The Duct Assembly,air Conditioning-H, cataloged under National Stock Number 1660-00-520-5643, is classified within Federal Supply Class 1660 (Aircraft Air Conditioning, Heating, and Pressurizing Equipment) of the Aircraft Components and Accessories group. The manufacturer of record is Ilco Tube Bending, Inc. Dba Ilco Industries Div Ilco Industries, Inc. Government technical data includes 4 specifications, cited from the U.S. Government catalog. The record lists 8 manufacturer part numbers for this item, enabling identification through both NSN and commercial part number lookups. 2 additional reference documents (drawings, advisory and superseded references) are recorded in the U.S. Government catalog. Current acquisition status: Active.
| Parameter | Value |
|---|---|
| NSN | 1660-00-520-5643 |
| Primary Part Number | 35-31551-1 |
| Item Name | Duct Assembly,air Conditioning-H |
| FSC / FSG | 1660 / 16 — Aircraft Air Conditioning, Heating, and Pressurizing Equipment |
| Manufacturer | Ilco Tube Bending, Inc. Dba Ilco Industries Div Ilco Industries, Inc |
| Status | ACTIVE |
| Material Document and Classification | MIL-T-8808A MIL SPEC SINGLE MATERIAL RESPONSE A |
| Material Thickness | 0.035 INCHES NOMINAL IN |
| Material | STEEL |
| Aircraft Mission Design Series | B-52 |
| Acquisition Status | ACTIVE |
| DEMIL Code | DEMIL Q — CCL Item — Commerce Control List |
| Hazard | No hazard code in the DLA record (HMIC N) |
| Criticality Code | X |
| Part Number | Manufacturer |
|---|---|
| 35-31551-1 | Ilco Tube Bending, Inc. Dba Ilco Industries Div Ilco Industries, Inc (USA) |
| 35-31551-1 | American Metal Fabrication Inc (USA) |
| 35-31551-1 | Aircraft Tubular Components Inc (USA) |
| 35-31551-1 | Aeroparts Manufacturing & Repair, Inc (USA) |
| 35-31551-1 | The Boeing Company Div Defense (USA) |
| 35-31551-1 | Aerometals, Inc. (USA) |
| 35-31551-1 | Precision Tube Bending (USA) |
| 35-31551-1 | Globe Engineering Co., Inc (USA) |
| Reference | Meaning |
|---|---|
| 35-31551-1 | 5/2 Secondary reference U.S. Government activity |
| 35-31551-1 | 3/2 Design control — primary reference U.S. Government activity |
NSN 1660-00-520-5643 is a Duct Assembly,air Conditioning-H, manufactured by Ilco Tube Bending, Inc. Dba Ilco Industries Div Ilco Industries, Inc, classified under FSC 1660, Aircraft Air Conditioning, Heating, and Pressurizing Equipment. Status: active.
NSN 1660-00-520-5643 has 8 manufacturer part numbers on file: 35-31551-1 (Ilco Tube Bending, Inc. Dba Ilco Industries Div Ilco Industries, Inc), 35-31551-1 (American Metal Fabrication Inc), 35-31551-1 (Aircraft Tubular Components Inc), 35-31551-1 (Aeroparts Manufacturing & Repair, Inc), 35-31551-1 (The Boeing Company Div Defense) and 3 more.
Key specifications for 35-31551-1: Material Document and Classification: MIL-T-8808A MIL SPEC SINGLE MATERIAL RESPONSE A; Material Thickness: 0.035 INCHES NOMINAL IN; Special Features: 2.500 IN. OD IN; End Item Identification: B-52 BOMBER. 4 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.
NSN 1660-00-520-5643 has DEMIL Code Q. Demilitarization may be required before disposal or transfer to non-military entities.
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.