Tel.: +1 (514) 954-8219 ext. 6726 

Ref.: AN 1/61.2 

AN 1/62.2 }07/34 25 May 2007 

Subject: Proposals for the amendment of Annex 16, 

Volumes I and II concerning Standards and 

Recommended Practices relating to environmental 

protection 

Action required: Comments to reach Montreal by 

7 September 2007 

Sir/Madam, 

1. I have the honour to inform you that the Air Navigation Commission, at the eleventh and 

twelfth meetings of its 174th Session held on 6 and 8 March 2007, respectively, considered proposals 

developed by the seventh meeting of the Committee on Aviation Environmental Protection (CAEP/7) to 

amend the Standards and Recommended Practices (SARPs) in Annex 16 — Environmental Protection, 

Volume I — Aircraft Noise and Volume II — Aircraft Engine Emissions relating to environmental 

protection. 

2. The proposed amendments to Annex 16, Volumes I and II are shown in Attachments A 

and B, respectively. No recommendations concerning the stringency of the noise or emissions Standards 

were made. 

3. The purpose of the amendment of the SARPs in Annex 16, Volume I is to clarify 

technical issues arising in the application of demonstration schemes and related guidance for aircraft noise 

certification. The amendment to Annex 16, Volume II addresses technical issues, mainly concerning the 

modernization of the demonstration schemes and guidance for engine certification. 

4. May I request that any comments you wish to make on the amendment proposals be 

dispatched to reach me not later than 7 September 2007. The Air Navigation Commission has asked me to 

specifically indicate that comments received after the due date may not be considered by the Commission 

and the Council. In this connection, should you anticipate a delay in the receipt of your reply, please let 

me know in advance of the due date. 
- 2 - 

5. For your information, the proposed amendments to Annex 16, Volumes I and II are 

envisaged for applicability on 20 November 2008. Any comments you may have thereon would be 

appreciated. 

6. The subsequent work of the Air Navigation Commission and the Council would be 

greatly facilitated by specific statements on the acceptability or otherwise of the proposals. Please note 

that for the review of your comments by the Air Navigation Commission and the Council, replies are 

normally classified as “agreement with or without comments”, “disagreement with or without comments” 

or “no indication of position”. If in your reply the expressions “no objections” or “no comments” are 

used, they will be taken to mean “agreement without comment” and “no indication of position”, 

respectively. In order to facilitate proper classification of your response, a form has been included in 

Attachment E which may be completed and returned together with your comments, if any, on the 

proposals in Attachments A and B. 

Accept, Sir/Madam, the assurances of my highest consideration. 

 

Taïeb Chérif 

Secretary General 

Enclosures: 

 A — Proposed amendment to Annex 16, Volume I 

B — Proposed amendment to Annex 16, Volume II 

C — Response form 
 

ATTACHMENT A to State letter AN 1/61.2, AN 1/62.2 - 07/34 

PROPOSED AMENDMENT TO 

INTERNATIONAL STANDARDS AND RECOMMENDED PRACTICES 

ENVIRONMENTAL PROTECTION 

ANNEX 16 

TO THE CONVENTION ON INTERNATIONAL CIVIL AVIATION 

VOLUME I 

AIRCRAFT NOISE 

1. The text of the amendment is arranged to show deleted text with a line through it and new text 

highlighted with grey shading, as shown below: 

1. Text to be deleted is shown with a line through it. text to be deleted

2. New text to be inserted is highlighted with grey shading. new text to be inserted

3. Text to be deleted is shown with a line through it followed 

by the replacement text which is highlighted with grey 

shading.

new text to replace existing text
 

TEXT OF PROPOSED AMENDMENT TO THE 

INTERNATIONAL STANDARDS 

AND RECOMMENDED PRACTICES 

ENVIRONMENTAL PROTECTION 

ANNEX 16 

TO THE CONVENTION ON INTERNATIONAL CIVIL AVIATION 

VOLUME I 

AIRCRAFT NOISE

. . . 

PART I. DEFINITIONS 

. . . 

Derived version of a helicopter. A helicopter which, from the point of view of airworthiness, is similar to 

the noise certificated prototype but incorporates changes in type design which may affect its noise 

characteristics adversely. 

Note 1.— In applying the Standards of this Annex, a helicopter that is based on an existing prototype 

but which is considered by the certificating authority to be a new type design for airworthiness purposes 

shall nevertheless be considered as a derived version if the noise source characteristics are judged by the 

certificating authority to be the same as the prototype. 

 Note 2.— “Adversely” refers to an increase of more than 0.3 EPNdB in any one of the noise 

certification levels for helicopters certificated according to Chapter 8 and 0.3 dB(A) in the certification 

level for helicopters certificated according to Chapter 11.

. . . 

PART II. AIRCRAFT NOISE CERTIFICATION 

CHAPTER 1. ADMINISTRATION 

. . . 

1.10 Unless otherwise specified in this volume of the Annex, the date to be used by Contracting 

States in determining the applicability of the Standards in this Annex shall be the date of application 

submitted to the State of Design for a type certificate, or the date of application under an equivalent 

prescribed procedure by the certificating authority of the State of Design. The application shall be 

effective for a duration equal to the period applied in the designation of the airworthiness regulations 

appropriate to the aircraft type, except in special cases where the certificating authority accepts an 

extension of this period. 

. . . 
A-2 

CHAPTER 2. SUBSONIC JET AEROPLANES — APPLICATION FOR TYPE

CERTIFICATE OF AIRWORTHINESS FOR THE PROTOTYPE ACCEPTEDSUBMITTED 

BEFORE 6 OCTOBER 1977 

2.1 Applicability 

Note.— See also Chapter 1, 1.91.10 and 1.11. 

 2.1.1 The Standards of this chapter shall be applicable to all subsonic jet aeroplanes for which either 

the application for a certificate of airworthiness for the prototype Type Certificate was accepted

submitted, or another equivalent prescribed procedure was carried out by the certificating authority, 

before 6 October 1977, except those aeroplanes: 

. . . 

c) powered by engines with a bypass ratio of less than 2 and for which either the application for a 

certificate of airworthiness for the prototype Type Certificate was accepted submitted, or another 

equivalent prescribed procedure was carried out by the certificating authority, before 1 January 

1969, and for which a certificate of airworthiness for the individual aeroplane was first issued 

before 1 January 1976. 

. . . 

CHAPTER 3. 1.— SUBSONIC JET AEROPLANES — 

Application for Type Certificate of Airworthiness

for the Prototype accepted submitted on or after 

6 October 1977 and before 1 January 2006 

 2.— PROPELLER-DRIVEN AEROPLANES OVER 5 700 kg — 

Application for Type Certificate of Airworthiness

for the Prototype accepted submitted on or after 

1 January 1985 and before 17 November 1988 

 3.— PROPELLER-DRIVEN AEROPLANES OVER 8 618 kg — 

Application for Type Certificate of Airworthiness

for the Prototype accepted submitted on or after 

17 November 1988 and before 1 January 2006 

3.1 Applicability 

Note 1.— See also Chapter 1, 1.9 1.10 and 1.11. 

 Note 2.— See Attachment E for guidance on interpretation of these applicability provisions.

 3.1.1 The Standards of this chapter shall be applicable to: 

a) all subsonic jet aeroplanes, including their derived versions, other than aeroplanes which require a 

runway1

 length of 610 m or less at maximum certificated mass for airworthiness, in respect of 

which either the application for a certificate of airworthiness for the prototype Type Certificate 

was accepted submitted, or another equivalent prescribed procedure was carried out by the 

certificating authority, on or after 6 October 1977 and before 1 January 2006; 
A-3 

b) all propeller-driven aeroplanes, including their derived versions, of over 5 700 kg maximum 

certificated take-off mass (except those described in Chapter 6, 6.1), for which either the 

application for a certificate of airworthiness for the prototype Type Certificate was accepted

submitted, or another equivalent prescribed procedure was carried out by the certificating 

authority, on or after 1 January 1985 and before 17 November 1988, except where the Standards 

of Chapter 10 apply; and 

c) all propeller-driven aeroplanes, including their derived versions, of over 8 618 kg maximum 

certificated take- off mass, for which either the application for a certificate of airworthiness for 

the prototype Type Certificate was accepted submitted, or another equivalent prescribed 

procedure was carried out by the certificating authority, on or after 17 November 1988 and before 

1 January 2006. 

. . . 

3.6 Noise certification 

reference procedures 

. . . 

3.6.2 Take-off reference procedure 

. . . 

d) the speed shall be the all-engines operating take-off climb speed selected by the applicant for use 

in normal operation, which shall be at least V2 + 19 km/h (V2 + 10 kt) but not greater than 

V2 + 37 km/h (V2 + 20 kt) and which shall be attained as soon as practicable after lift-off and be 

maintained throughout the take-off noise certification test. The increment applied to V2 shall be 

the same for all reference masses of an aeroplane model unless a difference in increment is 

substantiated based on performance characteristics of the aeroplane; 

. . . 

CHAPTER 4. 1.— SUBSONIC JET AEROPLANES — 

Application for Type Certificate of Airworthiness

for the Prototype accepted submitted on or after 1 January 

2006 

 2.— PROPELLER-DRIVEN AEROPLANES OVER 8 618 kg — 

Application for Type Certificate of Airworthiness for the

Prototype accepted submitted on or after 1 January 2006 

4.1 Applicability 

Note. — See also Chapter 1, 1.9 1.10 and 1.11. 

 4.1.1 The Standards of this chapter shall be applicable to: 

a) all subsonic jet aeroplanes, including their derived versions, other than aeroplanes which require a 

runway1

 length of 610 m or less at maximum certificated mass for airworthiness, in respect of 

which either the application for a certificate of airworthiness for the prototype Type Certificate 

was accepted submitted, or another equivalent prescribed procedure was carried out by the 

certificating authority, on or after 1 January 2006; 
A-4 

b) all propeller-driven aeroplanes, including their derived versions, of over 8 618 kg maximum 

certificated take-off mass, for which either the application for a certificate of airworthiness for the 

prototype Type Certificate was accepted submitted, or another equivalent prescribed procedure 

was carried out by the certificating authority, on or after 1 January 2006; and 

. . . 

