Knocking/popping heard and felt in front suspension when turning left regardless of speed or rpm. Diagnostic inspection showed the axle shaft had popped out of it's seat of the output shaft of transmission. Luckily, the transmission shaft splines were not damaged, but the CV axle splines showed damage requiring CV axle replacement. This is a known issue for Kia Optimas, though Kia has not issued any recalls or TSB's. The local dealership service manager says they have seen several come in with this issue.