Overview
ISO 7689:2008 - Aerospace - Bolts, with MJ threads, made of alloy steel, strength class 1 100 MPa - Procurement specification - defines the characteristics, manufacturing and quality-assurance requirements for MJ‑thread alloy‑steel bolts used in aerospace construction. It is a procurement standard intended to be applied whenever referenced in a definition document (drawing, in‑house standard or international standard).
Key topics and technical requirements
- Scope and applicability: Applies to MJ thread bolts of alloy steel, strength class 1 100 MPa, for aerospace use.
- Quality assurance: Manufacturer capability, recommended certification to a recognized quality management system and quality records retention for at least 10 years. Qualification inspections are required and are granted by purchaser certification authorities.
- Sampling & inspections: Qualification sample = 25 bolts selected by simple random sampling. Production acceptance inspections use lot sampling and referenced sampling plans (see Tables in the standard). Re-inspection rules and corrective actions are specified.
- Manufacturing controls:
- Heads formed by hot or cold forging before heat treatment; hot‑forging equipment must ensure uniform temperature.
- Forged blanks heat‑treated to specified condition; blanks shall not be heat‑treated more than twice.
- Threads formed by a single rolling process after full heat treatment.
- If machining (bearing face/shank) is required, contamination and dimensional controls must be respected.
- Mechanical tests and properties:
- Tensile and double‑shear strength requirements referenced to ISO 7961 and ISO 6892‑1 (with exceptions for some short/very small bolts).
- Hardness limits before coating: Brinell 327–370 HB, Rockwell 36–40 HRC, Vickers 344–390 HV30.
- Recess/driving feature must withstand specified removal torque test (e.g., end load ~45 ± 2.5 N during torque check).
- Surface and coating: Surface roughness per ISO 4288; coatings per the referenced surface‑coating standard.
- Statistical process control (SPC): SPC can replace final systematic sampling if justified and validated per ISO/TR 13425 and related ISO control‑chart standards.
Applications
- Procurement specifications for aerospace fasteners used in airframes, nacelles, landing gear attachments and other structural assemblies.
- Supplier qualification, incoming inspection procedures, and production acceptance testing of MJ thread alloy‑steel bolts.
- Engineering and procurement documents that reference standard fastener characteristics and test methods.
Who should use this standard
- Fastener manufacturers and heat‑treat shops
- Aerospace design and structural engineers
- Quality managers, incoming inspection and procurement professionals
- Certification bodies, prime contractors and aerospace purchasers
Related standards (selected)
Keywords: ISO 7689:2008, aerospace bolts, MJ threads, alloy steel bolts, strength class 1 100 MPa, procurement specification, bolt qualification, sampling plan, quality assurance.