The Nut,self-Locking,extended Washer, cataloged under National Stock Number 5310-01-172-5134, is classified within Federal Supply Class 5310 (Nuts and Washers) of the Hardware and Abrasives group. The manufacturer of record is Howmet Global Fastening Systems Inc. Government technical data includes 17 specifications, cited from the U.S. Government catalog. The record lists 6 manufacturer part numbers for this item, enabling identification through both NSN and commercial part number lookups. 3 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5310-01-172-5134 |
| Primary Part Number | H39921-4 |
| Item Name | Nut,self-Locking,extended Washer |
| FSC / FSG | 5310 / 53 — Nuts and Washers |
| Manufacturer | Howmet Global Fastening Systems Inc |
| Status | ACTIVE |
| Lubrication | DRY FILM LUBRICANT |
| Washer Outside Diameter | 0.414 INCHES MINIMUM AND 0.444 INCHES MAXIMUM IN |
| Width Across Flats | 0.367 INCHES MINIMUM AND 0.373 INCHES MAXIMUM IN |
| Surface Treatment Document and Classification | QQ-P-416,TYPE 2,CLASS 2 FED SPEC SINGLE TREATMENT RESPONSE OVERALL |
| Thread Series | UNIFIED NATIONAL JOINT FINE (UNJF) |
| Temp Rating | 450.0 FAHRENHEIT MAXIMUM DEGF |
| Hardness Rating | 34.0 ROCKWELL C MINIMUM AND 43.0 ROCKWELL C MAXIMUM |
| Washer Thickness | 0.040 INCHES MINIMUM IN |
| Material Document and Classification | AMS 6322 ASSN STD SINGLE MATERIAL RESPONSE OVERALL |
| Thread Direction | RIGHT-HAND |
| Nominal Thread Size | 0.250 INCHES IN |
| Locking Feature | PREVAILING TORQUE ALL METAL DESIGN |
| Surface Treatment | CADMIUM AND CHROMATE OVERALL |
| Nut Style | DOUBLE HEXAGON |
| Thread Class | 3B |
| Thread Quantity Per Inch | 28 |
| Material | STEEL COMP 8740 OVERALL |
| 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 |
|---|---|
| SLN149-428 | Space-Lok, Inc. Dba Space-Lok Inc Div Space-Lok (USA) |
| H39921-4 PRIMARY | Howmet Global Fastening Systems Inc (USA) |
| 48FLW-428 | Leonardo Spa Helicopters Division - Production Site (ITA) |
| 721009105300 | Leonardo Spa Divisione Sistemi Di Difesa (ITA) |
| 48FLW-428 PRIMARY | Sps Technologies, Llc Dba PB Fasteners (USA) |
| BH00510-4 PRIMARY | Bristol Industries, Llc (USA) |
| Reference | Meaning |
|---|---|
| LH13450-4 | 5/9 Secondary reference Harvard Industries Inc |
| HS262-428 | 5/9 Secondary reference Mcdonnell Douglas Helicopter Co Inc |
| HS262-428 | 7/2 Vendor item drawing reference The Boeing Company |
NSN 5310-01-172-5134 is a Nut,self-Locking,extended Washer, manufactured by Howmet Global Fastening Systems Inc, classified under FSC 5310, Nuts and Washers. Status: active.
NSN 5310-01-172-5134 has 6 manufacturer part numbers on file: SLN149-428 (Space-Lok, Inc. Dba Space-Lok Inc Div Space-Lok), H39921-4 (Howmet Global Fastening Systems Inc), 48FLW-428 (Leonardo Spa Helicopters Division - Production Site), 721009105300 (Leonardo Spa Divisione Sistemi Di Difesa), 48FLW-428 (Sps Technologies, Llc Dba PB Fasteners) and 1 more.
Key specifications for H39921-4: Lubrication: DRY FILM LUBRICANT; Overall Height: 0.290 INCHES MAXIMUM IN; Washer Outside Diameter: 0.414 INCHES MINIMUM AND 0.444 INCHES MAXIMUM IN; Width Across Flats: 0.367 INCHES MINIMUM AND 0.373 INCHES MAXIMUM IN. 17 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.