FprEN 4856

Aerospace series - Rotorcraft Emergency Breathing Systems (EBS) - Requirements, testing and marking

This document specifies requirements for Emergency Breathing Systems (EBS) for use by helicopter crew and passengers in the event of a ditching or water impact, to ensure minimum levels of performance. It applies to EBS capable of being successfully and reliably deployed in air and underwater, for use by adults only.
This document is applicable to compressed air and hybrid rebreather designs of EBS. It does not apply to EBS that cannot be successfully and reliably deployed underwater.

Luft-und Raumfahrt - Drehflügler Notfallbeatmungssystem (EBS) - Anforderungen, Prüfung und Kennzeichnung

Série aérospatiale - Systèmes de ventilation d'urgence (EBS) de giravion - Exigences, essais et marquage

Le présent document spécifie les exigences relatives aux systèmes de ventilation d'urgence (EBS) destinés à être utilisés par l'équipage et par les passagers des hélicoptères en cas d'amerrissage forcé ou d'impact avec un plan d'eau, afin de garantir des niveaux minimaux de performance. Il s’applique aux EBS pouvant être correctement déployés à l’air libre et sous l'eau, destinés à être utilisés uniquement par des adultes.
Le présent document s'applique aux modèles d'EBS à air comprimé ainsi qu’à masque à recirculation hybride. Il ne s’applique pas aux EBS ne pouvant pas être correctement déployés sous l'eau.

Aeronavtika - Rotoplani - Sistem prezračevanja v sili (EBS) - Zahteve, preskušanje in označevanje

General Information

• Status: Not Published
• Publication Date: 07-Feb-2023
• ICS: 49.095 - Passenger and cabin equipment
• Technical Committee: ASD-STAN - Aerospace
• Drafting Committee: ASD-STAN/D 12/WG 2 - Ditching Equipment
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 08-Feb-2023
• Completion Date: 08-Feb-2023
• Ref Project: kSIST FprEN 4856:2022 - Aerospace series - Rotorcraft - Emergency Breathing Systems (EBS) - Requirements, testing and marking

Relations

• Replaces: EN 4856:2018 - Rotorcraft - Emergency Breathing Systems (EBS) - Requirements, testing and marking
• Effective Date: 03-Feb-2021

Standards Content (Sample)

SLOVENSKI STANDARD
oSIST prEN 4856:2022
01-februar-2022

Aeronavtika - Rotoplani - Sistem prezračevanja v sili (EBS) - Zahteve, preskušanje

in označevanje

Aerospace series - Rotorcraft - Emergency Breathing Systems (EBS) - Requirements,

testing and marking
Luft-und Raumfahrt - Drehflügler - Notfallbeatmungssystem (EBS) - Anforderungen,
Prüfung und Kennzeichnung

Série aérospatiale - Giravion - Système de ventilation d'urgence (EBS) - Exigences,

essais et marquage
Ta slovenski standard je istoveten z: prEN 4856
ICS:
49.095 Oprema za potnike in Passenger and cabin
oprema kabin equipment
oSIST prEN 4856:2022 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 4856:2022
DRAFT
EUROPEAN STANDARD
prEN 4856
NORME EUROPÉENNE
EUROPÄISCHE NORM
December 2021
ICS 49.095 Will supersede EN 4856:2018
English Version
Aerospace series - Rotorcraft - Emergency Breathing
Systems (EBS) - Requirements, testing and marking

Série aérospatiale - Giravion - Système de ventilation Luft-und Raumfahrt - Drehflügler -

d'urgence (EBS) - Exigences, essais et marquage Notfallbeatmungssystem (EBS) - Anforderungen,

Prüfung und Kennzeichnung

This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee ASD-

STAN.

