prEN 17436
(Main)Cabin air quality on civil aircraft - Chemical compounds
Cabin air quality on civil aircraft - Chemical compounds
This document defines requirements and recommendations dealing with the quality of the air on civil aircraft concerning chemical compounds potentially originating from, but not limited, to, the ventilation air supplied to the cabin and flight deck.
A special emphasis is on the engine and APU bleed air contaminants potentially brought into the cabin through the air conditioning, pressurization and ventilation systems.
The document is applicable to civil aircraft in operation from the period that is defined as when the first person enters the aircraft until the last person leaves the aircraft.
The document defines requirements and recommendations in relation to the presence of, and means to prevent exposure to, chemical compounds, including those that could cause adverse effects, taking into account the Precautionary Principle.
Kabinenluftqualität in Verkehrsflugzeugen - Chemische Parameter
Dieses Dokument legt Anforderungen und Empfehlungen für die Luftqualität in Verkehrsflugzeugen in Bezug auf chemische Parameter fest, die möglicherweise aus der Belüftungsluft stammen, die der Kabine und dem Cockpit zugeführt wird, aber nicht darauf beschränkt sind.
Im Vordergrund stehen Schadstoffe, die aus der Zapfluft des Triebwerks und des Hilfsaggregats (en: Auxiliary Power Unit, APU) stammen, die möglicherweise durch die Klima , Druck und Luftversorgungssysteme in die Kabine gelangen.
Das Dokument ist anwendbar für den Zeitraum in dem ein Verkehrsflugzeug in Betrieb ist: Ab dem Zeitpunkt, in dem die erste Person in das Luftfahrzeug einsteigt, bis die letzte Person das Luftfahrzeug verlässt.
Das Dokument definiert Anforderungen und Empfehlungen in Bezug auf das Vorhandensein von chemischen Parametern und die Mittel zur Verhinderung der Exposition gegenüber chemischen Verbindungen, einschließlich solcher, die unter Berücksichtigung des Vorsorgeprinzips nachteilige Auswirkungen haben können.
Qualité de l'air en cabine d'avions civils - Composés chimiques
Le présent document définit les exigences et recommandations applicables à la qualité de l'air dans les avions civils, en ce qui concerne les composés chimiques potentiellement émis, sans toutefois s'y limiter, par l'air de ventilation qui alimente la cabine et le poste de pilotage.
Il met tout particulièrement l'accent sur les contaminants présents dans l'air de prélèvement du réacteur et du groupe auxiliaire de puissance et qui sont potentiellement véhiculés jusque dans la cabine à travers les systèmes de climatisation, de pressurisation et de ventilation.
Le présent document s'applique aux avions civils en service entre la période définie comme étant l'intervalle entre le moment où la première personne pénètre dans l'avion et le moment où la dernière personne quitte l'avion.
Le présent document définit les exigences et recommandations en lien avec la présence de composés chimiques, y compris ceux pouvant avoir des effets indésirables, ainsi qu'avec les moyens de prévenir l'exposition à de tels composés chimiques, en appliquant le principe de précaution.
Kakovost zraka v kabini civilnih letal - Kemijske spojine
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-april-2021
Kakovost zraka v kabini civilnih letal - Kemijske spojine
Cabin air quality on civil aircraft - Chemical compounds
Kabinenluftqualität in Verkehrsflugzeugen - Chemische Parameter
Qualité de l'air en cabine d'avions civils - Composés chimiques
Ta slovenski standard je istoveten z: prEN 17436
ICS:
13.040.01 Kakovost zraka na splošno Air quality in general
49.095 Oprema za potnike in Passenger and cabin
oprema kabin equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
DRAFT
EUROPEAN STANDARD
NORME EUROPÉENNE
EUROPÄISCHE NORM
March 2021
ICS 49.095
English Version
Cabin air quality on civil aircraft - Chemical compounds
Qualité de l'air en cabine d'avions civils - Composés Kabinenluftqualität in Verkehrsflugzeugen - Chemische
chimiques Parameter
This draft European Standard is submitted to CEN members for second enquiry. It has been drawn up by the Technical
Committee CEN/TC 436.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 17436:2021 E
worldwide for CEN national Members.
