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I finally got what my old instructor meant about torque wrenches
Had coffee with my old A&P instructor from the community college last week. He said "torque values are just a suggestion until you feel the fastener bind up" and it finally clicked after 6 years on the line. Has anyone else found that some bolts just need a little extra feel even at spec?
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the_harper1mo ago
Take that old torque wrench and throw it halfway across the hangar, that's what my first crew chief told me to do when I got too hung up on numbers. He said the spec is just a starting point, you gotta feel the thread pitch and the material give a little before you stop. Had a fuel line fitting on a 737 that would have snapped clean off at the listed torque on the chart. Sometimes that little extra feel is the difference between a good seal and a bad day in the office.
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michaeld481mo ago
Honestly, @the_harper said something about "feeling the thread pitch" and that is exactly why we need to talk about thread lubricant more. Ngl, torque specs are only valid if you account for friction, and most guys never factor in dry versus wet threads. On a fuel line fitting, a little lube can throw the torque off by 30 percent, but it also prevents galling on stainless. I've seen guys chase torque numbers while the threads are binding up, and then they blame the spec when the real problem was they didn't clean the threads first. The spec is a tool, but the condition of the parts should decide how you apply it.
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