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 4856:2021 E

worldwide for CEN national Members.
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Contents Page

European foreword ...................................................................................................................................................... 4

Introduction .................................................................................................................................................................... 5

1 Scope .................................................................................................................................................................... 6

2 Normative references .................................................................................................................................... 6

3 Terms and definitions ................................................................................................................................... 6

4 Design types .................................................................................................................................................... 10

4.1 Compressed air EBS ..................................................................................................................................... 10

4.2 Hybrid rebreather EBS ................................................................................................................................ 11

5 Performance requirements ....................................................................................................................... 11

5.1 General.............................................................................................................................................................. 11

5.2 Design ................................................................................................................................................................ 12

5.3 Materials .......................................................................................................................................................... 13

5.4 Breathing performance .............................................................................................................................. 13

5.4.1 General.............................................................................................................................................................. 13

5.4.2 Work of breathing ........................................................................................................................................ 14

5.4.3 Respiratory pressures................................................................................................................................. 14

5.4.4 Hydrostatic imbalance ................................................................................................................................ 14

5.4.5 Extreme cold water temperatures .......................................................................................................... 14

5.5 Safety devices ................................................................................................................................................. 14

5.6 Deployment ..................................................................................................................................................... 15

5.7 Ease of use and manoeuvrability in water ........................................................................................... 15

5.8 Buoyancy .......................................................................................................................................................... 15

5.9 Cold water performance ............................................................................................................................. 15

5.10 Compatibility .................................................................................................................................................. 15

5.10.1 General.............................................................................................................................................................. 15

5.10.2 Performance of equipment combination(s) ....................................................................................... 16

6 Testing .............................................................................................................................................................. 18

6.1 Visual inspection ........................................................................................................................................... 18

6.2 Nominal values and tolerances ................................................................................................................ 19

6.3 Magnetic properties testing ...................................................................................................................... 19

6.4 Temperature cycling.................................................................................................................................... 19

6.5 Breathing performance .............................................................................................................................. 19

6.6 Breathable volume of counterlung ......................................................................................................... 22

6.7 Buoyancy .......................................................................................................................................................... 22

6.8 Ergonomic performance ............................................................................................................................. 22

6.8.1 General.............................................................................................................................................................. 22

6.8.2 Test subjects ................................................................................................................................................... 23

6.8.3 Deployment ..................................................................................................................................................... 25

6.8.4 Ease of use, manoeuvrability and helicopter escape ....................................................................... 25

6.9 Cold water performance ............................................................................................................................. 27

6.10 Compatibility and performance of equipment combination(s) ................................................... 27

6.10.1 General.............................................................................................................................................................. 27

6.10.2 Test subjects ................................................................................................................................................... 27

6.10.3 Clothing............................................................................................................................................................. 28

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6.10.4 Compatibility and equipment combination performance testing .............................................. 28

6.10.5 Donning and fit .............................................................................................................................................. 28

6.10.6 Ride-up ............................................................................................................................................................. 28

6.10.7 Helicopter underwater escape ................................................................................................................ 29

6.10.8 Jump into water ............................................................................................................................................. 29

6.10.9 Freeboard ........................................................................................................................................................ 30

6.10.10 Turning .................................................................................................................................................... 30

6.10.11 Self-righting ............................................................................................................................................ 31

6.10.12 In-water stability .................................................................................................................................. 31

6.10.13 Freedom of movement and use of accessories .......................................................................... 32

6.10.14 Life raft boarding .................................................................................................................................. 32

6.10.15 Rescue and recovery ........................................................................................................................... 32

6.10.16 Escape buoyancy ................................................................................................................................... 32

6.11 Crew equipment compatibility ................................................................................................................ 34

6.12 Reporting ......................................................................................................................................................... 35

7 Marking ............................................................................................................................................................ 35

8 Information supplied by the manufacturer ........................................................................................ 36

Annex A (normative) Rating of breathing effort ............................................................................................. 37

A.1 Instruction ....................................................................................................................................................... 37

Annex B (informative) Evolution sheet.............................................................................................................. 38

Bibliography ................................................................................................................................................................. 39

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European foreword

This document (prEN 4856:2021) has been prepared by the Aerospace and Defence Industries

Association of Europe — Standardization (ASD-STAN).

