oSIST prEN 4072:2026

oSIST prEN 4072:2026 is the Slovenian publication of draft European Standard prEN 4072, prepared by ASD-STAN for CEN. It specifies aerospace screws with a 100° countersunk normal head, offset cruciform recess, close tolerance shank, short thread, titanium alloy body and aluminium IVD coating. The document is for manufacturers, purchasers, quality teams and qualification personnel who need a common product definition for the 1 100 MPa / 425 °C classification.

What does oSIST prEN 4072:2026 specify?

oSIST prEN 4072:2026 specifies the characteristics of one family of aerospace screws and the way they are identified, marked and technically qualified. The core content is in clauses 4 to 8, with clause 4 covering the product definition and clauses 5 to 8 covering designation, marking, technical specification and oversized bolts.

Clause 4 is the main engineering section. It fixes the configuration, dimensions, mass, form and position tolerances, material, and surface treatment, so a buyer or inspector can check whether a delivered screw matches the intended aerospace type.

What are the key requirements of oSIST prEN 4072:2026?

Geometry, dimensions and mass

Clause 4.1 ties the screw shape, dimensions and mass to Figure 1 and Table 1. The dimensions and tolerances are given in millimetres and apply after surface treatment, while details not stated are left to the manufacturer’s discretion. In practice, this tells the supplier which features are fixed and which are open to design choice.

The same clause also points to the thread and recess geometry shown in the figure and tables. Sharp edges are to be broken within the stated range, which matters for assembly, handling and coating quality.

Tolerances and material

Clause 4.2 requires tolerances of form and position to follow ISO 7913. Clause 4.3 requires the material to follow TR 3775 and to be titanium alloy in strength class 1 100 MPa. For users, this is the basis for checking both fit and mechanical capability.

Surface treatment and lubrication

Clause 4.4 requires aluminium coating in accordance with EN 6118 type I or type II, or MIL-DTL-83488 type II class 3, with coating thickness between 4 µm and 12 µm. Lubrication with cetyl alcohol, code E, in accordance with EN 6117, is optional after the aluminium deposit. In practice, this is the part that controls corrosion protection, friction and the final temperature classification.

Designation and marking

Clause 5 defines the designation structure using codes for hole option, diameter, length, drive and lubrication. This matters because ordering and traceability depend on the code string, not just the plain-language description.

Clause 6 requires marking in line with Table 4 and EN 2424 style. The marking code depends on diameter range, so production and inspection teams need to apply the correct identification for each size.

Technical specification, approval and qualification

Clause 7 states that the technical specification follows ISO 9152, with a modified recess removal torque test in which the torque values are taken from Table 5. This gives the acceptance and test basis for the drive recess, which is important for installation performance.

Clause 7.2 requires the manufacturer to be an approved production organization for aerospace products and to operate a suitable quality management system, such as EN 9100 or an equivalent. Clause 7.3 requires qualification by an aerospace standard-product procedure, such as EN 9133 or an equivalent, and the tests must be documented unless customer and supplier agree otherwise.

Oversized bolts

Clause 8 says oversized bolts shall follow EN 4016. That links oversize cases to a separate aerospace standard instead of folding them into the main dimension set.

What terms does oSIST prEN 4072:2026 define?

oSIST prEN 4072:2026 uses a small set of product terms and codes that shape how the screw is specified.

• Offset cruciform recess - the internal drive form is a cross recess with the offset geometry used by the referenced drive standards.
• Close tolerance shank - the shank is held to tighter dimensional control for precision fit in aerospace assemblies.
• MJ thread - the metric aerospace thread form used for the limit dimensions and thread references in this standard.
• Classification 1 100 MPa / 425 °C - the screw is identified by its ambient-temperature strength class and the maximum temperature associated with the surface treatment.

Who uses oSIST prEN 4072:2026?

oSIST prEN 4072:2026 is used by aerospace fastener manufacturers, procurement teams, quality managers, inspectors and qualification laboratories. They use it to select the correct screw type, verify dimensions and coating, define marking, and document manufacturing approval and product qualification. It also helps purchasers compare offers on the same technical basis.

What changed in oSIST prEN 4072:2026 from the previous edition?

oSIST prEN 4072:2026 will supersede EN 4072:2016 + AC:2017. The foreword states these technical changes: Clause 3, “Terms and definitions”, was added; Clause 7, “Technical specification”, was editorially revised; and Annex A, “Standard evolution form”, was deleted.

Which standards are used with oSIST prEN 4072:2026?

• EN 2424 - product marking for aerospace products.
• EN 4016 - oversized bolts.
• EN 6118 - pure aluminium IVD coating for fasteners.
• EN 6117 - lubrication of fasteners with cetyl alcohol.
• ISO 3353-1 - lead and runout threads for rolled external threads.
• ISO 5855-2 - MJ thread limit dimensions for bolts and nuts.
• ISO 5856 - dimensions for 100° normal countersunk head screws with internal offset cruciform drive.
• ISO 7913 - tolerances of form and position for bolts and screws.
• ISO 9152 - procurement specification for titanium alloy bolts in strength class 1 100 MPa.
• ISO 14275 and ISO 14276 - internal offset cruciform drive forms.
• TR 3775 - materials for bolts and pins.
• MIL-DTL-83488 - high-purity aluminium coating.

What does the oSIST prEN 4072:2026 document contain?

The document includes Figure 1 and Tables 1 to 5. Figure 1 shows the screw configuration, while Table 1 gives the dimensions, length codes and mass information. Table 2 defines the hole codes, Table 3 defines the drive codes, Table 4 sets the marking style, and Table 5 gives the recess removal torque test values.

It also includes the designation example needed to build an orderable part number from the code elements. For users, that means the standard is not only a geometry document - it is also a practical reference for ordering, marking, inspection and qualification.