Overview - ISO 7295:1988 (Tyre valves for aircraft - Interchangeability dimensions)
ISO 7295:1988 defines the basic dimensional requirements that ensure interchangeability of aircraft tyre valve components - specifically the valve stem, core (long and short types) and cap. The standard focuses on geometric and assembly interfaces that allow reliable connection of ground inflation equipment and replacement of cores/caps across different manufacturers. It does not cover functional performance of valve cores or caps.
Key topics and technical requirements
- Interchangeability dimensions: Drawings and dimensional requirements ensure valve stems accept both long and short cores and permit cap assembly and ground hose connection.
- Core types: Specifications cover short cores (with inside/outside spring variants) and long cores; the valve core chamber must accommodate the long core.
- Valve cap: Cap design must include a sealing gasket; cap dimensions are defined to allow a sealable connection on threaded valves.
- Core identification: Aircraft valve cores are identified by a brass- or copper-coloured core pin with a groove in the pin head and by a brass- or copper-coloured plunger cup.
- Torque limits for insertion: Limits are given for core insertion torque - for example:
- 0.17 N·m to 0.34 N·m for cores with an elastomeric barrel gasket
- 0.34 N·m to 0.54 N·m for cores with a metallic sealing gasket
- Access space (Annex A): Specifies the required envelope around the valve mouth so ground inflation hoses and valve assembly can be used while wearing arctic gloves; cap-plus-valve must not project beyond wheel width.
- Notes on manufacturing features: Surface finish for sealing with swivel gaskets, optional valve mouth counterbore, rotatable swivel requirements, and optional spring cup for long cores.
Practical applications and users
ISO 7295 is used where dimensional interchangeability and maintainability of aircraft tyre valves are critical:
- Aircraft manufacturers and wheel/tyre OEMs - for designing valve stems and wheel assemblies
- Valve and valve-core manufacturers - to produce cores and caps compatible across commercial aircraft valves
- MRO shops and ground-handling teams - to ensure replacement cores/caps and inflation equipment fit reliably
- Aviation procurement and regulatory bodies - to specify standard-compliant components and maintenance procedures
Related standards
- ISO 7442:1982 - Tyre valves - core chamber No. 7 (core chamber conformity referenced)
- ISO 4570-1:1977 - Tyre valve threads (threads SV7, 5V2, 6V7, 8V7) - referenced for valve thread specifications
By following ISO 7295 alongside the referenced standards, stakeholders achieve consistent, safe, and maintainable valve assemblies for aircraft tyres, improving interchangeability, field serviceability, and compatibility with ground inflation equipment.
