A flexible shaft of nonrigid components for use in pushing an eddy current probe through small diameter pipe bends includes a thin-walled flexible outer sleeve enclosing a data cable helically coiled around a central inner core, typically of braided wire. The inner core is functionally incompressible and inextensible to sustain compressive forces derived from pushing the shaft through a pipe. The outer sleeve supported from within by the data cable and the inner core for sustaining lateral forces of pusher rollers is longitudinally even and smooth to advance the shaft without damage to it.