ISO 8668-6:1994

Overview

ISO 8668-6:1994 - "Aircraft - Terminal junction systems - Part 6: Detail specification for type 4 system" is an ISO detail specification that defines the design, ratings and test requirements for a Type 4 Terminal Junction System (TJS) used in aircraft wiring and airframe electrical installations. It is intended to be read in conjunction with ISO 8668-1 (Characteristics) and ISO 8668-2 (Tests) and includes component specification sheets (Annex A), qualification samples (Annex B) and contact test methods (Annex C).

Key topics and requirements

• Scope and description
  • Defines a family of multicontact connecting devices: bussing modules, distribution and electronic modules, grounding junctions, in-line wire and electronic junctions, racks, mounting brackets, sealing plugs and tools.
  • Contacts are removable female crimp-type; modules are removable from anodized aluminum frames with unique contact identification.
• Electrical ratings
  • Contact current ratings specified by contact size (sizes 22, 20, 16, 12).
  • Working voltage: nominal 600 V at sea level; 300 V at high altitude (values in the standard); proof voltages also specified.
  • Contact resistance and insulation resistance limits are defined and referenced to ISO 8668-2 test methods.
• Environmental and mechanical requirements
  • Operating temperature range –65 °C to +200 °C.
  • Altitude, low-pressure immersion, vibration, mechanical shock, climatic, salt spray and endurance tests are specified using ISO 8668-2 procedures.
  • Resistance to fluids, magnetic effects and flammability are addressed.
• Materials, tools and accessories
  • Frames: anodized aluminum alloy; contacts and sealing plugs per annex sheets.
  • Crimp joints must comply with ISO 1966; insertion/extraction and crimping tools are specified in annexes.
• Qualification & production tests
  • Detailed type-approval test program, production 100% acceptance tests and batch sampling, recurring quality control schedules and Declaration of Performance requirements.

Applications

• Design and manufacture of aircraft wiring harnesses, terminal junction frames, bus distribution blocks, grounding systems and electronic junction blocks.
• Use in airframe and avionics interconnecting wiring systems where environmental ruggedness and interchangeability are required.
• Standard for integration of modular removable junctions in racks and cable looms.

Who should use this standard

• Avionics and aircraft electrical engineers
• Connector and module manufacturers
• Test laboratories performing type approval and production tests
• OEM procurement and quality engineers specifying TJS components for aircraft

Related standards

• ISO 8668-1: Characteristics
• ISO 8668-2: Tests
• ISO 1966: Crimped joints for aircraft electrical cables
• ISO 7137: Environmental conditions and test procedures (airborne equipment)

Keywords: ISO 8668-6, Terminal Junction System, TJS, aircraft connectors, crimp contacts, avionics wiring, type 4 system, terminal junction specification, aerospace electrical standards.