The 5010139 is a Pipistrel internal part number referring to a hexagon socket button head screw manufactured to ISO 7380 (commonly ISO 7380-1). This is a low-profile metric fastener with a rounded button-style head and an internal hex (Allen) drive, designed for applications where a smooth external surface, reduced snag risk, and controlled torque installation are required.

In Pipistrel aircraft assemblies, this type of fastener is typically used in lightweight structural and semi-structural applications such as composite fairings, access panels, interior structures, avionics mounting brackets, and non-primary load-bearing joints. The button head geometry provides a clean aerodynamic surface while still allowing reliable clamping force when properly torqued.

The hex socket drive allows precise torque application with reduced risk of cam-out compared to Phillips or slotted screws. ISO 7380 specifies the head dimensions and strength characteristics, and these screws are commonly produced in stainless steel (A2/A4), alloy steel (e.g., property class 8.8 / 10.9), or lightweight aerospace alloys depending on design requirements.

Because of the reduced head bearing area compared to standard hex bolts, load distribution is lower, so correct selection of diameter, thread engagement, and torque is critical in aircraft maintenance and assembly.

Key features include:

ISO 7380 hexagon socket button head screw (low-profile design)
Internal hex drive (Allen key) for controlled torque installation
Designed for lightweight aircraft and composite structure assembly
Common materials: A2/A4 stainless steel, alloy steel, or titanium (application dependent)
Suitable for fairings, panels, brackets, and interior mounting points
Smooth domed head reduces aerodynamic drag and snag risk
Requires correct torque values due to reduced head bearing surface
Compatible with metric coarse threads (e.g., M3–M8 typical aerospace use)
Corrosion-resistant variants commonly used in aviation environments
Used in both production assembly and maintenance operations