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BS EN 3745-410:2015 BSI Standards Publication Aerospace series — Fibres and cables, optical, aircraft use — Test methods Part 410: Thermal life BS EN 3745-410:2015 BRITISH STANDARD National foreword This British Standard is the UK implementation of EN 3745-410:2015 It supersedes BS EN 3745-410:2007 which is withdrawn The UK participation in its preparation was entrusted to Technical Committee ACE/6, Aerospace avionic electrical and fibre optic technology A list of organizations represented on this committee can be obtained on request to its secretary This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application © The British Standards Institution 2015 Published by BSI Standards Limited 2015 ISBN 978 580 88562 ICS 49.060 Compliance with a British Standard cannot confer immunity from legal obligations This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 July 2015 Amendments issued since publication Date Text affected BS EN 3745-410:2015 EN 3745-410 EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM July 2015 ICS 49.090 Supersedes EN 3745-410:2007 English Version Aerospace series - Fibres and cables, optical, aircraft use - Test methods - Part 410: Thermal life Série aérospatiale - Fibre et câbles optiques usage aéronautique - Méthodes d'essais - Partie 410 : Durée de vie en température Luft- und Raumfahrt - Faseroptische Leitungen für Luftfahrezuge - Prüfverfahren - Teil 410: Lebensdauer unter Temperatureinwirkung This European Standard was approved by CEN on 14 February 2015 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, 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: Avenue Marnix 17, B-1000 Brussels © 2015 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members Ref No EN 3745-410:2015 E BS EN 3745-410:2015 EN 3745-410:2015 (E) Contents Page Foreword Scope Normative references 3.1 Test specimens Fibre ends .4 4.1 4.2 4.3 4.4 4.4.1 4.4.2 4.4.3 4.4.4 Method A (without mechanical stress applied) Preparation of test specimens .4 Test conditions Apparatus .5 Procedure .5 Initial measurements .5 Test Final measurements and requirement Special precautions .6 5.1 5.2 5.3 5.4 5.5 5.5.1 5.5.2 5.5.3 5.5.4 Method B (with mechanical stress applied) Preparation of test specimens .6 Test conditions Information to be included in the product standard Apparatus .7 Procedure .8 Initial measurements .8 Test Calculation of the regression line Special precautions 10 Requirements 10 BS EN 3745-410:2015 EN 3745-410:2015 (E) European foreword This document (EN 3745-410:2015) 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 January 2016 and conflicting national standards shall be withdrawn at the latest by January 2016 Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights This document supersedes EN 3745-410:2007 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, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom BS EN 3745-410:2015 EN 3745-410:2015 (E) Scope This European Standard specifies a method of measuring the thermal endurance of a finished optical cable There are two test methods incorporated which estimate the cables thermal life with or without the mechanical stress Method A – without mechanical stress (temperature only), Method B – combined temperature and mechanical stress Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application For dated references, only the edition cited applies For undated references, the latest edition of the referenced document (including any amendments) applies EN 2591-100, Aerospace series — Elements of electrical and optical connection — Test methods — Part 100: General EN 3745-100, Aerospace series — Fibres and cables, optical, aircraft use — Test methods — Part 100: General EN 3745-301, Aerospace series — Fibres and cables, optical, aircraft use — Test methods — Part 301: Attenuation ASTM-D3032, Standard test methods for hookup wire insulation 1) 3.1 Test specimens Fibre ends The fibre ends shall be prepared in accordance with EN 2591-100 If not yet at standard test conditions, the specimens shall be subjected to standard test conditions and stabilized at these conditions for 24 h as defined in EN 3745-100 4.1 Method A (without mechanical stress applied) Preparation of test specimens Specimens have to be fixed on an apparatus representative of aircraft installation Ten specimens are fixed on apparatus and constitute a set for life testing at each temperature A minimum of four sets of specimens is necessary 1) Published by: ASTM National (US) American Society for Testing and Materials (http://www.astm.org/) BS EN 3745-410:2015 EN 3745-410:2015 (E) 4.2 Test conditions The following details shall be specified if not already included in the product standard: Type of fibre/cable from which the specimens were taken, Type/number/pitch of clamps Minimum authorized long term bend radius Length of specimens if not 10 m Maximum permissible variation in attenuation if not −3 dB Temperature values ( θ > θ > θ > θ 4) 4.3 Apparatus The apparatus shall comprise: A Light Launch System (LLS) as defined in EN 2591-100, A split coupler × 10, A Light Detection System (LDS) as defined in EN 2591-100, with 10 channel recorder, A fixture