SIST EN 3475-515:2009

Overview

SIST EN 3475-515:2009 is a European aerospace standard developed by CEN that specifies a method for testing the crush resistance of electrical cables used in aircraft. This standard measures the cable's ability to withstand mechanical crushing forces under defined environmental and operational conditions, such as those experienced during maintenance. It is part of the EN 3475 series focused on aerospace electrical cables and is intended for use alongside EN 3475-100, which covers general test methods.

The standard supports ensuring the reliability, durability, and safety of electrical cables critical to aircraft systems by evaluating their physical and electrical integrity after exposure to crushing.

Key Topics

• Scope: Defines the test method to evaluate crush resistance of electrical aircraft cables under specified environmental conditions.
• Test Conditions: Tests are carried out at 20 °C using three specimens, typically 2 meters in length, with specifics such as compressive force and test duration defined by the product standard.
• Apparatus: The test uses a steel fixture where the cable specimen is crushed between a fixed base plate and a movable plate applying a uniform force over 100 mm length. Plates are radiused to prevent damage from sharp edges.
• Measurement Parameters: Measurements taken before, during, and after crushing include:
  • Characteristic impedance (EN 3475-805)
  • Attenuation (EN 3475-806)
  • Return loss (EN 3475-812), monitored continuously during loading
• Test Procedure:
  1. Initial electrical tests with no load applied.
  2. Apply load gradually until specified force.
  3. Maintain load for designated period.
  4. Remove load and allow 15-minute recovery.
  5. Conduct final assessments including visual inspection (EN 3475-201) and electrical property tests.
• Performance Requirements: Test results must remain within the limits of the product standard, ensuring cables maintain required electrical performance despite mechanical crushing stress.

Applications

SIST EN 3475-515:2009 is principally applicable in the aerospace industry where electrical cables must retain functionality under physically demanding conditions. Its practical applications include:

• Cable qualification: Verifying that aircraft cables meet safety and durability requirements against crushing forces encountered during installation, maintenance, or operational scenarios.
• Quality assurance: Supporting manufacturers and maintenance providers to validate cable resilience ensuring minimal downtime and risk.
• Aircraft systems reliability: Confirming that communication, power, and control cables continue to perform optimally despite mechanical stresses.
• Maintenance procedures: Assisting in designing maintenance processes that consider cable crush resistance to prevent inadvertent damage.
• Component development: Providing test data to engineer cable designs with improved crush resistance for enhanced lifetime and reliability.

Related Standards

EN 3475-515 is part of an extensive set of standards for aerospace electrical cables, linking closely with:

• EN 3475-100: General test methods for aerospace electrical cables, providing foundational testing protocols.
• EN 3475-201: Visual examination of cables to detect physical defects or damage.
• EN 3475-805: Test methods for measuring cable characteristic impedance.
• EN 3475-806: Methods for determining cable attenuation.
• EN 3475-812: Procedures for assessing return loss (Voltage Standing Wave Ratio - VSWR).

These interrelated standards support comprehensive evaluation of aerospace cables, from physical integrity to electrical performance, ensuring compliance with stringent aerospace quality requirements.

By adhering to SIST EN 3475-515:2009, aerospace manufacturers and maintenance organizations can ensure electrical cables used in aircraft maintain their structural and functional integrity even after exposure to crush forces, thereby enhancing overall flight safety and system reliability.