Stainless safety wire is used on most critical aircraft fasteners. You should be able to get it at stores like Adam said .Special pliers are made for twisting it real tight ,guess you would call them safety wire pliers. I had never seen them before I started working on hydroplanes. I’ve thought about using safety wire on the lower unit attaching bolts ,as a friend builds racing outboards and he uses it in a few places on his motors .
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