Aerospace series - Elements of electrical and optical connection - Test methods - Part 326: Fire immersion test

This European Standard specifies a method of determining a component’s resistance to a liquid fuelled fire and the elements of connection.
It shall be used together with EN 2591-100.

Luft- und Raumfahrt - Elektrische und optische Verbindungselemente - Prüfverfahren - Teil 326: Feuereintauchtest

Série aérospatiale - Organes de connexion électrique et optique - Méthodes d'essais - Partie 326 : Immersion au feu

Aeronavtika - Električni in optični spojni elementi - Preskusne metode - 326. del: Preskus potapljanja v ogenj

Ta evropski standard določa metodo za ugotavljanje odpornosti sestavnih delov proti ognju, ki za gorenje porablja tekočino, in elemente povezave.
Uporabljati ga je treba skupaj s standardom EN 2591-100.

General Information

Status
Published
Publication Date
07-Aug-2018
Withdrawal Date
27-Feb-2019
Technical Committee
ASD-STAN - Aerospace
Drafting Committee
ASD-STAN/D 2 - Electrical
Current Stage
9093 - Decision to confirm - Review Enquiry
Start Date
21-Jan-2024
Completion Date
21-Jan-2026

Relations

Effective Date
28-Jan-2026
Effective Date
28-Jan-2026
Effective Date
28-Jan-2026
Effective Date
28-Jan-2026
Effective Date
28-Jan-2026
Effective Date
28-Jan-2026
Effective Date
28-Jan-2026
Effective Date
28-Jan-2026
Effective Date
28-Jan-2026
Effective Date
28-Jan-2026
Effective Date
28-Jan-2026
Effective Date
28-Jan-2026
Effective Date
28-Jan-2026
Effective Date
28-Jan-2026
Effective Date
28-Jan-2026

Overview

EN 2591-326:2018 is a CEN European Standard in the Aerospace series that defines a test method for determining the resistance of electrical and optical connection elements to a liquid‑fuelled fire. Published in 2018 and prepared by ASD‑STAN, it is Part 326 of the EN 2591 series and is intended to be used together with EN 2591-100 (General). The standard specifies specimen preparation, burner calibration, test fixtures, test procedures and acceptance criteria for both fire immersion and fire containment scenarios.

Key Topics and Technical Requirements

  • Two test methods
    • Method 1 - Liquid fuelled fire immersion: verify connectors sustain a fire for at least 5 minutes without electrical discontinuity.
    • Method 2 - Liquid fuelled fire containment: verify connector pair on a dividing wall sustains 5 minutes without discontinuity and contains flame on the exposed side for 20 minutes total (5 + 14).
  • Specimen preparation
    • Connectors fitted with backshells or integrated accessories; cables clamped 200–250 mm behind rear grommet; cable bundles ≥ 450 mm.
    • All cavities fitted with wired contacts; circuits wired in series using even-numbered and odd-numbered contacts.
  • Burner and calibration
    • Liquid fuel kerosene burner; temperature calibration using 7 K‑type thermocouples spaced 25 mm and positioned at X = 100 mm ± 10%, Y = 25 mm ± 10%.
    • Target flame temperature average (1100 ± 80) °C (per thermocouple over 2 min); heat flux calibrated with a continuous‑flow calorimeter.
  • Test conditions
    • Specimens exposed to flame and vibration: 30–60 Hz, 100 m/s² acceleration.
    • Electrical loading: first 5 min contacts carry nominal current; 6th minute apply 200–260 Vrms between circuits and 100–130 V between circuits and shell.
  • Acceptance criteria
    • No electrical discontinuity during the first 5 minutes; leakage current ≤ 2 A during the sixth minute.
    • For containment test, no flame visible on the non‑exposed side after phase 2.
  • Post‑test inspection
    • Failure analysis required; if cable causes failure, repeat testing with new cable/connector as appropriate.

Applications and Users

  • Intended for aerospace connector designers, qualification engineers, test laboratories, OEMs and certification bodies who need to verify connector performance in liquid‑fuel fire scenarios (aircraft designated fire zones).
  • Used to qualify electrical and optical connectors, backshells and cable assemblies for fire resistance, continuity under thermal/mechanical stress, and containment capability.
  • Valuable for procurement specifications, supplier qualification and safety compliance in aerospace electrical systems.

Related Standards

  • EN 2591-100 (General test methods) - mandatory companion document
  • EN 2234 (fire‑resistant cable)
  • ISO 2685 (aircraft resistance to fire in designated fire zones)
  • EN 2997, EN 3645, EN 3660 (related aerospace connector and accessory specifications)

Keywords: EN 2591-326, fire immersion test, aerospace connectors, liquid‑fuelled fire, connector fire resistance, burner calibration, test method, EN 2591-100.

Standard

EN 2591-326:2018 - BARVE

English language
16 pages
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Frequently Asked Questions

EN 2591-326:2018 is a standard published by the European Committee for Standardization (CEN). Its full title is "Aerospace series - Elements of electrical and optical connection - Test methods - Part 326: Fire immersion test". This standard covers: This European Standard specifies a method of determining a component’s resistance to a liquid fuelled fire and the elements of connection. It shall be used together with EN 2591-100.

This European Standard specifies a method of determining a component’s resistance to a liquid fuelled fire and the elements of connection. It shall be used together with EN 2591-100.

EN 2591-326:2018 is classified under the following ICS (International Classification for Standards) categories: 49.060 - Aerospace electric equipment and systems. The ICS classification helps identify the subject area and facilitates finding related standards.

