SIST EN 3745-407:2006

Overview

EN 3745-407:2005 is a CEN (European) aerospace test method that specifies a flammability test for optical fibres and cables for aircraft use. Prepared by AECMA‑STAN and adopted by CEN, the standard defines a reproducible Bunsen‑burner based procedure to determine the resistance of an optical cable to direct flame exposure. It is intended for manufacturers, test laboratories and airframers to assess fire behaviour of aircraft optical cables under controlled laboratory conditions.

Key topics and technical requirements

• Scope: Method to determine optical cable resistance to the flame of a Bunsen burner.
• Specimen preparation:
  • Specimens prepared per the product standard; if not at standard conditions, condition and stabilize for 24 h as defined in EN 3745‑100.
  • Typical specimen length: 1.00 ± 0.05 m.
• Apparatus:
  • Test chamber approximately 0.3 × 0.5 m footprint and 0.6 m height, open at top and front for ventilation.
  • Bunsen‑type burner with 6 mm inlet, ~9.5 mm bore, ~100 mm barrel above air inlets; adjusted to give a 75 mm conical flame with an inner core ~25 mm and a maximum flame temperature ≥ 955 °C.
  • Rigid wire support, clamps and ISO 4046 tissue paper to detect falling flaming particles.
• Test method:
  • Specimen mounted at 60° to horizontal; test point 200 mm above lower clamp.
  • Burner held perpendicular and at 30° from the specimen plane; hottest portion of flame applied to lower side of cable.
  • Tissue paper suspended 240 mm below flame application point, ≥15 mm above chamber floor.
  • Flame application period: 30 s, then flame withdrawn immediately.
• Acceptance criteria:
  • Burn length must not exceed 75 mm.
  • Time to extinction of the flame must not exceed the value specified in the product/contract specification.
  • No flaming particles may fall and ignite the tissue paper (holes/charred spots without flame are ignored).
  • Specimen breakage alone is not a failure if other criteria are met.
• Referenced documents: EN 3745‑100 (general), EN 3745‑201 (visual examination), ISO 4046 (tissue paper vocabulary).

Applications and users

• Used by aerospace cable manufacturers, optical cable designers, independent fire test laboratories, airframe OEMs and certification authorities to:
  • Validate cable material selections and designs for aircraft cabin and systems installations.
  • Support procurement specifications and compliance evidence for airworthiness and safety requirements.
  • Compare flame performance across cable variants and materials.

Related standards

• EN 3745‑100 - Aerospace series: general test conditions for optical fibres and cables.
• EN 3745‑201 - Visual examination procedures for aerospace optical cables.
• ISO 4046 - Paper and tissue specifications referenced for the falling‑particle test.