1、BRITISH STANDARDBS EN 4533-004:2006Aerospace series Fibre optic systems Handbook Part 004: Repair, maintenance and inspectionThe European Standard EN 4533-004:2006 has the status of a British StandardICS 49.060g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g
2、50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 4533-004:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 October 2006 BSI 2006ISBN 0 580 49447 0National forewordThis B
3、ritish Standard was published by BSI. It is the UK implementation of EN 4533-004:2006. The UK participation in its preparation was entrusted by Technical Committee ACE/6, Aerospace avionic electrical and fibre optic technology, to Subcommittee ACE/6/-/10, Aerospace Fibre optic systems and equipment.
4、A list of organizations represented on ACE/6/-/10 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.Compliance with a British Standard cannot confer immunity from lega
5、l obligations.Amendments issued since publicationAmd. No. Date CommentsEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 4533-004July 2006ICS 49.060English VersionAerospace series - Fibre optic systems - Handbook - Part 004:Repair, maintenance and inspectionSrie arospatiale - Systmes des fibres opti
6、ques - Manueldutilisation - Partie 004 : Rparation, maintenance etcontrleLuft- und Raumfahrt - Faseroptische Systemtechnik -Handbuch - Teil 004: Reparatur und InspektionThis European Standard was approved by CEN on 28 April 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulatio
7、ns which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European
8、Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national sta
9、ndards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROP
10、EAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2006 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 4533-004:2006: E2 Contents Page
11、Foreword3 Introduction .4 1 Scope 5 2 Normative references 5 3 Fault analysis and repair.5 3.1 From notification to repair 5 3.2 Fault notification5 3.3 Symptoms.6 3.4 Fault location6 3.4.1 General6 3.4.2 Inspection.6 3.4.3 Visible fault locator7 3.4.4 OTDR.8 3.4.5 Power measurement. 10 3.4.6 BIT in
12、formation . 10 3.5 Potential faults 11 3.5.1 General. 11 3.5.2 Fibre . 11 3.5.3 Cable 11 3.5.4 Connector 11 3.5.5 Backshell . 11 3.5.6 Conduit 11 3.5.7 Couplers 12 3.5.8 Splices . 12 3.5.9 Others 12 3.6 Repair techniques. 14 3.6.1 General. 14 3.6.2 Replace 14 3.6.3 Splice . 14 3.6.4 Structural repai
13、r 15 3.6.5 Re-terminate 15 3.6.6 Cleaning. 16 3.6.7 Re-polish 17 3.6.8 Dormant component substitution. 17 4 Scheduled maintenance and inspection 18 4.1 When to maintain / inspect? 18 4.2 Maintenance/Inspection of system . 18 4.2.1 System diagnostics/BIT . 18 4.2.2 Footprinting. 18 4.3 Maintenance/In
14、spection of components 19 4.3.1 Power measurement. 19 4.3.2 Visual inspection 19 4.3.3 Cleaning. 19 5 Good practices during maintenance / inspection . 19 6 Harness design considerations 20 EN 4533-004:20063 Foreword This European Standard (EN 4533-004:2006) has been prepared by the European Associat
15、ion of Aerospace Manufacturers - Standardization (AECMA-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 AECMA, prior to its present
16、ation 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 2007, and conflicting national standards shall be withdrawn at the latest by January 2007. Attention is drawn to the possibili
17、ty 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. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bo
18、und to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerlan
19、d and the United Kingdom. EN 4533-004:20064 Introduction a) The handbook The handbook draws on the work of the Fibre-Optic Harness Study, part sponsored by the United Kingdoms Department of Trade and Industry, plus other relevant sources. It aims to provide general guidance for experts and non-exper
20、ts alike in the area of designing, installing, and supporting multi-mode fibre-optic systems on aircraft. Where appropriate more detailed sources of information are referenced throughout the text. It is arranged in 4 parts, which reflect key aspects of an optical harness life cycle, namely: Part 001
21、: Termination methods and tools Part 002: Test and measurement Part 003: Looming and installation practices Part 004: Repair, maintenance and inspection b) Background It is widely accepted in the aerospace industry that photonic technology offers a number of significant advantages over conventional
22、electrical hardware. These include massive signal bandwidth capacity, electrical safety, and immunity of passive fibre-optic components to the problems associated with electromagnetic interference (EMI). To date, the latter has been the critical driver for airborne fibre-optic communications systems
23、 because of the growing use of non-metallic aerostructures. However, future avionic requirements are driving bandwidth specifications from 10s of Mbits/s into the multi-Gbits/s regime in some cases, i.e. beyond the limits of electrical interconnect technology. The properties of photonic technology c
24、an potentially be exploited to advantage in many avionic applications, such as video/sensor multiplexing, flight control signalling, electronic warfare, and entertainment systems, as well as in sensing many of the physical phenomena on-board aircraft. The basic optical interconnect fabric or optical
25、 harness is the key enabler for the successful introduction of optical technology onto commercial and military aircraft. Compared to the mature telecommunications applications, an aircraft fibre-optic system needs to operate in a hostile environment (e.g. temperature extremes, humidity, vibrations,
26、and contamination) and accommodate additional physical restrictions imposed by the airframe (e.g. harness attachments, tight bend radii requirements, and bulkhead connections). Until recently, optical harnessing technology and associated practices were insufficiently developed to be applied without
27、large safety margins. In addition, the international standards did not adequately cover many aspects of the life cycle. The lack of accepted standards thus lead to airframe specific hardware and support. These factors collectively carried a significant cost penalty (procurement and through-life cost
28、s), that often made an optical harness less competitive than an electrical equivalent. c) The fibre-optic harness study The Fibre-Optic Harness Study concentrated on developing techniques, guidelines, and standards associated with the through-life support of current generation fibre-optic harnesses
