propagation paths, respectively.

ii. The remainder of the procedure is the same for the approach condition as that prescribed in the subsection (31)(a) of this section regarding takeoff flight path.

(d) Sideline microphones.

i. The procedure prescribed in subsection (31)(a) of this section for takeoff paths is also used for the propagation to the sideline locations, with the values of SPL(i)r relating as follows to the measured sideline sound propagation path shown in Figure 10 as follows:

SPL(i)r = SPL(i) + C[α(i) −α(i)o]SX + Cα(i)o (SX − SXr) + 20 log (SX/SXr) where S is the sideline measuring station and, based upon the flight condition, the aircraft positions, X and Xr, correspond to:

X = L, and Xr = Lr for takeoff

X = M, and Xr = Mr for flyover

X = N, and Xr = Nr for approach

The remainder of the procedure is the same for the sideline paths as that prescribed in the paragraph (31)(a)ii of this section regarding takeoff flight paths.

(32) Detailed data Correction Procedures – Duration corrections (Reference RBAC 36, appendix H, section H36.205(g), as modified):

(a) If the measured takeoff, level flyover, and approach flight paths do not conform to those prescribed as the corrected and reference flight paths, respectively, under section (6) of this rule it will be necessary to apply duration corrections to the EPNL values calculated from the measured data. Such corrections must be calculated as follows:

i. Takeoff flight path. For the takeoff path shown in Figure 8, the correction term is calculated using the formula—

Δ2 = −7.5 log (AL/ALr) + 10 log (V/Vr)

which represents the correction that must be added algebraically to the EPNL calculated from the measured data. The lengths AL and ALr are the measured and reference takeoff distances from the noise measuring station A to the measured and the reference takeoff paths, respectively. A negative sign indicates that, for the particular case of a duration correction, the EPNL calculated from the measured data must be reduced if the measured takeoff path is at greater altitude than the reference takeoff path.

ii. Level flyover flight paths. For the level flyover flight path, the correction term is calculated using the formula—

Δ2 = −7.5 log (AM/AMr) + 10 log (V/Vr)

where AM is the measured flyover distance from the noise measuring station A to the measured flyover path, and AMr is the reference distance from station A to the reference flyover path.

iii. Approach flight path. For the approach path shown in Figure 10, the correction term is calculated using the formula—

Δ2 = −7.5 log (AN/ANr) + 10 log (V/Vr)

where AN is the measured approach distance from the noise measuring station A to the measured approach path, and ANr is the reference distance from station A to the reference approach path.

iv. Sideline microphones. For the sideline flight path, the correction term is calculated using the formula—

Δ2 = −7.5 log (SX/SXr) + 10 log (V/Vr)

where S is the sideline measuring station and based upon the flight condition, the aircraft positions, X and Xr, correspond to:

X = L, and Xr = Lr for takeoff

X = M, and Xr = Mr for flyover

X = N, and Xr = Nr for approach

(b) The adjustment procedure described in subsection (32)(a) of this section shall apply to the sideline microphones in the take-off, overflight, and approach cases. Although the noise emission is strongly dependent on the directivity pattern, variable from one aircraft to another, the propagation angle θ shall be the same for test and reference flight paths. The elevation angle ψ shall not be constrained but must be determined and reported. The certification authority shall specify the acceptable limitations on ψ. Corrections to data obtained when these limits are exceeded shall be applied using ANAC approved procedures.

(33) Noise Measurement, evaluation, and calculation (Reference: RBAC 36, appendix H, section H36.301, as modified): Compliance with section (34) of this rule must be shown with noise levels measured, evaluated, and calculated as prescribed in this rule.

(34) Noise Level Limit - Compliance (Reference RBAC 36, appendix K, section K4, as modified): For the compliance with this rule, the subject aircraft’s maximum noise levels, as determined in accordance with the noise evaluation in EPNdB and calculation method described in sections (5) through (32) of this rule, must not exceed the following noise limits, unless the exceedance complies with the tradeoffs in section (35) of this rule.

(a) At the takeoff flight path reference point: For a aircraft having a maximum certificated takeoff weight (mass) of 176,370 pounds (80,000 kg) or more, in VTOL/Conversion mode, 109 EPNdB, decreasing linearly with the logarithm of the aircraft’s weight (mass) at a rate of 3.0 EPNdB per halving of weight (mass) down to 89 EPNdB, after which the limit is constant. Figure 11 illustrates the takeoff noise limit as a solid line.

