bolts › machine bolts
AN4-33
Aeronautical Standard Machine Bolt
Description
Airframe Bolt; Drilled
Specifications
| Country of Origin | USA |
|---|---|
| Distance From Head Largest Bearing Surface To Shank Hole Center | 3.234 inches minimum first hole and 3.266 inches maximum first hole |
| Drilling | Drilled Head |
| Fastener Length | 3.391 inches minimum and 3.438 inches maximum |
| Features Provided | Finished head |
| Grip | 2 15/16 in |
| Grip Length | 2 15/16, 2.922 inches minimum and 2.953 inches maximum |
| Hardness Rating | 26.0 rockwell c minimum and 32.0 rockwell c maximum |
| Head Height | 0.140 inches minimum and 0.172 inches maximum |
| Head Style | Hexagon Head |
| Head Type | Hexagon |
| Industry Standards/Certification | AN4 |
| Length | 3 13/32 in, 3 7/16 |
| Material | Steel |
| Min. Tensile Strength (psi) | 125000 pounds per square inch |
| NIIN | 00-151-1138 |
| NSN | 5306-00-151-1138 |
| Nominal Length | 3 13/32 |
| Shank Unthreaded Hole Diameter | 0.076 inches minimum first hole and 0.086 inches maximum first hole |
| Surface Treatment | Cadmium and chromate |
| Surface Treatment Specification | Qq-p-416,type 2,class 3 fed spec all treatment responses |
| Thread Class | 3a |
| Thread Diameter | 0.250 |
| Thread Direction | Right-hand |
| Thread Length | 0.438 inches minimum and 0.516 inches maximum |
| Thread Qty | 28 |
| Thread Qty Per Inch (tpi) | 28 |
| Thread Series Designator | UNF |
| Thread Size | 1/4-28 |
| Weight | 0.05 lb |
| Width Between Flats | 0.428 inches minimum and 0.440 inches maximum |
Cross-reference
No interchangeable or dimensionally similar parts are on record for AN4-33. Try the cross-reference lookup to search by a different part number.
Catalog data updated 2026-07-05. Report a data error