The Breather,reservoir,hydraulic, cataloged under National Stock Number 4320-01-428-6664, is classified within Federal Supply Class 4320 (Power and Hand Pumps) of the Pumps and Compressors group. Government technical data includes 3 specifications, cited from the U.S. Government catalog. 5 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. 1 item shares a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 4320-01-428-6664 |
| Item Name | Breather,reservoir,hydraulic |
| FSC / FSG | 4320 / 43 — Power and Hand Pumps |
| Status | ACTIVE |
| General Characteristics Item Description | SINTERED POROUS BRONZE |
| Surface Treatment | CHROMATE AND ZINC |
| Material | COPPER ALLOY AND STEEL |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Reference | Meaning |
|---|---|
| 0179038 F38 | 3/2 Design control — primary reference U.S. Government activity |
| 0179038 | 5/2 Secondary reference U.S. Government activity |
| 4902-1 | C/1 Advisory reference — outside the item-of-supply concept Eaton Aeroquip Llc Dba Jackson North 1 Div Fluid and Electrical Distribution |
| 4902-1 | 5/9 Secondary reference Eaton Aviation Corporation |
| F38/20M | 5/9 Secondary reference U.S. Government activity |
NSN 4320-01-428-6664 is a Breather,reservoir,hydraulic, classified under FSC 4320, Power and Hand Pumps. Status: active.
1 possible match (shared part number, not a government interchangeability claim): 4130-01-559-5331. Verify interchangeability with system specifications before substitution.
Key specifications for 4320-01-428-6664: General Characteristics Item Description: SINTERED POROUS BRONZE; Overall Length: 0.750 INCHES NOMINAL IN; Special Features: ITEM HAS A 0.375" DIA EXTERNAL PIPE THREADS WITH A 0.,6875" HEX HEAD AND INCLUDES A ZINC-PLATED STEEL 20 MICRON FILTER WITH CHROMATE FINOISH; Surface Treatment: CHROMATE AND ZINC. 3 specifications are documented in the U.S. Government catalog.
No hazard code in the DLA record (HMIC N). Hazard information on this page is shown exactly as it appears in the DLA record.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-16.
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.