The Nut,self-Locking,hexagon, cataloged under National Stock Number 5310-01-028-0785, is classified within Federal Supply Class 5310 (Nuts and Washers) of the Hardware and Abrasives group. The manufacturer of record is Sps Technologies, Llc Dba PB Fasteners. Government technical data includes 14 specifications, cited from the U.S. Government catalog. The record lists 1 manufacturer part number for this item, enabling identification through both NSN and commercial part number lookups. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5310-01-028-0785 |
| Primary Part Number | 21FK-518 |
| Item Name | Nut,self-Locking,hexagon |
| FSC / FSG | 5310 / 53 — Nuts and Washers |
| Manufacturer | Sps Technologies, Llc Dba PB Fasteners |
| Status | ACTIVE |
| Lubrication | SOLUBLE LUBRICANT |
| Width Across Flats | 0.553 INCHES MINIMUM AND 0.564 INCHES MAXIMUM IN |
| Surface Treatment Document and Classification | QQ-P-416,TY 2,CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL |
| Thread Series | UNIFIED NATIONAL COARSE (UNC) |
| Thread Direction | RIGHT-HAND |
| Nominal Thread Size | 0.312 INCHES IN |
| Locking Feature | PREVAILING TORQUE ALL METAL DESIGN |
| Nut Height | 0.266 INCHES MAXIMUM IN |
| Surface Treatment | CADMIUM OVERALL |
| Nut Style | HEXAGON |
| Thread Class | 2B |
| Thread Quantity Per Inch | 18 |
| Material | STEEL OVERALL |
| Bearing Surface Type | CHAMFERED |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Part Number | Manufacturer |
|---|---|
| 21FK-518 PRIMARY | Sps Technologies, Llc Dba PB Fasteners (USA) |
| Reference | Meaning |
|---|---|
| 333-1460-030 | 5/2 Secondary reference U.S. Government activity |
| 333-1460-030 | 5/9 Secondary reference Rockwell Collins, Inc. Dba Collins Aerospace Government Systems Div Collins Aerospace - Government Systems |
NSN 5310-01-028-0785 is a Nut,self-Locking,hexagon, manufactured by Sps Technologies, Llc Dba PB Fasteners, classified under FSC 5310, Nuts and Washers. Status: active.
NSN 5310-01-028-0785 has 1 manufacturer part number on file: 21FK-518 (Sps Technologies, Llc Dba PB Fasteners).
Key specifications for 21FK-518: Lubrication: SOLUBLE LUBRICANT; Width Across Flats: 0.553 INCHES MINIMUM AND 0.564 INCHES MAXIMUM IN; Surface Treatment Document and Classification: QQ-P-416,TY 2,CL 3 FED SPEC SINGLE TREATMENT RESPONSE OVERALL; Thread Series: UNIFIED NATIONAL COARSE (UNC). 14 specifications are documented in the U.S. Government catalog.
No hazard code in the DLA record (HMIC N). Hazard information on this page is shown exactly as it appears in the DLA record.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-16.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.