3981940

View detailed technical data, stock status, and sourcing information for: 3981940
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Federal Supply Group

Engine Accessories

Federal Supply Classification

2990 Nonaircraft Miscellaneous Engine Accessories

National Stock Number

2990-00-991-3657

Item Name Code

10849

Assigment Date

01/01/1962 (64 years ago)

dry design type, 26.500 inches nominal overall length, 5.000 inches nominal overall diameter, 1.687 inches nominal 1st outlet1.687 inches nominal outlet inside diameter, unthreaded single inlet inlet connection type

Product Characteristics

Below you’ll find the complete technical specifications and performance data for this part, including material details and compliance information.

Overall Length: 26.500 inches nominal
Inlet Connection Type: unthreaded single inlet
Overall Diameter: 5.000 inches nominal
Outlet Inside Diameter: 1.687 inches nominal 1st outlet1.687 inches nominal
Design Type: dry
Coolant Type: air
Muffler Design: straight through
Body Shape: round
Operating Position: horizontal
Inlet Location: located in center of end section single inlet
Inlet Projection Length: 2.250 inches nominal single inlet2.250 inches nominal
Inlet Outside Diameter: 2.125 inches nominal single inlet2.125 inches nominal
Inlet Inside Diameter: 2.000 inches nominal single inlet2.000 inches nominal
Outlet Connection Type: unthreaded 1st outlet
Outlet Location: located in center of end section opposite inlet 1st outlet
Outlet Projection Length: 2.250 inches nominal 1st outlet2.250 inches nominal
Outlet Outside Diameter: 1.812 inches nominal 1st outlet1.812 inches nominal
Material: steel location not otherwise specified
Surface Treatment: zinc

Replaces National Stock Numbers

Below is a list of NSNs that have been officially superseded by this NSN:

NSN	Name	Date
2990-00-310-4512	No Name Available	09/06/1968
2990-00-845-6111	No Name Available	07/01/1979

Related Parts

This NSN group includes multiple components designed to meet specific performance and operational standards. Each listing provides detailed specs, functionality data, and replacement compatibility information:

Part Number	Name
101901	Exhaust Muffler
21028	Exhaust Muffler
3816360	Exhaust Muffler
3865285	Exhaust Muffler
3981940	Exhaust Muffler

FAQs

Find helpful answers about installation, operation, maintenance, compliance, and troubleshooting.

What is the FSCG of the NSN 2990-00-991-3657?

The FSCG of the NSN 2990-00-991-3657 is 2990

Does the NSN 2990-00-991-3657 have a Schedule B code assigned?

Yes, the Schedule B code is 8708925000

Does NSN 2990-00-991-3657 require demilitarization?

Items subject to the export administration regulations (ear) in parts 730-774 of title 15, code of federal regulations (cfr) (ccli or ear99) and determined by dod to present a low risk when released out of dod control. No demil, mut, or end use certificate is required. May require an export licensefrom doc.

Does NSN 2990-00-991-3657 contain precious materials?

Precious metal content is unknown

Does NSN 2990-00-991-3657 contain hazardous materials?

Indicates there is no data in the hmirs and the nsn is in a fsc not generally suspected of containing hazardous materials.

When the NSN 2990-00-991-3657 was assigned to the Federal Catalog?

It was assigned 64 years ago, on Mon, Jan 1, 1962