(b) At the Flyover path reference point: For a aircraft having a maximum certificated takeoff weight (mass) of 176,370 pounds (80,000 kg) or more, in VTOL/Conversion mode, 108 EPNdB, decreasing linearly with the logarithm of the aircraft’s weight (mass) at a rate of 3.0 EPNdB per halving of weight (mass) down to 88 EPNdB, after which the limit is constant. Figure 11 illustrates the flyover noise limit as a dashed line.

(c) At the approach flight path reference point: For a aircraft having a maximum certificated takeoff weight (mass) of 176,370 pounds (80,000 kg) or more, in VTOL/Conversion mode, 110 EPNdB, decreasing linearly with the logarithm of the aircraft’s weight (mass) at a rate of 3.0 EPNdB per halving of weight (mass) down to 90 EPNdB, after which the limit is constant. Figure 11 illustrates the approach noise limit as a dash-dot line.

Figure 11

(35) Noise Level Trade-Offs (Reference RBAC 36, appendix K, section K5, as modified): If the noise evaluation measurement exceeds the noise limits described in section (34) of this rule at one or two measurement points:

(a) The sum of excesses must not be greater than 4 EPNdB;

(b) The excess at any single point must not be greater than 3 EPNdB; and

(c) Any excess must be offset by the remaining noise margin at the other point or points.

(36) Manuals, Markings, and Placards - (Reference RBAC 36 §§36.1501 and 36.1581, as modified):

(a) All procedures, weights, configurations, and information or data used to obtain the certified noise levels required to demonstrate compliance with this rule, including equivalent procedures used for flight, testing, and analysis, must be approved by the ANAC.

(b) Noise levels achieved during type certification must be included in the approved portion of each Aircraft Flight Manual for the subject aircraft. If an Aircraft Flight Manual is not approved, the procedures and information must be furnished in a combination of manual material, markings, and placards approved by the ANAC. The noise level information that must be included is as follows:

i. The noise level information must be one value each for takeoff, flyover, and approach, as defined and required by the specifications of this rule. The noise level value must indicate the corresponding reference speed, weight, and configuration (rotor/propeller/proprotor, motor part numbers and, if applicable, software version) from which it was determined.

ii. If supplemental operational noise level information is included in the approved portion of the Aircraft Flight Manual, it must be segregated, identified as information that is provided in addition to the certificated noise levels, and clearly distinguished from the information required by paragraph (36)(b)i of this subsection.

iii. The following statement must be included in each approved manual near the listed noise level:

No determination has been made by the Agência Nacional de Aviação Civil that the noise levels of this aircraft are or should be acceptable or unacceptable for operation at, into, or out of, any location or environment that may be affected by operational noise.

(37) Test Plan Preparation and Approval: Prior to conducting any testing and data collection required by this rule, the applicant must prepare a test plan and obtain approval of it from the ANAC.

(38) Test Witnessing: The ANAC must witness the test and data collection required by this rule for the results to be valid for certification.

(39) Test Report Preparation and Approval: The applicant must prepare a report that includes all of the findings and data required under this rule. The report must be approved by the ANAC as a part of the aircraft certification record.

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Documento assinado eletronicamente por Cesar Silva Fernandes Junior, Gerente de Programa de Certificação, em 20/05/2026, às 11:20, conforme horário oficial de Brasília, com fundamento no art. 4º, do Decreto nº 10.543, de 13 de novembro de 2020.

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Documento assinado eletronicamente por Pedro Henrique Leite Paludo, Gerente Técnico de Programas de Certificação, em 20/05/2026, às 11:46, conforme horário oficial de Brasília, com fundamento no art. 4º, do Decreto nº 10.543, de 13 de novembro de 2020.

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Documento assinado eletronicamente por Antonio José Parente de Carvalho Júnior, Gerente Técnico de Engenharia de Produto, em 20/05/2026, às 15:20, conforme horário oficial de Brasília, com fundamento no art. 4º, do Decreto nº 10.543, de 13 de novembro de 2020.

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Documento assinado eletronicamente por Mário Igawa, Gerente de Certificação de Projeto de Produto Aeronáutico, em 20/05/2026, às 15:50, conforme horário oficial de Brasília, com fundamento no art. 4º, do Decreto nº 10.543, de 13 de novembro de 2020.

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A autenticidade deste documento pode ser conferida no site https://sei.anac.gov.br/sei/autenticidade, informando o código verificador 13184728 e o código CRC 82F091A4.

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