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6565-21-125-5104 — SEAT,HELICAL COMPRESSION SPRING

✓ Government record, cited
— · ORING SEAL
PRODUCT OVERVIEW

6565-21-125-5104: SEAT,HELICAL COMPRESSION SPRING.

SEAT,HELICAL COMPRESSION SPRING. Key specifications include material: STEEL COMP 630, design_type: SOLID, end_diameter: 0.4000 INCHES MINIMUM AND 0.4200 INCHES MAXIMUM IN, bore_diameter: 0.3120 INCHES MINIMUM AND 0.3140 INCHES MAXIMUM IN, overall_height: 0.3500 INCHES MINIMUM AND 0.3600 INCHES MAXIMUM IN, special_features: NOT CASEHARDENED. This part is cataloged in the U.S.

Government catalog under NSN 5340-00-436-5016, 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
6565-21-125-5104
NSN: 5340-00-436-5016
FSC: 5340 — Hardware, Commercial
CAGE: 78286 — SIKORSKY AIRCRAFT CORPORATION DBA SIKORSKY AIRCRAFT CORP (USA)
SPECIFICATIONS
materialSTEEL COMP 630
design_typeSOLID
end_diameter0.4000 INCHES MINIMUM AND 0.4200 INCHES MAXIMUM IN
bore_diameter0.3120 INCHES MINIMUM AND 0.3140 INCHES MAXIMUM IN
overall_height0.3500 INCHES MINIMUM AND 0.3600 INCHES MAXIMUM IN
special_featuresNOT CASEHARDENED
style_designatorSEAT
first_step_length0.0650 INCHES MINIMUM AND 0.0950 INCHES MAXIMUM IN
surface_treatmentPASSIVATE
counterbore_length0.0850 INCHES MINIMUM AND 0.0950 INCHES MAXIMUM IN
first_step_diameter0.4350 INCHES MINIMUM AND 0.4370 INCHES MAXIMUM IN
counterbore_diameter0.4100 INCHES MINIMUM AND 0.4200 INCHES MAXIMUM IN
NSN5340-00-436-5016
COMPONENT DIAGRAM
O-RING / SEAL — MATERIAL DETERMINES APPLICATION ID: — CROSS-SECTION CS: — SPECIFICATION Material: — Durometer: — Temp: — PN: 6565-21-125-5104 MFR: OEM ⚠ VERIFY BEFORE ORDERING Wrong material = failure. Viton for oil/fuel, EPDM for water/steam, Buna-N for general purpose, Silicone for food-grade. Chemical incompatibility causes swelling, brittleness, or rapid degradation ✓ BROKER TIP Durometer (hardness) affects sealing pressure tolerance. Higher Shore A = harder = higher pressure. Standard durometer is 70A — verify if application requires different hardness PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
FIRST STEP DIAMETER: 0.4350 INCHES MINIMUM AND 0.4370 INCHES MAXIMUM IN
•
MATERIAL HARDNESS RATING: 56.0 ROCKWELL C MINIMUM AND 60.0 ROCKWELL C MAXIMUM
•
END DIAMETER: 0.4000 INCHES MINIMUM AND 0.4200 INCHES MAXIMUM IN
•
DISTANCE FROM END TO FIRST STEP: 0.0900 INCHES MINIMUM AND 0.1100 INCHES MAXIMUM IN
•
DESIGN TYPE: SOLID
•
STYLE DESIGNATOR: SEAT
•
MATERIAL DOCUMENT AND CLASSIFICATION: AMS 5643 ASSN STD SINGLE MATERIAL RESPONSE
TECHNICAL CHARACTERISTICS
OVERALL HEIGHT0.3500 INCHES MINIMUM AND 0.3600 INCHES MAXIMUM IN
FIRST STEP DIAMETER0.4350 INCHES MINIMUM AND 0.4370 INCHES MAXIMUM IN
MATERIAL HARDNESS RATING56.0 ROCKWELL C MINIMUM AND 60.0 ROCKWELL C MAXIMUM
END DIAMETER0.4000 INCHES MINIMUM AND 0.4200 INCHES MAXIMUM IN
DISTANCE FROM END TO FIRST STEP0.0900 INCHES MINIMUM AND 0.1100 INCHES MAXIMUM IN
DESIGN TYPESOLID
STYLE DESIGNATORSEAT
MATERIAL DOCUMENT AND CLASSIFICATIONAMS 5643 ASSN STD SINGLE MATERIAL RESPONSE
COUNTERBORE LENGTH0.0850 INCHES MINIMUM AND 0.0950 INCHES MAXIMUM IN
SECOND STEP DIAMETER0.5900 INCHES MINIMUM AND 0.6100 INCHES MAXIMUM IN
OTHER ITEMS IN FSC 5340 — Hardware, Commercial
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5340-00-000-0068 5340-00-000-0132 5340-00-000-8150 5340-00-001-1251 5340-00-001-1264 5340-00-001-1265 5340-00-001-1266 5340-00-001-1275
SUBSTITUTES & CROSS-REFERENCES

No substitute or cross-reference records for this part.

LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Normally procured from the manufacturer (OEM)No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 6565-21-125-5104?
6565-21-125-5104 is a SEAT,HELICAL COMPRESSION SPRING.
What is the NSN for 6565-21-125-5104?
6565-21-125-5104 is cataloged in the U.S. Government catalog under NSN 5340-00-436-5016. 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.