The MS20426AD4-9 is a 100° flush (countersunk) solid aircraft rivet made from 2117-T4 aluminum alloy (AD series), designed for structural sheet metal assembly where a smooth aerodynamic surface is required.

The “4” indicates a 1/8" diameter, while the “-9” dash number corresponds to a 9/16" length, making it suitable for thin-to-medium sheet stacks where a flush finish is required after installation (unlike universal head rivets like MS20470 series).

This rivet is installed using a pneumatic rivet gun and bucking bar, with the head sitting flush inside a pre-countersunk hole (typically 100°). During installation, the shank is deformed to form a shop head on the backside, creating a permanent structural joint commonly used in aircraft skins and aerodynamic surfaces.

Compared to universal head rivets, the MS20426 series is preferred when airflow, drag reduction, or surface finish is critical, such as on aircraft skins, fairings, and external panels.

The 2117-T4 alloy (AD) provides good shear strength, corrosion resistance, and self-aging characteristics, making it a standard choice in certified aircraft manufacturing and repair.

Key features include:

MS20426 100° flush head solid aircraft rivet
Size: 1/8" diameter × 9/16" length (-9 dash number)
Material: 2117-T4 aluminum alloy (AD series)
Approx. ~1300–1400 rivets per 1 lb pack
Countersunk (flush) head for aerodynamic surfaces
Requires pre-countersunk hole (typically 100°)
Installed with rivet gun + bucking bar
High shear strength (~26,000 PSI typical for AD rivets)
Heat-treated self-aging aluminum alloy
Corrosion-resistant coating (MIL-spec anodize / chromate conversion)
Common in aircraft skins, fairings, and exterior sheet metal assemblies
Used when smooth surface finish is required (low drag applications)
Standard replacement for AN426AD4-9 in aircraft maintenance