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Cabin air quality — chemical compounds . 11
4.1 Chemical compounds in cabin air . 11
4.2 Sources of chemical compounds. 11
4.3 Sources of engine oil leakage in the bleed air system . 11
4.4 Fume event . 11
4.5 Marker compounds . 12
4.6 Environmental control systems (ECS) . 12
5 Precautionary Principle and hierarchy of controls . 13
5.1 General. 13
5.2 Precautionary Principle . 13
5.3 Hierarchy of controls . 14
5.4 Elimination measures . 14
5.5 Mitigation measures . 15
6 Filtration . 16
6.1 General. 16
6.2 Recirculation cabin air filtration. 16
6.3 Catalytic conversion filtration . 16
7 Air monitoring . 17
7.1 General. 17
7.2 Air monitoring planning/development . 17
7.3 Air monitoring methodology . 20
8 Preventative and corrective actions . 22
8.1 General. 22
8.2 Preventative measures pre-flight . 22
8.3 Corrective measures in-flight . 22
8.4 Corrective measures post-flight . 23
8.5 Aircraft Maintenance Manual (AMM) . 23
9 Monitoring of air crew and passengers . 24
9.1 Monitoring air crew . 24
9.2 Monitoring passengers . 24
10 Data compilation, analysis and reporting . 25
10.1 General. 25
10.2 Data compilation . 25
10.3 Analysis and reporting . 27
11 Airline worker education and training . 28
11.1 General . 28
11.2 Requirements . 28
Annex A (informative) Environmental Control Systems (ECS) . 30
A.1 General . 30
A.2 Bleed air environmental control systems (ECS) . 30
A.3 Bleed-free environmental control system . 32
Annex B (normative) Chemical marker compounds . 33
Annex C (informative) Precautionary Principle . 37
C.1 Precautionary Principle . 37
C.2 Precautionary Principle considerations: background information . 38
Annex D (informative) Approaches for online monitoring . 40
D.1 General . 40
Annex E (informative) Reference method for real-time and time-integrated measurement
of chemical marker compounds and (ultra) fine particles . 41
Annex F (informative) Examples of best practice intended to prevent or minimize
contamination . 53
Annex G (informative) Chemical marker compounds introduced into the cabin . 55
Annex H (informative) Sources of engine oil leakage into the bleed air system and
ventilation supply air . 58
H.1 Description of oil lubrication system . 58
H.2 Description of seal technology . 59
H.3 Oil path into bleed air system and ventilation supply air . 59
H.4 Maintenance response to oil fumes sourced to bleed air system (renumber H.4) . 60
Annex I (informative) Overview of aircraft cabin air and bleed air monitoring studies . 61
I.1 Introduction . 61
I.2 References cited in Table I.1 . 71
Bibliography . 74
European foreword
This document (prEN 17436:2021) has been prepared by Technical Committee CEN/TC 436 “Cabin air
quality”, the secretariat of which is held by AFNOR.
This document is currently submitted to the second Enquiry.
Introduction
Air quality on civil aircraft requires particular attention, given the characteristics of the cabin
environment.
An environmental control system (ECS) is used to regulate the aircraft cabin pressure, temperature and
ventilation supply air to provide a safe and comfortable environment for the passengers and air crew.
The aircraft cabin by design and operation is enclosed and is a densely occupied environment (with
only a small amount of per person dilution volume), creating the potential for elevated levels of bio-
effluents in the cabin, such as carbon dioxide (see Annex A). ECS architecture on civil passenger aircraft
can be broadly separated in two categories: bleed air ECS systems and bleed free ECS systems (see
Annex A). Most aircraft manufactured today, and nearly all aircraft in service, have bleed air ECS.
