If the above condition is present and the steering wheelnut is torqued lower than specified, break of the friction lock could result inloosening and separation of the steering wheel.
Steering wheel/shaft designed to use surface friction may loose this friction if grease or oil is present on the coneshaped surface of the steering shaft.
Remove the steering wheel of vehicles and clean friction surface and install a spring retainer, replace the steering wheel nut with a self locking nut.