ASD-STAN PREN 4533-004-2016 Aerospace series Fibre optic systems Handbook Part 004 Repair maintenance cleaning and inspection (Edition P 2).pdf

1、ASD-STAN STANDARD NORME ASD-STAN ASD-STAN NORM prEN 4533-004 Edition P 2 April 2016 PUBLISHED BY THE AEROSPACE AND DEFENCE INDUSTRIES ASSOCIATION OF EUROPE - STANDARDIZATION Rue Montoyer 10 - 1000 Brussels - Tel. 32 2 775 8126 - Fax. 32 2 775 8131 - www.asd-stan.org ICS: Supersedes edition P 1 of Ap

2、ril 2005 and will supersede EN 4533-004:2006 Descriptors: ENGLISH VERSION Aerospace series Fibre optic systems Handbook Part 004: Repair, maintenance, cleaning and inspection Srie arospatiale Systmes des fibres optiques Manuel dutilisation Partie 004 : Rparation, maintenance, nettoyage et contrle Lu

3、ft- und Raumfahrt Faseroptische Systemtechnik Handbuch Teil 004: Reparatur, Wartung, Reinigung und Inspektion This “Aerospace Series“ Prestandard has been drawn up under the responsibility of ASD-STAN (The AeroSpace and Defence Industries Association of Europe - Standardization). It is published for

4、 the needs of the European Aerospace Industry. It has been technically approved by the experts of the concerned Domain following member comments. Subsequent to the publication of this Prestandard, the technical content shall not be changed to an extent that interchangeability is affected, physically

5、 or functionally, without re-identification of the standard. After examination and review by users and formal agreement of ASD-STAN, it will be submitted as a draft European Standard (prEN) to CEN (European Committee for Standardization) for formal vote and transformation to full European Standard (

6、EN). The CEN national members have then to implement the EN at national level by giving the EN the status of a national standard and by withdrawing any national standards conflicting with the EN. Edition approved for publication 1st April 2016 Comments should be sent within six months after the date

7、 of publication to ASD-STAN Electrical Domain Copyright 2016 by ASD-STAN prEN 4533-004:2016 (E) 2 EN 4533-004:2006 (E)Contents Page Foreword 2 Introduction .3 1 Scope 4 2 Normative references 4 3 Fault analysis .5 4 Repair techniques . 10 5 Inspection and cleaning . 12 6 Scheduled maintenance and in

8、spection 19 Annex A (normative) Termini end face contamination . 22 Annex B (normative) Cleaning Methods. 26 B.1 Method 1 26 B.1.1 Method 1a, cleaning sticks 26 B.1.2 Method 1b, semi-automated cartridge tape cleaner 26 B.2 Method 2 28 B.2.1 Method 2a, cleaning sticks 28 B.2.2 Method 2b, semi-automat

9、ed cartridge tape cleaner 28 Foreword This standard was reviewed by the Domain Technical Coordinator of ASD-STANs Electrical Domain. After inquiries and votes carried out in accordance with the rules of ASD-STAN defined in ASD-STANs General Process Manual, this standard has received approval for Pub

10、lication. prEN 4533-004:2016 (E) 3 Introduction a) The Handbook This handbook aims to provide general guidance for experts and non-experts alike in the area of designing, installing, and supporting fibre-optic systems on aircraft. Where appropriate more detailed sources of information are referenced

11、 throughout the text. It is arranged in 4 parts, which reflect key aspects of an optical harness life cycle, namely: Part 001: Termination methods and tools Part 002: Test and measurement Part 003: Looming and installation practices Part 004: Repair, maintenance, cleaning and inspection b) Backgroun

12、d It is widely accepted in the aerospace industry that photonic technology significant advantages over conventional electrical hardware. These include massive signal bandwidth capacity, electrical safety, and immunity of passive fibre-optic components to the problems associated with electromagnetic

13、interference (EMI). Significant weight savings can also be realized in comparison to electrical harnesses which may require heavy screening. To date, the EMI issue has been the critical driver for airborne fibre-optic communications systems because of the growing use of non-metallic aerostructures.

