FprEN 3636
(Main)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
- 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
- Publication Date
- 29-Nov-2026
- Technical Committee
- ASD-STAN - Aerospace
- Drafting Committee
- ASD-STAN/D 3/S 2 - Fasteners
- Current Stage
- 6055 - CEN Ratification completed (DOR) - Publishing
- Start Date
- 28-Sep-2026
- Completion Date
- 28-Sep-2026
FprEN 3636 is a draft European Standard from CEN for reduced pan head aerospace screws with an offset cruciform recess, relieved shank, long thread, made in heat resisting steel FE-PA92HT (A286) and silver plated. It specifies the screw configuration, dimensions, material, surface coating, designation, marking, and technical specification for parts classified as 900 MPa at room temperature and a 650 °C maximum test temperature.
What does FprEN 3636 specify?
FprEN 3636 specifies the requirements for a specific family of aerospace screws, so it is the document to use when the product, material, coating, and identification need to match this exact design. The document is arranged in clauses on scope, normative references, terms and definitions, required characteristics, designation, marking, and technical specification.
Clause 4 is the core of the standard. It separates the requirements into configuration, dimensions and tolerances, material, and surface coating, which helps users check the part against geometry, material supply, and finishing requirements in a practical way.
What are the key requirements of FprEN 3636?
Configuration, dimensions, and tolerances
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 document uses millimetres, and Table 1 ties the diameter code to the thread size and recess information, while Table 2 gives the length codes and their permitted ranges.
In practice, this means the screw is not specified only by its nominal diameter and length - the buyer or inspector also needs to check the coded dimensions and the head/recess form. That matters when ordering, gauging, or receiving parts because the designation alone points to a defined size set.
Material and coating
Clause 4.2 requires the heat resisting steel FE-PA92HT to comply with EN 2398 or EN 2399. Clause 4.3 requires silver coating all over in accordance with EN 2786, with coating thickness on the thread flanks controlled at the pitch diameter.
For users, that means the base material and the silver plating are both controlled by external standards rather than by free choice. The clause also calls for breaking sharp edges within the stated range, which is important for fit, handling, and avoiding damage during assembly.
Thread form and recess system
The screw uses MJ threads and the lead and runout thread requirements of ISO 3353-1, ISO 5855-1, and ISO 5855-2. The offset cruciform recess is linked to ISO 14275, ISO 14277, and ISO 14278.
In practice, this means the drive system, thread form, and thread limits are standardized so the screws can be driven and gauged with the correct aerospace tools. That helps prevent mismatch between screw, driver, and inspection gauge.
Designation, marking, and technical specification
Clause 5 gives the designation format, clause 6 gives the marking location and marking style, and clause 7 points to EN 3043 for the technical specification. Table 3 updates the marking styles and links them to the diameter code.
For procurement and quality control, these clauses matter because they tell you how to specify the screw on paperwork, where to mark it, and which external technical specification governs the rest of the product requirements.
What terms does FprEN 3636 define?
- Reduced pan head - A low-profile head form used on these screws, shown in Figure 1.
- Offset cruciform recess - A cross recess set to the offset drive system named in the standard.
- Relieved shank - A reduced-shank section used to control the load-bearing geometry of the screw.
- Long thread - A thread length that extends close to the head, as used in this screw family.
- FE-PA92HT (A286) - The heat resisting steel named for the screw material.
- MJ threads - The aerospace thread form used for the screw thread dimensions and limits.
- Marking styles - The marking formats identified in Table 3 and applied in the marked position on the screw.
Who uses FprEN 3636?
FprEN 3636 is used in aerospace fastener supply chains, especially by manufacturers, buyers, design engineers, quality managers, and inspection personnel working with externally threaded fasteners. It is also relevant to anyone selecting the screw type, verifying material and coating, or checking designation and marking against an aerospace procurement or acceptance requirement.
What changed in FprEN 3636 from the previous edition?
FprEN 3636 will supersede EN 3636:2008. The foreword states two changes: Table 3 “Marking styles” has been updated, and the document has been editorially revised.
Which standards are used with FprEN 3636?
| Reference | What it contributes |
|---|---|
| EN 2398 | Heat resisting steel FE-PA2601 bars for machined bolts |
| EN 2399 | Heat resisting steel FE-PA2601 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, ribbed |
| ISO 14277 | Drivers for internal offset cruciform ribbed or unribbed drives |
| ISO 14278 | Gauges for internal offset cruciform ribbed or unribbed drives |
What does the FprEN 3636 document contain?
FprEN 3636 contains one configuration figure, three main tables, a designation example, and clauses that link the product to external aerospace standards. Figure 1 shows the screw form and marking position, while Tables 1 and 2 set out the dimensional coding for diameter and length.
Table 3 gives the marking styles used on the screw. The designation example shows how to build the order description from the diameter code and length code, which is useful for purchasing and part numbering.
Relations
- Effective Date
- 23-Oct-2024
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Frequently Asked Questions
FprEN 3636 is a draft published by the European Committee for Standardization (CEN). Its full title is "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". This standard covers: 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.
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.
FprEN 3636 is classified under the following ICS (International Classification for Standards) categories: 49.030.20 - Bolts, screws, studs. The ICS classification helps identify the subject area and facilitates finding related standards.
FprEN 3636 has the following relationships with other standards: It is inter standard links to EN 3636:2008. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
FprEN 3636 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
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.
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
© 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
...