Assembly and Rigging Which statement concerning the 100-hour inspection of an airplane equipped with a push-pull tube-type control system is true? a. The threaded rod ends should not be adjusted in length for rigging purposes because the rod ends have been properly positioned and staked during manufacture. b. The terminal end threads of the turnbuckles should be visible through the safety hole in the barrel. c. The threaded rod ends should be checked for the amount of thread engagement by means of the inspection hole provided.