14、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 can potentially be exploited to advantage in many avionic app

15、lications, 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 harness is the key enabler for the successful introduction

16、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, vibration, and contamination) and accommodate additional physical restri

17、ctions 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 large safety margins. In addition, the international standard

18、s 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 costs), that often made an optical harness less competitive than

19、an electrical equivalent. This situation is changing with the adoption of more standardized (telecoms type) fibre types in aerospace cables and the availability of more ruggedized COTS components. These improved developments have been possible due to significant research collaboration between compon

20、ent and equipment manufacturers as well as the end use airframers. prEN 4533-004:2016 (E) 4 EN 4533-004:2006 (E)1 Scope The handbook gives guidelines related to Fault analysis and repair as well as maintenance and inspection of fibre optic links. The first deals with what to do when something goes w

21、rong how to go from a fault notification 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. 2 Normative references The following documents, in whole or in part, are normativel

22、y 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 4533-001, Aerospace series Fibre optic systems Handbook Part 001

23、: Termination methods and tools EN 4533-002, Aerospace series Fibre optic systems Handbook Part 002: Test and measurement EN 4533-003, Aerospace series Fibre optic systems Handbook Part 003: Looming and installation practices EN 2591-601, Aerospace series Elements of electrical and optical connectio

24、n Test methods Part 601: Optical elements Insertion loss EN 3733 (all parts), Aerospace series Connector, optical, circular, single channel, coupled by self-locking ring, operating temperature up to 150 C continuous EN 4531-101, Aerospace series Connectors, optical, circular, single and multipin, co

25、upled by threaded ring Flush contacts Part 101: Optical contact for EN 4641-100 cable 55 C to 125 C Product standard EN 4639-101, Aerospace series Connectors, optical, rectangular, modular, multicontact, 1,25 diameter ferrule, with removable alignment sleeve holder Part 101 : Optical contact for cab

26、le EN 4641-100 Operating temperatures between 65 C and 125 C Product standard EN 4645 (all parts), Aerospace series Connectors, optical, circular, single and multipin, coupled by threaded ring, self-locking 1,25 mm diameter ferrule with removable alignment sleeve holder IEC 60825-1, Safety of laser

27、products Part 1: Equipment classification, requirements and users guide IEC 61300-3-35, Fibre optic interconnecting devices and passive components Basic test and measurement procedures Part 3-35: Examinations and measurements Visual inspection of fibre optic connectors and fibre-stub transceivers AR

28、INC 805, Harsh environment fibre optic connectors/testing SAE AS5675, Characterization and requirements for new aerospace fibre optic cable assemblies Jumpers, end face geometry, link loss measurement, and inspection prEN 4533-004:2016 (E) 5 3 Fault analysis 3.1 Fault notification A fault notificati

29、on will arise from one or more of three sources; scheduled maintenance, Built-In-Test (BIT), or failure of equipment. Ideally, scheduled maintenance should highlight all latent faults i.e. those which initially have no effect on the system performance but may lead to a problem sometime later during

30、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 faults that slipped through the BIT net. BIT is the ability of the aircrafts systems to diagnose themselves.

31、 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 provide some help in locating the fault. Failure is the worst case and should only be the result of a fault oc

32、curring which cannot be prepared for. 3.2 Symptoms This is where differences between fibre optic and electrical installations become apparent. The most common symptom in a fibre optic link is complete or partial loss of optical power. This occurs when light breaks its confinement from the fibre core

33、 and can be the result of damage to the fibre or interconnect. It can also be the result of contamination of the fibre optic terminus end face, excessive pressure, crushing or severe bending on the fibre optic cable. Depending on the magnitude of the loss, the result may be a fault that is above or

34、below the link threshold a fault below the link threshold is a failure. Severe damage, such as an optical fibre break may induce a complete loss of optical power. Intermittent optical signals are possible and may be the result of fibre movement e.g. vibration or bending of a fibre. An increase in op

