EN 4533-001:2006

Foreword
Introduction
1 Scope
  1.1 General
  1.2 Need for high integrity terminations
2 Normative references
3 Component selection
  3.1 Elements
  3.2 Fibre optic cables
       3.2.1 General
       3.2.2 Cable construction
       3.2.3 Fibre choice
       3.2.4 Cladding materials
  3.3 Primary coating materials
       3.3.1 Function
       3.3.2 Acrylate
       3.3.3 Polyimide
       3.3.4 Silicone
  3.4 Aramid yarn versus fibreglass strength member
  3.5 Fibre optic connectors
       3.5.1 Purpose
       3.5.2 Connector types
4 Health and safety aspects
  4.1 General
  4.2 Chemicals
  4.3 "Sharps"
5 Termination process
  5.1 Objective
  5.2 Cable preparation
       5.2.1 General
       5.2.2 Cutting to length
       5.2.3 Removal of outer jacket
       5.2.4 Strength member trimming/removal
  5.3 Removal of secondary coating(s)
  5.4 Removal of primary coating
       5.4.1 General
       5.4.2 Mechanical techniques for primary coating removal
       5.4.3 Alternative techniques
       5.4.4 Removal of troublesome coatings
       5.4.5 Evidence of strength reduction when stripping
             primary buffer coatings
       5.4.6 To clean or not to clean
  5.5 Adhesives
       5.5.1 General
       5.5.2 Adhesive types
       5.5.3 The importance of glass transition temperature (Tg)
       5.5.4 Epoxy cure schedules
       5.5.5 Usability
       5.5.6 Qualification
  5.6 Connector preparation
       5.6.1 Dry fitting (Don't do it)
       5.6.2 Cleanliness
  5.7 Sleeves, boots and backshells
  5.8 Attachment of fibre to connector
       5.8.1 Application of adhesive
       5.8.2 Inserting fibre 'best-practice'
  5.9 Adhesive cure
       5.9.1 General
       5.9.2 Orientation
       5.9.3 Curing equipment
  5.10 Excess fibre removal
       5.10.1 General
       5.10.2 Post-cure rough cleaving
       5.10.3 Pre-cleave
       5.10.4 Cleaving tools
  5.11 Polishing
       5.11.1 Rationale
       5.11.2 Performance metrics
       5.11.3 End-face geometry parameters
       5.11.4 Methods for achieving end-face geometry
       5.11.5 Polishing stages
       5.11.6 Polishing tools and equipment
  5.12 Inspection
Bibliography

1.1GeneralThis Part of EN 4533 examines the termination aspects of fibre optic design for avionic installations. By termination is meant the mechanism used to interface from one component (usually a fibre) to another. This is normally performed by a connector, which aligns the fibre with another component (usually another connector) to a sufficient accuracy to allow continued transmission of an optical signal throughout the operational envelope.This Part will explain the need for high integrity terminations, provide an insight into component selection issues and suggests best practice when terminating fibres into connectors for high integrity applications. A detailed review of the termination process can be found in Clause 4 of this part and is organised broadly in line with the sequence of a typical termination procedure.The vast number of cable constructions and connectors available make defining a single termination instruction that is applicable to all combinations almost impossible. Because of the problems of defining a generic termination instruction, this handbook has concentrated on defining best practice for current to near future applications of fibre optics on aircraft. This has limited the studies within this part to currently available ‘avionic’ silica fibre cables and adhesive filled butt-coupled type connectors. Many of the principles described however would still be applicable for other termination techniques. Other types of termination are considered further in the repair part of this handbook.1.2Need for high integrity terminations In order to implement a fibre optic based system on an aircraft it is vital to ensure that the constituent elements of the system will continue to operate, to specification, over the life of the system. An important aspect of this requirement is the need for reliable interconnection components. (continued)