CHAPTER 5. PROPELLER-DRIVEN AEROPLANES OVER 5 700 kg — 

APPLICATION FOR TYPE CERTIFICATE OF AIRWORTHINESS FOR THE PROTOTYPE

ACCEPTED SUBMITTED BEFORE 1 JANUARY 1985 

5.1 Applicability 

Note 1.— See also Chapter 1, 1.9 1.10 and 1.11.

. . . 

5.1.2 The Standards of this chapter shall be applicable to all propeller-driven aeroplanes, including 

their derived versions, of over 5 700 kg maximum certificated take-off mass for which either the 

application for a certificate of airworthiness for the prototype Type Certificate was accepted submitted, or 

another equivalent prescribed procedure was carried out by the certificating authority, on or after 

6 October 1977 and before 1 January 1985. 

 5.1.3 The Standards of Chapter 2, with the exception of Sections 2.1 and 2.4.2, shall be applicable 

to derived versions and individual aeroplanes of over 5 700 kg maximum certificated take-off mass and to 

which Standards of Chapter 6 do not apply and are of the type for which the application for a certificate of 

airworthiness for the prototype Type Certificate was accepted submitted, or another equivalent prescribed 

procedure was carried out by the certificating authority, before 6 October 1977, and for which a certificate 

of airworthiness for the individual aeroplane was issued on or after 26 November 1981. 

 5.1.4 The Standards of Chapter 3, with the exception of Section 3.1, shall be applicable to all 

propeller-driven aeroplanes, including their derived versions, of over 5 700 kg maximum take-off mass, 

for which either the application for a certificate of airworthiness for the prototype Type Certificate was 

accepted submitted, or another equivalent prescribed procedure was carried out by the certificating 

authority, on or after 1 January 1985. 

. . . 

CHAPTER 6. PROPELLER-DRIVEN AEROPLANES NOT EXCEEDING 

8 618 kg — APPLICATION FOR TYPE CERTIFICATE OF AIRWORTHINESS

FOR THE PROTOTYPE ACCEPTED SUBMITTED BEFORE 17 NOVEMBER 1988 

6.1 Applicability 

Note 1.— See also Chapter 1, 1.9 1.10 and 1.11. 

 Note 2.— See Attachment E for guidance on interpretation of these applicability provisions.

The Standards of this chapter shall be applicable to all propeller-driven aeroplanes, except those 

aeroplanes specifically designed for aerobatic purposes or agricultural or fire fighting uses, of a maximum 

certificated take-off mass not exceeding 8 618 kg for which: 
A-5 

a) the application for the certificate of airworthiness for the prototype Type Certificate was accepted

submitted, or another equivalent prescribed procedure was carried out by the certificating 

authority, on or after 1 January 1975 and before 17 November 1988, except for derived versions 

for which an application for a certificate of airworthiness Type Certificate was accepted

submitted, or another equivalent procedure was carried out by the certificating authority, on or 

after 17 November 1988, in which case the Standards of Chapter 10 apply; or 

. . . 

CHAPTER 8. HELICOPTERS 

8.1 Applicability 

Note.— See also Chapter 1, 1.9 1.10 and 1.11. 

. . . 

8.1.2 For a helicopter for which the application for the certificate of airworthiness for the prototype 

Type Certificate was accepted submitted, or another equivalent prescribed procedure was carried out by 

the certificating authority, on or after 1 January 1985, except for those helicopters specified in 8.1.4, the 

noise levels of 8.4.1 shall apply. 

 8.1.3 For a derived version of a helicopter for which the application for a change of type design was 

accepted submitted, or another equivalent prescribed procedure was carried out by the certificating 

authority, on or after 17 November 1988, except for those helicopters specified in 8.1.4, the noise levels 

of 8.4.1 shall apply. 

 8.1.4 For all helicopters, including their derived versions, for which the application for the 

certificate of airworthiness for the prototype Type Certificate was accepted submitted, or another 

equivalent prescribed procedure was carried out by the certificating authority, on or after 21 March 2002, 

the noise levels of 8.4.2 shall apply. 

. . . 

8.6 Noise certification reference procedures 

8.6.1 General conditions 

. . . 

8.6.1.6 In 8.6.2 c), 8.6.3.1 c) and 8.6.4 c), the maximum normal operating rpm shall be taken as the 

highest rotor speed for each reference procedure corresponding to the airworthiness limit imposed by the 

manufacturer and approved by the certificating authority. Where a tolerance on the highest rotor speed is 

specified, the maximum normal operating rotor speed shall be taken as the highest rotor speed about 

which that tolerance is given. If the rotor speed is automatically linked with flight condition, the 

maximum normal operating rotor speed corresponding with that the reference flight condition shall be 

used during the noise certification procedure. If rotor speed can be changed by pilot action, the highest 

maximum normal operating rotor speed specified in the flight manual limitation section for power-on the 

reference conditions shall be used during the noise certification procedure. 

. . . 
A-6 

CHAPTER 9. INSTALLED AUXILIARY POWER UNITS (APU) 

AND ASSOCIATED AIRCRAFT SYSTEMS 

DURING GROUND OPERATIONS 

Note.— Standards and Recommended Practices for this chapter are not yet developed. In the 

meantime, guidelines provided in Attachment C may be used for noise certification of installed auxiliary 

power units (APU) and associated aircraft systems in: 

a) all aircraft for which the application for a certificate of airworthiness for the prototype Type 

Certificate was accepted submitted, or another equivalent prescribed procedure was carried out 

by the certificating authority, on or after 6 October 1977; and 

. . . 

CHAPTER 10. PROPELLER-DRIVEN AEROPLANES NOT 

EXCEEDING 8 618 kg — APPLICATION FOR TYPE CERTIFICATE 

OF AIRWORTHINESS FOR THE PROTOTYPE OR DERIVED VERSION 

ACCEPTED SUBMITTED ON OR AFTER 17 NOVEMBER 1988 

10.1 Applicability 

Note 1.— See also Chapter 1, 1.9 1.10 and 1.11. 

. . . 

10.1.2 For an aeroplane for which the application for the certificate of airworthiness for the 

prototype Type Certificate or for all derived versions was accepted submitted, or another equivalent 

prescribed procedure was carried out by the certificating authority, on or after 17 November 1988, except 

for those aeroplanes specified in 10.1.4, the noise limits of 10.4 a) shall apply. 

 10.1.3 For aeroplanes specified in 10.1.2 which fail to comply with the Standards of this chapter 

and where the application for the certificate of airworthiness for the prototype Type Certificate or all 

derived versions was accepted submitted, or another equivalent prescribed procedure was carried out by 

the certificating authority, before 17 November 1993, the Standards of Chapter 6 shall apply. 

 10.1.4 For single-engined aeroplanes, except those aeroplanes specifically designed for aerobatic 

purposes and agricultural or fire fighting uses, self-sustaining powered sailplanes, float planes and 

amphibians, for which: 

a) the application for the certificate of airworthiness for the prototype Type Certificate or their 

derived versions was accepted submitted, or another equivalent procedure was carried out by the 

certificating authority, on or after 4 November 1999, the noise limits of 10.4 b) shall apply; 

b) an application for the certificate of airworthiness Type Certificate for the derived version was 

accepted submitted, or other procedure was carried out, on or after 4 November 1999, but for 

which the application for the certificate of airworthiness for the prototypeType Certificate, or 

another equivalent procedure was carried out by the certificating authority, before 4 November 

1999, the noise limits of 10.4 b) shall apply; 

. . . 
A-7 

CHAPTER 11. HELICOPTERS NOT EXCEEDING 3 175 kg 

MAXIMUM CERTIFICATED TAKE-OFF MASS 

11.1 Applicability 

Note.— See also Chapter 1, 1.9 1.10 and 1.11. 

. . . 

11.1.2 For a helicopter for which the application for the certificate of airworthiness for the 

prototype Type Certificate was issued submitted, or another equivalent prescribed procedure was carried 

out by the certificating authority, on or after 11 November 1993, except for those helicopters specified in 

11.1.4, the noise levels of 11.4.1 shall apply. 

 11.1.3 For a derived version of a helicopter for which the application for the certificate of 

airworthiness Type Certificate for a change of type design was issued submitted, or another equivalent 

prescribed procedure was carried out by the certificating authority, on or after 11 November 1993, except 

for those helicopters specified in 11.1.4, the noise levels of 11.4.1 shall apply. 

 11.1.4 For all helicopters, including their derived versions, for which the application for the 

certificate of airworthiness for the prototype Type Certificate was accepted submitted, or another 

equivalent prescribed procedure was carried out by the certificating authority, on or after 21 March 2002, 

the noise levels of 11.4.2 shall apply. 

. . . 

11.5 Noise certification reference procedure 

11.5.1 General conditions 

. . . 

11.5.1.5 The maximum normal operating rpm shall be taken as the highest rotor speed 

corresponding to the airworthiness limit imposed by the manufacturer and approved by the certificating 

authority for overflight. Where a tolerance on the highest rotor speed is specified, the maximum normal 

operating rotor speed shall be taken as the highest rotor speed about which that tolerance is given. If rotor 

speed is automatically linked with flight condition, the maximum normal operating rotor speed 

corresponding with that the reference flight condition shall be used during the noise certification 

procedure. If rotor speed can be changed by pilot action, the highest maximum normal operating rotor 

speed specified in the flight manual limitation section for power-on the reference conditions shall be used 

during the noise certification procedure. 

. . . 

CHAPTER 12. SUPERSONIC AEROPLANES 

12.1 Supersonic aeroplanes — application for 

certificate of airworthiness for the prototype

accepted Type Certificate submitted before 1 January 1975

 12.1.1 The Standards of Chapter 2 of this Part, with the exception of maximum noise levels 

specified in 2.4, shall be applicable to all supersonic aeroplanes, including their derived versions, in 
A-8 

respect of which either the application for the certificate of airworthiness for the prototype Type 

Certificate was accepted submitted, or another equivalent prescribed procedure was carried out by the 

certificating authority, before 1 January 1975, and for which a certificate of airworthiness for the 

individual aeroplane was first issued after 26 November 1981. 

