About this calculator
Type the bolt and the nut as they are on the drawing or the bag. The calculator reads the thread from the bolt, the tension or shear column from the nut, adds the friction drag of a self-locking nut and gives the wrench reading and the maximum from AC 43.13-1B Table 7-1.
Runs in your browser. Part numbers or thread size and nut type; values in inch-pounds, as in the AC.
How it works
Table 7-1 gives install and maximum torque for tension nuts (it names MS20365 and AN310) and shear nuts (MS20364 and AN320), fine and coarse threads, for oil-free cadmium-plated threads. Other nuts are read by type: regular-height nuts in the tension column, thin nuts in the shear column.
Self-locking nuts: run the nut on until the locking element engages, read the friction drag on the wrench and add it to the table value (par. 7-40d). Castle nuts: start aligning the cotter-pin hole at the minimum plus drag and never pass the maximum plus drag (par. 7-40f).
Limits — when NOT to use this
- The manufacturer's torque governs. Table 7-1 is for when the aircraft or engine data give none.
- Lubricated threads, other platings and titanium bolts need their own values.
- AN bolts AN3 to AN20 and NAS6203 to NAS6620 are read by part number; for other bolts choose the thread size.
Sources
- FAA AC 43.13-1B CHG 1, Chapter 7, par. 7-40 and Table 7-1 — recommended torque values (p. 7-9), friction drag and castle nut alignment (par. 7-40d, f, g).