This document focuses on the chemical compounds potentially present in cabin air. It sets out
requirements, recommendations, and supporting annexes to enable airline operators, manufacturers
and suppliers to identify - and either prevent or mitigate - exposure to contaminants in the cabin air,
with particular emphasis on bleed air contaminants sourced to or generated from engine oil and
hydraulic fluid. This includes some limited measures intended to protect workers assigned to
troubleshoot and service the aircraft ventilation supply air systems.
NOTE Aircraft accident investigation agencies, aviation regulators from the EU and US, and the International
Civil Aviation Organization (ICAO) have recognized that bleed air contamination can compromise flight safety.
The requirements and recommendations in this document take into account that the fluids used in
aviation (including jet engine oils) and their pyrolysis products are complex mixtures. Some of these
mixtures contain organophosphates, ultra-fine particles, and other chemical compounds.
The requirements set out in the document take into account current and developing legal frameworks
in order to enable the industry to meet their legal obligation to provide a safe environment for air crew
and passengers. This document also acknowledges, at the European Commission level, the value of
using the Precautionary Principle in relation to risk management, and the use of risk assessment in this
industry to protect workers and the environment.
Within this document, emphasis is placed upon exposure prevention, sensor technology, worker
training, reporting systems, and collation of data and information from air crew and passengers. Safety
Management Systems (SMS) can be a useful tool to enable operators to apply these measures to
monitor and respond to system degradation.
This document does not define acceptability/suitability for health, comfort, safety, or airworthiness of
the cabin air.
Annex I contains a summary of maximum levels of the marker compounds listed in Annex B that have
been published.
1 Scope
This document defines requirements and recommendations dealing with the quality of the air on civil
aircraft concerning chemical compounds potentially originating from, but not limited, to, the ventilation
air supplied to the cabin and flight deck.
A special emphasis is on the engine and APU bleed air contaminants potentially brought into the cabin
through the air conditioning, pressurization and ventilation systems.
This document is applicable to civil aircraft in operation from the period that is defined as when the
first person enters the aircraft until the last person leaves the aircraft.
This document defines requirements and recommendations in relation to the presence of, and means to
prevent exposure to, chemical compounds, including those that could cause adverse effects, taking into
account the Precautionary Principle.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 1822-1, High efficiency air filters (EPA, HEPA and ULPA) - Part 1: Classification, performance testing,
marking
EN ISO 16000-1, Indoor air - Part 1: General aspects of sampling strategy (ISO 16000-1)
ISO 29463-1, High efficiency filters and filter media for removing particles from air — Part 1:
1)
Classification, performance, testing and marking
IEST-RP-CC001, HEPA and ULPA filters
1)
Published by: ISO International Organization for Standardization http://www.iso.ch/
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• ISO Online browsing platform: available at http://www.iso.org/obp
• IEC Electropedia: available at http://www.electropedia.org/
3.1
adverse effect
change in morphology, physiology, growth, development or lifespan of an organism which results in
impairment of its functional capacity or impairment of its capacity to compensate for additional stress
or increased susceptibility to the harmful effects of other environmental influences
[SOURCE: ISO 13073-3:2016, 2.1]
3.2
aerosol
system of solid particles and/or liquid droplets suspended in gas
3.3
air crew
people working on an aircraft in the period that is defined as when the first person boards the aircraft
until the last person leaves the aircraft, including pilots and cabin crew
3.4
airline operator
entity authorized by an Air carrier Operator Certificate (AOC) from its national Civil Aviation Authority
to operate civil transport aircraft flights for commercial carriage of passengers, cargo or mail
Note 1 to entry: The airline operator holds responsibility for compliance with civil aviation authority regulations
on its flights, including when the relevant tasks are performed by sub-contractors.
