MS20426 — Solid Countersunk Rivet, 100° Precision Head
MS20426 covers solid rivets with a 100° countersunk precision head, produced in aluminum alloy and titanium-columbium alloy. Revision L (14 September 1993) superseded the earlier AN426 designation and has itself since been folded into NASM20426, though MS20426 part numbers remain the industry-standard callout in aircraft sheet metal work.
At a Glance
Overview
MS20426 covers solid rivets with a 100° countersunk "precision" head, manufactured from aluminum alloy or titanium-columbium alloy, and produced under the procurement specification MIL-R-5674. The countersunk head allows the rivet to sit flush with the surface once installed, making it the standard choice for aerodynamically smooth aircraft skin panels and structural lap joints.
The most common variant is the "AD" material code, made from 2117 aluminum alloy heat treated to the T4 condition, giving a shear strength around 26,000 PSI and a tensile strength around 38,000 PSI. A softer "A" material code (1100 pure aluminum) is also available for applications needing a more ductile rivet. Finish is typically chemical film per MIL-C-5541 or anodize per MIL-A-8625.
- Installation requires access to both sides of the joint along with a rivet gun/hammer and a bucking bar.
- Revision L (1993) superseded the older AN426 designation used before the AN-to-MS hardware consolidation.
- MS20426 has since been folded into the AIA/NAS-maintained NASM20426 document, though the "MS20426" part number prefix remains in universal industry use.
Part Number Reference
MS20426 part numbers combine a material code, diameter dash, and length dash.
MS20426 / AN426 / NASM20426 Lineage
| Designation | Status |
|---|---|
| AN426 | Original Army-Navy designation — superseded |
| MS20426 (Rev. L) | Superseded AN426; industry-standard part number still in universal use |
| NASM20426 | Current AIA/NAS-maintained governing document |
MS20426 is closely related to MS20427 (the same 100° countersunk head style in carbon steel, CRES, Monel, and copper) and MS20470 (universal/dome-head rivets in aluminum and titanium-columbium alloy). All three families are now maintained under their respective NASM-prefixed successor documents.
MS20426 — Frequently Asked Questions
What does the "AD" in MS20426AD3-3 mean?
"AD" is the material code for 2117-T4 aluminum alloy — the most common MS20426 rivet material, offering a good balance of strength and workability for aircraft sheet metal.
Is MS20426 still the correct document to reference?
MS20426 has been superseded by NASM20426 at the governing-document level, but the "MS20426" part number prefix remains the universal industry callout for this rivet family and is still what most drawings and catalogs use.
What's the difference between MS20426 and MS20427?
Both use the same 100° countersunk precision head geometry, but MS20426 covers aluminum and titanium-columbium alloy rivets, while MS20427 covers the same head style in carbon steel, corrosion resistant steel, Monel, and copper.
Need MS20426 Rivets?
Ananka Fasteners supplies MS20426 solid countersunk rivets with full material traceability and Mill Test Certification.
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