EN 2591-326:2018 has the following relationships with other standards: It is inter standard links to EN 2997-016:2010, EN 3660-026:2009, EN 3660-007:2010, EN 3660-020:2009, EN 2997-003:2012, EN 3660-008:2010, EN 3660-017:2009, EN 3660-019:2009, EN 3660-006:2010, EN 2997-008:2006, EN 2997-006:2024, EN 3660-010:2010, EN 3660-016:2009, EN 3660-009:2007, EN 2997-012:2024. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.

EN 2591-326:2018 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.

Standards Content (Sample)


SLOVENSKI STANDARD
01-november-2018
$HURQDYWLND(OHNWULþQLLQRSWLþQLVSRMQLHOHPHQWL3UHVNXVQHPHWRGHGHO
3UHVNXVSRWDSOMDQMDYRJHQM
Aerospace series - Elements of electrical and optical connection - Test methods - Part
326: Fire immersion test
Luft- und Raumfahrt - Elektrische und optische Verbindungselemente - Prüfverfahren -
Teil 326: Feuereintauchtest
Série aérospatiale - Organes de connexion électrique et optique - Méthodes d'essais -
Partie 326 : Immersion au feu
Ta slovenski standard je istoveten z: EN 2591-326:2018
ICS:
49.060 /HWDOVNDLQYHVROMVND Aerospace electric
HOHNWULþQDRSUHPDLQVLVWHPL equipment and systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 2591-326
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2018
EUROPÄISCHE NORM
ICS 49.060
English Version
Aerospace series - Elements of electrical and optical
connection - Test methods - Part 326: Fire immersion test
Série aérospatiale - Organes de connexion électrique et Luft- und Raumfahrt - Elektrische und optische
optique - Méthodes d'essais - Partie 326 : Immersion Verbindungselemente - Prüfverfahren - Teil 326:
au feu Feuereintauchtest
This European Standard was approved by CEN on 13 May 2018.

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. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 2591-326:2018 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Scope . 3
2 Normative references . 4
3 Test method . 4
4 Preparation of specimens . 5
5 Apparatus. 7
6 Test fixtures . 11
7 Testing . 12
8 Inspection after tests . 15
Annex A (normative) Monitoring diagram . 16

European foreword
This document (EN 2591-326:2018) 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 Standard has
received the approval of the National Associations and the Official Services of the member countries of
ASD, prior to its presentation to CEN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by February 2019, and conflicting national standards shall
be withdrawn at the latest by February 2019.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands,
Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
1 Scope
This European Standard specifies a method of determining a component’s resistance to a liquid fuelled
fire and the elements of connection.
It shall be used together with EN 2591-100.
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 2234, Aerospace series — Cable, electrical, fire resistant — Technical specification
EN 2591-100, Aerospace series — Elements of electrical and optical connection — Test methods —
Part 100: General
EN 2591-202, Aerospace series — Elements of electrical and optical connection — Test methods — Part 202:
Contact resistance at rated current
EN 2997 (all parts), Aerospace series — Connectors, electrical, circular, coupled by threaded ring, fire-
resistant or non fire-resistant, operating temperatures – 65 °C to 175 °C continuous, 200 °C continuous,
260 °C peak
EN 3645 (all parts), Aerospace series — Connectors, electrical, circular, scoop proof, triple start threaded
coupling, operating temperature 175 °C or 200 °C continuous
EN 3660 (all parts), Aerospace series — Cable outlet accessories for circular and rectangular electrical and
optical connectors
ISO 2685, Aircraft — Environmental test procedure for airborne equipment — Resistance to fire in
designated fire zones
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
4 Test method
EN 2591-326 is composed of two tests on 2 sample groups:
1) Liquid fuelled fire immersion test:
The purpose of this test is to verify the ability of a couple of connectors installed in the same area, to
sustain a fire for at least 5 min, without electrical discontinuity.
2) Liquid fuelled fire containment test:
The purpose of this test is to verify the ability of a couple of connectors installed on a wall dividing 2 areas,
to sustain a fire for at least 5 min, without electrical discontinuity and to contain the flame on the side
exposed to fire for 20 min.
5 Preparation of specimens
5.1 Layout
For EN 2997:
 8-06 for contact size 22;
 10-06 for contacts size 20;
 18-08 for contact size 12;
 24-30 for contact size 16.
In case of non-availability of one or more of above mentioned layout, equivalent layouts will be assessed
and justified by the mandated body representative.
For EN 3645:
 9-35 for contact size 22;
 11-98 for contacts size 20;
 17-06 for contact size 12;
 23-21 for contact size 16;
 21-48 for contacts size 8.
In case of non-availability of one or more of above mentioned layout, equivalent layouts will be assessed
and justified by the mandated body representative.
5.2 Specimen preparation
5.2.1 Model without integrated accessory
The connector shall be fitted with a straight backshell, unsealed with clamp strain relief type
EN 3660-XXX or equivalent on both sides.
Cables in the area between the clamps and rear grommet shall be exposed to the flame without
protection, see Figure 1 and Figure 2. Glass fibre sheath or equivalent shall be installed where the cables
contact the clamp, to avoid any electrical breakdown in this area.
Cables shall be clamped between 200 mm to 250 mm of the rear of the grommet in both sides.

Figure 1 Figure 2
5.2.2 Model with integrated accessory
Cables and rear grommet shall be exposed to the flame without protec
...

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