EN 3475-512:2021

Overview

EN 3475-512:2021 is a European standard developed under the Aerospace and Defence Industries Association of Europe (ASD-STAN) that defines the test methods for assessing the flexure endurance of electrical cables used in aircraft. Flexure endurance evaluates the ability of aerospace cables to withstand repeated bending cycles without electrical failure, a critical performance measure for cables subjected to dynamic mechanical stresses in flight environments. This latest edition updates the 2002 version and harmonizes testing procedures to ensure consistent, reliable assessment of aircraft cable durability under alternating flexing conditions.

This standard must be applied alongside EN 3475-100, which covers general test methods for aerospace electrical cables, ensuring a comprehensive testing framework for aircraft cable qualification.

Key Topics

• Scope and Purpose
  EN 3475-512:2021 specifies a method to test electrical aircraft cables’ endurance when subjected to repeated bending (flexure) cycles. The standard focuses on detecting damage from flexing via electrical discontinuity caused by conductor breakage.

• Test Setup and Apparatus
  The test apparatus includes:

  • Mandrels sized according to cable diameter
  • A weight attached to the cable
  • A clamp and rotational system that subjects the cable to alternating flexing at a uniform speed of 18 ± 2 cycles per minute
  • An automatic stop mechanism triggered by electrical continuity failure
    The system is designed to eliminate any swing or displacement that could affect bending consistency.

• Testing Procedure
  The cable specimen is mounted vertically, and flexure cycles consist of a 90° rotation to the left, return to vertical, 90° rotation to the right, and return to vertical again. The test runs continuously until electrical discontinuity is detected, indicating conductor damage.

• Compliance Requirements

  • Method A: Measures conductor endurance. Requires at least three specimens, with mean cycle counts meeting or exceeding product standard values.
  • Method B: Evaluates cable insulation endurance by subjecting specimens to flexure cycles followed by voltage proof testing per EN 3475-302. This method is optional unless otherwise specified.

• Product Standard Integration
  The specific flexure endurance values and apparatus parameters such as mandrel diameter and weight are detailed in the cable’s individual product standard to ensure testing reflects product design requirements.

Applications

EN 3475-512:2021 is essential for aerospace cable manufacturers, quality assurance engineers, and procurement specialists aiming to guarantee electrical cable reliability in aeronautical applications. It applies in scenarios where cables endure repeated mechanical flexure, including:

• Aircraft wiring harnesses exposed to vibration and movement during flight
• Dynamic control system cabling where flexibility and endurance are critical to safe operations
• Maintenance and qualification testing of aerospace cables to meet regulatory and certification requirements
• Design validation ensuring cables withstand real-world bending stresses over the service life

By adopting this standard, aviation stakeholders ensure cables meet rigorous endurance requirements, thereby enhancing overall aircraft system safety and reliability.

Related Standards

• EN 3475-100: Aerospace series - Cables, electrical, aircraft use - Test methods - Part 100: General
  Provides foundational testing methods and references for aerospace cable qualification.

• EN 3475-302: Aerospace series - Cables, electrical, aircraft use - Test methods - Part 302: Voltage proof test
  Covers voltage endurance testing, which complements the flexure endurance testing under Method B for insulation validation.

• Other EN 3475-series standards cover additional mechanical, electrical, and environmental tests relevant to aerospace cables, such as temperature resistance, insulation integrity, and fire retardance.

By applying EN 3475-512:2021 alongside related aerospace cable standards, manufacturers and engineers achieve a robust framework to certify electrical cables fit for the demanding flexural stresses encountered in modern aircraft systems. This contributes to enhanced aircraft safety, compliance with aviation regulations, and reliable in-field cable performance.