to secure the specimens, A climatic chamber capable of temperature control of ± °C 4.4 4.4.1 Procedure Initial measurements If the value of the highest temperature value is not specified in the product standard make a quick estimation of the highest test temperature with one specimen during 24 h at 80 °C above the nominal rating temperature The variation in attenuation shall not exceed the specified value 4.4.2 Test The attenuation shall be monitored throughout the test in accordance with EN 3745-301, method C Connect the specimen ends to the coupler, the coupler to LLS and the other specimen ends to LDS Place the fixture in the test chamber The coupler and connectors shall not be into climatic chamber Begin the test sequence with the highest test temperature (θ 1) since exposure times will be relatively short Record the exposure time to failure for each specimen A failure is defined when the variation in attenuation is higher than the specified value Stop the test sequence when all specimens in group have failed Calculate the log average life as defined in ASTM-D3032 If the log average life at this temperature (highest) is found to be less than 100 h, too high a test temperature has been selected and these data should be discarded Tests should be repeated at lower temperature BS EN 3745-410:2015 EN 3745-410:2015 (E) Repeat this procedure with the group N° of specimens for θ temperature value Calculate the log average life as defined in ASTM-D3032 Repeat this procedure with the group N° of specimens for θ temperature value Calculate the log average life as defined in ASTM-D3032 Repeat this procedure with the last group of specimens for θ temperature value (lowest) Calculate the log average life as defined in ASTM-D3032 If the average life found at this test temperature is less than 000 h, this test will be made at lower temperature 4.4.3 Final measurements and requirement The calculation of average life and extrapolation are defined in the ASTM-D3032 — Standard test methods for hookup wire insulation 4.4.4 Special precautions Extrapolation to a temperature index expected at the selected end of life (10 000 h, 20 000 h or 40 000 h) should not exceed 25 °C below the lowest aging test temperature The log average life at the highest test temperature (θ 1) shall not be less than 100 h The log average life at the lowest test temperature (θ 4) shall not be less than 000 h Method B (with mechanical stress applied) 5.1 Preparation of test specimens One set for life testing shall consist of ten specimens fixed on the apparatus (Figure 1) at each temperature A minimum of four sets of specimens is necessary In order to reduce the variation of stress to the fibre the cable shall be attached to the test fixture by trapping it between two padded plates rather than using standard aircraft cable clamps 5.2 Test conditions Length of specimens m Length of specimens within the test chamber m Maximum permissible variation in attenuation if not dB at 20 °C ± °C and at 850 nm Launch conditions to be 85/85 5.3 Information to be included in the product standard Type of fibre/cable from which the specimens were taken, Minimum long term bend radius (R), wave length if not 850 nm, Maximum permissible variation in attenuation if not dB, Launch conditions if not 85/85 BS EN 3745-410:2015 EN 3745-410:2015 (E) 5.4 Apparatus The apparatus shall comprise: A Light Launch System (LLS) as defined in EN 2591-100, A Light Detection System (LDS) as defined in EN 2591-100, A device allowing to connect the LLS to all specimen shall be used to focus the test on the ageing of cable, A device allowing measuring one of the specimens or all cable without disconnection shall be used in order to keep the baseline of initial measurement A test fixture is used to secure the specimens, this fixture shall be so designed that the cable is mounted so that it can be bent at 90° either side of its centre line and is free to freely follow a curve between the two clamp points that corresponds to it minimum bend radius (D = 2R) The test sample is to be so arranged that only the portion of the sample in the flexing area is stressed during the test The fixtures corner is to be rounded and padded see Figure and Figure A climatic chamber capable of temperature control of ± θ °C Key To the LLS To the LDS Fixed plate Moving plate D = is twice the cable minimum bend radius R = not less than the minimum bend radius least Figure — Test Fixture BS EN 3745-410:2015 EN 3745-410:2015 (E) Key Plate Cable Silicon rubber foam Figure — Fixture radius and padded edges 5.5 5.5.1 Procedure Initial measurements If the highest test temperature value is not specified in the product standard make an evaluation of the highest test temperature with one specimen during 24 h at 80 °C above the nominal rating temperature This evaluation needs to be done at temperatures below the degradation temperature of raw materials used in the cable under test The jacket shall not fail or the variation in attenuation shall not exceed the specified value in which case repeat the test at a lower temperature 5.5.2 Test The attenuation shall be measured at the end of each exposure cycle in accordance with EN 3745-301, method C Connect the