The Washer,flat, cataloged under National Stock Number 5310-01-477-5307, is classified within Federal Supply Class 5310 (Nuts and Washers) of the Hardware and Abrasives group. The manufacturer of record is Leonardo Spa Helicopters Division - Production Site. Government technical data includes 11 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through both NSN and commercial part number lookups. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog.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 | 5310-01-477-5307 |
| Primary Part Number | MS21299-3K |
| Item Name | Washer,flat |
| FSC / FSG | 5310 / 53 — Nuts and Washers |
| Manufacturer | Leonardo Spa Helicopters Division - Production Site |
| Status | ACTIVE |
| Surface Treatment Document and Classification | QQ-P-35 FED SPEC SINGLE TREATMENT RESPONSE OVERALL |
| Overall Diameter | 0.377 INCHES MINIMUM AND 0.387 INCHES MAXIMUM IN |
| Hardness Rating | 35.0 ROCKWELL C MINIMUM AND 42.0 ROCKWELL C MAXIMUM |
| Material Document and Classification | AMS 5604,COND H 1025 ASSN STD SINGLE MATERIAL RESPONSE OVERALL |
| Cross-Sectional Shape Style | RECTANGULAR |
| Surface Treatment | PASSIVATE OVERALL |
| Peripheral Shape Style | ROUND |
| Material | STEEL COMP 316 OVERALL |
| Center Hole Shape Style | ROUND |
| Hole Diameter | 0.191 INCHES MINIMUM AND 0.195 INCHES MAXIMUM IN |
| Thickness | 0.052 INCHES MINIMUM AND 0.072 INCHES MAXIMUM IN |
| 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 |
|---|---|
| MS21299-3K | Leonardo Spa Helicopters Division - Production Site (ITA) |
| Reference | Meaning |
|---|---|
| MS21299-3K | 3/2 Design control — primary reference U.S. Government activity |
| MS21299-3K | 5/9 Secondary reference U.S. Government activity |
NSN 5310-01-477-5307 is a Washer,flat, manufactured by Leonardo Spa Helicopters Division - Production Site, classified under FSC 5310, Nuts and Washers. Status: active.
NSN 5310-01-477-5307 has 1 manufacturer part number on file: MS21299-3K (Leonardo Spa Helicopters Division - Production Site).
Key specifications for MS21299-3K: Surface Treatment Document and Classification: QQ-P-35 FED SPEC SINGLE TREATMENT RESPONSE OVERALL; Overall Diameter: 0.377 INCHES MINIMUM AND 0.387 INCHES MAXIMUM IN; Hardness Rating: 35.0 ROCKWELL C MINIMUM AND 42.0 ROCKWELL C MAXIMUM; Material Document and Classification: AMS 5604,COND H 1025 ASSN STD SINGLE MATERIAL RESPONSE OVERALL. 11 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.