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

kSIST FprEN 3636:2026 is the Slovenian adoption of the draft European Standard prEN 3636:2025 from SIST/CEN. It specifies reduced pan head screws with an offset cruciform recess, relieved shank and long thread in heat resisting steel FE-PA92HT (A286), silver plated, for aerospace use. The screws are classified 900 MPa/650 °C, so the document is used when a fastener has to be selected, made, marked and checked against a defined high-temperature strength class.

What does kSIST FprEN 3636:2026 specify?

kSIST FprEN 3636:2026 specifies one family of aerospace screws and the rules needed to define, identify and inspect them. The document is organized into clauses 1 to 7, supported by Figure 1 and Tables 1 to 3.

Clause / figure / table	What it covers
1	Scope
2	Normative references
3	Terms and definitions
4	Required characteristics
5	Designation
6	Marking
7	Technical specification
Figure 1	Configuration and marking position
Tables 1-3	Dimensions, length codes, marking styles

In practice, the document gives the form of the screw, the material and coating requirements, the designation format and the marking rules that a buyer or manufacturer needs for ordering and inspection.

What are the key requirements of kSIST FprEN 3636:2026?

Geometry, thread and dimensions

Clause 4.1 requires the screw configuration to follow Figure 1, with dimensions and tolerances taken from Figure 1 and Tables 1 and 2. The dimensions are given in millimetres. This is the basis for dimensional inspection and for making sure the screw matches the intended recess, head and shank geometry.

The thread is an MJ thread, with lead and runout thread requirements linked to ISO 3353-1 and thread limits to ISO 5855-1 and ISO 5855-2. In practice, this means the fastener is not a generic metric screw - it uses the aerospace MJ system and must fit the matching aerospace nuts and gauges.

Material and surface coating

Clause 4.2 requires the heat resisting steel FE-PA92HT to comply with EN 2398 or EN 2399. That ties the screw to approved bar stock for machined or forged bolts, which matters when a manufacturer has to prove the starting material route.

Clause 4.3 requires silver coating all over in accordance with EN 2786, with coating thickness 3 µm to 6 µm on the thread flanks, measured at the pitch diameter. For production and incoming inspection, this is the key plating check because the coating affects both performance and conformity.

Clause 4.3 also requires sharp edges to be broken within the stated limits. In practice, that helps control handling, assembly and coating damage.

Identification, marking and technical specification

Clause 5 defines the designation format, using the diameter code and length code. The example designation shows how the reference is written on drawings, orders and certificates, so purchasers can specify the exact screw without ambiguity.

Clause 6 requires marking in the position shown in Figure 1 and in the styles given in Table 3, as defined by EN 2424. This gives the traceability mark that manufacturers and inspectors use to identify the part after production.

Clause 7 points to EN 3043 for the technical specification. That links this dimensional standard to the broader requirements for externally threaded fasteners in FE-PA92HT at the 900 MPa/650 °C classification.

What terms does kSIST FprEN 3636:2026 define?

kSIST FprEN 3636:2026 does not list separate definitions, but it uses several key terms that matter in practice.

• Reduced pan head - the screw head form used in this standard, shaped to the configuration shown in Figure 1.
• Offset cruciform recess - a cross-shaped drive recess arranged off the centerline, used with the specified internal drives and gauges.
• Relieved shank - the reduced shank portion between head and thread, used to achieve the required geometry.
• Long thread - a thread form extending close to the head, as shown by the configuration and dimensional tables.
• FE-PA92HT (A286) - the heat resisting steel specified for the screw material.
• MJ thread - the aerospace metric thread system referenced by ISO 5855-1 and ISO 5855-2.
• EN 2424 - the marking standard used for aerospace products.

Who uses kSIST FprEN 3636:2026?

kSIST FprEN 3636:2026 is used by aerospace fastener manufacturers, machining shops, plating suppliers, inspectors, quality managers and purchasers. Designers use it to specify the screw geometry and thread form, buyers use it to order the correct part, and quality staff use it to verify material, coating, dimensions and marking.

It is also relevant for organizations that prepare technical documentation, certificates and acceptance checks for aerospace screws in this classification.

What changed in kSIST FprEN 3636:2026 from the previous edition?

kSIST FprEN 3636:2026 supersedes EN 3636:2008. The stated significant technical changes are:

• Table 3, Marking styles, has been updated.
• The document has been editorially revised.

Which standards are used with kSIST FprEN 3636:2026?

Normative reference	What it contributes
EN 2398	FE-PA92HT bars for machined bolts
EN 2399	FE-PA92HT bars for forged bolts
EN 2424	Marking of aerospace products
EN 2786	Electrolytic silver plating of fasteners
EN 3043	Technical specification for externally threaded fasteners in FE-PA92HT
ISO 3353-1	Lead and runout threads for rolled external threads
ISO 5855-1	General requirements for MJ threads
ISO 5855-2	Limit dimensions for MJ bolts and nuts
ISO 14275	Internal offset cruciform drives, metric series
ISO 14277	Drivers for internal offset cruciform drives, metric series
ISO 14278	Gauges for internal offset cruciform drives, metric series

What does the kSIST FprEN 3636:2026 document contain?

The document contains the configuration drawing in Figure 1, the dimensional data in Tables 1 and 2, and the marking styles in Table 3. It also includes the designation example that shows how the diameter and length codes are combined.

For practice, these parts are used for design definition, drawing notes, incoming inspection, plating verification, product marking and procurement. The tables are the core reference when a team needs to match a screw to the correct size code and recess style.

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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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
...