EN 4073:2025

Aerospace series - Screw, pan head, hexalobular recess, coarse tolerance shank, medium length thread, in alloy steel, cadmium plated - Classification: 1 100 MPa (at ambient temperature) / 235 °C

This document specifies the characteristics of screws, pan head, six lobe recess, coarse tolerance shank, medium length thread, in alloy steel, cadmium plated.
Classification: 1 100 MPa   / 235 °C  .

Luft- und Raumfahrt - Flachkopfschraube, mit Innensechsrund, mit mittlerer Gewindelänge, aus legiertem Stahl, verkadmet - Klasse: 1 100 MPa (bei Umgebungstemperatur)/235 °C

Série aérospatiale - Vis à tête cylindrique, à empreinte six lobes, tige à tolérance large, filetage moyen, en acier allié, cadmiée - Classification : 1 100 MPa (à température ambiante)/235 °C

Le présent document spécifie les caractéristiques des vis à tête cylindrique, à empreinte six lobes, tige à tolérance large, filetage moyen, en acier allié, cadmiées.
Classification : 1 100 MPa /235 °C.

Aeronavtika - Vijaki, valjasta glava, šestzoba vdolbina, široka toleranca, srednja navojna dolžina, iz legiranega jekla, prevlečeni s kadmijem - Klasifikacija: 1 100 MPa (pri temperaturi okolice) / 235 °C

Ta dokument določa značilnosti vijakov: valjasta glava, šestzoba vdolbina, široka toleranca, srednja navojna dolžina, iz legiranega jekla, prevlečenih s kadmijem. Klasifikacija: 1100 MPa/235 °C.

General Information

• Status: Published
• Publication Date: 25-Mar-2025
• ICS: 49.030.20 - Bolts, screws, studs
• Technical Committee: ASD-STAN - Aerospace
• Drafting Committee: ASD-STAN/D 3/S 2 - Fasteners
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 26-Mar-2025
• Due Date: 21-Oct-2022
• Completion Date: 26-Mar-2025
• Ref Project: SIST EN 4073:2025 - Aerospace series - Screws, pan head, hexalobular recess, coarse tolerance shank, medium length thread, in alloy steel, cadmium plated - Classification: 1 100 MPa (at ambient temperature) / 235 °C

Relations

• Replaces: EN 4073:2016 - Aerospace series - Screws, pan head, hexalobular recess, coarse tolerance shank, medium length thread, in alloy steel, cadmium plated - Classification: 1 100 MPa (at ambient temperature) / 235 °C
• Effective Date: 18-Jan-2023

Overview

EN 4073:2025 specifies the characteristics of an aerospace-series fastener: screws with pan head and hexalobular (six‑lobe) recess, coarse‑tolerance shank and medium length MJ threads, manufactured in alloy steel and cadmium plated. Published by CEN (approved 20 Jan 2025), this standard replaces EN 4073:2016 and defines geometry, materials, surface treatment, marking and procurement/qualification requirements for these aerospace screws. Classification: 1 100 MPa (minimum tensile strength at ambient temperature) / 235 °C (maximum service temperature determined by surface treatment).

Key topics and requirements

• Configuration, dimensions and masses: Detailed head, shank and thread geometry, tolerances and mass values are given in Figure 1 and Table 1 (dimensions in millimetres; apply after surface treatment).
• Threads and tolerances: External threads per ISO 3353‑1, MJ thread limit dimensions per ISO 5855‑2, and form/position tolerances per ISO 7913.
• Material: Alloy steel classification per TR 3775 corresponding to the 1 100 MPa strength class.
• Surface treatment: Cadmium plating per EN 2133 (or QQ‑P‑416 F type II grade B class 2) with specified deposit thickness (8–14 µm) on load‑bearing surfaces; black colour option (code B) available.
• Designation and marking: Standardized designation format (example: SCREW EN4073 H 050 040 B), hole codes for locking options (lockwire, split pin), and marking styles referenced to EN 2424.
• Manufacturer approval & qualification: Producers must be approved aerospace production organizations and demonstrate quality management (e.g., EN 9100). Qualification of bolts follows aerospace procedures (e.g., EN 9133) unless otherwise agreed.