. . . 

12.2 Supersonic aeroplanes — application for 

certificate of airworthiness for the prototype

accepted Type Certificate submitted on or after 1 January 1975 

Note.— Standards and Recommended Practices for these aeroplanes are not yet developed but the 

noise levels of Chapter 3 of this Part applicable to subsonic jet aeroplanes may be used as guidelines for 

aeroplanes for which the application for a certificate of airworthiness for the prototype Type Certificate 

was accepted submitted, or another equivalent prescribed procedure was carried out by the certificating 

authority, on or after 1 January 1975. 

. . . 

CHAPTER 13. TILT-ROTOR AIRCRAFT 

Note 1.— Standards and Recommended Practices for this chapter are not yet developed. In the 

meantime, guidelines provided in Attachment F may be used for noise certification of tilt-rotor aircraft 

for which a type certificate of airworthiness was issued the application for a Type Certificate was 

submitted or another equivalent prescribed procedure was carried out by the certificating authority on or 

after 13 May 1998 and to provide data for land-use planning purposes.

. . . 

APPENDIX 1. EVALUATION METHOD FOR NOISE CERTIFICATION OF 

SUBSONIC JET AEROPLANES — APPLICATION FOR TYPE CERTIFICATE OF

AIRWORTHINESS FOR THE PROTOTYPE ACCEPTED SUBMITTED BEFORE 

6 OCTOBER 1977 

. . . 

APPENDIX 2. EVALUATION METHOD FOR NOISE CERTIFICATION OF:

1.— SUBSONIC JET AEROPLANES — 

Application for Type Certificate of Airworthiness

for the Prototype accepted submitted on or after 

6 October 1977

2.— PROPELLER-DRIVEN AEROPLANES OVER 5 700 kg — 

Application for Type Certificate of Airworthiness

for the Prototype accepted submitted on or after 

1 January 1985 and before 17 November 1988

3.— PROPELLER-DRIVEN AEROPLANES OVER 8 618 kg — 

Application for Type Certificate of Airworthiness

for the Prototype accepted submitted on or after 

17 November 1988

4.— HELICOPTERS

Note.— See Part II, Chapters 3, 4 and 8.
A-9 

. . . 

2. NOISE CERTIFICATION TEST AND 

MEASUREMENT CONDITIONS

Replace Section 2.2 as follows:

. . . 

2.2 Test environment 

2.2.1 Microphone locations 

Locations for measuring noise from an aircraft in flight shall be surrounded by relatively flat terrain 

having no excessive sound absorption characteristics such as might be caused by thick, matted, or tall 

grass, shrubs, or wooded areas. No obstructions which significantly influence the sound field from the 

aircraft shall exist within a conical space above the point on the ground vertically below the microphone, 

the cone being defined by an axis normal to the ground and by a half-angle 80° from this axis. 

Note.— Those people carrying out the measurements could themselves constitute such obstructions. 

2.2.2 Atmospheric conditions 

2.2.2.1 Specifications

For the purposes of noise certification in this section the following specifications apply: 

Time constant (of a first order system) is the time required for a device to detect and indicate 100*(1-1/e) 

percent (about 63%) of a step function change. (The mathematical constant, e, is the base number of 

the natural logarithm, approximately 2.7183 - also known as Euler’s number, or Napier’s constant.) 

Distance constant (or response length) is the passage of wind (in meters) required for the output of a 

wind speed sensor to indicate 100*(1-1/e) percent (about 63%) of a step-function increase of the input 

speed. 

Wind speed sample (at a certain moment) is the value measured at that moment for wind speed using a 

sensor/system with characteristics as follows: 

Range: 1 m/s (3.6 km/h) to more than 10 m/s (36 km/h); 

Linearity: +/- 0.5 m/s (1.8 km/h) over the specified range; and 

Distance constant (response length): less than 5 meters for systems having dynamic behaviour best 

characterised by a distance constant; or 

Time constant: less than 3 seconds for wind speeds at or above 5 m/s (18 km/h) 

for systems having dynamic behaviour best characterised by a 

time constant. 
A-10 

Wind direction sample (at a certain moment) is the value obtained at that moment from a wind direction 

sensor/system with characteristics as follows: 

Wind speed operating range: 1 m/s (3.6 km/h) to more than 10 m/s (36 km/h); 

Linearity: +/- 5 degrees over the specified range; and 

Resolution: 5 degrees. 

 

Note.— For the entire wind sensing system used to obtain wind speed and direction samples, the 

combined dynamic characteristics, including physical inertia of the sensor(s), and any temporal 

processing, such as filtering of the sensor signal(s), or smoothing or averaging of the wind sensor data, 

shall be equivalent to a first order system (such as an R/C circuit) with a time constant of no greater than 

3 seconds at a wind speed of 5 m/s (18 km/h). 

Wind vector (at a certain moment). At least once every second the wind vector shall be determined. Its 

magnitude will be represented at a certain moment by the wind speed sample at that moment and the 

direction of the vector shall be represented by the wind direction sample at that moment. 

Average wind speed shall be determined from the series of individual wind speed samples obtained 

during the aircraft test run, using a linear averaging process over 30 seconds, or an averaging process 

that has a time constant of no more than 30 seconds, the result of which is read out at a moment 

approximately 15 seconds after the time at which the aircraft passes either over or abeam the 

microphone. Alternatively, each wind vector shall be broken down into its “along track” (u) and 

“cross-track” (v) components. The u and v components of the series of individual wind samples 

obtained during the aircraft test run shall be separately averaged using a linear averaging process over 

30 seconds, or an averaging process that has a time constant of no more than 30 seconds, the result of 

which is read out at a moment approximately 15 seconds after the time at which the aircraft passes 

either over or abeam the microphone. The average wind speed and direction (with respect to the 

track) shall then be calculated from the averaged u and v components according to Pythagorean 

Theorem and “arctan(u/v)”. 

Average cross-wind component shall be determined from the series of individual values of the “cross 

track” (v) component of the wind samples obtained during the aircraft test run, using a linear 

averaging process over 30 seconds or an averaging process that has a time constant of no more than 

30 seconds, the result of which is read out at a moment approximately 15 seconds after the time at 

which the aircraft passes either over or abeam the microphone. 

Maximum wind speed. The maximum value within the series of individual wind speed samples recorded 

every second over a period that spans the 10 dB-down time interval. 

Maximum cross-wind component. The maximum value within the series of individual values of the 

“cross track” (v) component of the wind samples recorded every second over a period that spans the 

10 dB-down time interval. 

2.2.2.2 Except as provided in 2.2.2.5, the tests shall be carried out under the following atmospheric 

conditions: 

a) no precipitation; 

b) ambient air temperature not above 35°C and not below -10°C, and relative humidity not above 

95 per cent and not below 20 per cent over the whole noise path between a point 10 m (33 ft) 

above the ground and the aircraft; 
A-11 

Note.— Care should be taken to ensure that the noise measuring, aircraft flight path tracking and 

meteorological instrumentation are operated within the environmental limitations specified by the 

manufacturer. 

c) relative humidity and ambient temperature over the whole noise path between a point 10 m (33 ft) 

above the ground and the aircraft altitude at the time of PNLTM, such that the sound attenuation 

due to atmospheric absorption in the one-third octave band centred on 8 kHz will not be more 

than 12 dB/100 m; 

Note.— Section 7 of this appendix specifies the method for calculation of atmospheric absorption 

coefficients based on temperature, humidity, and frequency. 

d) if the atmospheric absorption coefficients vary over the PNLTM sound propagation path by more 

than ±0.5 dB/100 m in the 3 150 Hz one-third octave band from the value of the absorption 

coefficient derived from the meteorological measurement obtained at 10 m above the surface, 

‘layered’ sections of the atmosphere must be used to compute equivalent weighted sound 

attenuations in each one-third octave band, sufficient sections being used to the satisfaction of the 

certificating authority; where multiple layering is not required, equivalent sound attenuations in 

each one-third octave band shall be determined by averaging the atmospheric absorption 

coefficients for each such band at 10 m (33 ft) above ground level and at the flight level of the 

test aircraft at the time of PNLTM, for each measurements; 

e) at 10 m (33 ft) above ground, for aeroplanes, the average wind speed shall not exceed 22 km/h 

(12 kt) and the average cross-wind component shall not exceed 13 km/h (7 kt). For helicopters, 

the average wind speed shall not exceed 19 km/h (10 kt) and the average cross-wind component 

shall not exceed 9 km/h (5 kt). For aeroplanes, the maximum wind speed shall not exceed 

28 km/h (15 kt) and the maximum cross-wind component shall not exceed 18 km/h (10 kt). All 

wind speed samples shall be taken with the sensor installed such that the horizontal distance 

between the anemometer and any obstruction is at least 10 times the height of the obstruction. 

Installation error for the wind direction sensor shall be no greater than 5 degrees; and 

f) no anomalous meteorological or wind conditions that would significantly affect the measured 

noise levels when the noise is recorded at the measuring points specified by the certificating 

authority. 

2.2.2.3 Meteorological measurements of ambient temperature and relative humidity shall be obtained 

within 30 minutes of each noise test measurement. Meteorological data shall be interpolated to actual 

times of each noise measurement. Wind measurements shall be obtained continuously during each aircraft 

test run. 

2.2.2.4 When a multiple layering calculation is required by 2.2.2.2 d), the atmosphere between the 

aircraft and 10 m (33 ft) above the ground shall be divided into layers of equal depth. The depth of the 

layers shall be set to not more than the depth of the narrowest layer across which the variation in the 

atmospheric absorption coefficient of the 3 150 Hz one-third octave band is not greater than ±0.5 dB/100 

m, with a minimum layer depth of 30 m (100 ft). This shall apply over the propagation path at PNLTM. 

The mean of the values of the atmospheric absorption coefficients at the top and bottom of each layer may 

be used to characterize the absorption properties of each layer. 

