kSIST FprEN 3636:2026

• Abstract:

  This document specifies the requirements for offset cruciform recess pan head screws with relieved shank and long thread in heat resisting steel FE-PA92HT (A286), silver plated, tensile strength class 900 MPa at room temperature. The maximum test temperature of the material is 650 °C.

• Status: Not Published
• Public Enquiry End Date: 22-Oct-2025
• ICS: 49.025.10 - Steels
• ICS: 49.030.20 - Bolts, screws, studs
• Technical Committee: I13 - Imaginarni 13
• Current Stage: 5020 - Formal vote (FV) (Adopted Project)
• Start Date: 10-Jul-2026
• Due Date: 28-Aug-2026
• Completion Date: 10-Jul-2026
• Ref Project: FprEN 3636 - Aerospace series - Screws, reduced pan head, offset cruciform recess, relieved shank, long thread, in heat resisting steel FEPA92HT (A286), silver plated - Classification: 900 MPa/650 °C

• Revises: SIST EN 3636:2008 - Aerospace series - Screws, reduced pan head, offset cruciform recess, relieved shank, long thread, in heat resisting steel FE-PA92HT (A286), silver plated - Classification: 900 MPa/650 °C
• Effective Date: 23-Oct-2024

Overview

kSIST FprEN 3636:2026 defines the requirements for aerospace screws featuring a reduced pan head, offset cruciform recess, relieved shank, and extended thread length. These fasteners are manufactured in heat resisting steel FEPA92HT (A286) with silver plating and are specified for a tensile strength class of 900 MPa at room temperature. The maximum usable temperature for these screws is 650 °C. Developed and published by SIST, this European standard ensures high reliability and durability of fasteners used in demanding aerospace applications.

Key Topics

• Screw Characteristics

  • Reduced pan head design for optimized compact assemblies.
  • Offset cruciform recess for improved torque transmission and ease of installation.
  • Relieved shank for weight reduction and increased flexibility under load.
  • Long thread for secure engagement in critical assemblies.

• Material and Coating

  • Constructed from high-performance FEPA92HT (A286) heat resisting steel.
  • Silver-plated surface in accordance with EN 2786 for anti-galling and enhanced corrosion resistance.
  • Withstands operational environments up to 650 °C, ensuring reliability at elevated temperatures.

• Mechanical Classification

  • Certified for 900 MPa tensile strength class at room temperature.
  • Dimensional and marking requirements for traceability and compliance, based on EN 2424.
  • Thread, recess, and gauge dimensions in line with ISO and EN standards.

Applications

kSIST FprEN 3636:2026 is tailored for the aerospace sector, ensuring high performance where both strength and heat resistance are essential. Example applications include:

• Aircraft Structures
  Used in high-stress airframe joints and engine assemblies exposed to elevated temperatures.

• Turbine and Powerplant Components
  Suitable for critical fastener roles in Gas Turbine Engines and related sub-systems due to stable performance at up to 650 °C.

• Spacecraft Assemblies
  Applicable in satellite and spacecraft structures requiring lightweight, silver-plated screws for enhanced corrosion protection and conductor compatibility.

• Maintenance and Retrofit Projects
  Provides specification for replacement or upgrade of high-strength screws in existing aerospace platforms, ensuring compatibility and regulatory compliance.

Related Standards

To ensure comprehensive compatibility and adherence to broader aerospace fastener regulations, consider these referenced and related standards:

• EN 2398 / EN 2399:
  Aerospace series - Heat resisting steel specifications for bar material used in fastener manufacturing.
• EN 2424:
  Marking of aerospace products, ensuring traceability and identification.
• EN 2786:
  Specifications for electrolytic silver plating of fasteners, critical for corrosion resistance.
• EN 3043:
  Technical specifications for externally threaded fasteners in FEPA92HT (A286) for 900 MPa/650 °C classification.
• ISO 3353-1:
  Lead and runout threads - Rolled external threads for aerospace applications.
• ISO 5855-1 & 5855-2:
  General and limit dimension requirements for MJ thread forms.
• ISO 14275 / 14277 / 14278:
  Standards for offset cruciform recesses, drivers, and gauging, specific to aerospace fasteners.

kSIST FprEN 3636:2026 provides aerospace manufacturers, suppliers, and maintenance organizations with clear requirements for high-performance screws, helping ensure safety, durability, and regulatory alignment in high-temperature applications. This standard is integral for professionals involved with the procurement, design, or verification of critical aerospace fasteners.

SLOVENSKI STANDARD
oSIST prEN 3636:2025
01-oktober-2025
Aeronavtika - Vijaki, nizka valjasta glava, križna zareza, dolgi navoj do glave, iz
toplotnoodpornega jekla FE-PA92HT (A286), posrebreni - Klasifikacija: 900
MPa/650 °C
Aerospace series - Screws, reduced pan head, offset cruciform recess, relieved shank,
long thread, in heat resisting steel FEPA92HT (A286), silver plated - Classification: 900
MPa/650 °C
Luft- und Raumfahrt - Flachkopfschrauben mit geripptem Flügelkreuzschlitz, Dünnschaft,
langes Gewinde, aus hochwarmfestem Stahl FE‑PA92HT (A286), versilbert - Klasse:
900 MPa/650 °C
Série aérospatiale - Vis à tête cylindrique, réduite, à empreinte cruciforme déportée, à
tige réduite, à filetage long, en acier résistant à chaud FE-PA92HT (A286), argentées -
Classification: 900 MPa/650 °C
Ta slovenski standard je istoveten z: prEN 3636
ICS:
49.025.10 Jekla Steels
49.030.20 Sorniki, vijaki, stebelni vijaki Bolts, screws, studs
oSIST prEN 3636:2025 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN 3636:2025
oSIST prEN 3636:2025
DRAFT
EUROPEAN STANDARD
prEN 3636
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2025
ICS 49.030.20 Will supersede EN 3636:2008
English Version
Aerospace series - Screws, reduced pan head, offset
cruciform recess, relieved shank, long thread, in heat
resisting steel FEPA92HT (A286), silver plated -
Classification: 900 MPa/650 °C
Série aérospatiale - Vis à tête cylindrique, réduite, à Luft- und Raumfahrt - Flachkopfschrauben mit
empreinte cruciforme déportée, à tige réduite, à geripptem Flügelkreuzschlitz, Dünnschaft, langes
filetage long, en acier résistant à chaud FE-PA92HT Gewinde, aus hochwarmfestem Stahl FE-PA92HT
(A286), argentées - Classification: 900 MPa/650 °C (A286), versilbert - Klasse: 900 MPa/650 °C
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.

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Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
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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
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 3636:2025 E
worldwide for CEN national Members.

oSIST prEN 3636:2025
prEN 3636:2025 (E)
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 — Tolerances . 4
4.2 Material . 5
4.3 Surface coating . 5
5 Designation . 8
6 Marking . 8
7 Technical specification . 8
oSIST prEN 3636:2025
prEN 3636:2025 (E)
European foreword
This document (prEN 3636:2025) 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 document is
...