PartsTable
Technical Data Sheet
78-121 ✓ Verified by PartsTable
· MRO · MRO_GENERAL
WHAT YOU NEED TO KNOW
Match nut grade to bolt grade for full strength Lock nuts prevent loosening under vibration
Don't mix grades — weakens the joint
PRODUCT OVERVIEW

FILTER,RADIO FREQUENCY INTERFERE. Key specifications include material: STEEL LOCATION NOT OTHERWISE SPECIFIED, body_shape: ROUND, body_width: 1.300 INCHES NOMINAL IN, body_height: 1.300 INCHES NOMINAL IN, body_length: 2.750 INCHES NOMINAL IN, design_type: DRY. This part is cataloged in the Federal Logistics Information System (FLIS) under NSN 5310-00-209-4125, 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
MRO MRO_GENERAL 78-121
NSN: 5310-00-209-4125
FSC: 5310
CAGE: 96152 — BORG-WARNER CORP MARVEL-SCHEBLER/TILLOTSON DIV (USA)
SPECIFICATIONS
materialSTEEL LOCATION NOT OTHERWISE SPECIFIED
body_shapeROUND
body_width1.300 INCHES NOMINAL IN
body_height1.300 INCHES NOMINAL IN
body_length2.750 INCHES NOMINAL IN
design_typeDRY
coolant_typeAIR
body_materialMETAL
hole_diameter0.191 INCHES MINIMUM AND 0.196 INCHES MAXIMUM IN
overall_width15.000 INCHES NOMINAL IN
tube_quantity1
inclosure_typeENCASED
NSN5310-00-209-4125
COMPONENT DIAGRAM
NUT & WASHER — GRADE MATCHING REQUIRED Hex NUT CROSS-SECTION WASHER OD: — SIZE: — MATERIAL: — PN: 78-121 · OEM ⚠ VERIFY BEFORE ORDERING Grade matters for torque spec — don't mix grades. A Grade 5 nut on a Grade 8 bolt weakens the joint. Lock nuts, wing nuts, and castle nuts are NOT interchangeable with standard hex ✓ BROKER TIP Match nut to bolt thread class and material. Stainless bolt + zinc nut = galvanic corrosion. Always verify finish matches (plain, zinc, hot-dip galvanized) PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
HARDNESS RATING: 30.0 ROCKWELL B MINIMUM AND 50.0 ROCKWELL B MAXIMUM
OUTSIDE DIAMETER: 0.370 INCHES MINIMUM AND 0.380 INCHES MAXIMUM IN
HOLE DIAMETER: 0.191 INCHES MINIMUM AND 0.196 INCHES MAXIMUM IN
EXTERNAL KEY QUANTITY: 6
SURFACE TREATMENT: CADMIUM OVERALL
MATERIAL: STEEL OVERALL
OVERALL DISTANCE INCLUDING KEYS: 0.557 INCHES MINIMUM AND 0.567 INCHES MAXIMUM IN
MATERIAL THICKNESS: 0.026 INCHES MINIMUM AND 0.036 INCHES MAXIMUM IN
TECHNICAL CHARACTERISTICS (FLIS)
HARDNESS RATING30.0 ROCKWELL B MINIMUM AND 50.0 ROCKWELL B MAXIMUM
OUTSIDE DIAMETER0.370 INCHES MINIMUM AND 0.380 INCHES MAXIMUM IN
HOLE DIAMETER0.191 INCHES MINIMUM AND 0.196 INCHES MAXIMUM IN
EXTERNAL KEY QUANTITY6
SURFACE TREATMENTCADMIUM OVERALL
MATERIALSTEEL OVERALL
OVERALL DISTANCE INCLUDING KEYS0.557 INCHES MINIMUM AND 0.567 INCHES MAXIMUM IN
MATERIAL THICKNESS0.026 INCHES MINIMUM AND 0.036 INCHES MAXIMUM IN
STYLE DESIGNATORKEY
SURFACE TREATMENT DOCUMENT AND CLASSIFICATIONAN-QQ-P-421 FED SPEC SINGLE TREATMENT RESPONSE OVERALL
VERIFIED SUBSTITUTES & CROSS-REFERENCES 5
A78121Interchangeable
interchangeable cross-reference
interchangeable
D92276AInterchangeable
interchangeable cross-reference
interchangeable
78121Interchangeable
interchangeable cross-reference
interchangeable
T-2759Interchangeable
interchangeable cross-reference
interchangeable
50336Interchangeable
interchangeable cross-reference
interchangeable
LIFECYCLE
StatusCANCELLED
Availability
RoHS CompliantEAR99Not HAZMAT
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FREQUENTLY ASKED QUESTIONS
What is 78-121?
78-121 is a FILTER,RADIO FREQUENCY INTERFERE. It is classified as a MRO (MRO_GENERAL).
What parts can replace 78-121?
There are 5 known substitutes for 78-121: A78121, D92276A, 78121 and 2 more. Substitute compatibility should be verified for your specific system.
Is 78-121 still available?
78-121 is currently cancelled.
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