2.2.2.5 For helicopters the requirements of 2.2.2.2 b), c) and d) shall only be applied at a point 10 m 

(33 ft) above ground. 
A-12 

2.2.2.6 The atmospheric conditions shall be measured within 2 000 m (6 562 ft) from the microphone 

locations and shall be representative of the conditions existing over the geographical area in which noise 

measurements are made.

. . . 

3. MEASUREMENT OF AIRCRAFT 

NOISE RECEIVED ON THE GROUND 

3.1 Definitions 

For the purposes of this section the following definitions apply: 

. . . 

Sound incidence angle. In degrees, an angle between the principal axis of the microphone, as defined in 

IEC 61094-31 and IEC 61094-42, as amended and a line from the sound source to the centre of the 

diaphragm of the microphone. 

Note.— When the sound incidence angle is 0°, the sound is said to be received at the microphone at 

“normal (perpendicular) incident incidence”; when the sound incidence angle is 90°, the sound is said to 

be received at “grazing incidence”. The principal axis of a measurement microphone is through the 

centre of the diaphragm and perpendicular to it.

. . . 

3.7 Analysis systems 

. . . 

3.7.3 The one-third octave band analysis system shall at least conform to the class 2 1 electrical 

performance requirements of IEC 612604 612602 as amended, over the range of one-third octave nominal 

midband frequencies from 50 Hz to 10 kHz inclusive. 

Note 1.— The certificating authority may allow the substitution of an analysis system that complies 

with class 2 as an alternative to class 1 electrical performance requirements of IEC 612602. 

Note 2.—Tests of the one-third octave band analysis system should be made according to the methods 

described in IEC 6126044 612602 or by an equivalent procedure approved by the certificating authority, 

for relative attenuation, anti-aliasing filters, real-time operation, level linearity, and filter integrated 

response (effective bandwidth).

. . . 

3.8 Calibration systems 

The acoustical sensitivity of the measurement system shall be determined using a sound calibrator 

generating a known sound pressure level at a known frequency. The sound calibrator shall at least 

conform to the class 1L requirements of IEC 609425 609423 as amended. 

. . . 
A-13 

1 IEC 61094-3: 1995 entitled “Measurement microphones — Part 3: Primary method for free-field calibration of laboratory 

standard microphones by the reciprocity technique”. This IEC publication may be obtained from the Central Office of the 

International Electrotechnical Commission, 3 rue de Varembé, Geneva, Switzerland.

2 IEC 61094-4: 1995 entitled “Measurement microphones — Part 4: Specifications for working standard microphones”. This 

IEC publication may be obtained from the Central Office of the International Electrotechnical Commission, 3 rue de 

Varembé, Geneva, Switzerland.

3 1 IEC 61265: 1995 entitled “Electroacoustics — Instruments for measurement of aircrft noise — Performance requirements 

for systems to measure one-third-octave band sound pressure levels in noise certification of transport-category aeroplanes”. 

This IEC publication may be obtained from the Central Office of the International Electrotechnical Commission, 3 rue de 

Varembé, Geneva, Switzerland. 

4 2 IEC 61260: 1995 entitled “Electroacoustics — Octave-band and fractional-octave band filters”. This IEC publication may be 

obtained from the Central Office of the International Electrotechnical Commission, 3 rue de Varembé, Geneva, Switzerland. 

5 3 IEC 60942: 1997 2003 entitled “Electroacoustics – Sound calibrators”. This IEC publication may be obtained from the 

Central Office of the International Electrotechnical Commission, 3 rue de Varembé, Geneva, Switzerland. 

. . . 

5. REPORTING OF DATA TO THE 

CERTIFICATING AUTHORITY 

. . . 

5.2 Data reporting 

. . . 

5.2.3 The following atmospheric environmental data, measured immediately before, after, or during 

each test at the observation points prescribed in Section 2 of this appendix shall be reported: 

a) air temperature and relative humidity; 

b) maximum, minimum and average wind velocities speeds and wind directions; and 

. . . 

APPENDIX 3. NOISE EVALUATION METHOD FOR NOISE CERTIFICATION 

OF PROPELLER-DRIVEN AEROPLANES NOT EXCEEDING 8 618 kg — 

APPLICATION FOR TYPE CERTIFICATE OF AIRWORTHINESS FOR

THE PROTOTYPE ACCEPTED SUBMITTED BEFORE 17 NOVEMBER 1988 

. . . 
A-14 

APPENDIX 4. EVALUATION METHOD FOR NOISE CERTIFICATION 

OF HELICOPTERS NOT EXCEEDING 3 175 kg MAXIMUM 

CERTIFICATED TAKE-OFF MASS 

. . . 

2. NOISE CERTIFICATION 

TEST AND MEASUREMENT 

CONDITIONS 

. . . 

2.2 Test environment 

. . . 

 2.2.2 The tests shall be carried out under the following atmospheric conditions: 

 a) no precipitation; 

b) relative humidity not higher than 95 per cent or lower than 20 per cent and ambient temperature 

not above 35°C and not below 2°C at a height between 1.2 m (4 ft) and 10 m (33 ft) above ground 

(if the measurement site is within 2 000 m of aerodrome weather measuring equipment, the 

aerodrome reported temperature, relative humidity and wind speed may be used). Combinations 

combinations of temperature and humidity which lead to an absorption coefficient in the 8 KHz 

one-third octave band of greater than 10 dB/100 m shall be avoided. Absorption coefficients as a 

function of temperature and relative humidity are given in Section 7 of Appendix 2 or SAE ARP 

866 A; 

 Note.— Absorption coefficients as a function of temperature and relative humidity are given 

in Section 7 of Appendix 2 or SAE ARP 866A

.

c) at a height between 1.2 m (4 ft) and 10 m (33 ft) above ground, average wind speed shall not 

exceed 19 km/h (10 kt) and the average crosswind average wind speed component at right angles 

to the direction of flight shall not exceed 9 km/h (5 kt) at a height between 1.2 m (4 ft) and 10 m 

(33 ft) above ground; and 

Note.— Average wind speed is defined over a 30-second time period.

d) no other anomalous meteorological conditions that would significantly affect the noise level when 

recorded at the measuring points specified by the certificating authority. 

Note.— Meteorological specifications are given in Section 2.2.2.1 of Appendix 2. 

2.2.3 The atmospheric conditions shall be measured within 2 000 m (6 562 ft) from the microphone 

locations and shall be representative of the conditions existing over the geographical area in which noise 

measurements are made.

2.3 Flight path measurement 

. . . 

2.3.1 The helicopter position relative to the flight path reference point shall be determined by a 

method independent of normal flight instrumentation, such as radar tracking, theodolite triangulation or 
A-15 

photographic scaling techniques, approved by the certificating authority. 

 2.3.2 The helicopter noise shall be measured over a distance sufficient to ensure adequate data 

during the period that the noise is within 10 dB(A) of the maximum value of dB(A).

2.3.32.3.2 Position and performance data required to make the adjustments referred to in Section 5 

of this appendix shall be recorded at an approved sampling rate. Measuring equipment shall be approved 

by the certificating authority. 

2.4 Flight test conditions

 2.4.1 The helicopter shall be flown in a stabilized flight condition over a distance sufficient to 

ensure that the time-varying sound level is measured during the entire time period that the sound level is 

within 10 dB(A) of LAmax. 

Note.— LAmax is defined as the maximum of the A-frequency-weighted S-time-weighted sound level 

measured during the test run. 

 2.4.1 2.4.2 The helicopter flyover noise test shall be conducted at the airspeed referred to in Part II, 

Chapter 11, 11.5.2 with such airspeed adjusted as necessary to produce the same advancing blade tip 

Mach number as associated with the reference conditions. 

 2.4.2 2.4.3 Advancing The reference advancing blade tip Mach number (Mat) (MR) is defined as the 

ratio of the arithmetic sum of blade tip rotational speed (Vt) (VT) and the reference helicopter true 

airspeed (Vr) (Vr) divided by the speed of sound (c) (cR) at 25°C such that: 

(Vt + Vr) Mat =

c

(VT + Vr) MR = 

cR

3. NOISE UNIT DEFINITION 

 3.1 The value of sound exposure level LAE is defined as the level, in decibels, of the time integral of 

squared A-weighted sound pressure (PA) over a given time period or event, with reference to the square of 

the standard reference sound pressure (P0) or of 20 micropascals μPa and a reference duration of one 

second. 

 3.2 This unit is defined by the expression: 

where T0 is the reference integration time of one second and (t2 – t1) is the integration time interval. 

 3.3 The above integral can also be expressed be approximated from periodically sampled 

measurement as: 

dt

P

P t

T

L A t

t AE

2

0

2

1

0

1 ( ) 10 log ⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛ = ∫
A-16 

where LA(t) is the time varying A-weighted A-frequency-weighted S-time-weighted sound level and n is 

the number of samples per second. 

 3.4 The integration time (t2 – t1) in practice shall not be less than the 10 dB-down time interval 

during which LA(t) first rises to within 10 dB(A) of below its maximum value (LAmax) and last falls below 

10 dB(A) of its maximum value. 

 3.5 The SEL may be approximated by the following expression:

LAE = LAmax + ∆A

where ∆A is the duration allowance given by

∆A = 10 log10τ

where τ = (t2 – t1)/2.

LAmax is defined as the maximum level, in decibels, of the A-weighted sound pressure (slow response) 

with reference to the square of the standard reference sound pressure P0.

4. MEASUREMENT OF 

HELICOPTER NOISE RECEIVED 

ON THE GROUND 

4.1 General 

 4.1.1 All measuring equipment shall be approved by the certificating authority. 

 4.1.2 Sound pressure level data for noise evaluation purposes shall be obtained with acoustical 

equipment and measurement practices that conform to the specifications given in 4.2. 

4.2 Measurement system 

The acoustical measurement system shall consist of approved equipment equivalent to the following: 

a) a microphone system with frequency response compatible with measurement and analysis system 

accuracy as stated in performance characteristics meeting the requirements of 4.3; 

b) tripods or similar microphone mountings that minimize interference with the sound being 

dt

T

L

t

L t

t AE A 10

( ) 2

1

0

10 1 10 log ∫ =

∑

−

=

=

( 2 1)

1

(0.1 ( ))

0

10 1 10 log

n t t

t

L t

AE A

T

L
A-17 

measured; 

c) recording and reproducing equipment characteristics, frequency response, and dynamic range 

compatible with the response and accuracy requirements with performance characteristics 

meeting the requirements of 4.3; and 

d) acoustic sound calibrators using sine wave or broadband noise signals of known sound pressure 

level meeting the requirements of 4.3. If broadband noise is used, the signal shall be described in 

terms of its average and maximum root-mean-square (rms) value for non-overload signal level.