specimen ends to the LLS and the other specimen ends to LDS during all the cycles Place the fixture in the test chamber The connectors shall not be in the climatic chamber Measure the attenuation of each test specimen Begin the test sequence with the highest test temperature (θ 1) since exposure times will be relatively short Expose the specimens for the first test cycle NOTE This measurement is for reference only and does not form part of the qualification testing To monitor the behaviour of the cable/s under test at high temperature, an attenuation measurement of each cable shall be made at the maximum point of the high temperature cycle immediately prior to reducing the temperature to ambient On completion of the exposure period allow the specimen to return to ambient o Bend the specimen to 90 once in each direction then return the specimen to the neutral position before measuring the attenuation value Inspect the cable jacket in the bend area for major cracks or splits without disturbing the cable BS EN 3745-410:2015 EN 3745-410:2015 (E) Start the next exposure cycle Record the number of exposure cycles to failure for each specimen A failure is defined when the variation in attenuation is higher than the specified value or the jacket splits or cracks The life of each specimen is defined as the number of cycles to failure times the length of each cycle Stop the test sequence when all specimens in the set have failed Calculate the log average life as defined in ASTM-D3032 If the log average life at this temperature (highest) is found to be less than 100 h, too high a test temperature has been selected and these data should be discarded Tests should be repeated at lower temperature Repeat this procedure with the group N° of specimens for temperature value Calculate the log average life as defined in ASTM-D3032 Repeat this procedure with the group N° of specimens for temperature value Calculate the log average life as defined in ASTM-D3032 If the calculated regression line does not indicate a life of less than 40 000 h at a temperature less than 30 °C below the test temperature repeat this procedure with another group of specimens at temperature not greater than 30 °C above the calculated 40 000 h temperature 5.5.3 Calculation of the regression line It has been established that many materials deteriorate in a manner so that the following equation applies: L = Ae b/K where L is the insulation life; K is the absolute temperature (in kelvins); A, b are constants for each insulation; e is the base of natural logarithms Equation may be expressed as a linear function by taking logarithms: log L = log A + b/K Let Y = log L a = log A X = 1/K Then Y = a + bX BS EN 3745-410:2015 EN 3745-410:2015 (E) Thus, data from testing at higher temperatures may be plotted on log L versus 1/K graph paper and a line extrapolated to lower temperatures However, since the nature of logarithmic plots does not allow accurate extrapolation by the method of drawing the best apparent straight line through the data points, a more rigorous method has to be used for greater accuracy and uniformity By the use of the method of least squares, the constants a and b may be derived in terms of the experimental data obtained These equations are as follows: a = [(∑ (YX) − c(∑Y))/((− cn) + ∑X)] b = (∑Y − an) / ∑X c = ∑X /∑X where X = 1/K is the reciprocal of the test temperature, K (°C + 273); n is the number of end points used in the calculation; Y = log L is the logarithm of the average life at each test point; ∑ is the summation of n values Knowing the constants a and b, the slope of the regression line is readily found by use of equation: Y = a + bX K= 1/X = b/(Y − a) For example Temperature at 20 000 h (in °C) = [b/(4.301 − a)] − 273 Temperature at 000 h (in °C) = [b/(3.301 − a)] − 273 5.5.4 Special precautions Extrapolation to a temperature index expected at the selected end of life (10 000 h, 20 000 h or 40 000 h) should not exceed 30 °C below the lowest aging test temperature For longer life times this may be exceeded provided that the plot demonstrates a minimum of 40 000 h at 30 °C below the lowest ageing test temperature The log average life at the highest test temperature (θ 1) shall not be less than 100 h The log average life at the lowest test temperature (θ 4) shall not be less than 000 h The exposure cycle length is defined as too short if the mean number of cycles to failure exceeds 15 cycles Requirements The required lifetime and temperature shall be given in the product standard 10 This page deliberately left blank NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW British Standards Institution (BSI) BSI is the national body responsible for preparing British Standards and other standards-related publications, information and services BSI is incorporated by Royal Charter British Standards and other standardization products are published by BSI Standards Limited About us Revisions We bring together business, industry, government, consumers, innovators and others to shape their combined experience and expertise into standards -based solutions Our British Standards and other publications are updated by amendment 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