SIST EN 3911:2014

• Abstract:

  This European Standard specifies the dimensions and tolerances of a six lobe recess.

• Status: Published
• Publication Date: 10-Feb-2014
• ICS: 49.030.01 - Fasteners in general
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 13-Jan-2014
• Due Date: 20-Mar-2014
• Completion Date: 11-Feb-2014
• Ref Project: EN 3911:2010 - Aerospace series - Six lobe recess - Geometrical definition

• Referred By: SIST EN 4323:2005 - Aerospace series - Screws, 100° countersunk head, six lobe recess, threaded to head, in titanium alloy TI-P64001, anodized, MoS2 coated - Classification: 900 MPa (at ambient temperature) / 350 °C
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4635:2009 - Aerospace series - Screws, 100° countersunk head, six lobes recess, short thread, in heat resisting nickel base alloy NI-PH2601 (Inconel 718) - Classification: 1270 MPa (at ambient temperature)/650 °C
• Effective Date: 28-Jan-2026
• Referred By: SIST 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: 28-Jan-2026
• Referred By: SIST EN 3905:2008 - Aerospace series - Six lobe recesses for bolts - Technical specification
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4178:2017 - Aerospace series - Screws, pan head, six lobe recess, coarse tolerance normal shank, medium length thread, in titanium alloy, anodized, MoS2 lubricated - Classification: 1 100 MPa (at ambient temperature)/315 °C
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4178:2010 - Aerospace series - Screws, pan head, six lobe recess, coarse tolerance normal shank, medium length thread, in titanium alloy, anodized, MoS2 lubricated - 1100 MPa (at ambient temperature)/315 °C
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4634:2009 - Aerospace series - Screws, 100° countersunk head, six lobe recess, short thread, in heat resisting steel FE-PA2601 (A286), passivated - Classification: 900 MPa (at ambient temperature)/650 °C
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 3912:2009 - Aerospace series - Bolts, pan head, six lobe recess, relieved shank, long thread, in heat resisting steel FE-PA2601 (FE-PA92HT, A286), silver plated - Classification: 1 100 MPa (at ambient temperature) / 650 °C
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 7010:2020 - Aerospace series - Configuration - Definition and designation for product standards for externally threaded fasteners
• Effective Date: 28-Jan-2026
• Referred By: 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
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4636:2009 - Aerospace series - Screws, 100° countersunk head, six lobe recess, short thread, in titanium alloy TI-P64001, with aluminium pigmented coating - Classification: 1 100 MPa (at ambient temperature) / 315 °C
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4359:2009 - Aerospace series - Six lobe recess - Drivers - Technical specification
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 3725:2005 - Aerospace series - Screws, pan head, six lobe recess, normal shank, long thread, in titanium alloy TI-P64001, anodized, MoS2 coated - Strength class: 1 100 MPa (at ambient temperature)
• Effective Date: 28-Jan-2026
• Referred By: SIST EN 4074:2009 - Aerospace series - Screws, pan head, six lobe recess, coarse tolerance normal shank, medium length thread, in titanium alloy, aluminium IVD coated - Classification: 1100 MPa (at ambient temperature)/425 °C
• Effective Date: 28-Jan-2026

Overview

SIST EN 3911:2014 is a European Standard developed by CEN that specifies the dimensions and tolerances of a six lobe recess, widely used in aerospace and defense industries. This standard defines the geometrical characteristics of six lobe recesses to ensure interchangeability, reliability, and precision in the manufacturing of aerospace fasteners and components. The standard provides detailed configurations including measurements, tolerances, and designations to support the consistent production of six lobe drive systems.

Key Topics

• Six Lobe Recess Geometry
  The standard covers the exact geometrical definitions necessary for six lobe recesses. It includes the shape, size, profiles, and critical dimensions essential for ensuring proper fit and torque transmission in aerospace applications.

• Dimensions and Tolerances
  SIST EN 3911:2014 specifies key dimensional parameters, including recess codes corresponding to precise measurements (e.g., diameter, radius, depths) expressed in millimeters. Tight tolerances are defined to meet the high-quality standards required in aerospace fasteners.

• Designation System
  The document introduces a clear designation methodology for identifying different six lobe recess sizes and types by referencing recess codes, facilitating standardized communication in design and manufacturing processes.

• Normative References
  This standard relies on complementary standards such as EN 3905 (technical specifications for six lobe recesses) and NAS 1800 (US aerospace industry reference for recesses), ensuring alignment across international aerospace specifications.

Applications

SIST EN 3911:2014 is primarily intended for use in the aerospace engineering sector, where components must meet stringent safety and performance criteria. Its applications include:

• Aerospace Fasteners Manufacturing
  Ensuring accurate six lobe recess dimensions improves fastener engagement, reduces risks of cam-out, and enhances torque transmission efficiency in aircraft assemblies.

• Component Design and Quality Control
  Engineers and quality inspectors utilize this standard for developing component drawings and carrying out dimensional verifications to maintain conformance with aerospace industry requirements.

• Tooling and Testing
  The standardized dimensions support the design of tooling, gauges, and assembly equipment, enabling manufacturers and maintenance providers to perform consistent installation and maintenance.

• Cross-border Aerospace Projects
  Because SIST EN 3911:2014 is harmonized among European nations and recognized internationally, it aids in collaborative aerospace projects by providing a common technical language for six lobe recess features.

Related Standards

• EN 3905: Aerospace Series - Six Lobe Recesses for Bolts - Technical Specification
  Establishes detailed technical requirements for six lobe recess fasteners complementing SIST EN 3911:2014 geometrical definitions.

• NAS 1800:1990 - Recess, Six Lobe Drive - Internal - Dimensions for Recess and Gages
  A US aerospace standard referenced for dimension derivation and tolerances, ensuring cross-standard compatibility.

• ASD-STAN Standards
  The Aerospace and Defence Industries Association of Europe (ASD-STAN) supports broader aerospace standardization efforts, facilitating integration of SIST EN 3911:2014 with other aerospace fastener standards.

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Keywords: SIST EN 3911:2014, six lobe recess, aerospace fasteners, geometrical definition, CEN standard, aerospace series, six lobe drive, dimensions and tolerances, aerospace manufacturing, aerospace industry standards, ASD-STAN, EN 3905, NAS 1800, aerospace component design, aerospace tooling standards, European aerospace standards.

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Aeronavtika - Šestzoba vdolbina, notranji pogon - Geometrijske definicijeLuft- und Raumfahrt - Verbindungselemente, Innenantrieb - Sechs-BogenzahnSérie aérospatiale - Empreinte six lobes - Définition géometriqueAerospace series - Six lobe recess - Geometrical definition49.030.01Vezni elementi na splošnoFasteners in generalICS:Ta slovenski standard je istoveten z:EN 3911:2010SIST EN 3911:2014en01-marec-2014SIST EN 3911:2014SLOVENSKI
STANDARD
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 3911
October 2010 ICS 49.030.01 English Version
Aerospace series - Six lobe recess - Geometrical definition
Série aérospatiale - Empreinte six lobes - Définition géometrique
Luft- und Raumfahrt - Sechs-Bogenzahn, Innenantrieb - Definition der Geometrie This European Standard was approved by CEN on 16 April 2010.
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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2010 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 3911:2010: ESIST EN 3911:2014
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