FprEN 4266

Aerospace series - Bearing spherical plain, metal to metal, in corrosion resisting steel, cadmium plated - Wide series - Dimensions and loads - Inch series

This document specifies the characteristics of spherical plain bearings, metal to metal, in corrosion resisting steel, cadmium plated and chromated, wide series, inch series for aerospace applications.
Spherical plain bearings, metal to metal, in corrosion resisting steel, cadmium plated and chromated, wide series, are intended for use in fixed or moving parts of the aircraft structure and their control mechanisms.
Spherical plain bearings, metal to metal, in corrosion resisting steel, cadmium plated and chromated, wide series, are intended for use in the temperature range −54 °C to 150 °C, and intended to be lubricated by means of the following greases:
- Code A: grease conforming to MIL-PRF-23827, operating temperature range −73 °C to 121 °C;
- Code B: grease conforming to MIL-PRF-81322, operating temperature range −54 °C to 177 °C.
For the purposes of this document, the range of application for bearings lubricated with grease conforming to code A is limited to 121 °C.
For the purposes of this document, the range of applications for bearings lubricated with grease conforming to code B is limited to 177 °C.
NOTE In both cases it is important to provide the spherical surface of the outer or inner ring with a dry-film lubricant conforming to MIL-PRF-46010 or equivalent (anti-seizing protection).

Luft- und Raumfahrt - Gelenklager, Metall auf Metall, aus korrosionsbeständigem Stahl, kadmiert - Breite Reihe - Maße und Belastungen - Inch Reihe

No Scope available

Série aérospatiale - Rotule lisse, métal à métal en acier résistant à la corrosion, cadmiée - Série large - Dimensions et charges - Série en inches

Le présent document spécifie les caractéristiques des rotules lisses, métal à métal, en acier résistant à la corrosion, cadmiées et chromatées, série large, série en inches, pour les applications aérospatiales.
Elles sont destinées à être utilisées pour les parties fixes ou mobiles de la structure de l’aéronef et leurs mécanismes de commande.
Elles doivent être utilisées dans une plage de températures de -54 °C à 150 °C. En cas de lubrification à l’aide des graisses suivantes :
-   code A : graisse conforme à la MIL-PRF-23827C, plage de températures de fonctionnement de -73 °C à 121 °C ;
-   code B : graisse conforme à la MIL-PRF-81322G, plage de températures de fonctionnement de -54 °C à 177 °C.
La plage d’application des rotules lubrifiées à l’aide de graisse suivant le code A est limitée à 121 °C.
Dans les deux cas, la surface sphérique de la bague extérieure ou intérieure doit être pourvue d’un lubrifiant à film sec selon la MIL-PRF-46010G ou équivalente (protection anti-grippage).
Le traitement des trous de coulissement se situe au niveau de la bague extérieure ou de la bague intérieure.

Aeronavtika - Ležaj, krogelni, drsni, kovina na kovino, iz korozijsko odpornega jekla, kadmiran - Široki tip - Mere in obremenitve - Colske serije

General Information

• Status: Not Published
• Publication Date: 20-Sep-2026
• ICS: 49.035 - Components for aerospace construction
• Technical Committee: ASD-STAN - Aerospace
• Drafting Committee: ASD-STAN/D 3/S 1 - Parts of Mechanical Systems
• Current Stage: 5020 - Submission to Vote - Formal Approval
• Start Date: 23-Apr-2026
• Completion Date: 23-Apr-2026
• Ref Project: oSIST prEN 4266:2024 - Aerospace series - Bearing spherical plain, metal to metal, in corrosion resisting steel, cadmium plated - Wide series - Dimensions and loads - Inch series

Relations

• Revises: EN 4266:2013 - Aerospace series - Bearing spherical plain, metal to metal, in corrosion resisting steel, cadmium plated - Wide series - Dimensions and loads - Inch series
• Effective Date: 03-May-2023

Overview

FprEN 4266 is a draft European Standard developed by CEN for the aerospace sector, focusing on spherical plain bearings, metal-to-metal, made from corrosion resisting steel, cadmium plated and chromated. This standard provides comprehensive guidelines on the dimensions, loads, material characteristics, surface treatments, and lubrication requirements for these wide series, inch series bearings used in aerospace applications. Spherical plain bearings covered by this standard are essential components in both fixed and moving parts of aircraft structures and control mechanisms, where high reliability and resistance to environmental factors are critical.

