ISO 8668-1:1986

Overview

ISO 8668-1:1986, Aircraft - Terminal Junction Systems - Part 1: Characteristics, developed by the International Organization for Standardization (ISO), establishes the fundamental characteristics and standardization principles for terminal junction systems used in aircraft. This part of the standard specifies the basic requirements for mechanical structure, electrical performance, and environmental conditions, providing a general framework to ensure safety, reliability, and interchangeability. However, ISO 8668-1 does not prescribe specific dimensional patterns for connection systems but sets boundaries for system design and performance.

Key Topics

• General Operating Characteristics: Outlines core properties and performance attributes for terminal junction systems.
• Mechanical Structure:
  • Specifies requirements for removable modules, frames, clamps, and sealing grommets.
  • Ensures robust construction and resistance to mechanical stresses, including vibration and shock.
• Electrical Performance:
  • Defines standards for voltage and current handling, insulation resistance, and contact resistance.
  • Stipulates crimped contact characteristics and compatibility with standard conductor sizes.
• Environmental Conditions:
  • Sets classifications based on temperature range, up to 200°C and use at altitudes up to 31,000 m.
  • Addresses requirements for sealing, fluid resistance, salt spray, dust, and flammability.
• Identification and Marking: Requires legible and indelible markings for contact positions, modules, splices, and frames to ensure traceability and ease of maintenance.
• Tooling and Assembly:
  • Specifies the use of appropriate tools for insertion, extraction, and crimping without affecting system integrity.
  • Crimping tools must produce joints that meet ISO standards.
• Type Approval and Quality Testing:
  • Details procedures for type approval testing and outlines ongoing production and quality testing for consistent performance across batches.

Applications

Terminal junction systems covered by ISO 8668-1 are critical in both civil and military aircraft, including:

• Aircraft Wiring and Electrical Systems: Ensures secure and reliable electrical connections for vital avionics, power distribution, and control systems.
• Modular Electrical Harnesses: Facilitates maintenance, replacement, and upgrades by standardizing module components and interfaces.
• Environments with Stringent Requirements: Applies to aircraft operating in extreme temperatures, high altitudes, and challenging environmental conditions where reliability is paramount.
• Manufacturing and Maintenance:
  • Supports manufacturers in designing terminal junction systems that meet robust quality and interoperability requirements.
  • Enables maintenance teams to easily identify, replace, or test terminal assemblies according to standardized benchmarks.

Related Standards

For comprehensive implementation and testing, ISO 8668-1 recognizes and aligns with other key standards, including:

• ISO 8668-2: Aircraft - Terminal Junction Systems - Part 2: Tests: Details testing procedures referenced in ISO 8668-1.
• ISO 1966: Crimped Joints for Aircraft Electrical Cables: Provides requirements for crimped joint performance.
• ISO 7137: Aircraft - Environmental Conditions and Test Procedures for Airborne Equipment: Specifies environmental testing guidelines for compliance.
• ISO 2100: Aircraft - Electrical Connectors - Tests: Outlines relevant test protocols for electrical connectors in aviation.

These interrelated standards ensure the comprehensive safety, performance, and interoperability of terminal junction systems in the demanding aircraft environment.

Keywords: ISO 8668-1, aircraft terminal junction systems, electrical connectors, mechanical structure, environmental conditions, aircraft wiring standards, aviation electrical testing, standardization, type approval, quality testing, crimped contacts, marking and identification.