[SOURCE: ISO 16412:2005, 3.3, modified — The terms originally defined were “operator”, “airline” and
“carrier”.][2]
3.5
auxiliary power unit
APU
gas turbine-powered unit delivering rotating shaft power, compressor air, or both, which is not
intended for direct propulsion of an aircraft
[SOURCE: EASA CS Definitions] [3]
3.6
best available technology
BAT
most effective and advanced stage in the development of activities and their methods of operation
which indicate the practical suitability of particular technologies for providing, in principle, the basis to
mitigate, or eliminate exposure to contaminants in cabin air
[SOURCE: Council Directive 2008/1/EC, modified] [4]
3.7
bleed air
air bled off the compressor stages of the aircraft engines or APU, prior to the combustion chamber;
source of ventilation air
3.8
cabin air
air within the section of an aircraft in which passengers and/or air crew travel (including the cabin and
flight deck)
3.9
cabin material
cabin interior which includes seats, flooring, walls, cabinets and overhead bins
3.10
chemical compound
chemical element or compound on its own or admixed as it occurs in the natural state or as produced,
used, or released, including release as waste, by any work activity, whether or not produced
intentionally and whether or not placed on the market
[SOURCE: Council Directive 98/24/EC Art. 2(a)][5]
3.11
contaminant
substance emitted into the air adversely affecting air quality
[SOURCE: ISO 4225:2020] [6]
3.12
early warning system
system or a procedure to detect the presence of contaminants that may require intervention
3.13
electrical-environmental control system
E-ECS
bleed-free ECS
3.14
environment control system
ECS
system of an aircraft which provides ventilation supply air, temperature control, and cabin
pressurization for the crew and passengers
3.15
fresh air (see also: outside air)
air taken from outside the vehicle
Note 1 to entry: In this document, the vehicle is the aircraft.
3.16
fumes
odorous, gaseous emission of compound(s) and/or aerosols which may be sourced to the cabin/flight
deck ventilation supply air vents and is not visible
3.17
hazardous
substance or mixture fulfilling the criteria relating to physical hazards, health hazards, or
environmental hazards
[SOURCE: Regulation (EC) No 1272/2008 “CLP”, Article 3] [7]
Note 1 to entry: (i) any chemical agent which meets the criteria for classification as hazardous within any physical
and/or health hazard classes laid down in Regulation (EC) No 1272/2008 of the European Parliament and of the
Council, whether or not that chemical agent is classified under that Regulation; and(ii) any chemical agent which,
whilst not meeting the criteria for classification as hazardous in accordance with point (i) may, because of its
physico-chemical, chemical or toxicological properties and the way it is used or is present in the workplace,
present a risk to the safety and health of workers, including any chemical agent that is assigned an occupational
exposure limit value under Article 3.
[SOURCE: Directive (EC) No 98/24, Article 2]
Note 2 to entry This definition of hazardous is different to the definition applied in the airworthiness context.
3.18
marker compound
chemical compound representing/indicating specific/potential sources of airborne contaminants in the
cabin air
3.19
outside air (see also: fresh air)
air taken from outside the vehicle
[SOURCE: ISO 19659-1:2017, 3.4.1] [8]
Note 1 to entry: In this document, the vehicle is the aircraft.
3.20
real-time sampling
use of online monitoring using instrumental analysers with sensors; the output describes the change in
concentration of the analyte(s) as a function of time during the sampling period
3.21
risk analysis
systematic use of available information to identify hazards and to estimate the risk
[SOURCE: ISO/IEC Guide 51:2014, 3.10] [9]
3.22
safety management system
SMS
administrative framework that is designed to manage safety risks in workplaces and is applied to
enable the operator to systematically monitor and respond to fume events
3.23
sensor
electronic device that senses a physical condition or chemical compound and delivers an electronic
signal proportional to the observed characteristic
[SOURCE: ISO/IEC TR 29181-9:2017,3.14] [10]
3.24
soot
particulate matter with a particle size of 0 nanometres (nm) to 10 nm produced and deposited during
or after combustion
[SOURCE: EN ISO 472:2013, 2.1278 modified] [11]
3.25
steady state
condition during single engine power setting characterized by stable temperature and bleed pressure
[SOURCE: SAE (2018)] [12]
3.26
supply air
air introduced into an enclosure by mechanical means including engines, APU, onboard electric
compressors, or ground supply units
3.27
time-integrated sampling
either passive or active sampling methodology, followed by analysis of the collected sample in
dedicated equipment or a laboratory; the output describes the average concentration of the analyte(s)
during the sampling period
3.28
transient operating condition
condition other than steady state engine power setting characterized by unstable temperature and/or
changing pressure; examples include engine start, take-off top-of-descent and changes in engine regime
including changing the power setting from idle to take off power and back
3.29
ultra-fine particles
ultra-fine particles (UFP) or ultrafine dust are the most commonly used definitions of airborne particles
with a diameter between 1 and 100 nanometres (nm)
[SOURCE: ISO 2007] [13]
4 Cabin air quality — chemical compounds
4.1 Chemical compounds in cabin air
The presence and concentration of many chemical compounds have been measured in the cabin air and
are reported in numerous studies, providing a large database of chemical compounds. Most of these
data were collected in the cabin or flight deck during normal operating conditions and not during a
reported “fume event” (see 4.4). Some of these data were collected directly from a bleed air source.
