ISO 11:1987

Overview

ISO 11:1987 - Aircraft: Ground pressure testing connections for pressure cabins - defines the basic dimensional and access clearance requirements for pressure-testing connections on pressurized aircraft. The standard ensures mechanical and functional compatibility between aircraft cabin fittings and the hose units or adaptors of ground pressurizing equipment used for leak and pressurization testing.

Key topics and requirements

• Connection sizes and recommended cabin volumes
  • 22.22 mm (0.875 in) - recommended for cabin volumes not exceeding 10 m³ (≈300 ft³)
  • 46.04 mm (1.8125 in) - recommended for cabin volumes 10–45 m³ (≈300–1,500 ft³)
  • 72.39 mm (2.85 in) - recommended for cabin volumes 45–170 m³ (≈1,500–6,000 ft³)
• Dimensional specifications
  • Fundamental dimensions for each connection size are provided (including diameter, minimum/maximum limits and key geometric details).
  • Drawings and tables in the standard define profile, chamfers (notably for the 0.875 and 1.8125 sizes), and permitted material/structure limits around the fitting.
• Access clearance
  • Required clearance envelope around each connection is specified to allow coupling with ground pressurizing hoses or adaptors without interference.
• Threading and mating
  • Threads conform to inch-thread conventions referenced to ISO 725; specific thread forms and start/lead details are provided to ensure interchangeability with ground equipment.
• Notes and usage guidance
  • The 22.22 mm connection is identified as the recommended connector for tube pressure testing.

Applications

• Standardizes the interface between aircraft fuselage/cabin pressure ports and ground pressurizing/test equipment.
• Used for routine maintenance, pre-flight pressurization checks, leak detection, and certification testing of pressurized cabins.
• Ensures interchangeability and safe, repeatable coupling of ground test hoses and adaptors across different aircraft types and ground support equipment.

Who should use this standard

• Aircraft structural and systems designers specifying cabin test ports
• Ground support equipment (GSE) and adaptor manufacturers
• Maintenance, Repair & Overhaul (MRO) organizations performing cabin pressurization tests
• Aircraft certification and regulatory engineers responsible for compliance and test procedures

Related standards

• ISO 725 - referenced for inch thread dimensions (used for the threaded connections in ISO 11:1987)

Keywords: ISO 11:1987, ground pressure testing connections, aircraft cabin pressurization, pressure testing adaptor, hose coupling, dimensional requirements, access clearance, aircraft maintenance.