The Circuit Breaker,air, cataloged under National Stock Number 4920-01-557-0002, is classified within Federal Supply Class 4920 (Aircraft Maintenance and Repair Shop Specialized Equipment) of the Maintenance and Repair Shop Equipment group. The manufacturer of record is Siemens Industrial Automation Inc. The record lists 1 manufacturer part number for this item, enabling identification through both NSN and commercial part number lookups. 1 additional reference document (drawings, advisory and superseded references) is recorded in the U.S. Government catalog. 2 items share a part number with this NSN in the catalog (possible match — not a government interchangeability claim). Current acquisition status: Active.
| Item Name | Circuit Breaker,air |
| FSC / FSG | 4920 — Aircraft Maintenance and Repair Shop Specialized Equipment (FSG 49) |
| Manufacturers | Siemens Industrial Automation Inc (CAGE 0TX97) |
| Parameter | Value |
|---|---|
| NSN | 4920-01-557-0002 |
| Primary Part Number | 3RV2021-4AA10 |
| Item Name | Circuit Breaker,air |
| FSC / FSG | 4920 / 49 — Aircraft Maintenance and Repair Shop Specialized Equipment |
| Manufacturer | Siemens Industrial Automation Inc |
| Status | ACTIVE |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL A — No Demilitarization Required |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Part Number | Manufacturer |
|---|---|
| 3RV2021-4AA10 PRIMARY | Siemens Industrial Automation Inc (USA) |
| Reference | Meaning |
|---|---|
| 3RV1021-4AA10 | 3/9 Design control — primary reference Siemens Industrial Automation Inc |
NSN 4920-01-557-0002 is a Circuit Breaker,air, manufactured by Siemens Industrial Automation Inc, classified under FSC 4920, Aircraft Maintenance and Repair Shop Specialized Equipment. Status: active.
NSN 4920-01-557-0002 has 1 manufacturer part number on file: 3RV2021-4AA10 (Siemens Industrial Automation Inc).
2 possible matches (shared part number, not a government interchangeability claim): 5925-01-571-9549, 5925-01-668-2779. Verify interchangeability with system specifications before substitution.
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.