If you're airplane's props were serviced by T and W Propellers, of Chino, Calif., they may need doing again and the sooner the better. An Airworthiness Directive has been issued essentially ordering a recall of certain props certified and returned to service by the company. The AD follows investigation of a prop failure on a Beech Travel Air that determined the prop was zero-timed by the company even though it had visible corrosion and a four-inch crack. Other props that had been serviced by the company, and offered for inspection by their owners to the FAA, showed a variety of defects. Compliance with the AD essentially calls for a full overhaul of the affected props. It affects 434 Hartzell, McCauley, Sensenich and Raytheon props serviced by the company since Jan. 8, 2000.