In aviation lingo, what does AD mean? As in, "this plane has all its ADs." Thanks!?

AD stands for Airworthiness Directive. AD's are issued by the FAA in the United States and by other regulatory agencies worldwide(JAA in Europe). AD's are issued to correct a potentially dangerous situation (operationally or mechanically) for a specific aircraft,component,or engine. AD's usually start as SB's(Service Bulletins) issued as the manufacturer. SB's compliance is usually not mandatory unless the aircraft is still under warranty.When AD's are issued they have to be complied with within a certain time frame or the aircraft becomes unairworthy. It is the job of the owner and the aircraft's mechanic or maintenance center to insure compliance of all AD's issued for the aircraft.