Jam nuts serve a purpose and that is to prevent actuating arms from becoming disconnected. I found three examples on the same airplane. Two flap jam nuts were loose and should have been caught on a preflight, and the autopilot servo arm jam nut was loose as well. Any of these could cause a flight control problem if they came completely loose.
In Case You Missed it
Build It Better: Testing, testing, one, two, three
There's no substitute for real-world testing--;something homebuilders should keep in mind when moving from the theoretical to the actual application.
Loctite and safety wire , I have yet to have one come loose