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RB56638-2 — SCREW,MACHINE

✓ Government record, cited
— · BOLT SCREW
PRODUCT OVERVIEW

RB56638-2: SCREW,MACHINE.

The SCREW,MACHINE is a the manufacturer industrial component. Key specifications include head_diameter: 0.240 INCHES MINIMUM AND 0.260 INCHES MAXIMUM IN, nominal_thread_diameter: 0.138 INCHES IN, screw_surface_treatment: TIN, thread_quantity_per_inch: 32, thread_series_designator: UNIFIED NATIONAL COARSE (UNC), part_name_assigned_by_controlling_agency: SCREW,RD.HD.ELECT. This part is cataloged in the U.S.

Government catalog under NSN 5305-01-652-8645, indicating validated use in U.S. government and defense logistics supply chains. Available through authorized enterprise resellers and TPM (Third Party Maintenance) channels.

Verify compatibility with your specific system configuration before ordering.

WHERE IT FITS
RB56638-2
NSN: 5305-01-652-8645
FSC: 5305 — Screws
CAGE: 51663 — HYDRO-AIRE AEROSPACE CORP. DBA LEAR ROMEC DIV LEAR ROMEC (USA)
SPECIFICATIONS
head_diameter0.240 INCHES MINIMUM AND 0.260 INCHES MAXIMUM IN
nominal_thread_diameter0.138 INCHES IN
screw_surface_treatmentTIN
thread_quantity_per_inch32
thread_series_designatorUNIFIED NATIONAL COARSE (UNC)
part_name_assigned_by_controlling_agencySCREW,RD.HD.ELECT
NSN5305-01-652-8645
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: RB56638-2 · OEM ⚠ VERIFY BEFORE ORDERING Verify thread pitch before ordering — metric (M8×1.25) ≠ imperial (5/16-18). Wrong thread = wrong part. Grade/class stamped on bolt head determines tensile strength ✓ BROKER TIP Grade/class stamped on head determines tensile strength. Grade 8 > Grade 5 > Grade 2. Always confirm head marking matches specification requirement PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
SCREW SURFACE TREATMENT: TIN
•
NOMINAL THREAD DIAMETER: 0.138 INCHES IN
•
THREAD QUANTITY PER INCH: 32
•
THREAD SERIES DESIGNATOR: UNIFIED NATIONAL COARSE (UNC)
•
HEAD DIAMETER: 0.240 INCHES MINIMUM AND 0.260 INCHES MAXIMUM IN
TECHNICAL CHARACTERISTICS
SCREW SURFACE TREATMENTTIN
NOMINAL THREAD DIAMETER0.138 INCHES IN
PART NAME ASSIGNED BY CONTROLLING AGENCYSCREW,RD.HD.ELECT
THREAD QUANTITY PER INCH32
THREAD SERIES DESIGNATORUNIFIED NATIONAL COARSE (UNC)
HEAD DIAMETER0.240 INCHES MINIMUM AND 0.260 INCHES MAXIMUM IN
OTHER ITEMS IN FSC 5305 — Screws
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5305-00-000-0094 5305-00-000-1397 5305-00-000-2625 5305-00-000-3669 5305-00-000-3830 5305-00-000-3831
SUBSTITUTES & CROSS-REFERENCES

No substitute or cross-reference records for this part.

LIFECYCLE
NSN statusActive· U.S. Government catalog
No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is RB56638-2?
RB56638-2 is a SCREW,MACHINE.
What is the NSN for RB56638-2?
RB56638-2 is cataloged in the U.S. Government catalog under NSN 5305-01-652-8645. This indicates validated use in U.S. government and defense supply chains.
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✓ PartsTable — the parts reference. Every fact cited to its source.
PartsTable Design LLC · partstable.com
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.
PartsTable commercial catalog: edition Unified commercial catalog snapshot through 2026-09-28, edition date not on file, retrieved 2026-09-28.