After enquiries and votes carried out in accordance with the rules of this Association, this document has

received the approval of the National Associations and the Official Services of the member countries of

ASD-STAN, prior to its presentation to CEN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 4856:2018.
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Introduction

This document prescribes the minimum standards of design and performance for rotorcraft emergency

breathing systems (EBS), used to reduce the risks of drowning in the event of submersion. An EBS is a

form of personal protective equipment that provides the user with a means to breathe underwater,

thereby improving the probability of successfully escaping from a submerged rotorcraft cabin. If used

correctly, EBS should mitigate the risk of drowning.

This document aims to ensure that the equipment user is able to carry out the necessary emergency

procedures whilst being provided with an appropriate level of protection under foreseeable conditions

of use. It also aims to ensure that the equipment presents a minimal hazard in relation to escape from

the rotorcraft, and that the equipment has no detrimental effect on the health and safety of the user or

on the performance of other equipment.

This document is applicable to all rotorcraft. Rotorcraft include helicopters, tilt rotor/wing and

gyroplanes. For the purpose of this standard the term helicopter is used generically hereinafter.

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1 Scope

This document specifies requirements for Emergency Breathing Systems (EBS) for use by helicopter

crew and passengers in the event of a ditching or water impact, to ensure minimum levels of

performance. It applies to EBS capable of being successfully and reliably deployed in air and

underwater, for use by adults only.

This document is applicable to compressed air and hybrid rebreather designs of EBS. It does not apply

to EBS that cannot be successfully and reliably deployed underwater.
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 250, Respiratory equipment — Open-circuit self-contained compressed air diving apparatus -

Requirements, testing and marking

EN 4862, Rotorcraft — Constant Wear Lifejackets — Requirements, testing and marking

EN 4863:— , Aerospace series — Rotorcraft immersion suits — Requirements, testing and marking

prEN 4886, Aerospace series — Rotorcraft — Liferafts for operations in hostile sea areas — Requirements,

testing and marking
EN 12021, Respiratory equipment — Compressed gases for breathing apparatus

EN 14143:2013, Respiratory equipment — Self-contained re-breathing diving apparatus

EN ISO 9227, Corrosion tests in artificial atmospheres — Salt spray tests (ISO 9227)

EN ISO 12894, Ergonomics of the thermal environment — Medical supervision of individuals exposed to

extreme hot or cold environments (ISO 12894)

EASA CS-25 Amendment 26:2020, Certification Specifications and Acceptable Means of Compliance for

Large Aeroplanes CS-25, Book 1 — Appendix F
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 https://www.iso.org/obp
• IEC Electropedia: available at https://www.electropedia.org/
Under preparation; current stage is: prEN 4862:2021.
Under preparation; current stage is: prEN 4863:2021.
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3.1
emergency breathing system
EBS

system that allows a person to breathe underwater, overcoming the need to breath-hold for the

complete duration of an underwater escape from a helicopter, that can be deployed under emergency

conditions
3.2
lifejacket

garment or device which, when correctly worn and used in water will provide the user with buoyancy

positioned to provide protection from drowning and increase the likelihood of survival and rescue

3.3
helicopter constant wear lifejacket

lifejacket worn on the body throughout a helicopter flight, provided to protect the user in the event of a

ditching or water impact
3.4
immersion suit

garment designed to protect the user’s body from the cooling effects of unintended immersion in water

Note 1 to entry: Cooling effects include cold shock and hypothermia.

Note 2 to entry: An immersion suit may be integrated or worn with a separate constant wear lifejacket.

3.5
integrated immersion suit
immersion suit that incorporates the functionality of a lifejacket
3.6
buoyancy element

inflatable chamber incorporated into an integrated immersion suit that, when inflated, provides the suit

with the functionality of a lifejacket
3.7
helicopter immersion suit

immersion suit worn on the body throughout a helicopter flight, provided to protect the user in the

event of a ditching or water impact
3.8
immersion suit system

helicopter immersion suit (with or without thermal insulation) and its components and accessories

including either a constant wear lifejacket or buoyancy element and/or emergency breathing system, as

applicable
3.9
fully inflated

inflation of a lifejacket or buoyancy element achieved by using the manual inflation system (stored gas)

with no subsequent deflation
3.10
manual inflation system

means of inflation achieved by a person operating a mechanism that actively releases stored gas into

the buoyancy chamber(s) of a lifejacket or buoyancy element
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3.11
oral inflation system

means of inflation achieved by a person blowing expired air into the buoyancy chamber(s) of a

lifejacket or buoyancy element
3.12
rotorcraft

heavier-than-air aircraft that depends principally for its support in flight on the lift generated by one or

more rotors
3.13
helicopter

rotorcraft that, for its horizontal motion, depends principally on its engine-driven rotors

