EN 3745-406:2005

Overview

EN 3745-406:2005 is a European standard developed under the Aerospace series, focusing on optical fibres and cables intended for aircraft use. It specifies the cold bend test method, which assesses the ability of an optical fibre cable to withstand bending under low-temperature conditions. This test is particularly vital for ensuring the reliability and durability of optical cable systems in aerospace environments where cables are exposed to extreme cold and mechanical stress.

The standard was approved by CEN (European Committee for Standardization) in 2005 and is widely adopted across various European countries. It aligns with general aerospace series test standards for optical fibres and cables, ensuring compatibility and harmonization within the industry.

Key Topics

• Scope and Purpose
  The standard determines the mechanical robustness of optical fibre cables at low temperatures by subjecting them to bending cycles around a mandrel within a controlled cold chamber.

• Test Specimen Preparation
  Specimens must be conditioned under standard test conditions for 24 hours before testing. Attenuation measurements are taken prior to the cold bend test as per the EN 3745-301 standard.

• Test Apparatus and Conditions
  The test requires a temperature-controlled cold chamber capable of maintaining ±2 °C, a mandrel with a specified diameter, and optical testing equipment including a Light Launch System (LLS) and Light Detector System (LDS) compliant with EN 2591-100.

• Testing Procedure

  • Samples are conditioned at low temperature for one hour.
  • Fibres are wrapped around a mandrel a specified number of times and held in place.
  • The cable remains in the cold environment for an additional hour.
  • The specimen is then unwound and re-wound in the opposite direction to complete the second bending cycle.
  • The cycle is repeated according to product-specific requirements.

• Post-Test Evaluation
  After returning to standard temperature, visual inspection (EN 3745-201) and attenuation measurement (EN 3745-301, method C) are conducted. The maximum allowable increase in attenuation confirms cable integrity.

Applications

EN 3745-406:2005 is essential for aerospace manufacturers and suppliers involved in the design, testing, and qualification of optical fibre cables used aboard aircraft. Typical applications include:

• Aircraft Communication Systems
  Ensuring optical cables maintain signal integrity despite harsh cold and vibration conditions.

• Avionics Wiring Harnesses
  Verifying cable flexibility and resilience to cold bending to maintain system reliability.

• Satellite and Spacecraft Optical Links
  Testing optical fibres for extreme cold in aerospace and space environments.

• Quality Control and Compliance
  Aerospace component manufacturers use this standard to certify cables meet rigorous mechanical and environmental resilience criteria.

Related Standards

EN 3745-406:2005 works in conjunction with several aerospace fibre and cable standards that ensure comprehensive testing and quality assurance:

• EN 3745-100 – Aerospace series general test methods for optical fibres and cables.
• EN 3745-201 – Visual inspection test methods for optical fibre cables.
• EN 3745-301 – Attenuation measurement techniques for optical cables.
• EN 2591-100 – General test methods for electrical and optical connectors in aerospace applications.

Together, these standards provide a unified framework assuring optical fibre cables meet strict performance and safety requirements demanded by the aerospace industry.

Keywords: EN 3745-406:2005, aerospace optical fibre cables, cold bend test, low temperature cable testing, optical fibre aircraft standards, aerospace cable durability, optical cable attenuation, aerospace fibre test methods, CEN aerospace standards.