4.3 Sensing, recording and 

reproducing equipment 

 4.3.1 The microphone shall be of the type that has a pressure or a diffuse-field sensitivity whose 

frequency response is nearly flat at grazing incidence. 

 4.3.1 4.3.2 With the approval of the certificating authority the sound level produced by the 

helicopter may be stored on a magnetic tape recorder for later evaluation. Alternatively, the A-weighted 

sound level time history may be written onto a graphic level recorder set at “slow” response from which 

the SEL value may be determined or the SEL may be directly determined from an integrating sound level 

meter complying with the Standards of International Electrotechnical Commission (IEC) Publication No. 

8041 for a Type 1 instrument set at “slow” response. The SEL may be directly determined from an 

integrating sound level meter. Alternatively, with the approval of the certificating authority the sound 

pressure signal produced by the helicopter may be stored on an analog magnetic tape recorder or a digital 

audio recorder for later evaluation using an integrating sound level meter. The SEL value may also be 

calculated from one-third octave band data obtained from measurements made in conformity with 

Section 3 of Appendix 2 and using the equation given in 3.3. In this case each one-third octave band 

sound pressure level shall be weighted in accordance with the A-weighting values given in IEC 

Publication No. 651.

1

 IEC Publication 61672-1.1

 4.3.2 4.3.3 The characteristics of the complete system shall comply with the recommendations 

given in IEC Publication No. 6511 with regard to the sections concerning microphone, amplifier and 

indicating instrument characteristics. The text and specifications of IEC Publication No. 651 entitled 

“Sound Level Meters” are incorporated by reference into this section and are made a part hereof.The 

characteristics of the complete system with regard to directional response, frequency weighting A, time 

weighting S (slow), level linearity, and response to short-duration signals, shall comply with the class 1 

specifications given in IEC 61672-1.1 The complete system may include tape recorders or digital audio 

recorders according to IEC 61672-1.1

Note.— The certificating authority may approve the use of equipment compliant with class 2 of the 

current IEC standard, or the use of equipment compliant with class 1 or Type 1 specifications of an 

earlier standard, if the applicant can show that the equipment had previously been approved for noise 

certification use by a certificating authority. This includes the use of a sound level meter and graphic 

level recorder to approximate SEL using the equation given in 3.3. The certificating authority may also 

approve the use of magnetic tape recorders that comply with the specifications of the older IEC 561 

standard if the applicant can show that such use had previously been approved for noise certification use 

by a certificating authority.

4.3.3 If a tape recording is used, the tape recorder shall comply with IEC Recommendation 561.

1

4.3.4 The response of the complete system to a sensibly plane progressive sinusoidal wave of 
A-18 

constant amplitude shall lie within the tolerance limits specified in Table IV and Table V for Type I 

instruments in IEC Publication No. 651, for weighting curve A over the frequency range 45 to 11 500 Hz.

 4.3.5 4.3.4 The overall sensitivity of the measuring system shall be checked before tests start, after 

testing has ended, and at intervals during testing using an acoustic a sound calibrator generating a known 

sound pressure level at a known frequency. The sound calibrator should conform to the class 1 

requirements of IEC 60942. The output of the acoustic sound calibrator shall have been checked by a 

standardizing laboratory within 6 months of the test series; tolerable changes in output shall be not more 

than 0.2 dB. The equipment shall be considered satisfactory if the variation over the period immediately 

prior to and immediately following each test series within a given test day is not greater than 0.5 dB. 

Note.— A pistonphone operating at a nominal 124 dB and 250 Hz is generally used for this purpose. The 

certificating authority may approve the use of calibrators compliant with class 2 of the current IEC 

standard, or the use of calibrators compliant with class 1 of an earlier standard, if the applicant can 

show that the calibrator had previously been approved for noise certification use by a certificating 

authority.

 4.3.5 When the sound pressure signals from the helicopter are recorded, the SEL may be 

determined by playback of the recorded signals into the electrical input facility of an approved sound 

level meter that conforms to the class 1 performance requirements of IEC 61672-1. The acoustical 

sensitivity of the sound level meter shall be established from playback of the associated recording of the 

signal from the sound calibrator and knowledge of the sound pressure level produced in the coupler of the 

sound calibrator under the environmental conditions prevailing at the time of the recording of the sound 

from the helicopter. 

 4.3.6 A wind screen should be employed with the microphone during all measurements of 

helicopter noise sound levels. Its characteristics should be such that when it is used, the complete system 

including the wind screen will meet the specifications above. Its insertion loss at the frequencies of the 

pistonphone should also be known and included in the acoustic reference level for analysis of the 

measurements. in 4.3.3.

4.4 Noise measurement procedures 

 4.4.1 The microphone shall be of the pressure-sensitive type designed for nearly uniform grazing 

incidence response.

4.4.2 4.4.1 The microphone shall be mounted with the centre of the sensing element 1.2 m (4 ft) 

above the local ground surface and shall be oriented for grazing incidence, i.e. with the sensing element 

substantially in the plane defined by the nominal flight path of the helicopter and the measuring station. 

The microphone mounting arrangement shall minimize the interference of the supports with the sound to 

be measured. 

 4.4.3 4.4.2 If the noise helicopter sound pressure signal is tape-recorded, the frequency response of 

the electrical system shall be determined, during each test series, at a level within 10 dB of the full-scale 

reading used during the tests, utilizing random or pseudo-random pink noise. The output of the noise 

generator shall have been checked by an approved standards laboratory within six months of the test 

series, and tolerable changes in the relative output at each one-third octave band shall be not more than 

0.2 dB. Sufficient determinations shall be made to ensure that the overall calibration of the system is 

known for each test. 

 4.4.4 4.4.3 Where a an analog magnetic tape recorder forms part of the measuring chain, each reel 
A-19 

of magnetic tape shall carry 30 s of this electrical calibration signal at its beginning and end for this 

purpose. In addition, data obtained from tape-recorded signals shall be accepted as reliable only if the 

level difference in the 10 kHz one-third octave band filtered levels of the two signals is not more than 

0.75 dB. 

Note.— Digital audio recorders typically do not exhibit substantial variation in frequency response 

or level sensitivity, therefore the pink noise testing described in 4.4.3 is not necessary for digital audio 

recorders. 

 4.4.5 4.4.4 Background The A-frequency-weighted sound level of the background noise, including 

ambient noise and electrical noise of the measurement systems, shall be determined in the test area with 

the system gain set at levels which will be used for helicopter noise measurements. If helicopter sound 

pressure levels do not exceed background sound pressure levels If the LAmax of each test run does not 

exceed the A-frequency-weighted sound level of the background noise by at least 15 dB(A), flyovers at 

an approved lower height may be used and the results adjusted to the reference measurement point height 

by an approved method. 

1 Available from the Central Office of the International Electrotechnical Commission, 3 rue de Varembé, Geneva, 

Switzerland.IEC 61672-1: 2002 entitled “Electroacoustics – Sound level meters – Part I: Specifications”. This IEC 

publication may be obtained from the Bureau central de la Commission électrotechnique internationale, 1 rue de Varembé, 

Geneva, Switzerland.

2 IEC 60942: 2003 entitled “Electroacoustics – Sound calibrators”. This IEC publication may be obtained from the Bureau 

central de la Commission électrotechnique internationale, 1 rue de Varembé, Geneva, Switzerland. 

. . . 

APPENDIX 6. NOISE EVALUATION METHOD FOR NOISE CERTIFICATION 

OF PROPELLER-DRIVEN AEROPLANES NOT EXCEEDING 8 618 kg — 

APPLICATION FOR TYPE CERTIFICATE OF AIRWORTHINESS FOR

THE PROTOTYPE ACCEPTED SUBMITTED ON OR AFTER 17 NOVEMBER 1988 

. . . 

2. NOISE CERTIFICATION TEST AND 

MEASUREMENT CONDITIONS 

. . . 

2.2 General test conditions 

. . . 

2.2.2 The tests shall be carried out under the following atmospheric conditions: 

. . . 

c) average wind speed shall not exceed 19 km/h (10 kt) and crosswind average wind speed shall not 

exceed 9 km/h (5 kt); 

 Note.— Average wind speed is defined over a 30-second time period. Meteorological 

specifications are defined in Section 2.2.2.1 of Appendix 2.

. . . 
A-20 

 2.2.3 The atmospheric conditions shall be measured within 2 000 m (6 562 ft) from the microphone 

locations and shall be representative of the conditions existing over the geographical area in which noise 

measurements are made. 

. . . 

Replace Section 4 as follows: 

4. MEASUREMENT OF AEROPLANE 

NOISE RECEIVED ON THE GROUND 

4.1 General 

4.1.1 All measuring equipment shall be approved by the certificating authority. 

4.1.2 Sound pressure level data for noise evaluation purposes shall be obtained with acoustical 

equipment and measurement practices that conform to the specifications given hereunder in 4.2. 

4.2 Measurement system 

The acoustical measurement system shall consist of approved equipment equivalent to the following: 

a) a microphone system designed to have mostly-uniform frequency response for sound incident on 

the diaphragm from random directions, or in the pressure field of a closed cavity, with 

performance characteristics meeting the requirements of 4.3; 

b) microphone installation and mounting hardware that minimizes interference with the sound being 

measured, in the configuration specified in 4.4; 

c) recording and reproducing equipment performance characteristics meeting the requirements of 

4.3; and 

d) sound calibrators using sine wave signals of known sound pressure level meeting the 

requirements of 4.3. 

4.3 Sensing, recording and reproducing equipment 

4.3.1 The sound level produced by the aeroplane shall be recorded. A magnetic tape recorder, 

graphic level recorder or sound level meter is acceptable at the option of the certificating authority. 

