H ANDS ON HINTS FOR HOMEBUILDERS
Handy Torque Limits Reference BY JOE NORRIS
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86 Sport Aviation December 2010
NO MATTER WHAT TYPE of homebuilt project you’re working on, you’re going to run into many different types of fasteners. Most of these fasteners—whether a bolt, nut, or screw—have a tightening torque specification. Some specialty fasteners will have a specific torque spec called out in the assembly instructions or the construction drawings. But many will be standard AN or MS fasteners, and finding their tightening torque limits will require you to pull out your trusty Aviation Mechanic’s Handbook or Advisory Circular (AC) 43.13-1A. When you look at these standard references, you see that the table doesn’t actually say “AN3” or whatever size fastener you’re working with. It will instead list the torque values by thread diameter and pitch. You’ll see “10-32” or “1/4-28” and you’ll have to translate that info into the associated AN or MS fastener size. Unless you work with this info regularly it will take a bit of thinking (and possibly measuring) to come up with the right limits. While working with fellow EAA staff member Charlie Becker, I found an easy way to keep track of standard aircraft fastener torque limits. It was one of those “Why didn’t I think of that” moments! Charlie simply looked up the torque limits, translated them into the corresponding AN fastener sizes, and wrote the info right in his torque wrench box. Now every time he opens the box to get out his torque wrench the torque limits are right there. No more digging out AC 43.13-1A. No more translating thread size into AN size. Just open the box and you’re ready to set the wrench and tighten your fasteners. My torque wrench boxes will soon feature the same info!
Recording often-needed torque values right on your torque wrench box will save time and keep your project moving smoothly.
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Joe Norris, EAA Lifetime 113615, is EAA’s homebuilders’ community manager. He is a technical counselor, flight advisor, certificated flight instructor, airframe and powerplant mechanic with an inspection authorization, and a designated airworthiness representative. To see these Hints for Homebuilders videos visit www.SportAviation.org.
Have you found a way to do something easier, faster, less expensively? Have you found unique ways to use tools or developed a special tool? Don’t keep it to yourself! Share your tips with your fellow EAA members by sending your idea to
[email protected]. Make sure to include an explanation of your hint along with photos or drawings! Your ideas will help your fellow homebuilders!
PHOTOGRAPHY BY JOE NORRIS
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