These are the tools to measure and set the torque of the AN hardware:
To determine the friction drag I used a new bolt and nyloc nut and measured the torque required to rotate the nut when 1 thread is protruding:
Description | Unit | AN3 | AN4 | AN5 | AN6 |
---|---|---|---|---|---|
USA size | inch | 3/16 | 1/4 | 5/16 | 3/8 |
EU size | mm | 4,80 | 6,35 | 7,94 | 9,53 |
Thread size | 10-32 | 1/4-28 | 5/16-24 | 3/8-24 | |
Wrench size | inch | 3/8 | 7/16 | 1/2 | 9/16 |
AC 43.13 torque range AN365 fine thread | inch/lbs | 20-25 | 50-70 | 100-140 | 160-190 |
TAF maintenance manual (including friction drag) | inch/lbs | 18-24 | 51-70 | 99-139 | 159-189 |
Measured friction drag torque | inch/lbs | 5 | 7 | 12 | |
Total torque* | inch/lbs | 29 | 76 | 150 |
* AC4.13 max torque + (measured friction drag * 0.8 for torque wrench accuracy)
Update:
There’s an interesting movie on this topic: Homebuilt Help – How Accurate is your Hand for Torquing Bolts Properly?
On 1m37s it states to add 0.5 foot/lbs = 6 inch/lbs for the friction drag when using nyloc nuts; which is about the same I figured out when measuring the friction drag.
Update for NAS6603 bolts:
The Cirrus manual for the SR22 shows slightly higher torque values for the NAS6603 bolts:
Another nice article:
Kitplanes Torque Wrench Basics