29、applied in civil and military airframes (fixed and rotary wing). Some aspects of optical system design were also investigated. This programme has been largely successful. Guidelines and standards based primarily on harness study work are beginning to emerge through a number of standards bodies. Beca
30、use of the aspects covered in the handbook, European prime contractors are in a much better position to utilise and support available fibre optic technology. EN 4533-004:20065 1 Scope The original task headings in the Fibre Optic Harness Study were Inspection and Fault Analysis and Repair and Mainte
31、nance. However, to create a more coherent and readable handbook these have been re-arranged in this part of EN 4533 to make two new topic headings Fault analysis and repair and Scheduled maintenance and inspection. The first deals with what to do when something goes wrong how to go from a fault noti
32、fication to locating the fault, and finally, repairing it. The second covers the recommended procedures for upkeep and maintaining harness health over the lifetime of its installation. It is beneficial to read both sections together as many of the practices and techniques are applicable to both situ
33、ations. Two supplemental sections consider designing a harness with repair and maintenance in mind and good practices when maintaining or repairing a harness. To keep the handbook to a reasonable size, other Harness Study reports are called up where more detail is required. This handbook does not co
34、ntain sufficient information, for example, to be the sole reference for harness fault finding but it should provide adequate background for somebody working in that field. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated refe
35、rences, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 4533-002, Aerospace series Fibre optic systems Handbook Part 002: Test and measurement. 3 Fault analysis and repair 3.1 From notification to repair Onc
36、e notified of a fault, choosing a repair strategy depends on a multitude of factors; accessibility of the fault, criticality of the system, availability of spares etc. These same issues already exist for electrical harnesses for which proven strategies are in place. What the Harness Study set out to
37、 provide were similar strategies taking into account the unique aspects of fibre optic harnesses. The result is the “Repair and Maintenance Strategy” which contains a comprehensive list of fibre optic harness faults, their symptoms and how to locate and repair them. Much of the information in this s
38、ection is taken from that document. 3.2 Fault notification A fault notification will arise from one or more of three sources; scheduled maintenance, Built-In-Test (BIT), or failure of equipment dependent upon the harness. Ideally, scheduled maintenance should highlight all latent faults i.e. those w
39、hich initially have no effect on the system performance but may lead to a problem sometime later during aircraft operation. It should also highlight faults of the gradual degradation type i.e. those which gradually deteriorate the system performance but have yet to cause a failure and any other faul
40、ts that slipped through the BIT net. BIT is the ability of the aircrafts systems to diagnose themselves. It should identify all faults that occur in the time between scheduled maintenance and, with the exception of sudden catastrophic faults, before a failure occurs. It should also be able to provid
41、e some help in locating the fault. Failure is the worst case and should only be the result of a fault occurring which cannot be prepared for. EN 4533-004:20066 3.3 Symptoms This is where differences between fibre optic and electrical harnesses become apparent. The most common symptom in a fibre opti
42、c harness is complete or partial loss of optical power. This occurs when light breaks its confinement from the fibre core and can be the result of damage to the fibre or connector. It can also be the result of contamination, excessive pressure on the cable or bending of the cable. Depending on the m
43、agnitude of the loss, the result may be a fault that is above or below the link threshold a fault below the link threshold is a failure. Severe damage, such as a fibre break may induce a complete loss of optical power. Intermittent optical signals are possible and may be the result of fibre movement
44、 e.g. vibration or bending of a fibre. An increase in optical power is also possible although this is more likely to be due to stability of the light source rather than the harness itself. Gradual degradation of optical power is an important symptom to be able to detect as it could indicate the onse
45、t of a failure. Increasing contamination or proliferation of damage to the fibre could be responsible. Outside of the harness it could be due to degradation of an optical source. Back reflection occurs at any interface with different refractive index, e.g. glass/air. Connectors are designed to minim
46、ise back reflection but a fault in this area can lead to an increase. Back reflection is of particular worry in laser-based systems where the returning light can damage the optical source. A final category of symptoms are latent fault symptoms i.e. those which have no effect on the optical power of
47、the system but could be the first stage of a fault that does. These are most likely to be noticed during inspection and include chafing of cables and poor stress relief on connectors. 3.4 Fault location 3.4.1 General Fault finding techniques and strategies will play a key role in restoring and maint
48、aining the integrity of aircraft fibre-optic systems. Unless appropriate solutions are available the aircraft operator could incur significant down time, cost, and inconvenience whilst the fault is being located. The problem is exasperated by the fact that the fibre-optic networks in question could
49、be relatively complex, incorporating fan-out connection paths (enabled by passive couplers or active switches, for example) and may be harnessed into relatively inaccessible areas of the airframe. Criteria considered when assessing potential fault finding techniques included: effectiveness of the technique for likely fault scenarios; skill level and time required to perform the technique; size, weight, power requirements, and robustness of equipment; safety issues. The first factor that will influence the choice of fault location
