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Technical Data Sheet
PartsTable / COMPONENT / MS21921-6D
MS21921-6D ✓ Verified by PartsTable
— · HOSE FITTING
WHAT YOU NEED TO KNOW
PTFE tape on tapered threads (NPT/BSPT) JIC/AN flare connections seal metal-to-metal — no tape
NPT != BSPT — look identical, NOT interchangeable
PRODUCT OVERVIEW

The INJECTOR ASSEMBLY,FUEL is a the manufacturer industrial component. Key specifications include material: ALUMINUM ALLOY 7075 OVERALL, nut_style: TUBE COUPLING, nut_height: 0.800 INCHES NOMINAL IN, seat_angle: 45.00 DEGREES NOMINAL, thread_class: 3B, thread_series: UNF. This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 4730-00-554-7397, 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
MS21921-6D
NSN: 4730-00-554-7397
FSC: 4730
CAGE: 50948 — PARKER HANNIFIN CORP STRATOFLEX DIV AIRCRAFT FITTINGS OPN (USA)
SPECIFICATIONS
materialALUMINUM ALLOY 7075 OVERALL
nut_styleTUBE COUPLING
nut_height0.800 INCHES NOMINAL IN
seat_angle45.00 DEGREES NOMINAL
thread_class3B
thread_seriesUNF
thread_directionRIGHT-HAND
surface_treatmentANODIZE OVERALL
fabrication_methodMACHINED
length_to_shoulder0.578 INCHES NOMINAL IN
width_across_flats0.688 INCHES NOMINAL IN
nominal_thread_size0.562 INCHES IN
NSN4730-00-554-7397
COMPONENT DIAGRAM
HOSE FITTING — THREAD TYPE IS CRITICAL END A: — STRAIGHT END B: — SPECIFICATIONS Thread: — Material: — Pressure: — PN: MS21921-6D · OEM ⚠ VERIFY BEFORE ORDERING NPT ≠ BSPT — tapered threads look identical but are NOT interchangeable. Wrong thread = leak. JIC (37°) ≠ AN (37°) ≠ SAE 45° — flare angles must match exactly. Measure thread pitch with gauge — visual identification is unreliable ✓ BROKER TIP Always use thread sealant (PTFE tape or pipe compound) on tapered threads (NPT/BSPT). JIC/AN flare fittings seal metal-to-metal — never use tape on flare connections PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
SEAT ANGLE: 45.00 DEGREES NOMINAL
•
THREAD QUANTITY PER INCH: 18
•
SMALLEST INSIDE DIAMETER: 0.425 INCHES NOMINAL IN
•
NOMINAL TUBE OUTSIDE DIAMETER: 0.375 INCHES IN
•
SPECIFICATION/STANDARD DATA: 81343-AS21921 PROFESSIONAL/INDUSTRIAL ASSOCIATION SPECIFICATION
•
MATERIAL: ALUMINUM ALLOY 7075 OVERALL
•
SURFACE TREATMENT: ANODIZE OVERALL
•
MATERIAL DOCUMENT AND CLASSIFICATION: QQ-A-225/6,T6 FED SPEC SINGLE MATERIAL RESPONSE OVERALL
TECHNICAL CHARACTERISTICS (FLIS)
SEAT ANGLE45.00 DEGREES NOMINAL
THREAD QUANTITY PER INCH18
SMALLEST INSIDE DIAMETER0.425 INCHES NOMINAL IN
NOMINAL TUBE OUTSIDE DIAMETER0.375 INCHES IN
SPECIFICATION/STANDARD DATA81343-AS21921 PROFESSIONAL/INDUSTRIAL ASSOCIATION SPECIFICATION
MATERIALALUMINUM ALLOY 7075 OVERALL
SURFACE TREATMENTANODIZE OVERALL
MATERIAL DOCUMENT AND CLASSIFICATIONQQ-A-225/6,T6 FED SPEC SINGLE MATERIAL RESPONSE OVERALL
LENGTH TO SHOULDER0.578 INCHES NOMINAL IN
NUT STYLETUBE COUPLING
VERIFIED SUBSTITUTES & CROSS-REFERENCES 23
1561Interchangeable
interchangeable cross-reference
interchangeable
1561GSKT3INInterchangeable
interchangeable cross-reference
interchangeable
1561HInterchangeable
interchangeable cross-reference
interchangeable
10116602Interchangeable
interchangeable cross-reference
interchangeable
3F-9556Interchangeable
interchangeable cross-reference
interchangeable
1915Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusCANCELLED
Availability—
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is MS21921-6D?
MS21921-6D is a INJECTOR ASSEMBLY,FUEL.
What parts can replace MS21921-6D?
There are 23 known substitutes for MS21921-6D: 1561, 1561GSKT3IN, 1561H and 20 more. Substitute compatibility should be verified for your specific system.
Is MS21921-6D still available?
MS21921-6D is currently cancelled.
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✓ Validated with multiple authoritative sources, including Government, OEM, and Certified sources.
PartsTable Design LLC · partstable.com
Last verified: July 2026