35、tical power is also possible although this is more likely to be due to stability of the light source rather than the link itself. Gradual degradation of optical power is an important symptom to be able to detect as it could indicate the onset of a failure. Increasing contamination or proliferation o

36、f damage to the fibre optic terminus end face could be responsible. Outside of the harness it could be due to degradation of an optical source. Back reflection is a phenomenon that occurs at any interface with different refractive index, e.g. glass/air. Back reflection is of particular concern where

37、 active devices utilise laser-based systems where reflected light can affect the transmitting capabilities of the optical source. This can result in degradation of the transmitted signal and potentially damage the optical source. Latent fault symptoms i.e. those which have no effect on the optical p

38、ower of the system but could be the first stage of a fault that does. These are most likely to be noticed during inspection and include poor routing, incorrect retention methods leading to exertion of excessive pressure on the fibre optic cable and poor stress relief on interconnects. 3.3 Potential

39、faults 3.3.1 Fibre Fibre breaks can occur in the cable where the fibre enters a connector and inside the connector ferrules. A broken fibre would lead to total loss of optical power or, if an optical path was maintained across the break, a reduction in power which could oscillate under vibration. Fi

40、bre breaks are most likely to occur during installation or other maintenance work when the fibre is placed under excessive stress. Latent faults such as damage to the structure of a backshell may lead to a break where the fibre is at its most vulnerable entering the connector ferrules. prEN 4533-004

41、:2016 (E) 6 EN 4533-004:2006 (E)Other fibre faults are cracks which may develop under environmental stress and micro-bending which is where the fibre is bent into ripples of millimetre bend radii within the cable. This effect has been seen in telecommunication cables when exposed to cold temperature

42、s which cause the cable jacketing to contract. Damage and contamination of the fibre end face are listed as connector faults. Another possible fibre fault can also occur, which is due to localized stress (for instance unappropriated cable-tie mounting, low bend radius, fibre crush) applied to the fi

43、bre that may induce unwanted optical attenuation. 3.3.2 Cable Physical damage to the cable can come from abrasion or clamping/crush damage. The cable also has a long and short-term minimum bend radius. If these are not adhered to, there is risk of damage to the fibre. 3.3.3 Connector The connector a

44、nd the area around the connector is perhaps the most susceptible to faults. De-mating can lead to the most common problem; contamination. De-mating is discouraged as far as possible but it is unavoidable in some circumstances. Contamination can range from mild, where a wipe clean with a lint-free cl

45、oth will suffice, to severe, where the connection mechanism is affected. Contamination may lead to permanent damage of the fibre end face. Fluid contamination presents some unique problems. There are also issues of fibre grow in/out (when the adhesion between fibre and ferrule fails) and fibre misal

46、ignment. Connectors also have the potential to be carrying latent faults such as over-tightening of the connection mechanism and inadequate strain relief. 3.3.4 Backshell Apart from physical damage to the backshell there is also potential for fibres to be crushed, bent or strangled if the routing wi

47、thin the backshell is not correct. 3.3.5 Conduit Breaking, kinking or crushing of conduit could have an effect on the optical fibre but experience with electrical harnesses suggests that damage to a conduit is likely to be a latent fault which is found during scheduled maintenance before it affects

48、harness performance. 3.3.6 Pigtailed components A break or crack of a pigtailed fibre from a component would give rise to a total or partial optical power loss symptom. 3.3.7 Splices Splice faults that could have a direct effect on the optical signal include fibre separation. Additionally, mechanica

49、l splices may be degraded by contamination, fluids ingress, migration of index matching means. Latent faults are similar to those for connectors; inadequate strain relief and support. 3.3.8 Others The faults listed above are limited in scope to the harness. Faults at the hardware interface level e.g. transceivers and controlling electronics would result in a selection of the symptoms detailed in 3.2. Potential faults are