EN 3745-514:2009

Overview

EN 3745-514:2009 is a CEN aerospace test-method standard that specifies how to measure the combined torsion and bending properties of fibre optic cables intended for aircraft use. It defines the specimen preparation, required apparatus and the test cycle (commonly known as the cable twist bend test). This standard is intended to be used together with EN 3745-100 (general test requirements) and referenced product standards that set specific parameters (e.g., mandrel diameter, mass, number of cycles).

Key Topics and Requirements

• Test purpose: Quantify combined torsional and bending effects on optical fibres and their cable jackets to ensure in-service mechanical reliability.
• Specimen preparation: Prepare specimens per the product standard and stabilize at standard test conditions (referencing EN 2591-100). Typical sample length is 1.7 m.
• Apparatus: Must include transmitted power monitoring (LLS and LDS), attenuation test equipment (EN 3745-301), mandrel (diameter per product standard), specified mass, tensile load (if required), and temperature control (default 25 °C).
• Test cycle: One cycle = rotate cable 180° clockwise, return to start, then 180° anticlockwise and return. Arm is driven typically at 30 cycles per minute; number of cycles is set by the product standard. Twist per mm must remain constant when changing pulleys or clamp arms.
• Conditioning: Test samples conditioned at standard atmospheric conditions for at least 2 hours before testing; initial attenuation recorded.
• Acceptance criteria / final measurements: Perform visual examination per EN 3745-201 - no jacket softening, cracking, splitting, or legibility impairment of identification markings. No fibre breaks allowed. Change in optical transmittance must not exceed limits specified in the product standard (as measured per EN 3745-301).

Applications and Who Uses It

• Aerospace cable manufacturers: to verify cable designs meet torsion-and-bend durability requirements for aircraft installations.
• Test laboratories and QA teams: to perform standardized cable twist bend tests for qualification and production acceptance.
• Aircraft OEMs and systems integrators: to specify and validate optical cable performance during installation routing and in-service loads.
• Certification bodies and procurement: to reference a harmonized method for contractual testing and compliance.

Practical benefits include improved in-service reliability of fibre optic links, early detection of design or materials weaknesses, and consistent test data for supplier qualification.

Related Standards

• EN 3745-100 - Fibres and cables, optical, aircraft use - Test methods - Part 100: General
• EN 3745-301 - Attenuation test methods for aerospace optical cables
• EN 3745-201 - Visual examination requirements
• EN 2591-100 - General conditioning and test environment references

Keywords: EN 3745-514:2009, cable twist bend, fibre optic cable torsion and bending, aerospace optical cable test methods, aircraft optical cable testing.