- 1/4‑28 UNF plain castellated hex nut used as a general‑purpose airframe castle nut
- Carbon steel, cadmium plated per QQ‑P‑416 Type II Class 3 for corrosion resistance
- Hex, castellated design used with a cotter pin for positive mechanical locking in critical joints
| Type | Nut |
| Style | Castellated Hexagon |
| Size | 1/4" |
| Material | Carbon Steel |
| Max Temp. | Not Rated |
| Thread Style | UNF, 1/4‑28, right‑hand |
| Head Style | Plain castellated hexagon |
| Height | 0.3" |
| Locking Element | Secured with Cotter Pin |
| Mil-Spec | AN310-4 |
