ISO 12278:1999

Aerospace — Nuts, barrel, self-locking, floating, self-aligning, with MJ threads, classifications: 900 MPa (at ambient temperature) / 235 degrees C, 1100 MPa (at ambient temperature) / 235 degrees C, 1250 MPa (at ambient temperature) / 235 degrees C and 1550 MPa (at ambient temperature) / 235 degrees C — Dimensions

This International Standard specifies the dimensions of self-locking, floating, self-aligning barrel nuts, with MJ threads, for classifications : 900 MPa1)/235 °C2), 1 100 MPa1)/235 °C2), 1 250 MPa1)/235 °C2) and 1 550 MPa1)/235 °C2). This International Standard is only applicable for the compilation of aerospace product standards.

Aéronatique et espace — Écrous à portée cylindrique, à freinage interne, flottants, orientables, à filetage MJ, classifications: 900 MPa (à température ambiante) / 235 degrés C, 1100 MPa (à température ambiante) / 235 degrés C, 1250 MPa (à température ambiante) / 235 degrés C et 1550 MPa (à température ambiante) / 235 degrés C — Dimensions

La présente Norme internationale spécifie les dimensions des écrous à portée cylindrique, à freinage interne, flottants, orientables, à filetage MJ, de classifications: 900 MPa1)/235 °C2), 1 100 MPa1)/235 °C2), 1 250 MPa1)/235 °C2) et 1 550 MPa1)/235 °C2). La présente Norme internationale est applicable uniquement à l'élaboration de normes de produit destinées aux constructions aérospatiales.

General Information

• Status: Published
• Publication Date: 20-Oct-1999
• ICS: 49.030.30 - Nuts
• Technical Committee: ISO/TC 20/SC 4 - Aerospace fastener systems
• Drafting Committee: ISO/TC 20/SC 4 - Aerospace fastener systems
• Current Stage: 9093 - International Standard confirmed
• Start Date: 19-Oct-2021
• Completion Date: 14-Feb-2026

Overview

ISO 12278:1999 is an international standard developed by the International Organization for Standardization (ISO) for the aerospace industry. It specifies the dimensions of self-locking, floating, self-aligning barrel nuts with MJ threads for use in aerospace fastener applications. The standard covers several strength classifications, designated by their minimum tensile stress (900 MPa, 1100 MPa, 1250 MPa, and 1550 MPa at ambient temperature) and a maximum operating temperature of 235°C.

ISO 12278:1999 serves as a vital reference for the creation of component standards within aerospace manufacturing, ensuring dimensional consistency, compatibility, and safety in high-performance aerospace assemblies.

Key Topics

• Barrel Nut Types: Focuses on nuts that are self-locking, floating, and self-aligning. These features provide enhanced resistance to loosening due to vibration, accommodate misalignment, and allow for slight movement within the assembly.
• Thread Specification: All nuts are designed with MJ threads, which are standard metric threads optimized for aerospace fasteners according to ISO 5855-2.
• Strength Classifications: The nuts are classified by their minimum tensile stress ratings (900, 1100, 1250, and 1550 MPa at ambient temperature) and their maximum temperature rating (235°C).
• Dimensional Consistency: Specifies detailed dimensions in millimetres, ensuring uniformity after coating or lubrication, as required for precise and reliable installation.
• Procurement Alignment: Dimensions are set to comply with requirements found in ISO 5858 for the procurement of self-locking nuts.

Applications

ISO 12278:1999 is used throughout the aerospace industry for product standardization and component design, particularly in applications where:

• Vibration Resistance is Critical: The self-locking feature prevents unintentional loosening under vibration, vital for airframe and engine environments.
• Assembly Flexibility is Required: The floating and self-aligning properties simplify installation in structures where perfect alignment is difficult due to tolerances or structural movement.
• High Strength & Temperature Resistance: The multiple strength classes and temperature rating (up to 235°C) allow for use in a range of demanding aerospace environments, such as:
  • Aircraft primary and secondary structures
  • Engine assemblies
  • Spacecraft components
  • Avionics and instrumentation mounts

Manufacturers, suppliers, and engineers apply this standard to select or design fasteners compatible with aerospace systems, ensuring both product reliability and regulatory compliance.

Related Standards

Understanding and using ISO 12278:1999 in context often involves consideration of other associated standards:

• ISO 5855-2:1999 - Aerospace - MJ threads - Part 2: Defines the limit dimensions for bolts and nuts with MJ threads, forming the foundation for the thread requirements in ISO 12278.
• ISO 5858:1999 - Aerospace - Self-locking nuts with maximum operating temperature ≤425°C - Procurement specification: Provides procurement criteria and performance requirements for self-locking nuts, of which ISO 12278 specifies the dimensional aspects.
• Other Aerospace Fastener Standards: Including ISO/TC 20/SC 4 standards for aerospace fastener systems, which address performance, testing, and material requirements.

