SIST EN 3745-517:2017

Overview

SIST EN 3745-517:2017 is a European Standard developed by CEN for the aerospace sector, specifically addressing optical fibres and cables used in aircraft. This standard details a test method for determining the attenuation variation of an optical cable when clamped to a mandrel with cable ties, effectively simulating the typical conditions found in installed aerospace harnesses. By standardizing this cable tie clamping test, the standard supports consistent assessment of optical cable performance under mechanical stress conditions commonly encountered in aircraft environments.

Key Topics

• Scope of Application: SIST EN 3745-517:2017 is focused on the evaluation of optical fibre cables in aerospace environments where cable ties are used for securing harnesses. The procedure is intended to simulate the impact of installation practices on cable performance.
• Test Methodology: The standard outlines procedures for preparation, testing, and measurement, including required apparatus. Key steps involve:
  • Aligning the cable on a mandrel and applying cable ties at specified intervals.
  • Measuring optical attenuation at two key wavelengths (850 nm and 1300 nm) before and after clamping.
  • Assessing any variation in signal attenuation after applying and removing cable ties.
• Test Parameters: Details such as the number and spacing of cable ties, mandrel diameter, and preparation of fibre ends are specified to ensure repeatability and reliability.
• Supporting Equipment: The test relies on calibrated light launch and detection systems, cable tie fitting tools, and specific test conditions consistent with aerospace requirements.
• Reference to Other Standards: EN 3745-517 makes use of related standards for visual inspection (EN 3745-201) and attenuation measurement (EN 3745-301).

Applications

SIST EN 3745-517:2017 is essential in multiple aerospace engineering contexts, particularly where optical fibres and cables are used for avionics, communication, or data transfer systems. Its main practical applications include:

• Aircraft Harness Assembly: Ensures the optical performance of fibre cables is not compromised when secured with cable ties-a common practice during aircraft wiring and installation.
• Quality Assurance and Compliance: Enables manufacturers and maintenance organizations to verify that their cable harness assembly processes do not negatively impact optical signal transmission, reducing the likelihood of in-service failures.
• Product Validation: Supports testing during development and qualification of new optical cable designs intended for aerospace harness applications.
• Maintenance and Repair: Provides a reference for testing cables that may need to be reclamped or resecured during routine aircraft maintenance, ensuring continued compliance with electrical system reliability standards.

Related Standards

SIST EN 3745-517:2017 is part of the broader EN 3745 series, which defines test methods for optical fibres and cables in aerospace applications. Key related standards include:

• EN 2591-100: Aerospace series - Elements of electrical and optical connection - Test methods - General requirements.
• EN 3745-201: Aerospace series - Visual examination of fibres and cables.
• EN 3745-301: Aerospace series - Attenuation measurement of optical cables.
• EN 4056-003: Aerospace series - Cable ties for harnesses - Product standard for plastic cable ties.

These standards collectively ensure reliability, safety, and performance of fibre optic systems in demanding aerospace environments.

Keywords: SIST EN 3745-517:2017, cable tie clamping test, aerospace optical cables, fibre attenuation testing, aircraft harness, CEN standard, optical cable reliability, aerospace cable standards, fibre optic cable testing