The Screw,close Tolerance, cataloged under National Stock Number 5305-00-548-5077, is classified within Federal Supply Class 5305 (Screws) of the Hardware and Abrasives group. The manufacturer of record is Northrop Grumman Corp Electronic Systems Defensive System Div. Government technical data includes 22 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through both NSN and commercial part number lookups. 4 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 5305-00-548-5077 |
| Primary Part Number | 51B581-4-9H |
| Item Name | Screw,close Tolerance |
| FSC / FSG | 5305 / 53 — Screws |
| Manufacturer | Northrop Grumman Corp Electronic Systems Defensive System Div |
| Status | ACTIVE |
| Surface Finish | 32.0 MICROINCHES GRIP |
| Fastener Length | 0.862 INCHES MINIMUM AND 0.909 INCHES MAXIMUM IN |
| Surface Treatment Document and Classification | QQ-P-416,TY 2,CL 2 FED SPEC SINGLE TREATMENT RESPONSE OVERALL |
| Thread Length | 0.290 INCHES MINIMUM AND 0.357 INCHES MAXIMUM IN |
| Hardness Rating | 39.0 ROCKWELL C MINIMUM AND 43.0 ROCKWELL C MAXIMUM OVERALL |
| Shank Unthreaded Hole Diameter | 0.076 INCHES NOMINAL FIRST HOLE IN |
| Nominal Thread Diameter | 0.250 INCHES IN |
| Head Style | FLAT COUNTERSUNK |
| Thread Direction | RIGHT-HAND |
| Specification/standard Data | 76823-51B581 MANUFACTURERS STANDARD |
| Grip Length | 0.552 INCHES MINIMUM AND 0.572 INCHES MAXIMUM IN |
| Grip Diameter | 0.2485 INCHES MINIMUM AND 0.2495 INCHES MAXIMUM IN |
| Surface Treatment | CADMIUM AND CHROMATE OVERALL |
| Minimum Tensile Strength | 180000 POUNDS PER SQUARE INCH LBS |
| Internal Drive Style | OFFSET CRUCIFORM (TORQUE SET) |
| Countersink Angle | 100.0 DEGREES NOMINAL |
| Thread Class | 3A A |
| Thread Quantity Per Inch | 28 |
| Material | STEEL COMP 4340 OR STEEL COMP 4140 OR STEEL COMP 8740 OVERALL |
| Thread Series Designator | UNIFIED NATIONAL JOINT FINE (UNJF) |
| Distance From Head Largest Bearing Surface to Shank Hole Center | 0.736 INCHES MINIMUM AND 0.803 INCHES MAXIMUM FIRST HOLE IN |
| Head Diameter | 0.390 INCHES MINIMUM AND 0.395 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 |
|---|---|
| 51B581-4-9H | Northrop Grumman Corp Electronic Systems Defensive System Div (USA) |
| 51B581-4-9H | Hi-Shear Corporation (USA) |
| 51B581-4-9H | Howmet Global Fastening Systems Inc (USA) |
| 51B581-4-9H | Sps Technologies Llc Dba PB Fasteners Div PB Fasteners (USA) |
| 51B581-4-9H | Sps Technologies, Llc Dba Air Industries Company Div Air Industries Company (USA) |
| 51B581-4-9H | Lisi Aerospace Canada Corp Div Hi Shear Holdings Inc (CAN) |
| Reference | Meaning |
|---|---|
| 51B581-4-9H | 5/2 Secondary reference U.S. Government activity |
| 51B581-4-9H | C/1 Advisory reference — outside the item-of-supply concept Northrop Grumman Technical Services, Inc. Dba Defense Systems Sector |
| 51B581-4-9 | C/1 Advisory reference — outside the item-of-supply concept Northrop Grumman Systems Corporation Dba Northrop Grumman Is Div Northrop Grumman Aeronautics Systems |
| 51B581-4-9H | 3/9 Design control — primary reference Northrop Grumman Systems Corporation Dba Northrop Grumman Is Div Northrop Grumman Aeronautics Systems |
NSN 5305-00-548-5077 is a Screw,close Tolerance, manufactured by Northrop Grumman Corp Electronic Systems Defensive System Div, classified under FSC 5305, Screws. Status: active.
NSN 5305-00-548-5077 has 6 manufacturer part numbers on file: 51B581-4-9H (Northrop Grumman Corp Electronic Systems Defensive System Div), 51B581-4-9H (Hi-Shear Corporation), 51B581-4-9H (Howmet Global Fastening Systems Inc), 51B581-4-9H (Sps Technologies Llc Dba PB Fasteners Div PB Fasteners), 51B581-4-9H (Sps Technologies, Llc Dba Air Industries Company Div Air Industries Company) and 1 more.
Key specifications for 51B581-4-9H: Surface Finish: 32.0 MICROINCHES GRIP; Fastener Length: 0.862 INCHES MINIMUM AND 0.909 INCHES MAXIMUM IN; Surface Treatment Document and Classification: QQ-P-416,TY 2,CL 2 FED SPEC SINGLE TREATMENT RESPONSE OVERALL; Thread Length: 0.290 INCHES MINIMUM AND 0.357 INCHES MAXIMUM IN. 22 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.