ISO 23887-2021 PDF

Full title and description

Aerospace — Blind fasteners, threaded type, self-locking — Test method for locking torque. This international standard defines a laboratory test method to measure the locking torque of threaded blind fasteners (drive nut, nut, sleeve and corebolt assemblies with a cross recess at the top of the nut) used in aerospace applications.

Abstract

This document describes the locking torque test method for blind fasteners, threaded type. It specifies the test specimen configuration (drive nut, nut, sleeve and corebolt), test apparatus and procedure to determine the locking (prevailing) torque of the fastener assembly. The method is intended for blind fasteners having an internal thread and an external sleeve.

General information

• Status: Published.
• Publication date: July 21, 2021 (Edition 1, 2021).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 49.030.99 (Other fasteners / aerospace fastener systems).
• Edition / version: Edition 1 (2021).
• Number of pages: 4 pages (concise test method document).

Scope

Specifies a standardized test method to measure the locking (prevailing) torque of blind fasteners of the threaded, self-locking type used in aerospace applications. It applies to blind fasteners made of four elements — drive nut, nut, sleeve and corebolt — where the nut has a cross recess at the top; the standard covers specimen preparation, test apparatus, measurement procedure and reporting. It is limited to measurement of locking torque and does not itself define acceptance criteria for specific applications.

Key topics and requirements

• Definition of the test specimen: configuration and relevant features of drive nut, nut, sleeve and corebolt.
• Test apparatus and calibration requirements for torque measuring instruments (reference to applicable torque-instrument standards where appropriate).
• Step-by-step test procedure to determine locking torque (including application of torque, measurement method and any preconditioning required).
• Reporting requirements: how to record measured locking torque, test conditions and specimen identification.
• Normative references used by the method (for example, torque instrument specifications and relevant GPS/tolerance standards cited in the document).

Typical use and users

Used by aerospace OEMs, fastener manufacturers, independent test laboratories, quality and inspection teams, and procurement/specification engineers to: (1) verify locking torque characteristics of blind threaded fasteners during product development and incoming inspection, (2) support qualification or conformity assessment of fastener lots, and (3) provide consistent test data for design and fitness-for-purpose decisions.

Related standards

Standards from the same ISO technical committee (ISO/TC 20/SC 4) and other fastener test or product standards are commonly referenced alongside ISO 23887:2021, for example ISO 23886 (torque and preload test methods for threaded collars), ISO fastener dimension and material specifications, and relevant torque-instrument standards cited normatively within the document. Users often consult other aerospace fastener specifications and procurement standards when applying test results.

Keywords

blind fastener, threaded fastener, self-locking, locking torque, prevailing torque, aerospace fasteners, test method, torque measurement, ISO 23887

FAQ

Q: What is this standard?

A: ISO 23887:2021 is an international test-method standard that specifies how to measure the locking (prevailing) torque of self-locking, threaded blind fasteners used in aerospace applications.

Q: What does it cover?

A: It covers the test specimen configuration (drive nut, nut, sleeve, corebolt), the required test apparatus and calibration considerations, the stepwise measurement procedure for locking torque, and the format for reporting results. It does not prescribe acceptance limits for specific applications.

Q: Who typically uses it?

A: Aerospace OEMs, fastener manufacturers, test laboratories, quality assurance and inspection teams, design engineers and procurement/specification professionals use this standard to obtain repeatable locking torque data.

Q: Is it current or superseded?

A: ISO 23887:2021 is the current (first) edition published in 2021. No superseding edition or amendment is indicated as of its publication.

Q: Is it part of a series?

A: It is part of the suite of aerospace fastener standards maintained by ISO/TC 20/SC 4; related test-method documents (for example ISO 23886) and product/dimension standards complement it within the committee’s portfolio.

Q: What are the key keywords?

A: blind fastener, self-locking, threaded, locking torque, torque test, aerospace fastener, test method, prevailing torque (ISO 23887).