Key Topics

• Design and Dimensional Requirements:
  The standard specifies critical configuration details, including bore and outside diameters, tolerances, and bearing width according to inch series conventions. Dimensional values are provided to ensure interoperability and replacement compatibility.

• Material Specifications:
  Bearings must be produced using corrosion resistant steels, referencing EN 2030 and EN 3161, with hardening and tempering conditions for inner and outer rings. Alternative materials are addressed as described in TR 4661.

• Surface Treatments:

  • Cadmium plating (5 µm to 8 µm thickness) of the outer ring, as per EN 2133, is required for corrosion protection, followed by chromating.
  • Inner ring treatment follows ISO 8075.
  • Application of a dry-film lubricant (compliant with MIL-PRF-46010 or equivalent) is recommended for anti-seizing protection.

• Load Capacities and Clearances:

  • Detailed permissible static and ultimate loads (both radial and axial) are provided for different diameter codes.
  • Radial and axial clearances are defined for both normal and reduced types, according to EN 2337.

• Lubrication Compatibility:
  Bearings are designed for lubrication with specific aerospace greases:

  • Code A: MIL-PRF-23827 - For operating temperatures from −73 °C to 121 °C.
  • Code B: MIL-PRF-81322 - For wider range −54 °C to 177 °C.
    The document also details maximum operating temperatures depending on the grease type used.

• Identification and Marking:
  Marking must comply with EN 2424. Manufacturers may add their part numbers according to the standard's format.

Applications

FprEN 4266 bearings are engineered for use in:

• Aircraft structure assemblies - joints and pivots exposed to fluctuating loads and varying temperatures.
• Control mechanisms - actuation systems requiring low friction operation and high lifespan.
• Both fixed and moving mechanical interfaces in the aerospace sector that demand durability, repeatability, and resistance against corrosion and wear.
• Extreme environment operations - maintaining performance from −54 °C up to 150 °C or more, depending on lubrication.

These bearings are vital for ensuring the safety, reliability, and longevity of aircraft components operating under stringent aerospace conditions.

Related Standards

For implementation and technical reference, the following standards are directly associated with FprEN 4266:

• EN 2030: Aerospace series - Hardened and tempered steel bars
• EN 2133: Cadmium plating for steels and alloys
• EN 2337: Aerospace series - Spherical plain bearings - Technical specification
• EN 2424: Marking of aerospace products
• EN 3161: Aerospace series - Precipitation-hardened steel bars
• ISO 8075: Surface treatment of hardenable stainless steel
• MIL-PRF-23827 & MIL-PRF-81322: Greases for bearing lubrication
• MIL-PRF-46010: Dry film solid lubricant

Referencing and implementing FprEN 4266 ensures conformity with international best practices for aerospace bearing selection, installation, and maintenance, supporting both safety and regulatory compliance within aviation and defense industries.

Standards Content (Sample)

SLOVENSKI STANDARD
01-november-2024
Aeronavtika - Ležaj, krogelni, drsni, kovina na kovino, iz korozijsko odpornega
jekla, kadmiran - Široki tip - Mere in obremenitve - Colske serije
Aerospace series - Bearing spherical plain, metal to metal, in corrosion resisting steel,
cadmium plated - Wide series - Dimensions and loads - Inch series
Luft- und Raumfahrt - Gelenklager, Metall auf Metall, aus korrosionsbeständigem Stahl,
kadmiert - Breite Reihe - Maße und Belastungen - Inch Reihe
Série aérospatiale - Rotule lisse, métal à métal en acier résistant à la corrosion, cadmiée
- Série large - Dimensions et charges - Série en inches
Ta slovenski standard je istoveten z: prEN 4266
ICS:
21.100.01 Ležaji na splošno Bearings in general
49.035 Sestavni deli za letalsko in Components for aerospace
vesoljsko gradnjo construction
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
prEN 4266
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2024
ICS 49.035 Will supersede EN 4266:2013
English Version
Aerospace series - Bearing spherical plain, metal to metal,
in corrosion resisting steel, cadmium plated - Wide series -
Dimensions and loads - Inch series
Série aérospatiale - Rotule lisse, métal à métal en acier Luft- und Raumfahrt - Gelenklager, Metall auf Metall,
résistant à la corrosion, cadmiée - Série large - aus korrosionsbeständigem Stahl, kadmiert - Breite
Dimensions et charges - Série en inches Reihe - Maße und Belastungen - Inch Reihe
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee ASD-
STAN.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 4266:2024 E
worldwide for CEN national Members.