Monitoring the cabin air for the presence of appropriate chemical marker compounds is a method to
indicate the source(s) of contamination, rather than to assess any health effects of exposure.
4.2 Sources of chemical compounds
Chemical compounds can be sourced to the outside environment and can also originate from the
aircraft itself. These may include, but are not limited to the following:
— engine oil;
— hydraulic fluid;
— engine exhaust;
— fuel (unburned and vapours);
— de-icing fluid;
— chemical products used to wash engines or turbines;
— occupants;
— cabin materials and cleaning products;
— air conditioning equipment;
— faulty/failed electrical items.
An overview of a subset of the chemical compounds associated with some of these sources that may be
introduced to the cabin air is provided in Annex G.
4.3 Sources of engine oil leakage in the bleed air system
The presence of oil fumes in the cabin air can, in some instances, be linked to the oil lubrication system.
A description of the oil lubrication system, the seal technology and possible contamination of the cabin
air with engine oil are discussed in Annex H.
4.4 Fume event
A fume event is characterized by the presence of fumes in the cabin, emanating from the ventilation
supply air vents which can indicate the presence of a specific contamination of the ventilation supply air
(e.g. engine oil, hydraulic fluid, de-icing fluid) that has originated from or entered the engine or APU.
Alternatively, the presence of fumes and/or aerosols in cabin may emanate from a source within the
cabin (e.g. galley ovens, electrical faults).
4.5 Marker compounds
A subset of marker compounds that can be present in cabin air is listed in Annex B, Table B.1. These
marker compounds are associated with major contaminant sources from bleed air and outside air.
They are deemed to be useful markers for these specific sources of air contamination in the aircraft
environment.
Table B.2 lists “reliability ratings” (A through C) for each marker compound, intended to assist the
reader in determining which combination of compounds to monitor for each source of contamination
listed in 4.2.
Annex I lists published studies that, together, include measurement data for 14 of the 16 marker
compounds in Annex B. The maximum value of each measured compound was commonly reported so is
provided in Table I.1 for comparison purposes.
4.6 Environmental control systems (ECS)
The purpose of the ECS is to provide ventilation supply air and regulate the aircraft cabin pressure and
temperature in order to provide a safe and comfortable environment for the passengers and crew.
Most commercial passenger aircraft are equipped with an ECS that processes bleed air from engine
compressors, whilst some ECS process air from electrical compressors. Airborne chemical compounds
can be introduced into the cabin air through the aircraft ventilation supply air system. Further details
on these two types of ECSs are provided in Annex A.
5 Precautionary Principle and hierarchy of controls
5.1 General
Airborne chemical agents can be sourced to the ventilation supply air (e.g. engine oil, hydraulic fluid,
de-icing fluid, and exhaust fumes) and the aircraft cabin surfaces, equipment, and occupants (see
Clause 4). Exposure to these chemical agents can be prevented/minimized through the application of
the design and maintenance requirements in this document, all of which shall be planned and
implemented according to the Precautionary Principle (see 5.2) and the hierarchy of controls (see 5.3).
