| B-4 | |
|---|---|
.jpg) Keystone Y1B-4 (S/N 30-281) | |
| General information | |
| Type | Light bomber |
| Manufacturer | Keystone Aircraft |
| Status | Retired |
| Primary user | United States Army Air Corps |
| Number built | 5 Y1B-4 25 B-4A |
| History | |
| Developed from | Keystone B-3 |
The Keystone B-4 was a biplane bomber, built by the Keystone Aircraft company for the United States Army Air Corps.