Applications and who uses it

• Aerospace OEMs and suppliers specifying aerospace fasteners for airframe, engine accessories and structural assemblies where controlled strength (1 100 MPa) and cadmium corrosion protection are required.
• Fastener manufacturers and heat‑treatment/plating subcontractors implementing production, inspection and plating processes to meet EN 4073 requirements.
• Procurement specialists, quality managers and avionics/maintenance engineers who require standardized designation, marking and qualification for safety‑critical fasteners.
• Maintenance, repair and overhaul (MRO) organizations replacing or approving fasteners in conformity with aerospace standards.

Related standards and references

• EN 2133 (cadmium plating), EN 2424 (marking), EN 3911 (six‑lobe recess geometry)
• ISO 3353‑1, ISO 5855‑2, ISO 7689, ISO 7913
• TR 3775 (materials), EN 9100 (quality management), EN 9133 (qualification procedures)

EN 4073:2025 is essential for anyone specifying or producing pan‑head, hexalobular aerospace screws with MJ threads, cadmium plating and 1 100 MPa strength - ensuring interchangeability, traceability and compliance across the aerospace supply chain.

Standards Content (Sample)

SLOVENSKI STANDARD
01-junij-2025
Aeronavtika - Vijaki, valjasta glava, šestzoba vdolbina, široka toleranca, srednja
navojna dolžina, iz legiranega jekla, prevlečeni s kadmijem - Klasifikacija: 1 100
MPa (pri temperaturi okolice) / 235 °C
Aerospace series - Screws, pan head, hexalobular recess, coarse tolerance shank,
medium length thread, in alloy steel, cadmium plated - Classification: 1 100 MPa (at
ambient temperature) / 235 °C
Luft- und Raumfahrt - Flachkopfschraube, mit Innensechsrund, mit mittlerer
Gewindelänge, aus legiertem Stahl, verkadmet - Klasse: 1 100 MPa (bei
Raumtemperatur) / 235 °C
Série aérospatiale - Vis à tête cylindrique, à empreinte six lobes, tige a tolérance large,
filetage moyen, en acier allié, cadmiées - Classification: 1 100 MPa (à température
ambiente) / 235 °C
Ta slovenski standard je istoveten z: EN 4073:2025
ICS:
49.030.20 Sorniki, vijaki, stebelni vijaki Bolts, screws, studs
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 4073
EUROPEAN STANDARD
NORME EUROPÉENNE
March 2025
EUROPÄISCHE NORM
ICS 49.030.20 Supersedes EN 4073:2016
English Version
Aerospace series - Screw, pan head, hexalobular recess,
coarse tolerance shank, medium length thread, in alloy
steel, cadmium plated - Classification: 1 100 MPa (at
ambient temperature) / 235 °C
Série aérospatiale - Vis à tête cylindrique, à empreinte Luft- und Raumfahrt - Flachkopfschraube, mit
six lobes, tige à tolérance large, filetage moyen, en acier Innensechsrund, mit mittlerer Gewindelänge, aus
allié, cadmiée - Classification : 1 100 MPa (à legiertem Stahl, verkadmet - Klasse: 1 100 MPa (bei
température ambiante)/235 °C Umgebungstemperatur)/235 °C
This European Standard was approved by CEN on 20 January 2025.

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. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists 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.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 4073:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Required characteristics . 4
4.1 Configuration – Dimensions – Masses . 4
4.2 Tolerances of form and position . 5
4.3 Materials . 5
4.4 Surface treatment . 5
5 Designation . 8
6 Marking . 8
7 Technical specification . 8
7.1 General. 8
7.2 Approval of manufacturers . 8
7.3 Qualification of bolts. 9
Bibliography . 10

European foreword
This document (EN 4073:2025) has been prepared by 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 European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by September 2025, and conflicting national standards
shall be withdrawn at the latest by September 2025.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 4073:2016.
This document includes the following significant technical changes with respect to EN 4073:2016:
— Clause 3 “Terms and definitions” added;
— Figure 1 corrected;
— Table 1 Footnote added;
— Annex A has been removed.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CE
...