SIST EN 3475-406:2004

Overview

SIST EN 3475-406:2004 is a European aerospace standard that defines the cold bend test method for electrical cables used in aircraft. Developed by the European Association of Aerospace Manufacturers (AECMA) and published by the CEN, this standard ensures the mechanical and electrical integrity of finished cables under low temperature stress conditions. It is intended to be used in conjunction with EN 3475-100, which covers general test methods for aircraft electrical cables.

The cold bend test specified in EN 3475-406 evaluates the behavior of cables after exposure to extremely low temperatures (-55 ± 2°C) followed by mechanical bending. This test simulates operational stresses in aerospace environments where cables face harsh temperature variations and mechanical handling.

Key Topics

• Scope: The standard applies to finished electrical cables designed for aircraft use, assessing their performance after cold bending.
• Test Specimen Preparation: A minimum cable length of 750 mm is required for testing to ensure consistency.
• Test Conditions:
  • Cooling to -55 °C ± 2 °C for 1 hour in a cold chamber.
  • Mechanical bending by winding the cable around a horizontal mandrel.
  • Twisting the cable in opposite directions twice to simulate compression and stretching.
• Mandrel Specification: Diameter and mass are defined by the product technical requirements to reflect real-world bending stresses.
• Evaluation Criteria:
  • Post-test cable insulation must show no cracking or crazing.
  • The cable must pass a post-test voltage test according to EN 3475-302 to confirm electrical integrity.
• Normative References: The test is used alongside EN 3475-100 (general test methods) and EN 3475-302 (voltage proof test) for comprehensive cable assessment.

Applications

EN 3475-406 is critical for aerospace manufacturers, cable suppliers, and quality assurance teams specializing in aircraft electrical systems. This standard ensures that cables:

• Maintain mechanical durability and insulation integrity at very low operational temperatures.
• Withstand bending stresses encountered during installation and in-flight conditions.
• Are compliant with safety and reliability requirements for electrical wiring in aircraft environments.

Typical users include aerospace OEMs, maintenance organizations, and testing laboratories responsible for certifying electrical cables intended for civil and military aviation applications.

Adhering to EN 3475-406 enhances:

• Product reliability to prevent electrical failures due to insulation damage.
• Safety compliance by meeting rigorous aerospace industry standards.
• Lifecycle durability of wiring installations exposed to cold and mechanical stresses.

Related Standards

For a complete test program on aerospace electrical cables, EN 3475-406 should be applied together with the following standards:

• EN 3475-100: Aerospace series – Electrical cables for aircraft – General test methods. Provides foundational procedures and definitions used across all cable testing.
• EN 3475-302: Aerospace series – Electrical cables – Voltage proof test. Specifies the high voltage testing procedure to verify insulation withstand capability after mechanical testing.

These complementary standards form a structured approach to ensure electrical cables meet stringent aerospace operational requirements from mechanical stress to electrical performance.

By following SIST EN 3475-406:2004, aerospace manufacturers and testing bodies can verify that electrical cables maintain their structural and electrical integrity under simulated cold environmental stresses, helping to guarantee system reliability and flight safety. This standard remains an essential reference for cable qualification in the aerospace industry.