Overview
ISO 7689:2025 - "Aerospace series - Bolts, with MJ threads, made of alloy steel, strength class 1100 MPa - Procurement specification" - is the third edition international standard that defines characteristics and quality‑assurance requirements for MJ‑thread alloy‑steel bolts (strength class 1100 MPa) used in aerospace construction. It applies whenever referenced in a definition document (for example an in‑house standard, drawing or other specification) and replaces the 2008 edition with updated sampling tables and additional mechanical and dimensional requirements.
Key topics and technical requirements
- Scope and applicability: Requirements apply to bolts ready for use at ambient temperature and complement any requirements in the referenced definition document.
- Material and strength class: Bolts of alloy steel, strength class 1100 MPa; material verification follows the referenced material standard.
- Manufacturing controls:
- Heads formed by hot or cold forging prior to heat treatment.
- Forged blanks heat‑treated to achieve properties in the definition document (blanks shall not be heat‑treated more than twice).
- Threads formed by single rolling after final heat treatment.
- Quality assurance and inspection:
- Manufacturer responsibility for continuous compliance and maintenance of quality records for 10 years.
- Qualification inspection: typically 25 bolts selected by simple random sampling for each type/diameter.
- Acceptance inspection: sampling of production batches/inspection lots per AS/EN 9138; destructive and nondestructive tests specified in Table 1.
- Use of statistical process control (SPC) is permitted when formally justified and validated; SPC is not applicable to destructive tests.
- Mechanical and test requirements: Table 1 in the standard lists mandatory inspections (dimensions per ISO 5855‑2, tensile strength per ISO 7961, hardness per ISO 6506/6507/6508, surface texture per ISO 21920‑3, surface coating standards, recess removal torque, etc.). Annex A and B provide formulae for tensile and double shear load calculations.
- Definitions and sampling concepts: Clear definitions for production batch, inspection lot, AQL/LQ, major/minor defects and sampling plans are provided.
Practical applications and users
ISO 7689:2025 is intended for:
- Aerospace OEMs and suppliers specifying MJ‑thread bolts in procurement documents and drawings.
- Fastener manufacturers who must qualify production routes, perform acceptance testing and retain traceable quality records.
- Quality engineers and procurement specialists implementing inspection plans, sampling, SPC and supplier surveillance.
- Design and structural engineers who require standard test methods, tensile/double‑shear formulae (Annex A/B) and minimum mechanical requirements for bolt selection.
Practical uses include supplier qualification, batch acceptance, manufacturing process validation, and contractual procurement requirements for flight‑critical or structural fastening systems.
Related standards
Key normative references cited in ISO 7689:2025:
- ISO 5855‑2 - MJ threads limit dimensions for bolts and nuts
- ISO 7961 - Aerospace bolts - Test methods (tensile/double shear)
- ISO 21920‑3 - Surface texture (profile)
- ISO 6506 / 6507 / 6508 - Brinell, Vickers, Rockwell hardness tests
- AS/EN 9138 - Aerospace quality management - statistical product acceptance requirements
Keywords: ISO 7689:2025, aerospace bolts, MJ threads, alloy steel bolts, 1100 MPa, procurement specification, quality assurance, sampling plan, tensile strength, SPC, acceptance inspection.