The objective of these design and maintenance requirements is to prevent/minimize onboard exposure
to airborne contaminants, with a special emphasis on the ventilation supply air. This is accomplished
by:
a) implementing an onboard monitoring system that gives, at the earliest possible time, an indication
of a system degradation or change in the cabin air quality (see Clause 7). This allows for
appropriate operational and/or maintenance actions which will enhance flight safety and protect
the health of crew and passengers;
b) using portable monitoring equipment (see 7.3) based on the presence of selected chemical marker
compounds (see Annex B) as an additional maintenance monitoring and troubleshooting tool; and
c) adopting other design, operational, and maintenance measures (see Clause 8 and Annex F).
The chemical marker compounds listed in Annex B (see Table B.1) are deemed to be the most reliably
associated with the primary contaminant sources (see 4.2) and are, thus, an appropriate basis for
onboard and portable monitoring equipment (see Clause 7). However, alternative methods could be
also applied to indicate the presence of a specific contaminant source (e.g. by pattern recognition;
see 7.1 and Annex D).
In addition to these design and maintenance requirements, requisite administrative measures (i.e.
medical monitoring, standardized reporting, airline worker training/education) are described in
Clauses 9, 10 and 11.
Also, examples of “best practice” exposure control measures are described in Annex F, and
supplemental information on relevant aircraft systems and contaminant sources is provided in the
remaining annexes.
5.2 Precautionary Principle
Airline operators, maintenance organisations and manufacturers shall apply the Precautionary
Principle while performing a risk assessment to characterize the risks of exposure to the main
contamination sources listed in Clause 4.
As a part of this risk assessment for aircraft engines and APUs that supply bleed air, manufacturers shall
measure engine and APU-generated contaminants over the full range of engine power settings expected
to occur in service, including on-wing testing and transient power settings, and shall assess the
potential for fluid loss during normal operation, as well as accidental leaks, spillage, and overfills.
Airline operators shall perform a risk assessment on cabin air contamination, including risks that
cannot be avoided. For most carcinogens and mutagens, it is not feasible to identify levels below which
exposure cannot lead to adverse effects.
Based on these risk assessments, airline operators, maintenance organisations, and manufacturers shall
apply the Precautionary Principle and the hierarchy of controls (see 5.3) to mitigate the risks of
onboard exposure to airborne contaminants. This shall include designing systems to minimize fluid
emissions during the full range of normal operations.
For additional information on the Precautionary Principle, see Annex C.
5.3 Hierarchy of controls
Airline operators, maintenance organisations and manufacturers shall apply the hierarchy of controls to
prevent occupant exposure to airborne chemical agents, as follows:
— avoid risks;
— evaluate risks that cannot be avoided;
— control risks at the source;
— eliminate or reduce hazardous chemical exposures by the design and organization of system;
— adapt to technical progress;
— replace the dangerous by the non-dangerous, less dangerous, or safe;
— develop a coherent overall prevention policy which covers technology, organization of work,
working conditions, and the influence of factors related to the working environment;
— give appropriate instructions to the workers; and
— give collective protective measures priority over individual protective measures.
Airline operators, maintenance organisations and manufacturers shall address potential hazards at the
source by the application of Best Available Technology (BAT), such as filters, to minimize the presence
of outside air and engine/APU-generated contaminants in the ventilation supply air.
NOTE 1 BAT has been used successfully as a mean to prevent or reduce/minimize exposure to chemical agents.
NOTE 2 Examples of elimination of oil-contaminated bleed air sourced to a mechanical failure, malfunction, or
fluctuations in the efficiency of engine seals could be the inclusion of a bleed free architecture, and/or oil free
bearing systems.
NOTE 3 See Directive 89/391/EEC [14] (OSH Framework directive) for further information on the hierarchy of
controls. Aircraft-specific applications of the hierarchy of controls are listed in the next two sections.
