Overview
ISO 12280:1999 defines the dimensions of sheet‑metal spring retainers used with self‑locking barrel nuts in aerospace assemblies. Intended specifically for the compilation of aerospace product standards, this International Standard ensures consistent geometry, tolerances and basic functional requirements for retainers that secure self‑locking barrel nuts (see ISO 12278). Dimensions and tolerances are expressed in millimetres and apply after any surface coating(s).
Key topics and technical requirements
- Scope: Dimensional specification for sheet‑metal spring retainers intended for use with self‑locking barrel nuts (ISO 12278). Applicable only for aerospace product standards.
- Normative reference: ISO 12278 (barrel nuts) is referenced for nut outline and installation hole requirements.
- Configuration and supply condition:
- Retainers are supplied in the open position.
- The standard provides figure(s) showing retainer geometry and interaction with the barrel nut.
- Retainer types:
- Code A (Index type) - used in blind areas where an index feature in the hole prevents retainer rotation or vertical movement.
- Code B (Clearance type) - used where the nut is accessible or where a through‑bolt hole in the far side of the barrel cavity is undesirable.
- Push‑out force: Code B retainers and the assembled nut require a specified push‑out force when installed in the hole defined by ISO 12278; values are given in Table 1.
- Dimensional data: Table 1 lists diameter codes (e.g., 060 through 390), multiple dimensional parameters (A, B, C, D, E, F, H, S, T) and corresponding push‑out force values. All dimensions and tolerances are in millimetres.
Applications and users
ISO 12280:1999 is practical for:
- Aerospace design engineers specifying fastener retention for aircraft and space hardware
- Mechanical designers creating mating parts and installation holes per ISO 12278
- Quality and procurement teams ensuring incoming retainers match aerospace dimensional requirements
- Standards writers compiling aerospace product standards and parts lists
- Maintenance and repair organizations verifying replacement retainers meet original dimensional and functional criteria
Practical benefits include reliable anti‑rotation/retention behavior, consistent push‑out characteristics for assembly/disassembly, and interchangeability across suppliers when used with ISO 12278 barrel nuts.
Related standards
- ISO 12278:1999 - Nuts, barrel, self‑locking (referenced normative document for nut outline and installation holes)
- Other ISO/TC 20 aerospace fastener system standards (for designers and specifiers to consult when integrating fasteners into product standards)
Keywords: ISO 12280:1999, aerospace retainers, spring sheet metal retainers, self‑locking barrel nuts, dimensions, ISO 12278, push‑out force, fastener standards.