3.14
ditching

controlled emergency landing on water, deliberately executed in accordance with Rotorcraft Flight

Manual procedures, with the intent of abandoning the rotorcraft as soon as practical

3.15
water impact

helicopter contact with water that is unintentional or exceeds the ditching capability of the helicopter

for water entry
3.16
crew member
person assigned by an operator to perform duties on board an aircraft
3.17
mouthpiece

device that goes into the mouth of the user, usually held by the teeth, sealing against the lips and

through which a breathable gas is inhaled and exhaled
3.18
nose occlusion system
means of preventing water from entering the nose
Note 1 to entry: A nose clip is one example of a nose occlusion system.
3.19
demand regulator
device which consists of a pressure reducer connected to a demand valve
3.20
medium pressure hose

hose with an interface connection at each end, between the pressure reducer and a demand valve

3.21
breathing hose

flexible hose connecting a counterlung to the mouthpiece of a hybrid rebreather EBS, at approximately

ambient pressure
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3.22
pressure indicator
device to indicate to the user the pressure of gas in a cylinder
3.23
purging device

part of the demand regulator that can be operated manually to deliver breathable gas, intended to force

water out of the mouthpiece
3.24
dead space

volume of the cavity formed between the mouth and the inhalation and exhalation parts

3.25
activation device

mechanism which switches breathing from the atmosphere to the counterlung of a hybrid rebreather

EBS
3.26
counterlung
variable volume container for the user to exhale to and inhale from
3.27
breathable gas
gas that will support life under the intended conditions of use
3.28
work of breathing

work expended during one breathing cycle which is proportional to the area bounded by the pressure

volume diagram divided by the tidal volume
Note 1 to entry: Measured in J/l.
3.29
respiratory pressure

differential pressure at the mouth relative to the no flow pressures measured at the end of inhalation

and exhalation
3.30
hydrostatic imbalance

difference at end exhalation no flow between the pressure at the mouth and that at the lung centroid

reference point
3.31
tidal volume

volume of breathing gas displaced by the breathing simulator during one half cycle (inhalation or

exhalation)
Note 1 to entry: Measured in l.
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3.32
respiratory minute volume
product of the tidal volume and breathing frequency
Note 1 to entry: Measured in l/min.
3.33
useable volume of air

volume of breathable air available to the user while the demand regulator is operating within the

specified breathing performance
3.34
rated working pressure
maximum working pressure of the respective components
3.35
pressure volume diagram

diagram generated during one breathing cycle by plotting the respiratory pressure against the

displaced (tidal) volume
3.36
elastance
change in pressure that results from a given volume change of the human lung
Note 1 to entry: Measured in kPa/l.

Note 2 to entry: This is a typical term for the elastic behaviour of a breathing system.

3.37
reference pressure

equilibrium pressure which exists in the mouthpiece when there is no respiratory flow at the end of

exhalation
3.38
escape buoyancy

buoyancy of an equipment combination, with the lifejacket or buoyancy element uninflated, that must

be overcome when escaping from an immersed helicopter

Note 1 to entry: It includes the inherent buoyancy of the components of the immersion suit system and entrapped

air but excludes the inflated buoyancy elements.
4 Design types
4.1 Compressed air EBS

A compressed air EBS is a system where air or some other breathable gas is supplied to the user on

demand from a high pressure gas cylinder, the period of breathing being limited by the volume of

useable gas.
The apparatus shall comprise at least the following components:
• mouthpiece;
• medium pressure hose;
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• gas cylinder;
• demand regulator;
• pressure indicator;
• purging device;
• nose occlusion system.
4.2 Hybrid rebreather EBS