5.4 Elimination measures
Aircraft manufacturers shall take into account the Precautionary Principle and the hierarchy of controls
in the design of the ventilation supply air system to eliminate occupant exposure to the airborne
chemical agents sourced to the ventilation supply air system listed in 4.2, as follows:
a) ensure breathing air conducive to a safe and comfortable environment for air crew and passengers
in all phases of flight, without design features that experience has shown to be hazardous;
b) not cause harm, ill-health, or adverse effects (impairment or incapacitation) to air crew;
c) not cause harm, ill-health or adverse effects (impairment or incapacitation) to passengers;
d) provide monitoring and notification systems (see Clause 7) to provide an alert regarding system
degradation or a change in the cabin air quality (per EASA CS 25.1309) [15] which could require
maintenance or pilot intervention; and
e) be assessed using a risk analysis which includes normal and accidental leaks, fluid contamination,
spillage, overfills, the effects on occupants, and an assessment of the mixture of potential
contaminants.
Aircraft manufacturers shall also design the ventilation supply air system to facilitate maintainability of
the system by cleaning or replacement of parts.
NOTE Existing airworthiness requirements describe how to analyse the potential for degraded or impaired
crew performance or incapacitation due to contamination of the ventilation supply air with engine oil and other
aircraft fluids, and to apply an SMS that reflects the full range of operating conditions.
Manufacturers should review service data from airline operators and reporting systems when assessing
the frequency of cabin air contamination events.
5.5 Mitigation measures
When elimination by design is not possible, airline operators, aircraft and engine manufacturers, and
maintenance organisations, where applicable, shall apply the Precautionary Principle (see 5.2) and
hierarchy of controls (see 5.3) to prevent/minimize exposure to chemical compounds, particularly
those sourced from the aircraft ventilation supply air system, as follows:
— applying designs with mitigation measures such as filters (see Clause 6) and air monitoring
(see Clause 7);
— applying preventive and corrective maintenance measures (see Clause 8); and
— implementing administrative mitigation measures such as medical monitoring (see Clause 9),
reporting and analysis (see Clause 10), and airline worker training (see Clause 11).
Airline operators and manufacturers shall give priority to collective protective measures over
individual protective measures, as set out in the hierarchy of controls.
Airline operators and manufacturers shall apply the principle of substitution to reduce hazards in
relation to products utilized in aviation and engineering solutions. The dangerous shall be substituted
by the non-dangerous or the less dangerous, according to manufacturing specifications.
Airline operators and manufacturers shall document procedures to prevent and mitigate cabin air
contamination, including in the aircraft maintenance manual (AMM) and troubleshooting manual (TSM)
(see Clause 8).
Aircraft and engine manufacturers, maintenance organisations, and airline operators should also apply
the “best practice” measures listed in Annex F, as they impact design, maintenance, and operation.
6 Filtration
6.1 General
Aircraft manufacturers and suppliers shall design and install any ventilation supply air filtration
systems to remove airborne contaminants (particulate, aerosol, and gaseous) associated with the
sources listed in 4.2 in order to prevent/minimize occupant exposure in the occupied zones of the
aircraft. Airline operators shall operate maintain and replace the filtrations systems, per aircraft
manufacturer requirements. Filtration systems can process contaminants in the outside air stream, the
recirculated air stream, or both.
NOTE The terms “filter” and “filtration” are understood to include (a) devices intended to capture
particles/gases in the air stream; (b) air cleaning technologies designed to remove impurities from air through
chemical reactions; (c) or both.
6.2 Recirculation cabin air filtration
Aircraft manufacturers shall design ventilation supply air systems to ensure that recirculated
ventilation supply air is passed through a high-efficiency particulate air (HEPA) filter, or equivalent,
before it is supplied to the cabin in order to prevent the recirculation of particles through the
ventilation system.
NOTE 1 Particles can contain chemical compounds and pathogens.
NOTE 2 For certain ECS architecture, recirculation filtration may not be an option during certain operations.