4.3.2 The characteristics of the complete system with regard to directional response, frequency 

weighting A, time weighting S (slow), level linearity, and response to short-duration signals, shall comply 

with the class 1 specifications given in the IEC Publication 61672-1.1

 The complete system may include 

tape recorders according to IEC 61672-1.1

Note.— The certificating authority may approve the use of equipment compliant with class 2 of the 

current IEC standard, or the use of equipment compliant with class 1 or Type 1 specifications of earlier 

standards, as an alternative to equipment compliant with class 1 of the current IEC standard, if the 
A-21 

applicant can show that the equipment had previously been approved for noise certification use by a 

certificating authority. The certificating authority may also approve the use of magnetic tape recorders 

that comply with the specifications of the older IEC 561 standard if the applicant can show that such use 

had previously been approved for noise certification use by a certificating authority. 

4.3.3 The over-all sensitivity of the measuring system shall be checked before tests start, after 

testing has ended, and at intervals during testing using a sound calibrator generating a known sound 

pressure level at a known frequency. The sound calibrator should conform to the class 1 requirements of 

IEC 60942.2

Note.— The certificating authority may approve the use of calibrators compliant with the class 2 

specifications of the current IEC standard, or the use of calibrators compliant with class 1 of an earlier 

standard, if the applicant can show that the calibrator had previously been approved for noise 

certification use by a certificating authority. 

4.3.4 When the sound from the aeroplane is tape recorded, the maximum A-frequency-weighted 

and S-time-weighted sound level may be determined by playback of the recorded signals into the 

electrical input facility of an approved sound level meter that conforms to the class 1 performance 

requirements of IEC 61672-1.1

 The acoustical sensitivity of the sound level meter shall be established 

from playback of the associated recording of the signal from the sound calibrator and knowledge of the 

sound pressure level produced in the coupler of the sound calibrator under the environmental conditions 

prevailing at the time of the recording of the sound from the aeroplane. 

4.4 Noise measurement procedures 

4.4.1 The microphone shall be a 12.7 mm diameter pressure type, with its protective grid, mounted 

in an inverted position such that the microphone diaphragm is 7 mm above and parallel to a circular metal 

plate. This white-painted metal plate shall be 40 cm in diameter and at least 2.5 mm thick, and shall be 

placed horizontally and flush with the surrounding ground surface with no cavities below the plate. The 

microphone shall be located three-quarters of the distance from the centre to the edge along a radius 

normal to the line of flight of the test aeroplane. 

4.4.2 If the noise signal is tape-recorded, the frequency response of the electrical system shall be 

determined, during each test series, at a level within 10 dB of the full-scale reading used during the tests, 

utilizing random or pseudorandom pink noise. The output of the noise generator shall have been checked 

by an approved Standards laboratory within six months of the test series, and tolerable changes in the 

relative output at each one-third octave band shall be not more than 0.2 dB. Sufficient determinations 

shall be made to ensure that the over-all calibration of the system is known for each test. 

4.4.3 Where a magnetic tape recorder forms part of the measuring chain, each reel of magnetic tape 

shall carry 30 s of this electrical calibration signal at its beginning and end for this purpose. In addition, 

data obtained from tape recorded signals shall be accepted as reliable only if the level difference in the 10 

kHz one-third octave band filtered levels of the two signals is not more than 0.75 dB.

Note.— Digital audio recorders typically do not exhibit substantial variation in frequency response 

or level sensitivity, therefore the pink noise testing described in 4.4.3 is not necessary for digital audio 

recorders. Design characteristics for digital audio recorders should be compliant with class 1 

performance specifications of IEC 61672-1.1
A-22 

4.4.4 The A-frequency-weighted sound level of the background noise, including ambient noise and 

electrical noise of the measurement systems, shall be determined in the test area with the system gain set 

at levels which will be used for aeroplane noise measurements. If the maximum A-frequency-weighted 

and S-time-weighted sound level of the aeroplane does not exceed the A frequency-weighted sound level 

of the background noise by at least 10 dB, a take-off measurement point nearer to the start of roll shall be 

used and the results adjusted to the reference measurement point by an approved method.

1 IEC 61672-1: 2002 entitled “Electroacoustics – Sound level meters – Part I: Specifications”. This IEC publication may be 

obtained from the Bureau central de la Commission électrotechnique internationale, 1 rue de Varembé, Geneva, 

Switzerland. 

2 IEC 60942: 2003 entitled “Electroacoustics – Sound calibrators”. This IEC publication may be obtained from the Bureau 

central de la Commission électrotechnique internationale, 1 rue de Varembé, Geneva, Switzerland. 

End of new text. 

5. ADJUSTMENT TO 

TEST RESULTS 

. . . 

5.2 Corrections 

and adjustments 

Replace the equation under the Note to 5.2.2 c) 3) as follows: 

. . . 

ATTACHMENT C. GUIDELINES FOR NOISE CERTIFICATION OF 

INSTALLED AUXILIARY POWER UNITS (APU) AND ASSOCIATED 

AIRCRAFT SYSTEMS DURING GROUND OPERATION 

Note.— See Part II, Chapter 9. 

1. INTRODUCTION 

. . . 

 1.2 It should apply to installed APU and associated aircraft systems in all aircraft for which the 

application for a certificate of airworthiness for the prototypeType Certificate, or another equivalent 

prescribed procedure, is made submitted on or after 26 November 1981. 

c

V D N

M

T

R

1/ 2

2

2

60 ⎥

⎥

⎦

⎤

⎢

⎢

⎣

⎡ ⎟ + ⎠

⎞ ⎜

⎝

⎛

=

π
A-23 

. . . 

Replace Attachment E as follows: 

ATTACHMENT E. APPLICABILITY OF ANNEX 16 

NOISE CERTIFICATION STANDARDS FOR PROPELLER-DRIVEN AEROPLANES1
A-24 

ATTACHMENT F. GUIDELINES FOR NOISE CERTIFICATION 

OF TILT-ROTOR AIRCRAFT 

. . . 

1. APPLICABILITY 

The following guidelines should be applied to all tilt-rotor aircraft, including their derived versions, for 

which a type certificate of airworthiness an application for Type Certificate was issued submitted on or 

after 13 May 1998. 

. . . 

ATTACHMENT H. GUIDELINES FOR OBTAINING HELICOPTER 

NOISE DATA FOR LAND-USE PLANNING PURPOSES 

. . . 

2. DATA COLLECTION 

PROCEDURES 

 2.1 Data suitable for land-use planning purposes may be derived directly from Chapter 8 noise 

certification data. Chapter 8 applicants may optionally elect to acquire data suitable for land-use planning 

purposes via alternative take-off, approach and/or flyover procedures defined by the applicant and 

approved by the certificating authority. Alternative flyover procedures should be performed overhead the 

flight path reference point at a height of 150 m. In addition, an applicant may optionally elect to provide 

data at additional microphone locations.

 2.2 Chapter 11 noise certification data may be provided for land-use planning purposes. Chapter 11 

applicants may optionally elect to provide data acquired via alternative flyover procedures at 150 m above 

ground level. In acquiring data for land-use planning purposes, Chapter 11 applicants should give 

consideration to acquiring data from two additional microphones symmetrically disposed at 150 m on 

each side of the flight path and/or additional take-off and approach procedures defined by the applicant 

and approved by the certificating authority. In addition, an applicant may optionally elect to provide data 

at additional microphone locations.

— — — — — — — — 
ATTACHMENT B to State letter AN 1/61.2, AN 1/62.2 - 07/34 

PROPOSED AMENDMENT TO 

INTERNATIONAL STANDARDS AND RECOMMENDED PRACTICES 

ENVIRONMENTAL PROTECTION 

ANNEX 16 

TO THE CONVENTION ON INTERNATIONAL CIVIL AVIATION 

VOLUME II 

AIRCRAFT ENGINE EMISSIONS 

1. The text of the amendment is arranged to show deleted text with a line through it and new text 

highlighted with grey shading, as shown below: 

1. Text to be deleted is shown with a line through it. text to be deleted

2. New text to be inserted is highlighted with grey shading. new text to be inserted

3. Text to be deleted is shown with a line through it followed 

by the replacement text which is highlighted with grey 

shading.

new text to replace existing text
TEXT OF PROPOSED AMENDMENT TO THE 

INTERNATIONAL STANDARDS 

AND RECOMMENDED PRACTICES 

ENVIRONMENTAL PROTECTION 

ANNEX 16 

TO THE CONVENTION ON INTERNATIONAL CIVIL AVIATION 

VOLUME II 

AIRCRAFT ENGINE EMISSIONS 

. . . 

PART I. DEFINITIONS AND SYMBOLS 

CHAPTER 1. DEFINITIONS 

. . . 

Rated output thrust. For engine emissions purposes, the maximum power/thrust available for take-off 

take-off thrust approved by the certificating authority for use under normal operating conditions at ISA 

sea level static conditions, and without the use of water injection as approved by the certificating 

authority. Thrust is expressed in kilonewtons. 

. . . 

Take-off phase. The operating phase defined by the time during which the engine is operated at the 

rated output thrust. 

. . . 

CHAPTER 2. SYMBOLS 

. . . 

Foo Rated output (see definition) thrust

F*oo Rated output thrust with afterburning applied 

. . . 
B-2 

PART III. EMISSIONS CERTIFICATION 

CHAPTER 1. ADMINISTRATION 

. . . 

1.3 The document attesting emissions certification for each individual engine shall include at least 

the following information which is applicable to the engine type: 

. . . 

d) rated output thrust; 

. . . 

CHAPTER 2. TURBO-JET AND TURBOFAN ENGINES INTENDED FOR 

PROPULSION ONLY AT SUBSONIC SPEEDS 

. . . 

2.1.4.2 Thrust settings 

The engine shall be tested at sufficient power thrust settings to define the gaseous and smoke emissions of 

the engine so that mass emission rates and Smoke Numbers corrected to the reference ambient conditions 

can be determined at the following specific percentages of rated output thrust as agreed by the 

certificating authority: 

LTO Operating mode Thrust setting 

Take-off 100 per cent Foo

Climb 85 per cent Foo

Approach 30 per cent Foo

Taxi/ground idle 7 per cent Foo

. . . 