A rebreather EBS is a system with a counterlung which allows the user to move air out of and back into

their lungs, the period of rebreathing being limited by a build-up of carbon dioxide and a reduction in

oxygen concentration. A hybrid rebreather EBS is a rebreather system that incorporates a compressed

gas cylinder, allowing a small volume of air or other breathable gas to be introduced into the

counterlung, the period of rebreathing being limited by a build-up of carbon dioxide and a reduction in

oxygen concentration.
The system shall comprise at least the following components:
• mouthpiece;
• breathing hose;
• counterlung;
• gas cylinder with gas release system;
• activation device;
• nose occlusion system.
5 Performance requirements
5.1 General

5.1.1 EBS covered by this European standard shall be capable of being rapidly deployed and used

both in air and underwater. They shall be suitable for use when capsize and/or sinking occurs

immediately after the helicopter makes contact with the water.

5.1.2 Where applicable, EBS shall be tested in combination with associated equipment, including an

immersion suit, accessories and/or lifejacket that is intended to be worn with it, in accordance with 6.8.

It shall be deployed in the same manner as it would be in normal service, and from the intended stowed

position (6.1 and 6.8.3).

NOTE Helicopter immersion suits are hereinafter referred to as immersion suits. Helicopter constant wear

lifejackets are hereinafter referred to as lifejackets.

5.1.3 If a compressed breathable gas other than air is used, additional assessment and testing might

be required. This shall be determined following visual inspection in accordance with 6.1.

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5.2 Design

5.2.1 The EBS shall be practicable in use and light in weight without prejudice to the design strength

and performance. Testing shall be carried out in accordance with 6.1 and 6.8.

5.2.2 The EBS shall be simple to deploy and capable of being operated with either hand. The number

of deployment actions shall be minimized; for example, no more than one action should be required to

activate a hybrid rebreather system on submersion, i.e. opening the valve of the counterlung. Testing

shall be carried out in accordance with 6.1, 6.8.3 and 6.8.4.

5.2.3 The equipment shall not have any sharp edges or protruding parts which might injure the user,

or damage the lifejacket, immersion suit system or other emergency equipment. Testing shall be carried

out in accordance with 6.1 and 6.8.

5.2.4 Compressed air EBS shall provide the user with a minimum useable volume of air of 50 l

Standard Temperature and Pressure Dry (STPD), meeting the requirements of EN 12021. Testing shall

be carried out in accordance with 6.1 and 6.5.

5.2.5 Where a counterlung is incorporated into a hybrid rebreather system, the counterlung shall

have sufficient breathable capacity to accommodate an expired volume of at least 6 l (STPD). Additional

capacity shall be provided equivalent to the volume of breathable gas discharged into the counterlung

from the gas cylinder. The counterlung shall be designed to prevent collapse, taking panic breathing

into account. Testing shall be carried out in accordance with 6.1 and 6.6.

5.2.6 The EBS design shall minimize the amount of water that can enter the mouthpiece (dead space).

It shall be possible to expel this water from the mouthpiece. Testing shall be carried out in accordance

with to 6.1, 6.8.3.2, 6.8.4.4, 6.8.4.5 and 6.8.4.6.

5.2.7 Subjects shall be provided with a means to prevent water entering the nose that is easy to

deploy and effective when used underwater. Nose occlusion systems (including nose clips) shall be

designed to fit a wide range of user sizes. Nose clips shall be easy to open with either hand and shall be

permanently attached to the EBS, on or adjacent to the mouthpiece. Testing shall be carried out in

accordance with 6.1 and 6.8.

5.2.8 Where an EBS includes a harness to fit the EBS to the body, this shall allow correct positioning

on the body when used according to the manufacturer's instructions. Testing shall be carried out in

accordance with 6.1 and 6.8.

5.2.9 Gas cylinders and connections with demand regulators shall comply with the appropriate

European specifications and shall be approved and tested with respect to the rated working pressure

and for underwater use. Testing shall be carried out in accordance with 6.1.
NOTE Some composite cylinders are not approved for underwater use.

5.2.10 Leakage from compressed air EBS shall not exceed 10 % of the initial cylinder pressure, in any

single case, when tested in accordance with 6.5.6.
...