Aircraft manufacturers shall design the filters and their mountings to prevent unintentional bypassing
of unfiltered air and to prevent filter overloading. The required HEPA filters shall meet one or more of
the following standards, or equivalent:
— IEST-RP-CC001; Type A or higher (99,97 % collection efficiency for 0.3-micron particles);
— EN 1822-1; Type H13 (99,95 % overall collection efficiency at the most penetrating particle size
MPPS); and
— ISO 29463-1; Type ISO 35 H (99,95 % overall collection efficiency at the most penetrating particle
size MPPS).
When recirculation fans are turned on, airline operators shall operate and replace these filters and their
mountings, all according to manufacturer recommendations.
Alternative technologies and test methods may be used to meet this requirement if they provide
equivalent or better removal efficiency and the test methods are approved by a cognizant authority.
6.3 Catalytic conversion filtration
If an aircraft is equipped with catalytic converters to remove ozone gas from the outside air stream
inflight, then the manufacturer and airline operator shall ensure that the devices are designed and
maintained according to the relevant regulations.
Devices that utilize catalytic conversion can be used to prevent/reduce exposure to/recirculation of
certain gaseous compounds, including but not limited to some of the sources of contaminants in the
ventilation supply air and cabin air, as defined in Annex B.
NOTE For more information on the standard to which aircraft ventilation systems have to be designed
regarding allowed ozone concentrations as a function of cabin altitude, see EASA CS 25.832 [16].
7 Air monitoring
7.1 General
Airline manufacturers shall install, and airline operators shall operate and maintain, air monitoring
equipment intended to identify the presence of at least the following contaminant sources: engine oil,
hydraulic fluid, engine exhaust/fuel, and de-icing fluid (see Annex B). When available technology allows,
the monitoring data shall also distinguish between these contaminant sources. The monitoring
requirements in Clause 7 also apply to maintenance organisations, where applicable.
The primary monitoring objective is to distinguish between normal conditions and system degradation,
such as fume events (see 4.4) that may require pilot and/or maintenance intervention. Monitoring the
air for those contaminant sources is intended to prevent/reduce onboard exposure.
All air monitoring shall be planned and conducted consistent with defined objectives (see 7.2).
Specifically, the location of each sensor shall be defined according to the potential source of
contamination (e.g. engine versus APU), the marker compound(s), and the physical constraints related
to the sensor itself (e.g. temperature, pressure, and humidity conditions).
All monitoring equipment shall be calibrated and suitable for the intended use (i.e. suitable limit of
detection, response time, accuracy, and reliability) and sampling environment to ensure that the data
collected is reliable according to the objectives sought (see Annex E).
Where available, sensor technology that can be integrated into the aircraft systems and interpreted in
real-time (see 7.3.1) shall be used to meet the requirements of this section. When real-time sensor
technology is available but cannot be integrated into aircraft systems, then a portable real-time device
should be used. Real-time sensor data could also be analysed post-flight.
Data collected with portable sampling equipment used for time-integrated measurement methods
(see 7.3.2) may also be useful, either to supplement real-time data collected onboard or to perform a
routine system inspection/maintenance for any of the airborne contaminant sources listed in Annex B.
The following approaches can be applied, either in isolation or in combination, to meet the
requirements of contamination source recognition:
a) indicative chemical marker compounds;
b) pattern recognition; and
c) differential measurement.
See Annex D for further information on these approaches.
All sampling data shall be carefully interpreted in the context of the sampling conditions.
Cross-sensitivities should be taken into account.
7.2 Air monitoring planning/development
7.2.1 Overview
In coordination with aircraft manufacturers, airline operators shall establish a monitoring strategy
according to EN ISO 16000-1, in order to define the most appropriate methodology to be utilized and to
ensure that the integrity of the measurement data are maintained.
Sampling equipment shall be securely located and shall not interfere with aircraft operations, nor alter
the air. Monitoring shall be part of a planned approach to prevent or reduce exposure.
Competent persons, with the skill, knowledge, practical experience and training shall plan and oversee
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