2.1.4.4 Fuel specifications

The fuel used during tests shall meet the specifications of Appendix 4, unless a deviation and any 

necessary corrections have been agreed by the certificating authority. Additives used for the purpose of 

smoke suppression (such as organo-metallic compounds) shall not be present. 

. . . 

2.1.62.5.3 When test conditions differ from the reference atmospheric conditions in 2.1.4 2.1.4.1 the 

gaseous emission test results shall be corrected to the reference atmospheric conditions by the methods 

given in Appendix 3. 

. . . 
B-3 

2.2.2 Regulatory Smoke Number 

The Smoke Number at any of the four LTO Operating Modes thrust setting when measured and computed 

in accordance with the procedures of Appendix 2 and converted to a characteristic level by the procedures 

of Appendix 6 shall not exceed the level determined from the following formula: 

Regulatory Smoke Number = 83.6 (Foo)

–0.274 

 or a value of 50, 

 whichever is lower 

2.3 Gaseous emissions 

2.3.1 Applicability 

The provisions of 2.3.2 shall apply to engines whose rated output thrust is greater than 26.7 kN and whose 

date of manufacture is on or after 1 January 1986 and as further specified for oxides of nitrogen. 

2.3.2 Regulatory levels 

Gaseous emission levels when measured and computed in accordance with the procedures of Appendix 3 

and converted to characteristic levels by the procedures of Appendix 6 shall not exceed the regulatory 

levels determined from the following formulas: 

. . . 

d) for engines of a type or model for which the date of manufacture of the first individual production 

model was after 31 December 2007: 

. . . 

3) for engines with a pressure ratio of 82.6 or more: 

 Dp /Foo = 32 + (1.6 * πoo) 

Note.— The characteristic level of the Smoke Number or gaseous pollutant emissions is the mean of 

the values of all the engines tested, measured and corrected to the reference standard engine and 

reference ambient conditions divided by the coefficient corresponding to the number of engines tested, as 

shown in Appendix 6.

2.4.1 General information 

The following information shall be provided for each engine type for which emissions certification is 

sought: 

 a) engine identification; 

 b) rated output thrust (in kilonewtons); 

. . . 
B-4 

2.4.3 Derived information 

. . . 

2.4.3.2 The characteristic Smoke Number and gaseous pollutant emission levels shall be provided for 

each engine type for which emissions certification is sought. 

Note.— The characteristic level of the Smoke Number or gaseous pollutant emissions is the mean of 

the values of all the engines tested, measured and corrected to the reference standard engine and 

reference ambient conditions, divided by the coefficient corresponding to the number of engines tested, as 

shown in Appendix 6.

. . . 

APPENDIX 2. SMOKE EMISSION EVALUATION 

. . . 

2. MEASUREMENT OF SMOKE EMISSIONS 

2.1 Sampling probe for smoke emissions 

a) The probe material with which the exhaust emission sample is in contact shall be made of 

stainless steel or any other non-reactive material. If a mixing probe is used, all sampling orifices 

shall be of equal diameter.

b) If a probe with multiple sampling orifices is used, all sampling orifices shall be of equal diameter. 

The probe design shall be such that at least 80 per cent of the pressure drop through the probe 

assembly is taken at the orifices. 

c) The number of sampling orifices locations sampled shall not be less than 12. 

d) The sampling plane shall be as close to the engine exhaust nozzle exit plane as permitted by 

considerations of engine performance but in any case shall be within 0.5 nozzle diameters of the 

exit plane. 

e) The applicant shall provide evidence to the certificating authority, by means of detailed traverses, 

that the proposed probe design and position does provide a representative sample for each 

prescribed power thrust setting. 

2.2 Sampling line for 

smoke emissions 

. . . 

2.2.2 Sampling lines shall be as “straight through” as possible. Any necessary bends shall have radii 

which are greater than 10 times the inside diameter of the lines. The material of the lines shall be such as 

to discourage build up of particulate matter or static electricity. 
B-5 

Note.— Stainless steel, copper or carbon loaded grounded polytetrafluoroethylene (PTFE) meet these 

requirements. 

2.3 Smoke analysis system 

. . . 

f) temperature control: the incoming analyser internal sample line through to the filter holder shall 

be maintained at a temperature between 60°C and 175°C with a stability of ±15°C; 

Note.— The objective is to prevent water condensation prior to reaching the filter holder and 

within it.

. . . 

j) reflectometer: the measurements of the reflectance of the filter material shall be by an instrument 

conforming to the American National Standards Institute (ANSI) International Standards 

Organization, Standard No. PH2.17/1977 ISO 5.4 for diffuser diffuse reflection density. The 

diameter of the reflectometer light beam on the filter paper shall not exceed D/2 nor be less than 

D/10 where D is the diameter of filter stained spot as defined in Figure 2-1. 

Replace Figure 2-1. Smoke analysis system as follows: 
B-6 

2.5 Smoke measurement procedures 

2.5.1 Engine operation 

. . . 

2.5.1.2 The tests shall be made at the power thrust settings approved by the certificating authority. 

The engine shall be stabilized at each setting. 

2.5.2 Leakage and cleanliness checks 

. . . 

a) leakage check: isolate probe and close off end of sample line, perform leakage test as specified in 

2.3 g) h) with the exceptions that valve A is opened and set to “bypass”, valve D is closed and 

that the leakage limit is 2 L. Restore probe and line interconnection; 

. . . 

2.5.3 Smoke measurement 

. . . 

b) set valve A to “bypass”, close valve D and clamp clean filter into holder. Continue to draw 

exhaust sample in the bypass setting for at least five minutes while the engine is at or near to the 

requisite operating mode required operating condition, valve C being set to give a flow rate of 

14 ±0.5 L/min; 

. . . 

APPENDIX 3. INSTRUMENTATION AND MEASUREMENT TECHNIQUES 

FOR GASEOUS EMISSIONS 

. . . 

3. DATA REQUIRED 

3.1 Gaseous emissions 

Concentrations of the following emissions shall be determined: 

a) Hydrocarbons (HC): a combined estimate of all hydro-carbon compounds present in the exhaust 

gas. 

b) Carbon monoxide (CO). 

c) Carbon dioxide (CO2). 

Note.— CO2 is not considered a pollutant a regulated engine emission but its concentration is 

required for calculation and check purposes.
B-7 

. . . 

5. DESCRIPTION OF 

COMPONENT PARTS 

. . . 

5.1 Sampling system 

5.1.1 Sampling probe 

a) The probe material with which the exhaust emission sample is in contact shall be made of 

stainless steel. If a mixing probe is used, all sampling orifices shall be of equal diameter or any 

other non-reactive metal; 

b) the if a probe with multiple sample orifices is used, all sampling orifices shall be of equal 

diameter. The probe design shall be such that at least 80 per cent of the pressure drop through the 

probe assembly is taken at the orifices; 

c) the number of sampling orifices locations sampled shall not be less than 12; 

. . . 

e) the applicant shall provide evidence to the certificating authority, by means of detailed traverses, 

that the proposed probe design and position does provide a representative sample for each 

prescribed power thrust setting. 

. . . 

6. GENERAL TEST PROCEDURES 

6.1 Engine operation 

. . . 

 6.1.2 The emissions tests shall be made at the power thrust settings prescribed by the certificating 

authority. The engine shall be stabilized at each setting. 

. . . 

6.3 Operation 

. . . 

6.3.2 The following procedure shall be adopted for operational measurements: 

. . . 

c) when the engine has been stabilized at the requisite operating mode required thrust setting, 

continue to run it and observe pollutant concentrations until a stabilized reading is obtained, 

which shall be recorded; 

. . . 
B-8 

7. CALCULATIONS 

7.1 Gaseous emissions 

7.1.1 General 

The analytical measurements made shall be the concentrations of the various classes of pollutant, as 

detected at their respective analysers for the several engine operation modes, and these values shall be 

reported. In addition, other parameters shall be computed and reported, as follows**.gaseous emissions, 

as detected at their respective analysers for a range of combustor inlet temperatures (TB) encompassing 

the four LTO operating modes. Using the calculations of 7.1.2, or the alternative methods defined in 

Attachment E to this appendix, the measured emissions indices (EI) for each gaseous emission shall be 

established. To account for deviations from reference atmospheric conditions, the corrections of 7.1.3 

shall be applied. Note that these corrections may also be used to account for deviations of the tested 

engine from the reference standard engine where appropriate (see Appendix 6, paragraph 1 f)). Using 

combustor inlet temperature (TB) as a correlating parameter, the emissions indices and fuel flow 

corresponding to operation at the four LTO operating modes of a reference standard engine under 

reference day conditions shall then be established using the procedures of 7.2.

7.1.2 Basic parameters 

where 

2Z – (n/m) P0/m = 4(1 + h – |TZ/2|)

2Z – (n/m) P0/m = 4(1 + hvol – [TZ/2]) 

and 

2 – [CO] – (|2/x| – |y/2x|) [HC} + [NO2] Z = [CO2] + [CO] + [HC]

2 – [CO] – ([2/x] – [y/2x]) [HC] + [NO2] Z = [CO2] + [CO] + [HC] 

. . . 

η efficiency of NO2/NO converter 

hvol humidity of ambient air, vol water/vol dry air 

. . . 
B-9 

7.1.3 Correction of emission indices 

to reference conditions 

Corrections shall be made to the measured engine emission indices for all pollutants in all relevant engine 

operating modes to account for deviations from the reference atmospheric conditions (ISA at sea level) of 

the actual test inlet air conditions of temperature and pressure. These corrections may also be used to 

account for deviations of the tested engine from the reference standard engine where appropriate (see 

Appendix 6, paragraph 1 f)). The reference value for humidity shall be 0.00634 kg water/kg dry air. 

 Thus, EI corrected = K × EI measured, 

where the generalized expression for K is: 

K = (PBref/PB)

a

 × (FARref/FARB)

b

× exp ( |TBref – TB|/c) × exp (d|h – 0.00634| )

K = (PBref/PB)

a

 × (FARref/FARB)

b

 × exp ( [TBref – TB]/c) × exp (d[hmass – 0.00634] ) 

. . . 

hmass Ambient air humidity, kg water/kg dry air

. . . 