By adhering to ISO 12278:1999 and related standards, aerospace industry stakeholders can ensure the interchangeability, safety, and performance of fastener products in global markets. This standard is a cornerstone for quality control and harmonization in the design and certification of aerospace components.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 12278
First edition
1999-11-01
Aerospace — Nuts, barrel, self-locking,
floating, self-aligning, with MJ threads,
classifications: 900 MPa (at ambient
temperature)/235 °C, 1 100 MPa (at ambient
temperature)/235 °C, 1 250 MPa (at ambient
temperature)/235 °C and 1 550 MPa (at
ambient temperature)/235 °C —
Dimensions
Aéronautique et espace — Écrous à portée cylindrique, à freinage interne,
flottants, orientables, à filetage MJ, classifications: 900 MPa (à température
ambiante)/235 °C, 1 100 MPa (à température ambiante)/235 °C,
1 250 MPa (à température ambiante)/235 °C et 1 550 MPa
(à température ambiante)/235 °C — Dimensions
A
Reference number
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
International Standard ISO 12278 was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles,
Subcommittee SC 4, Aerospace fastener systems.
©  ISO 1999
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet [e-mail]
Printed in Switzerland
ii
© ISO
Introduction
The dimensions specified in this International Standard have been determined to allow production of a part which
will satisfy the requirements of the procurement specification ISO 5858:1999, Aerospace — Self-locking nuts with
maximum operating temperature less than or equal to 425 °C — Procurement specification.
iii
INTERNATIONAL STANDARD  © ISO ISO 12278:1999(E)
Aerospace — Nuts, barrel, self-locking, floating, self-aligning, with
MJ threads, classifications:
900 MPa (at ambient temperature)/235 °C, 1 100 MPa (at ambient
temperature)/235 °C, 1 250 MPa (at ambient temperature)/235 °C
and 1 550 MPa (at ambient temperature)/235 °C — Dimensions
1 Scope
This International Standard specifies the dimensions of self-locking, floating, self-aligning barrel nuts,
1) 2) 1) 2) 1) 2)
with MJ threads, for classifications : 900 MPa /235 °C , 1 100 MPa /235 °C , 1 250 MPa /235 °C and
1) 2)
1 550 MPa /235 °C .
This International Standard is only applicable for the compilation of aerospa
...

NORME ISO
INTERNATIONALE 12278
Première édition
1999-11-01
Aéronautique et espace — Écrous à portée
cylindrique, à freinage interne, flottants,
orientables, à filetage MJ, classifications:
900 MPa (à température ambiante)/235 °C,
1 100 MPa (à température ambiante)/235 °C,
1 250 MPa (à température ambiante)/235 °C
et 1 550 MPa (à température
ambiante)/235 °C — Dimensions
Aerospace — Nuts, barrel, self-locking, floating, self-aligning, with MJ
threads, classifications: 900 MPa (at ambient temperature)/235 °C,
1 100 MPa (at ambient temperature)/235 °C, 1 250 MPa (at ambient
temperature)/235 °C and 1 550 MPa (at ambient temperature)/235 °C —
Dimensions
A
Numéro de référence
Avant-propos
L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes nationaux de
normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est en général confiée aux
comités techniques de l'ISO. Chaque comité membre intéressé par une étude a le droit de faire partie du comité
technique créé à cet effet. Les organisations internationales, gouvernementales et non gouvernementales, en
liaison avec l'ISO participent également aux travaux. L'ISO collabore étroitement avec la Commission
électrotechnique internationale (CEI) en ce qui concerne la normalisation électrotechnique.
Les Normes internationales sont rédigées conformément aux règles données dans les Directives ISO/CEI, Partie 3.
Les projets de Normes internationales adoptés par les comités techniques sont soumis aux comités membres pour
vote. Leur publication comme Normes internationales requiert l'approbation de 75 % au moins des comités
membres votants.
La Norme internationale ISO 12278 a été élaborée par le comité technique ISO/TC 20, Aéronautique et espace,
sous-comité SC 4, Éléments de fixation pour constructions aérospatiales.
©  ISO 1999
Droits de reproduction réservés. Sauf prescription différente, aucune partie de cette publication ne peut être reproduite ni utilisée sous quelque
forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et les microfilms, sans l'accord écrit de l'éditeur.
Organisation internationale de normalisation
Case postale 56 • CH-1211 Genève 20 • Suisse
Internet [e-mail]
Imprimé en Suisse
ii
© ISO
Introduction
Les dimensions spécifiées dans la présente Norme internationale ont été définies pour permettre la production d'une pièce
satisfaisant aux exigences de la spécification d'approvisionnement ISO 5858:1999, Aéronautique et espace — Écrous
à freinage interne dont la température maximale d’utilisation est inférieure ou égale à 425 °C — Spécification
d’approvisionnement.
iii
NORME INTERNATIONALE  © ISO ISO 12278:1999(F)
Aéronautique et espace — Écrous à portée cylindrique, à freinage
interne, flottants, orientables, à filetage MJ, classifications:
900 MPa (à température ambiante)/235 °C, 1 100 MPa (à
température ambiante)/235 °C, 1 250 MPa (à température
ambiante)/235 °C et 1 550 MPa (à température ambiante)/235 °C —
Dimensions
1 Domaine d’application
La présente Norme internationale spécifie les dimensions des écrous à portée cylindrique, à freinage
1) 2) 1) 2)
interne, flottants, orientables, à filetage MJ, de classifications: 900 MPa /235 °C , 1 100 MPa /235 °C ,
1) 2) 1) 2)
1 250 MPa /235 °C et 1 550 MPa /235 °C .
La présente Norme internationale est applicable uniquement à l'élaboration de normes de produit destinées aux
cons
...