prEN 4266:2024 (E)
Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 5
4 Symbols and abbreviations . 5
5 Requirements . 5
5.1 Configuration, dimensions, tolerances and mass. 5
5.2 Surface roughness . 5
5.3 Material . 5
5.4 Surface treatment . 6
5.5 Loads and clearances . 6
6 Designation . 13
7 Marking . 14
8 Technical specification . 14
Bibliography . 15
prEN 4266:2024 (E)
European foreword
This document (prEN 4266:2024) has been prepared by the Aerospace and Defence Industries
Association of Europe — Standardization (ASD-STAN).
After enquiries and votes carried out in accordance with the rules of this Association, this document has
received the approval of the National Associations and the Official Services of the member countries of
ASD-STAN, prior to its presentation to CEN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 4266:2013.
prEN 4266:2024 includes the following significant technical changes with respect to EN 4266:2013:
— Value for the outer diameter for diameter code 05 in Table 1 corrected;
— Reference on TR 4661 for alternative materials added.
— Reference on TR 4661 for alternative materials added.
prEN 4266:2024 (E)
1 Scope
This document specifies the characteristics of spherical plain bearings, metal to metal, in corrosion
resisting steel, cadmium plated and chromated, wide series, inch series for aerospace applications.
They are intended for use in fixed or moving parts of the aircraft structure and their control
mechanisms.
They are used in the temperature range − 54 °C to 150 °C. As they are lubricated by means of the
following greases:
— Code A: Grease as per MIL-PRF-23827C, operating temperature range − 73 °C to 121 °C;
— Code B: Grease as per MIL-PRF-81322G, operating temperature range − 54 °C to 177 °C.
The range of application for bearings lubricated with grease per code A is limited to 121 °C.
In both cases it is important to provide the spherical surface of the outer or inner ring with a dry-film
lubricant as per MIL-PRF-46010G or equivalent (anti-seizing protection).
The slide hole treatment either at the outer ring or inner ring.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 2030, Aerospace series — Steel X105CrMo17 (1.3544) — Hardened and tempered — Bars — De ≤
150 mm
EN 2133, Aerospace series — Cadmium plating of steels with specified tensile strength ≤ 1 450 MPa,
copper, copper alloys and nickel alloys
EN 2337, Aerospace series — Spherical plain bearings — Technical specification
EN 2424, Aerospace series — Marking of aerospace products
EN 3161, Aerospace series — Steel FE-PM3801 (X5CrNiCu17-4) — Air melted, solution treated and
precipitation treated, bar a or D ≤ 200 mm, Rm ≥ 930 MPa
ISO 1132-1, Rolling bearings — Tolerances — Part 1: Terms and definitions
ISO 8075, Aerospace — Surface treatment of hardenable stainless steel parts
TR 4475, Aerospace series — Bearings and mechanical transmissions for airframe applications —
Vocabulary
TR 4661, Aerospace series — Bearings, flight controls — Materials and surface treatments

Published as ASD-STAN Technical Report at the date of publication of this document (www.asd-stan.org).
prEN 4266:2024 (E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in TR 4475 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
4 Symbols and abbreviations
Symbols of limit deviations are in accordance with definitions of ISO 1132-1.
α is the maximum angle of tilt of the outer ring with respect to the inner ring, with the
spherical surface of the outer ring being completely in contact with the inner ring;
C is the permissible static axial load;
a
C is the permissible static
...