Loading…
14
A guy at the hangar in Wichita told me torque values on old bolts are basically a guess, and I looked it up
I was torquing the bolts on a Cessna 172 landing gear last month and grabbed the wrong spec sheet out of habit. An old mechanic named Ray watched me for a second and said the number I was using only works if the bolt is new and clean. He pulled out an advisory circular from 2001 that says torque values can drop by up to 40 percent on a used bolt with any corrosion or stretched threads. I went back and checked the bolts I had already done, and two of them had visible pitting I had missed. We replaced all four and I started keeping a wire brush in my box now. Does anyone else here actually measure bolt stretch or do you all just go by feel like Ray does?
1 comments
Log in to join the discussion
Log In1 Comment
the_julia10d ago
That pitting sneaking past you is such a real fear, and good on you for going back and checking your own work. Ray sounds like the kind of guy who has seen enough to know better than the book, and that 40 percent drop number is scary when you picture it on a gear bolt. I have never measured stretch myself, mostly because I do not have the right tool for it, so I go by feel and sound like a lot of folks. But after reading this I am grabbing a wire brush and a bright light next time, because missing corrosion on a landing gear bolt is not something I want to think about later. Thanks for sharing the AC number too, that is going in my notes.
1