SIST EN 3475-411:2018

Overview

SIST EN 3475-411:2018 is a European Standard developed by CEN, focusing on the aerospace industry’s requirements for electrical cables used in aircraft. Specifically, this part of the aerospace series addresses test methods for resistance to fluids that aircraft electrical cables must undergo to ensure durability and safety. This standard supersedes EN 3475-411:2014 and forms part of a comprehensive testing framework used alongside EN 3475-100 and EN 3909.

Cables in aerospace applications are exposed to various fluids-such as fuels, hydraulic fluids, oils, solvents, and de-icing fluids-that could degrade cable performance and safety. Thus, SIST EN 3475-411:2018 defines reliable, repeatable laboratory test methods to evaluate the resistance of finished cables to such fluid contamination under controlled conditions.

Key Topics

• Test Methods:
  Two distinct methods are specified:

  • Method 1 (Occasional Contamination Test): Simulates sporadic fluid exposure by dipping or spraying cables with test fluids.
  • Method 2 (Contamination Test): A more rigorous immersion test where cables are exposed to fluids for extended durations, simulating continuous contamination conditions in aircraft environments.

• Test Fluids:
  The standard mandates use of specific fluids listed in EN 3909. These include:

  • Fuels (gasoline, kerosene)
  • Hydraulic fluids (phosphate-based, silicone, mineral)
  • Oils (mineral, synthetic)
  • Cleaning solvents (isopropanol, ethanol, methylethylketone)
  • De-icing fluids and ground/flight chemicals
  • Fire extinguishants (not currently testable via immersion)

• Testing Procedures:
  Specimens are prepared by cutting cables into defined lengths, stripping ends for measurement, and exposing samples to fluids at prescribed temperatures and durations. Tests involve immersion, temperature control, draining, and post-exposure resting to simulate real-world exposure conditions.

• Performance Requirements:
  Post-test evaluation consists of:

  • Visual inspection for insulation crazing, delamination, color fading, and legibility of markings.
  • Dimensional checks ensuring less than 5% diameter variation.
  • Mechanical and electrical tests, such as ambient bend, voltage proof, and scrape abrasion tests, to confirm continued cable integrity.

Applications

• Aerospace and Defense Industry:
  SIST EN 3475-411:2018 is critical for manufacturers and quality assurance engineers designing and testing aircraft electrical cables that must withstand harsh fluid exposures.
• Compliance Testing:
  Ensures cables meet stringent aerospace regulations and safety requirements before installation in aircraft wiring harnesses.
• Supplier and OEM Qualification:
  Used as a benchmark for suppliers of electrical cables to demonstrate fluid resistance performance, ensuring compatibility with aircraft systems exposed to fuels, hydraulic oils, cleaning agents, and de-icing chemicals.
• Maintenance and Reliability Engineering:
  Helps evaluate service life and failure modes related to fluid exposure, supporting maintenance schedules and safety audits in aerospace operations.

Related Standards

• EN 3475-100: General test methods for aerospace electrical cables.
• EN 3475-201: Visual examination of cables.
• EN 3475-203: Cable dimensional measurement standards.
• EN 3475-302: Voltage proof test for electrical insulation.
• EN 3475-405: Bending tests at ambient temperature.
• EN 3475-503: Scrape abrasion tests.
• EN 3909: Specification of test fluids for electrical and optical aerospace components.
• ISO 1817: Rubber and elastomer testing for liquid effects, often referenced for specific fluid types.

Keywords: Aerospace cable testing, electrical cable fluid resistance, aircraft electrical wiring, EN 3475-411, aerospace cable standards, fluid contamination test, cable durability, aviation electrical cable compliance, cable immersion testing, aviation fluid resistance testing.