7.1.4 Using the recommended curve fitting technique of paragraph 7.2 to relate emission indices to 

combustor inlet temperature effectively eliminates the exp ((TBref – TB)/c) term from the generalized 

equation and for most cases the (FARref /FARB) term may be considered unity. For the emissions indices 

of CO and HC many testing facilities have determined that the humidity term is sufficiently close to unity 

to be eliminated from the expression and that the exponent of the (PBref /PB) term is close to unity. 

. . . 

EI(NOx) corrected = EI derived from 

EI(NOx) (PBref /PB)

0.5 exp (19 | h – 0.00634 | ) v. TB curve

EI(NOx) corrected = EI derived from 

EI(NOx) (PBref /PB)

0.5 exp (19 [ hmass – 0.00634 ] ) v. TBcurve 

. . . 

7.2 Control parameter functions 

(Dp, Foo, π) 

7.2.1 Definitions 

. . . 

Foo The maximum thrust available for take-off under normal operating conditions at ISA sea level 

static conditions, without the use of water injection, as approved by the applicable certificating 

authority.Rated thrust (see definition)
B-10 

Fn Thrust at LTO operating mode, n. (kN) 

Wf Fuel mass flow rate of the reference standard engine under ISA sea level conditions. (kg/s) 

Wf

n Fuel mass flow rate of the reference standard engine under ISA sea level conditions at LTO 

operating mode, n. 

π The ratio of the mean total pressure at the last compressor discharge plane of the compressor to 

the mean total pressure at the compressor entry plane when the engine is developing take-off 

thrust rating at ISA sea level static conditions. 

7.2.2 The emission indices (EI) for each pollutant, corrected for pressure and humidity (as 

appropriate) to the reference ambient atmospheric conditions as indicated in 7.1.4 and, if necessary, to the 

reference standard engine, EI (corrected), shall be obtained for the required each LTO engine operating 

mode settings (n) of idle, approach, climb-out and take-off, at each of the equivalent corrected thrust 

conditions. A minimum of three test points shall be required to define the idle mode. The following 

relationships shall be determined under reference atmospheric conditions for each pollutant gaseous 

emission: 

a) between EI (corrected) and TB ; and 

b) between Wf (engine fuel mass flow rate) and TB ; and 

c) between Fn (corrected to ISA sea level conditions) F and TB (corrected to ISA sea level 

conditions); 

Note 1.— These are illustrated, for example, by Figure 3-2 a), b) and c).

Note 2.— The relationships b) and c) may be established directly from engine test data, or may be 

derived from a validated engine performance model.

When the engine being tested is not a “reference” engine, the data may be corrected to “reference” 

engine conditions using the relationships b) and c) obtained from a reference engine. A reference engine 

is defined as an engine substantially configured to the description of the engine to be certificated and 

accepted by the certificating authority to be representative of the engine type for which certification is 

sought.A reference engine is defined as an engine substantially configured to the production standard of 

the engine type and with fully representative operating and performance characteristics.

 The manufacturer shall also supply to the certificating authority all of the necessary engine 

performance data to substantiate these relationships and for ISA sea level ambient conditions: 

d) maximum rated thrust (Foo); and 

e) engine pressure ratio (π) at maximum rated thrust. 

 Note.— These are illustrated by Figure 3-2 d). 

 7.2.3 The estimation of EI (corrected) for each pollutant at each of the required engine mode 

settings, corrected to the reference ambient conditions,gaseous emission at the four LTO operating modes 

shall comply with the following general procedure: 
B-11 

a) at each mode ISA thrust condition Fn, determine the equivalent combustor inlet temperature (TB) 

(Figure 3-2 c)) at the values of Fn corresponding to the four LTO operating modes, n, under 

reference atmospheric conditions ; 

b) from the EI (corrected)/TB characteristic (Figure 3-2 a)), determine the EIn value corresponding to 

TB; 

c) from the Wf /TB characteristic (Figure 3-2 b)), determine the Wf

n

 value corresponding to TB; 

. . . 

ATTACHMENT E TO APPENDIX 3. THE CALCULATION OF THE EMISSIONS 

PARAMETERS — BASIS, MEASUREMENT CORRECTIONS AND 

ALTERNATIVE NUMERICAL METHOD 

Editorial Note.— Replace straight brackets and use vol.– index for humidity. 

1. SYMBOLS 

. . .

hvol humidity of ambient air, vol water/vol dry air 

. . . 

2. BASIS OF CALCULATION OF EI 

AND AFR PARAMETERS 

2.1 It is assumed that the balance between the original fuel and air mixture and the resultant state of 

the exhaust emissions as sampled can be represented by the following equation: 

CmHn + P0[R(O2) + S(N2) + T(CO2) + hvol (H2O)] 

= P1(CO2) + P2(N2) + P3(O2) + P4(H2O) 

+ P5(CO) + P6(CxHy) + P7(NO2) + P8(NO) 

from which the required parameters can, by definition, be expressed as 

. . .

2.3 The ambient air humidity, hvol, is as measured at each test condition. It is recommended that, in 

the absence of contrary evidence as to the characterization (x, y) of the exhaust hydrocarbon, values of 

x = 1 and y = 4 are assigned. 

2.4 Determination of the remaining unknowns requires the solution of the following set of linear 

simultaneous equations, where (1) to (4) derive from the fundamental atomic conservation relationships 

and (5) to (9) represent the gaseous product concentration relationships. 

m + TP0 = P1 + P5 + xP6 .......................................................................... (1) 
B-12 

n + 2hvolP0 = 2P4 + yP6 ............................................................................. (2) 

(2R + 2T + hvol)P0 

 = 2P1 + 2P3 + P4 + P5+ 2P7 + P8 .......................................................... (3)

. . .

3. ANALYTICAL FORMULATIONS 

. . . 

3.2 Equation for conversion of 

dry concentration measurements 

to wet basis 

Concentration wet = K × concentration dry; that is, 

 [ ] = K [ ]d

The following expression for K applies when CO and CO2 are determined on a “dry” basis: 

{4 +(n/m) T + ( |n/m| T − 2h) ([NO2] − (2[HC]/x)) K =

(2 + h) {2 + (n/m) (1 + hd) ([CO2]d + [CO]d)}

+ (2 + h) (|y/x| − |n/m|) [HC]} (1 + hd)

−(|n/m|T − 2h) (1 −|1 + hd|[CO]d)

{4 + (n/m) T + ([n/m]T − 2hvol) ([NO2] − (2[HC]/x)) K = 

(2 + h) {2 + (n/m) (1 + hd) ([CO2]d + [CO]d)}

+ (2 + hvol) ([y/x] − [n/m]) [HC]} (1 + hd) 

−([n/m]T − 2h) (1 − [1 + hd] [CO]d)

. . . 

3.4 Equation for estimation of 

sample water content 

Water concentration in sample 

(|n/2m| + h|P0/m|) ([CO2] + [CO] + [HC]) [H2O] = 1 + T(Po/m) − (y/2x) [HC]

([n/2m] + hvol[P0/m]) ([CO2] + [CO] + [HC]) [H2O] = 1 + T(Po/m) − (y/2x) [HC] 

where 
B-13 

2Z − (n/m) P0/m = 4(1 + h − |TZ/2|)

2Z − (n/m) P0/m = 4(1 + hvol − [TZ/2]) 

and 

2 − [CO] − (|2/x| − |y/2x|) [HC] + [NO2] Z = [CO2] + [CO] + [HC]

2 − [CO] − ([2/x] − [y/2x]) [HC] + [NO2] Z = [CO2] + [CO] + [HC] 

It should be noted that this estimate is a function of the various analyses concentration readings, 

which may them-selves require water interference correction. For better accuracy an iterative procedure is 

required in these cases with successive recalculation of the water concentration until the requisite stability 

is obtained. The use of the alternative, numerical solution methodology (4) avoids this difficulty. 

. . . 

APPENDIX 6. COMPLIANCE PROCEDURE FOR 

GASEOUS EMISSIONS AND SMOKE 

. . . 

2. COMPLIANCE PROCEDURES 

The certificating authority shall award a certificate of compliance if the mean of the values measured and 

corrected (to the reference standard engine and reference ambient atmospheric conditions) for all the 

engines tested, when converted to a characteristic level using the appropriate factor which is determined 

by the number of engines tested (i) as shown in the table below, does not exceed the regulatory level. 

Note.— The characteristic level of the Smoke Number or gaseous pollutant emissions is the mean of 

the values of all the engines tested, measured and, for gaseous emissions only, appropriately corrected to 

the reference standard engine and reference ambient conditions atmospheric conditions, divided by the 

coefficient corresponding to the number of engines tested, as shown in the table below. 

. . . 

— — — — — — — — 
ATTACHMENT C to State letter AN 1/61.1, AN 1/62.2 – 07/34 

RESPONSE FORM TO BE COMPLETED AND RETURNED TO ICAO TOGETHER 

WITH ANY COMMENTS YOU MAY HAVE ON THE PROPOSED AMENDMENTS

To: The Secretary General 

International Civil Aviation Organization 999 University Street 

Montreal, Quebec 

Canada, H3C 5H7 

(State) 

Please make a checkmark (9) against one option for each amendment. If you choose options “agreement 

with comments” or “disagreement with comments”, please provide your comments on separate sheets. 

Agreement 

without 

comments 

Agreement 

with 

comments* 

Disagreement 

without 

comments 

Disagreement

with 

comments 

No position 

Amendment to Annex 16 — Environmental Protection, 

Volume I — Aircraft Noise (Attachment A refers) 

Amendment to Annex 16 — Environmental Protection, 

Volume II — Aircraft Engine Emissions 

(Attachment B refers) 

*“Agreement with comments” indicates that your State or organization agrees with the intent and overall 

thrust of the amendment proposal; the comments themselves may include, as necessary, your reservations 

concerning certain parts of the proposal and/or offer an alternative proposal in this regard. 

Signature: Date: 

— END —