SIST EN 3745-508:2004

Overview

SIST EN 3745-508:2004 is a European Standard developed by CEN, specifically addressing the torsion resistance testing of optical fibres and cables used in aerospace applications. This standard forms part of the aerospace series dedicated to ensuring the reliability and durability of optical cables in aircraft systems. It outlines a precise method to assess the cable’s ability to withstand mechanical stress caused by twisting forces, crucial for maintaining signal integrity and operational safety in aerospace environments.

Key Topics

• Scope: Defines the method for testing torsion resistance of optical cables designed for aircraft use, ensuring the cables do not suffer damage under twisting loads.
• Normative references: Incorporates related aerospace standards such as EN 2591-100 (General test methods for electrical and optical connections) and related parts of the EN 3745 series for fibers and cables.
• Specimen preparation: Details requirements for test sample termination, standard environmental conditioning (24 hours stabilization), and specifies parameters such as cable length, load applied, number of torsion cycles, and insertion loss limits.
• Testing apparatus: Specifies equipment including:
  • Light Launch System (LLS)
  • Light Detection System (LDS)
  • Mechanical test rig capable of applying torsion loads with controlled cycles
• Test procedure: Defines a cyclic torsion test where a cable is twisted 360° in one direction, then 720° in the opposite direction, and back to 360°. The test involves 100 cycles at a rate of 6 cycles per minute with continuous attenuation monitoring.
• Measurement standards: Calls for final inspections according to EN 3745-201 (visual examination) and EN 3745-505 (tensile strength) to verify cable integrity after testing.

Applications

SIST EN 3745-508:2004 applies primarily in the aerospace industry for optical fibre cables used in aircraft electrical systems and avionics. Its torsion resistance test assures the following practical benefits:

• Enhanced durability: Confirms that optical cables can sustain twisting during installation or operational vibration without performance degradation.
• Safety assurance: Helps prevent optical signal loss or cable failure critical for flight systems communication and control.
• Quality control: Enables manufacturers and aerospace component suppliers to validate product robustness per recognized standards.
• Maintenance and certification: Supports regulatory compliance and inspection protocols for optical cabling in aerospace platforms.

This standard is essential for aerospace engineers, cable manufacturers, testing laboratories, and quality assurance teams focused on high-reliability aircraft electrical infrastructure.

Related Standards

• EN 2591-100: General test methods for aerospace electrical and optical connections relevant to termination and measurement equipment.
• EN 3745-100: General conditions for preparing optical cables and fibres for aerospace testing.
• EN 3745-201: Visual examination procedures for detecting physical defects in aerospace optical fibres and cables.
• EN 3745-301: Optical attenuation measurement methods critical for tracking signal loss during mechanical tests.
• EN 3745-505: Tensile strength test methods to ensure mechanical robustness post torsion testing.

Summary

SIST EN 3745-508:2004 establishes a standardized, repeatable test method for evaluating the torsion resistance of optical cables used in aircraft systems. By verifying that cables withstand twisting forces without damage or excessive signal loss, the standard contributes to the safety, reliability, and performance of aerospace optical communication networks. Adopting this standard supports manufacturing consistency, regulatory compliance, and improved lifecycle management of fibre optic cables in the demanding aerospace environment.