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Technical Data Sheet
PartsTable / COMPONENT / GS521B9
GS521B9 ✓ Verified by PartsTable
— · BOLT SCREW
WHAT YOU NEED TO KNOW
Grade/class stamped on head determines strength Metric and imperial threads look similar — measure pitch
Verify thread pitch — metric != imperial
PRODUCT OVERVIEW

STUD ASSEMBLY,TURNLOCK FASTENER. Key specifications include diameter: 0.244 INCHES MINIMUM AND 0.256 INCHES MAXIMUM IN, material: STEEL COMP 1009 EYELET, drive_type: SLOTTED, eyelet_length: 0.328 INCHES NOMINAL IN, stud_head_height: 0.069 INCHES MINIMUM AND 0.076 INCHES MAXIMUM IN, surface_treatment: CADMIUM AND CHROMATE OVERALL. This product is currently in active production with full OEM support.

This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 5325-01-284-6741, 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
GS521B9
NSN: 5325-01-284-6741
FSC: 5325
CAGE: 26512 — NORTHROP GRUMMAN SYSTEMS CORPORATION (USA)
SPECIFICATIONS
diameter0.244 INCHES MINIMUM AND 0.256 INCHES MAXIMUM IN
materialSTEEL COMP 1009 EYELET
drive_typeSLOTTED
eyelet_length0.328 INCHES NOMINAL IN
stud_head_height0.069 INCHES MINIMUM AND 0.076 INCHES MAXIMUM IN
surface_treatmentCADMIUM AND CHROMATE OVERALL
stud_assembly_styleSTUD ASSEMBLY
securing_device_typeWASHER
eyelet_outside_diameter0.244 INCHES MINIMUM AND 0.250 INCHES MAXIMUM IN
turnlock_stud_head_styleSTUD HEAD
material_accommodated_thickness0.270 INCHES MINIMUM AND 0.299 INCHES MAXIMUM IN
material_document_and_classificationASTM A109 ASSN STD SINGLE MATERIAL RESPONSE EYELET
NSN5325-01-284-6741
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: GS521B9 · 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
•
STUD HEAD HEIGHT: 0.069 INCHES MINIMUM AND 0.076 INCHES MAXIMUM IN
•
MATERIAL: STEEL PIN
•
MATERIAL DOCUMENT AND CLASSIFICATION: ASTM A228 ASSN STD SINGLE MATERIAL RESPONSE EJECTOR SPRING
•
SURFACE TREATMENT DOCUMENT AND CLASSIFICATION: QQ-P-416,TY 2,CL 2 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
•
DISTANCE FROM ENGAGING MEMBER TO LARGEST BEARING SURFACE OF HEAD: 0.707 INCHES NOMINAL IN
•
EYELET LENGTH: 0.328 INCHES NOMINAL IN
TECHNICAL CHARACTERISTICS (FLIS)
STUD HEAD HEIGHT0.069 INCHES MINIMUM AND 0.076 INCHES MAXIMUM IN
MATERIALSTEEL PIN
MATERIAL DOCUMENT AND CLASSIFICATIONASTM A228 ASSN STD SINGLE MATERIAL RESPONSE EJECTOR SPRING
MATERIAL DOCUMENT AND CLASSIFICATIONASTM A228 ASSN STD SINGLE MATERIAL RESPONSE PIN
SURFACE TREATMENT DOCUMENT AND CLASSIFICATIONQQ-P-416,TY 2,CL 2 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
MATERIAL DOCUMENT AND CLASSIFICATIONASTM A109 ASSN STD SINGLE MATERIAL RESPONSE EYELET
DISTANCE FROM ENGAGING MEMBER TO LARGEST BEARING SURFACE OF HEAD0.707 INCHES NOMINAL IN
EYELET LENGTH0.328 INCHES NOMINAL IN
EYELET OUTSIDE DIAMETER0.244 INCHES MINIMUM AND 0.250 INCHES MAXIMUM IN
TURNLOCK STUD HEAD STYLESTUD HEAD
VERIFIED SUBSTITUTES & CROSS-REFERENCES 5
27009Interchangeable
interchangeable cross-reference
interchangeable
5266840Interchangeable
interchangeable cross-reference
interchangeable
3823-2Interchangeable
interchangeable cross-reference
interchangeable
5740675Interchangeable
interchangeable cross-reference
interchangeable
1127000-9Interchangeable
Same NIIN cross-reference
interchangeable
LIFECYCLE
StatusACTIVE
AvailabilityOEM and secondary market
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is GS521B9?
GS521B9 is a STUD ASSEMBLY,TURNLOCK FASTENER.
What parts can replace GS521B9?
There are 5 known substitutes for GS521B9: 27009, 5266840, 3823-2 and 2 more. Substitute compatibility should be verified for your specific system.
What is the NSN for GS521B9?
GS521B9 is cataloged in the Federal Logistics Information System (FLIS) under NSN 5325-01-284-6741. This indicates validated use in U.S. government and defense supply chains.
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✓ Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
PartsTable Design LLC · partstable.com
Last verified: July 2026